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  Subjects -> BIOLOGY (Total: 3026 journals)
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BIOLOGY (1437 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 1720 Journals sorted alphabetically
AAPS Journal     Hybrid Journal   (Followers: 21)
Achievements in the Life Sciences     Open Access   (Followers: 4)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 23)
Acta Biologica Colombiana     Open Access   (Followers: 7)
Acta Biologica Hungarica     Full-text available via subscription   (Followers: 4)
Acta Biologica Sibirica     Open Access  
Acta Biomaterialia     Hybrid Journal   (Followers: 27)
Acta Biotheoretica     Hybrid Journal   (Followers: 5)
Acta Chiropterologica     Full-text available via subscription   (Followers: 6)
acta ethologica     Hybrid Journal   (Followers: 4)
Acta Limnologica Brasiliensia     Open Access   (Followers: 3)
Acta Médica Costarricense     Open Access   (Followers: 2)
Acta Musei Silesiae, Scientiae Naturales : The Journal of Silesian Museum in Opava     Open Access  
Acta Neurobiologiae Experimentalis     Open Access  
Acta Parasitologica     Hybrid Journal   (Followers: 9)
Acta Scientiarum. Biological Sciences     Open Access   (Followers: 2)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
Actualidades Biológicas     Open Access   (Followers: 1)
Advanced Health Care Technologies     Open Access   (Followers: 4)
Advanced Studies in Biology     Open Access  
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
Advances in Bioinformatics     Open Access   (Followers: 20)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 6)
Advances in Cell Biology     Open Access   (Followers: 25)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 13)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 12)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 6)
Advances in Ecological Research     Full-text available via subscription   (Followers: 46)
Advances in Environmental Sciences - International Journal of the Bioflux Society     Open Access   (Followers: 21)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 8)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11)
Advances in High Energy Physics     Open Access   (Followers: 19)
Advances in Human Biology     Open Access   (Followers: 2)
Advances in Life Science and Technology     Open Access   (Followers: 14)
Advances in Life Sciences     Open Access   (Followers: 6)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 23)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3)
Advances in Regenerative Biology     Open Access   (Followers: 1)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 5)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Virus Research     Full-text available via subscription   (Followers: 6)
African Journal of Range & Forage Science     Hybrid Journal   (Followers: 6)
AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 1)
Ageing Research Reviews     Hybrid Journal   (Followers: 9)
Aging Cell     Open Access   (Followers: 11)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Agrokreatif Jurnal Ilmiah Pengabdian kepada Masyarakat     Open Access  
AJP Cell Physiology     Full-text available via subscription   (Followers: 14)
AJP Endocrinology and Metabolism     Full-text available via subscription   (Followers: 23)
AJP Lung Cellular and Molecular Physiology     Full-text available via subscription   (Followers: 3)
Al-Kauniyah : Jurnal Biologi     Open Access  
Alasbimn Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Biology Teacher     Full-text available via subscription   (Followers: 13)
American Fern Journal     Full-text available via subscription   (Followers: 1)
American Journal of Agricultural and Biological Sciences     Open Access   (Followers: 10)
American Journal of Bioethics     Hybrid Journal   (Followers: 10)
American Journal of Human Biology     Hybrid Journal   (Followers: 13)
American Journal of Medical and Biological Research     Open Access   (Followers: 8)
American Journal of Plant Sciences     Open Access   (Followers: 19)
American Journal of Primatology     Hybrid Journal   (Followers: 16)
American Malacological Bulletin     Full-text available via subscription   (Followers: 3)
American Naturalist     Full-text available via subscription   (Followers: 73)
Amphibia-Reptilia     Hybrid Journal   (Followers: 6)
Anaerobe     Hybrid Journal   (Followers: 4)
Analytical Methods     Full-text available via subscription   (Followers: 10)
Anatomical Science International     Hybrid Journal   (Followers: 2)
Animal Cells and Systems     Hybrid Journal   (Followers: 4)
Annales de Limnologie - International Journal of Limnology     Hybrid Journal   (Followers: 1)
Annales françaises d'Oto-rhino-laryngologie et de Pathologie Cervico-faciale     Full-text available via subscription   (Followers: 3)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Biologia     Open Access   (Followers: 1)
Annals of Applied Biology     Hybrid Journal   (Followers: 7)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 18)
Annals of Human Biology     Hybrid Journal   (Followers: 4)
Annual Review of Biomedical Engineering     Full-text available via subscription   (Followers: 16)
Annual Review of Biophysics     Full-text available via subscription   (Followers: 25)
Annual Review of Cancer Biology     Full-text available via subscription   (Followers: 1)
Annual Review of Cell and Developmental Biology     Full-text available via subscription   (Followers: 39)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Annual Review of Genomics and Human Genetics     Full-text available via subscription   (Followers: 20)
Annual Review of Phytopathology     Full-text available via subscription   (Followers: 10)
Anthropological Review     Open Access   (Followers: 24)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antibiotics     Open Access   (Followers: 9)
Antioxidants     Open Access   (Followers: 4)
Antioxidants & Redox Signaling     Hybrid Journal   (Followers: 8)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apidologie     Hybrid Journal   (Followers: 4)
Apmis     Hybrid Journal   (Followers: 1)
APOPTOSIS     Hybrid Journal   (Followers: 8)
Applied Bionics and Biomechanics     Open Access   (Followers: 8)
Applied Vegetation Science     Full-text available via subscription   (Followers: 9)
Aquaculture Environment Interactions     Open Access   (Followers: 2)
Aquaculture International     Hybrid Journal   (Followers: 22)
Aquaculture Reports     Open Access   (Followers: 3)
Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society     Open Access   (Followers: 6)
Aquatic Biology     Open Access   (Followers: 5)
Aquatic Ecology     Hybrid Journal   (Followers: 32)
Aquatic Ecosystem Health & Management     Hybrid Journal   (Followers: 14)
Aquatic Science and Technology     Open Access   (Followers: 3)
Aquatic Toxicology     Hybrid Journal   (Followers: 20)
Archaea     Open Access   (Followers: 3)
Archiv für Molluskenkunde: International Journal of Malacology     Full-text available via subscription   (Followers: 3)
Archives of Biomedical Sciences     Open Access   (Followers: 7)
Archives of Microbiology     Hybrid Journal   (Followers: 8)
Archives of Natural History     Hybrid Journal   (Followers: 8)
Archives of Oral Biology     Hybrid Journal   (Followers: 2)
Archives of Virology     Hybrid Journal   (Followers: 5)
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2)
Arid Ecosystems     Hybrid Journal   (Followers: 3)
Arquivos do Instituto Biológico     Open Access   (Followers: 1)
Arquivos do Museu Dinâmico Interdisciplinar     Open Access  
Arthropod Structure & Development     Hybrid Journal   (Followers: 2)
Arthropods     Open Access   (Followers: 1)
Artificial DNA: PNA & XNA     Hybrid Journal   (Followers: 3)
Artificial Photosynthesis     Open Access   (Followers: 1)
Asian Bioethics Review     Full-text available via subscription   (Followers: 2)
Asian Journal of Biodiversity     Open Access   (Followers: 5)
Asian Journal of Biological Sciences     Open Access   (Followers: 3)
Asian Journal of Cell Biology     Open Access   (Followers: 6)
Asian Journal of Developmental Biology     Open Access   (Followers: 2)
Asian Journal of Medical and Biological Research     Open Access   (Followers: 2)
Asian Journal of Nematology     Open Access   (Followers: 3)
Asian Journal of Poultry Science     Open Access   (Followers: 4)
Australian Life Scientist     Full-text available via subscription   (Followers: 2)
Australian Mammalogy     Hybrid Journal   (Followers: 6)
Autophagy     Hybrid Journal   (Followers: 2)
Avian Biology Research     Full-text available via subscription   (Followers: 5)
Avian Conservation and Ecology     Open Access   (Followers: 13)
Bacteriology Journal     Open Access   (Followers: 2)
Bacteriophage     Full-text available via subscription   (Followers: 4)
Bangladesh Journal of Bioethics     Open Access  
Bangladesh Journal of Plant Taxonomy     Open Access  
Bangladesh Journal of Scientific Research     Open Access   (Followers: 2)
Berita Biologi     Open Access   (Followers: 1)
Between the Species     Open Access   (Followers: 1)
Bio Tribune Magazine     Hybrid Journal  
BIO Web of Conferences     Open Access  
BIO-Complexity     Open Access  
Bio-Grafía. Escritos sobre la Biología y su enseñanza     Open Access  
Bioanalytical Reviews     Hybrid Journal   (Followers: 2)
Biocatalysis and Biotransformation     Hybrid Journal   (Followers: 6)
Biochemistry and Cell Biology     Hybrid Journal   (Followers: 14)
Biochimie     Hybrid Journal   (Followers: 7)
BioControl     Hybrid Journal   (Followers: 5)
Biocontrol Science and Technology     Hybrid Journal   (Followers: 5)
Biodemography and Social Biology     Hybrid Journal   (Followers: 1)
BioDiscovery     Open Access   (Followers: 2)
Biodiversity : Research and Conservation     Open Access   (Followers: 28)
Biodiversity and Natural History     Open Access   (Followers: 6)
Biodiversity Data Journal     Open Access   (Followers: 3)
Biodiversity Informatics     Open Access   (Followers: 1)
Biodiversity Information Science and Standards     Open Access  
Bioedukasi : Jurnal Pendidikan Biologi FKIP UM Metro     Open Access  
Bioeksperimen : Jurnal Penelitian Biologi     Open Access  
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Bioelectromagnetics     Hybrid Journal   (Followers: 1)
Bioenergy Research     Hybrid Journal   (Followers: 2)
Bioengineering and Bioscience     Open Access   (Followers: 1)
BioEssays     Hybrid Journal   (Followers: 10)
Bioethics     Hybrid Journal   (Followers: 14)
BioéthiqueOnline     Open Access  
Biofabrication     Hybrid Journal   (Followers: 3)
Biogeosciences (BG)     Open Access   (Followers: 10)
Biogeosciences Discussions (BGD)     Open Access   (Followers: 1)
Bioinformatics     Hybrid Journal   (Followers: 296)
Bioinformatics and Biology Insights     Open Access   (Followers: 15)
Bioinspiration & Biomimetics     Hybrid Journal   (Followers: 7)
Biointerphases     Open Access   (Followers: 1)
Biojournal of Science and Technology     Open Access  
Biologia     Hybrid Journal  
Biologia on-line : Revista de divulgació de la Facultat de Biologia     Open Access  
Biological Bulletin     Partially Free   (Followers: 5)
Biological Control     Hybrid Journal   (Followers: 4)
Biological Invasions     Hybrid Journal   (Followers: 17)
Biological Journal of the Linnean Society     Hybrid Journal   (Followers: 16)
Biological Letters     Open Access   (Followers: 4)
Biological Procedures Online     Open Access  
Biological Psychiatry     Hybrid Journal   (Followers: 43)
Biological Psychology     Hybrid Journal   (Followers: 6)
Biological Research     Open Access  
Biological Rhythm Research     Hybrid Journal   (Followers: 2)
Biological Theory     Hybrid Journal   (Followers: 2)
Biological Trace Element Research     Hybrid Journal  
Biologicals     Full-text available via subscription   (Followers: 9)
Biologics: Targets & Therapy     Open Access   (Followers: 1)
Biologie Aujourd'hui     Full-text available via subscription  
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 41)
Biologija     Open Access  
Biology     Open Access   (Followers: 5)
Biology and Philosophy     Hybrid Journal   (Followers: 17)
Biology Bulletin     Hybrid Journal   (Followers: 1)
Biology Bulletin Reviews     Hybrid Journal  

        1 2 3 4 5 6 7 8 | Last

Journal Cover Aquatic Toxicology
  [SJR: 1.671]   [H-I: 105]   [20 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0166-445X - ISSN (Online) 1879-1514
   Published by Elsevier Homepage  [3118 journals]
  • Effects of lanthanum on Microcystis aeruginosa: Attention to the changes
           in composition and content of cellular microcystins
    • Authors: Fei Shen; Lihong Wang; Qing Zhou; Xiaohua Huang
      Pages: 9 - 16
      Abstract: Publication date: March 2018
      Source:Aquatic Toxicology, Volume 196
      Author(s): Fei Shen, Lihong Wang, Qing Zhou, Xiaohua Huang
      Algal blooms threaten human health and aquatic ecosystem through the production of microcystins (MCs) by toxic strains. The accumulation of rare earth elements (REEs) in water affects the growth and physiological activities of algae. However, whether or how REEs affect cellular microcystins (MCs) is largely unknown. In this study, the effects of lanthanum ion [La(III)], a type of REE, on the MCs in Microcystis aeruginosa were investigated, and the mechanism of the effect was analyzed using ecological stoichiometry. The different concentrations of La(III) were selected to correlate environmental pollution status. Low-dose La(III) (0.2, 2.0, and 4.0 μM) exposure increased the total content of MCs and the percentage contents of microcystin-YR (MC-YR) and microcystin-LW (MC-LW) and decreased the percentage content of microcystin-LR (MC-LR). High-dose La(III) (8.0, 20, 40, and 60 μM) exposure decreased the total content of the MCs, increased the percentage content of MC-LR, and decreased the percentage contents of MC-YR and MC-LW. The changes in the total MCs content were positively associated with the ratios of C:P and N:P in algal cells. The composition of MCs was dependent on the ratio of C:N in algal cells; for example, the percentage content of MC-LR decreased and the percentage content of MC-YR and MC-LW increased as the ratio of C:N in algal cells increased. In conclusion, La(III) could affect the content and composition of MCs via changes in the growth and chlorophyll-a content of Microcystis aeruginosa, and these effects depended on the ratios of C:P, N:P, and C:N in Microcystis aeruginosa. Such changes may influence the toxicity of Microcystis blooms. The results provides a new insight into the mechanism of REEs effects on algal toxins and provide references for evaluating environmental risks of REEs pollution in aquatic ecosystems.

      PubDate: 2018-01-10T02:01:24Z
      DOI: 10.1016/j.aquatox.2018.01.007
      Issue No: Vol. 196 (2018)
       
  • Effects of ocean acidification on copepods
    • Authors: Minghua Wang; Chang-Bum Jeong; Young Hwan Lee; Jae-Seong Lee
      Pages: 17 - 24
      Abstract: Publication date: March 2018
      Source:Aquatic Toxicology, Volume 196
      Author(s): Minghua Wang, Chang-Bum Jeong, Young Hwan Lee, Jae-Seong Lee
      Ocean acidification (OA) leads to significant changes in seawater carbon chemistry, broadly affects marine organisms, and considered as a global threat to the fitness of marine ecosystems. Due to the crucial role of copepods in marine food webs of transferring energy from primary producers to higher trophic levels, numerous studies have been conducted to examine the impacts of OA on biological traits of copepods such as growth and reproduction. Under OA stress, the copepods demonstrated species-specific and stage-dependent responses. Notably, different populations of the same copepod species demonstrated different sensitivities to the increased pCO2. In copepods, the deleterious effects of OA are also reinforced by other naturally occurring co-stressors (e.g., thermal stress, food deprivation, and metal pollution). Given that most OA stress studies have focused on the effects of short-term exposure (shorter than a single generation), experiments using adults might have underestimated the damaging effects of OA and the long-term multigenerational exposure to multiple stressors (e.g., increased pCO2 and food shortage) will be required. Particularly, omics-based technologies (e.g., genomics, proteomics, and metabolomics) will be helpful to better understand the underlying processes behind biological responses (e.g., survival, development, and offspring production) at the mechanistic level which will improve our predictions of the responses of copepods to climate change stressors including OA.

      PubDate: 2018-01-10T02:01:24Z
      DOI: 10.1016/j.aquatox.2018.01.004
      Issue No: Vol. 196 (2018)
       
  • Feeding inhibition in Corbicula fluminea (O.F. Muller, 1774) as an effect
           criterion to pollutant exposure: perspectives for ecotoxicity screening
           and refinement of chemical control
    • Authors: Bruno Branco Castro; Carlos Silva; Inês Patrunilho Efe Macário; Bruno Oliveira; Fernando Gonçalves; Joana Luísa Pereira
      Pages: 25 - 34
      Abstract: Publication date: Available online 4 January 2018
      Source:Aquatic Toxicology
      Author(s): Bruno Branco Castro, Carlos Silva, Inês Patrunilho Efe Macário, Bruno Oliveira, Fernando Gonçalves, Joana Luísa Pereira
      Bivalves are commonly used in biomonitoring programs to track pollutants. Several features, including its filter-feeding abilities, cumulatively argue in favour of the use of the Asian clam (Corbicula fluminea) as a biosentinel and an ecotoxicological model. Filtration in bivalves is very sensitive to external stimuli and its control is dictated by regulation of the opening/closure of the valves, which may be used as an avoidance defence against contaminants. Here, we investigate the filter-feeding behaviour of the Asian clam as an endpoint for assessing exposure to pollutants, driven by two complementary goals: (i) to generate relevant and sensitive toxicological information based on the ability of C. fluminea to clear an algal suspension, using the invasive species as a surrogate for native bivalves; (ii) to gain insight on the potential of exploring this integrative response in the refinement of chemical control methods for this pest. Clearance rates and proportion of algae removed were measured using a simple and reproducible protocol. Despite some variation across individuals and size classes, 50–90% of food particles were generally removed within 60–120 min by clams larger than 20 mm. Removal of algae was sensitive to an array of model contaminants with biocide potential, including fertilizers, pesticides, metals and salts: eight out of nine tested substances were detected at the μg l−1 or mg l−1 range and triggered valve closure, decreasing filter-feeding in a concentration-dependent manner. For most toxicants, a good agreement between mortality (96 h − LC50 within the range 0.4–5500 mg l−1) and feeding (2 h − IC50 within the range 0.005–2317 mg l−1) was observed, demonstrating that a 120-min assay can be used as a protective surrogate of acute toxicity. However, copper sulphate was very strongly avoided by the clams (IC50 = 5.3 μg l−1); on the contrary, dichlorvos (an organophosphate insecticide) did not cause feeding depression, either by being undetected by the clams’ chemosensors and/or by interfering with the valve closure mechanism. Such an assay has a large potential as a simple screening tool for industry, environmental agencies and managers. The ability of dichlorvos to bypass the Asian clam’s avoidance strategy puts it in the spotlight as a potential agent to be used alone or combined with others in eradication programs of this biofouler in closed or semi-closed industrial settings.

      PubDate: 2018-01-10T02:01:24Z
      DOI: 10.1016/j.aquatox.2018.01.002
      Issue No: Vol. 196 (2018)
       
  • Title: Vitamin C attenuates biochemical and genotoxic damage in common
           carp (Cyprinus carpio) upon joint exposure to combined toxic doses of
           fipronil and buprofezin insecticides
    • Authors: Madiha Ghazanfar; Sana Shahid; Irfan Zia Qureshi
      Pages: 43 - 52
      Abstract: Publication date: Available online 5 January 2018
      Source:Aquatic Toxicology
      Author(s): Madiha Ghazanfar, Sana Shahid, Irfan Zia Qureshi
      In the present study, potential protective role of Vitamin C (L-ascorbic acid) was investigated in aquaria acclimated common carp (Cyprinus carpio) following exposure for 96 h to combined toxic doses of fipronil (FP) and buprofezin (BPFN) insecticides in combination (FP: 200 μg/L; 4.57 × 10−7 mol/L and BPFN: 50 mg/L; 1.64 × 10−4 mol/L). At end of 96 h exposure, fish were supplemented with low (25 mg/L) and high (50 mg/L) doses of Vitamin C, added once daily to aquaria water for continuous three weeks. Appropriate control groups were run in parallel. Fish behavior was monitored throughout for signs of toxicity. At completion of experiments, liver, kidney, brain and gills were excised for toxicity assessment and possible remediation by the Vitamin C through biochemical determination of reactive oxygen species (ROS), thiobarbituric acid reactive substances or TBARS, reduced glutathione (GSH) and total protein content, levels of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD), and the Comet assay. Hepatosomatic index (HSI), condition factor (CF), survival rate (SR), and combination index (CI) were also determined. Data were compared statistically at p < 0.05. Results showed significant behavioral and biochemical alterations, and DNA damage in the fish group exposed to FP and BPFN in combination. In fish groups supplemented with Vitamin C following FP and BPFN treatment, significant alleviation in tissue damage and toxic effects was represented by substantial decreases in ROS and TBARS production (p < 0.001), along with a concomitant significant increase in the survival rate, GSH and total protein content, HSI, CF, and activities of SOD, CAT and POD enzymes (p < 0.001). Mean tail length of comet and percent tail DNA decreased significantly (p < 0.001), which indicated amelioration of DNA damage. The study concludes that Vitamin C is an effective remedial treatment against FP and BPFN-induced damage in exposed fish.
      Graphical abstract image

      PubDate: 2018-01-10T02:01:24Z
      DOI: 10.1016/j.aquatox.2017.12.015
      Issue No: Vol. 196 (2018)
       
  • Oxidative and interactive challenge of cadmium and ocean acidification on
           the smooth scallop Flexopecten glaber
    • Authors: Alessandro Nardi; Maura Benedetti; Daniele Fattorini; Francesco Regoli
      Pages: 53 - 60
      Abstract: Publication date: Available online 8 January 2018
      Source:Aquatic Toxicology
      Author(s): Alessandro Nardi, Maura Benedetti, Daniele Fattorini, Francesco Regoli
      Ocean acidification (OA) may affect sensitivity of marine organisms to metal pollution modulating chemical bioavailability, bioaccumulation and biological responsiveness of several cellular pathways. In this study, the smooth scallop Flexopecten glaber was exposed to various combinations of reduced pH (pH/pCO2 7.4/∼3000 μatm) and Cd (20 μg/L). The analyses on cadmium uptake were integrated with those of a wide battery of biomarkers including metallothioneins, single antioxidant defenses and total oxyradical scavenging capacity in digestive gland and gills, lysosomal membrane stability and onset of genotoxic damage in haemocytes. Reduced pH slightly increased concentration of Cd in scallop tissues, but no effects were measured in terms of metallothioneins. Induction of some antioxidants by Cd and/or low pH in the digestive gland was not reflected in variations of the total oxyradical scavenging capacity, while the investigated stressors caused a certain inhibition of antioxidants and reduction of the scavenging capacity toward peroxyl radical in the gills. Lysosomal membrane stability and onset of genotoxic damages showed high sensitivity with possible synergistic effects of the investigated factors. The overall results suggest that indirect effects of ocean acidification on metal accumulation and toxicity are tissue-specific and modulate oxidative balance through different mechanisms.
      Graphical abstract image

      PubDate: 2018-01-10T02:01:24Z
      DOI: 10.1016/j.aquatox.2018.01.008
      Issue No: Vol. 196 (2018)
       
  • Multixenobiotic resistance in Mytilus edulis: Molecular and functional
           characterization of an ABCG2- type transporter in hemocytes and gills
    • Authors: Yosra Ben Cheikh; Benoit Xuereb; Céline Boulangé-Lecomte; Frank Le Foll
      Pages: 88 - 96
      Abstract: Publication date: February 2018
      Source:Aquatic Toxicology, Volume 195
      Author(s): Yosra Ben Cheikh, Benoit Xuereb, Céline Boulangé-Lecomte, Frank Le Foll
      Among the cellular protection arsenal, ABC transporters play an important role in xenobiotic efflux in marine organisms. Two pumps belonging to B and C subfamily has been identified in Mytilus edulis. In this study, we investigated the presence of the third major subtype ABCG2/BCRP protein in mussel tissues. Transcript was expressed in hemocytes and with higher level in gills. Molecular characterization revealed that mussel ABCG2 transporter shares the sequence and organizational structure with mammalian and molluscan orthologs. Overall identity of the predicted amino acid sequence with corresponding homologs from other organisms was between 49% and 98%. Moreover, protein efflux activity was demonstrated using a combination of fluorescent allocrites and specific inhibitors. The accumulation of bodipy prazosin and pheophorbide A was heterogeneous in gills and hemocytes. Most of the used blockers enhanced probe accumulation at different levels, most significantly for bodipy prazosin. Moreover, Mrp classical blocker MK571 showed a polyspecificity. In conclusion, our data demonstrate that several ABC transporters contribute to MXR phenotype in the blue mussel including ABCG2 that forms an active pump in hemocytes and gills. Efforts are needed to distinguish between the different members and to explore their single function and specificity towards allocrites and chemosensitizers.

      PubDate: 2018-01-03T12:04:03Z
      DOI: 10.1016/j.aquatox.2017.12.012
      Issue No: Vol. 195 (2018)
       
  • The effect of chlorpyrifos on salinity acclimation of juvenile rainbow
           trout (Oncorhynchus mykiss)
    • Authors: Bagher Mojazi Amiri; Elvis Genbo Xu; Allison Kupsco; Marissa Giroux; Mahbubeh Hoseinzadeh; Daniel Schlenk
      Pages: 97 - 102
      Abstract: Publication date: February 2018
      Source:Aquatic Toxicology, Volume 195
      Author(s): Bagher Mojazi Amiri, Elvis Genbo Xu, Allison Kupsco, Marissa Giroux, Mahbubeh Hoseinzadeh, Daniel Schlenk
      As a part of their unique life cycle, most salmonids undergo a transition from fresh water to salt water requiring various adjustments in metabolism, osmoregulation and ion regulation. Exposure to pesticides may affect the acclimation of juvenile salmonids to salt water during downstream migration to estuaries. Using the Caspian Sea as a model waterbody, the present study aimed to determine how the toxicity of the organophosphate pesticide chlorpyrifos (CPF) impacts saline acclimation of rainbow trout (Oncorhynchus mykiss). We pre-exposed 4-month-old fish to nominal concentrations of 0, 20, 40, 80, 160 μg/L of CPF for seven days, and then gradually to salinity (12 ppt) for another seven days. Mortality, levels of cortisol, T3 and T4 in serum, and expression of genes involved in gill ion transport (Na+/K+ATPase α1a and α1b) and liver xenobiotic detoxification (Glutathione-S-Transferase pi, GST) were measured at day fourteen. Cortisol concentrations in serum were not changed by CPF exposure in freshwater, but serum T3 increased up to three fold relative to controls in freshwater. Following salinity acclimation, T3 and T4 concentrations in the serum were both increased up to 2.5 and 8.8 fold in animals treated with CPF followed by saltwater. Na+/K + ATPase α1a and α1b mRNA in gill were unchanged by CPF treatment in freshwater but trended higher in CPF-treated animals after salinity acclimation. Hepatic mRNA of GST was significantly increased following exposure to CPF but was unchanged after saltwater exposure. Although saltwater treatment reduced the acute lethality of CPF, changes in T3/T4 suggest sublethal impacts may occur in CPF-treated fish after they acclimate to Caspian seawater.

      PubDate: 2018-01-03T12:04:03Z
      DOI: 10.1016/j.aquatox.2017.12.011
      Issue No: Vol. 195 (2018)
       
  • Effects of copper and butyltin compounds on the growth, photosynthetic
           activity and toxin production of two HAB dinoflagellates : the planktonic
           Alexandrium catenella and the benthic Ostreopsis cf. ovata
    • Authors: Douglas Couet; Olivier Pringault; Chrystelle Bancon-Montigny; Nicolas Briant; Françoise Elbaz Poulichet; Sophie Delpoux; Ons Kéfi-Daly Yahia; BenGharbia Hela; M’Rabet Charaf; Fabienne Hervé; Georges Rovillon; Zouher Amzil; Mohamed Laabir
      Abstract: Publication date: Available online 6 January 2018
      Source:Aquatic Toxicology
      Author(s): Douglas Couet, Olivier Pringault, Chrystelle Bancon-Montigny, Nicolas Briant, Françoise Elbaz Poulichet, Sophie Delpoux, Ons Kéfi-Daly Yahia, BenGharbia Hela, M’Rabet Charaf, Fabienne Hervé, Georges Rovillon, Zouher Amzil, Mohamed Laabir
      Controlled laboratory experiments were conducted to test the effects of copper (Cu2+) and butyltins (BuT) on the growth, photosynthetic activity and toxin content of two HABs (Harmful Algal Blooms) dinoflagellates, the planktonic Alexandrium catenella and the benthic Ostreopsis cf. ovata. Microalgae were exposed to increasing concentrations of Cu2+ (10−4 to 31 nM) or BuT (0.084 to 84 nM) for seven days. When considering the growth, EC50 values were 0.16 (±0.09) nM and 0.03 (±0.02) nM of Cu2+ for A. catenella and O. cf. ovata, respectively. Regarding BuT, EC50 was 14.2 (±6) nM for O. cf. ovata, while A. catenella growth inhibition appeared at BuT concentrations ≥27 nM. Photosynthetic activity of the studied dinoflagellates decreased with increasing Cu and BuT concentrations. For O. cf. ovata, the response of this physiological parameter to contamination was less sensitive than the biomass. Cu exposure induced the formation of temporary cysts in both organisms that could resist adverse conditions. The ovatoxin-a and -b concentrations in O. cf. ovata cells increased significantly in the presence of Cu. Altogether, the results suggest a better tolerance of the planktonic A. catenella to Cu and BuT. This could result in a differentiated selection pressure exerted by these metals on phytoplankton species in highly polluted waters. The over-production of toxins in response to Cu stress could pose supplementary health and socio-economic threats in the contaminated marine ecosystems where HABs develop.

      PubDate: 2018-01-10T02:01:24Z
      DOI: 10.1016/j.aquatox.2018.01.005
       
  • Effects of domestic effluent discharges on mangrove crab physiology:
           integrated energetic, osmoregulatory and redox balances of a key engineer
           species
    • Authors: Dimitri Theuerkauff; Georgina A. Rivera-Ingraham; Yann Mercky; Mathilde Lejeune; Elliott Sucré; Jehan-Hervé Lignot
      Abstract: Publication date: Available online 6 January 2018
      Source:Aquatic Toxicology
      Author(s): Dimitri Theuerkauff, Georgina A. Rivera-Ingraham, Yann Mercky, Mathilde Lejeune, Elliott Sucré, Jehan-Hervé Lignot
      Mangroves are increasingly used as biofiltering systems of (pre-treated) domestic effluents. However, these wastewater discharges may affect local macrofauna. This laboratory study investigates the effects of wastewater exposure on the mangrove spider crab Neosarmatium meinerti, a key engineering species which is known to be affected by waste waters in effluent-impacted areas. These effects were quantified by monitoring biological markers of physiological state, namely oxygen consumption, the branchial cavity ventilation rate, gill physiology and morphology, and osmoregulatory and redox balance. Adults acclimated to clean seawater (SW, 32 ppt) and freshwater (FW, ∼0 ppt) were compared to crabs exposed to wastewater for 5 hours (WW, ∼0 ppt). Spider crabs exposed to WW increased their ventilation and whole-animal respiration rates by 2- and 3-fold respectively, while isolated gill respiration increased in the animals exposed to FW (from 0.5 to 2.3 and 1.1 nmol O2 min−1 mgDW−1 for anterior and posterior gills, respectively) but was not modified in WW-exposed individuals. WW exposure also impaired crab osmoregulatory capacity; an 80 mOsm.kg−1 decrease was observed compared to FW, likely due to decreased branchial NKA activity. ROS production (DCF fluorescence in hemolymph), antioxidant defenses (superoxide dismutase and catalase activities) and oxidative damage (malondialdehyde concentration) responses varied according to animal gender. Overall, this study demonstrates that specific physiological parameters must be considered when focusing on crabs with bimodal breathing capacities. We conclude that spider crabs exposed to WW face osmoregulatory imbalances due to functional and morphological gill remodeling, which must rapidly exhaust energy reserves. These physiological disruptions could explain the ecological changes observed in the field.

      PubDate: 2018-01-10T02:01:24Z
      DOI: 10.1016/j.aquatox.2018.01.003
       
  • Copper induces expression and methylation changes of early development
           genes in Crassostrea gigas embryos
    • Authors: Rossana Sussarellu; Morgane Lebreton; Julien Rouxel; Farida Akcha; Guillaume Rivière
      Abstract: Publication date: Available online 3 January 2018
      Source:Aquatic Toxicology
      Author(s): Rossana Sussarellu, Morgane Lebreton, Julien Rouxel, Farida Akcha, Guillaume Rivière
      Copper contamination is widespread along coastal areas and exerts adverse effects on marine organisms such as mollusks. In the Pacific oyster, copper induces severe developmental abnormalities during early life stages; however, the underlying molecular mechanisms are largely unknown. This study aims to better understand whether the embryotoxic effects of copper in Crassostrea gigas could be mediated by alterations in gene expression, and the putative role of DNA methylation, which is known to contribute to gene regulation in early embryo development. For that purpose, oyster embryos were exposed to 4 nominal copper concentrations (0.1, 1, 10 and 20 μg L−1 Cu2+) during early development assays. Embryotoxicity was monitored through the oyster embryo-larval bioassay at the D-larva stage 24 h post fertilization (hpf) and genotoxicity at gastrulation 7 hpf. In parallel, the relative expression of 15 genes encoding putative homeotic, biomineralization and DNA methylation proteins was measured at three developmental stages (3 hpf morula stage, 7 hpf gastrula stage, 24 hpf D-larvae stage) using RT-qPCR. Global DNA content in methylcytosine and hydroxymethylcytosine were measured by HPLC and gene-specific DNA methylation levels were monitored using MeDIP-qPCR. A significant increase in larval abnormalities was observed from copper concentrations of 10 μg L−1, while significant genotoxic effects were detected at 1 μg L−1 and above. All the selected genes presented a stage-dependent expression pattern, which was impaired for some homeobox and DNA methylation genes (Notochord, HOXA1, HOX2, Lox5, DNMT3b and CXXC-1) after copper exposure. While global DNA methylation (5-methylcytosine) at gastrula stage didn’t show significant changes between experimental conditions, 5-hydroxymethylcytosine, its degradation product, decreased upon copper treatment. The DNA methylation of exons and the transcript levels were correlated in control samples for HOXA1 but such a correlation was diminished following copper exposure. The methylation level of some specific gene regions (HoxA1, Hox2, Engrailed2 and Notochord) displayed changes upon copper exposure. Such changes were gene and exon-specific and no obvious global trends could be identified. Our study suggests that the embryotoxic effects of copper in oysters could involve homeotic gene expression impairment possibly by changing DNA methylation levels.

      PubDate: 2018-01-03T12:04:03Z
      DOI: 10.1016/j.aquatox.2018.01.001
       
  • The protective role of multixenobiotic resistance (MXR)-mediated
           ATP-binding cassette (ABC) transporters in biocides-exposed rotifer
           Brachionus koreanus
    • Authors: Young Hwan Lee; Hye-Min Kang; Min-Sub Kim; Jin-Sol Lee; Chang-Bum Jeong; Jae-Seong Lee
      Abstract: Publication date: Available online 30 December 2017
      Source:Aquatic Toxicology
      Author(s): Young Hwan Lee, Hye-Min Kang, Min-Sub Kim, Jin-Sol Lee, Chang-Bum Jeong, Jae-Seong Lee
      P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) are ATP-binding cassette (ABC) transporters that confer multixenobiotic resistance (MXR) via their efflux activity, which enables a variety of xenobiotics to be expelled from cells. MXR has been proposed as the first line of defense against xenobiotics. In this study, the protective roles of P-gp and MRP in the rotifer Brachionus koreanus were examined in response to four biocides (alachlor, chlorpyrifos, endosulfan, and molinate) using fluorescent substrates and inhibitors specific to P-gp and MRP. Exposure of rotifers to the four biocides resulted in increased P-gp and MRP activity. Moreover, the rotifers became more sensitive to the biocides with a reduced tendency in survival and slower population growth rates, when P-gp or MRP was inhibited. These findings suggest that P-gp and MRP are involved in the defense system in response to biocide exposure. Furthermore, the transcriptional levels of the genes encoding P-gp and MRP were examined to uncover the mechanism by which MXR is regulated. Our results demonstrate a crucial role of the MXR efflux system in the defense response to biocides, thereby providing a better understanding of rotifer defense mechanisms on the molecular level.
      Graphical abstract image

      PubDate: 2018-01-03T12:04:03Z
      DOI: 10.1016/j.aquatox.2017.12.016
       
  • Toxicokinetic and toxicodynamic of depleted uranium in the zebrafish,
           Danio rerio
    • Authors: Olivier Simon; Béatrice Gagnaire; Virginie Camilleri; Isabelle Cavalié; Magali Floriani; Christelle Adam-Guillermin
      Abstract: Publication date: Available online 30 December 2017
      Source:Aquatic Toxicology
      Author(s): Olivier Simon, Béatrice Gagnaire, Virginie Camilleri, Isabelle Cavalié, Magali Floriani, Christelle Adam-Guillermin
      This study investigated the accumulation pattern and biological effects (genotoxicity and histopathology) to adult zebrafish (male and female) exposed to a nominal waterborne concentration of 20 μg L−1 of depleted uranium (DU) for 28 days followed by 27 days of depuration. Accumulation pattern showed that (i) DU accumulated in brain, (ii) levels in digestive tract were higher than those measured in gills and (iii) levels remained high in kidney, brain and ovary despite the 27 days of depuration period. Genotoxicity, assessed by comet assay, was significant not only during DU exposure, but also during depuration phase. Gonads, in particular the testes, were more sensitive than gills. The histology of gonads indicated severe biological damages in males. This study improved knowledge of ecotoxic profile of uranium, for which a large range of biological effects has already been demonstrated.

      PubDate: 2018-01-03T12:04:03Z
      DOI: 10.1016/j.aquatox.2017.12.013
       
  • Novel approach for evaluating pharmaceuticals toxicity using Daphnia
           model: analysis of the mode of cytochrome P450-generated metabolite action
           after acetaminophen exposure
    • Authors: Ryeo-Ok Kim; Min-A Jo; Jinhaeng Song; Il-Chan Kim; Seokjoo Yoon; Woo-Keun Kim
      Abstract: Publication date: Available online 30 December 2017
      Source:Aquatic Toxicology
      Author(s): Ryeo-Ok Kim, Min-A Jo, Jinhaeng Song, Il-Chan Kim, Seokjoo Yoon, Woo-Keun Kim
      Because of its widespread use, the pharmaceutical acetaminophen (APAP) is frequently detected in aquatic environments. APAP can have serious physiological effects, such as reduced reproduction, low growth rates, and abnormal behavior, in aquatic organisms. However, the methods available for evaluation of the aquatic toxicity of APAP are of limited usefulness. The present study aimed to develop reliable and sensitive markers for evaluation of APAP toxicity using Daphnia as a model organism. We focused on N-acetyl-p-benzoquinoneimine (NAPQI) production from APAP via cytochrome P450 metabolism because NAPQI causes APAP toxicity. Daphnia magna were exposed to APAP (0, 50, or 100 mg/L for 12 h or 24 h), and the total metabolites were extracted and analyzed for NAPQI. Direct detection of NAPQI was difficult because of its high reactivity, and its peak was close to that for APAP. Therefore, we tried to identify molecular and biochemical indicators associated with NAPQI generation, elimination, and its interactions with macromolecules. We identified changes in CYP370A13 gene expression, glutathione depletion, inhibition of thioredoxin reductase activity, and production of reactive oxygen species as indicators of D. magna exposure to APAP. These indicators could be used to develop sensitive and accurate techniques to evaluate the environmental toxicity of APAP.

      PubDate: 2018-01-03T12:04:03Z
      DOI: 10.1016/j.aquatox.2017.12.017
       
  • Role of mTOR in autophagic and lysosomal reactions to environmental
           stressors in molluscs
    • Authors: Susanna Sforzini; Michael Moore Caterina Oliveri Anna Volta Awadhesh Jha
      Abstract: Publication date: Available online 28 December 2017
      Source:Aquatic Toxicology
      Author(s): Susanna Sforzini, Michael N. Moore, Caterina Oliveri, Anna Volta, Awadhesh Jha, Mohamed Banni, Aldo Viarengo
      Lysosomal membrane stability (LMS) has been used in various organisms as a very sensitive biomarker of stress. However, despite the abundance of data about regulation of the autophagic process in mammals, in the invertebrates there is only limited mechanistic understanding. Marine mussels (Mytilus galloprovincialis Lam.) are bivalve molluscs, widely used as models in ecotoxicology and as environmental bioindicators of sea water quality. In order to elucidate this fundamental process, in the present study, mussels were exposed for 3 days to a “priority”, ubiquitous environmental contaminant, benzo[a]pyrene (B[a]P) at different concentrations (i.e. 5, 50, 100 μg/L seawater). B[a]P accumulated in lysosomes of digestive tubule epithelial cells (digestive cells) and in enlarged lipid-rich lysosomes (autolysosomes) as detected by immunofluorescence and UV-fluorescence. B[a]P also activated the autophagic process with a marked decrease of LMS and concurrent increase in lysosomal/cytoplasmic volume ratio. Dephosphorylation of mTOR contributes to increased lysosomal membrane permeability and induced autophagy. B[a]P induced a decrease in phosphorylated (active form) mTOR. The probable role of mTOR in cell signalling and the regulation of the cellular responses to the contaminants has been also confirmed in a field study, where there was significant inactivation of mTOR in stressed animals. Statistical and network modelling supported the empirical investigations of autophagy and mTOR; and was used to integrate the mechanistic biomarker data with chemical analysis and DNA damage.

      PubDate: 2018-01-03T12:04:03Z
       
  • Effect of cadmium exposure on hepatopancreas and gills of the estuary mud
           crab (Scylla paramamosain): Histopathological changes and expression
           characterization of stress response genes
    • Authors: Qi-Hui Zhu; Zhong-Kai Zhou; Dan-Dan Tu; Yi-Lian Zhou; Cong Wang; Ze-Peng Liu; Wen-Bin Gu; Yu-Yin Chen; Miao-An Shu
      Pages: 1 - 7
      Abstract: Publication date: February 2018
      Source:Aquatic Toxicology, Volume 195
      Author(s): Qi-Hui Zhu, Zhong-Kai Zhou, Dan-Dan Tu, Yi-Lian Zhou, Cong Wang, Ze-Peng Liu, Wen-Bin Gu, Yu-Yin Chen, Miao-An Shu
      Cadmium (Cd) is a heavy metal that accumulates easily in organisms and causes several detrimental effects, including tissue damage. Cd contamination from anthropogenic terrestrial sources flows into rivers, and through estuaries to the ocean. To evaluate the toxic effects of Cd on estuary crustaceans, we exposed the mud crab Scylla paramamosain to various Cd concentrations (0, 10.0, 20.0, and 40.0mg/L) for 24h. We also exposed mud crabs to a fixed Cd concentration (20.0mg/L) for various periods of time (0, 6, 12, 24, 48, and 72h). We observed that after exposure to Cd, the surfaces of the gill lamellae were wrinkled, and the morphologies of the nuclei and mitochondria in the hepatopancreas were altered. We analyzed the expression profiles of 36 stress-related genes after Cd exposure, including those encoding metallothioneins, heat shock proteins, apoptosis-related proteins, and antioxidant proteins, with quantitative reverse transcription PCR. We found that exposure to Cd altered gene expression, and that some genes might be suitable bioindicators of Cd stress. Gene expression profiles were organ-, duration-, and concentration-dependent, suggesting that stress-response genes might be involved in an innate defense system for handling heavy metal exposure. To the best of our knowledge, this study is the first one of histopathology and stress-response gene expression pattern of Scylla paramamosain after Cd exposure. Our work could increase our understanding of the effect of environmental toxins on estuary crustaceans.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.020
      Issue No: Vol. 195 (2017)
       
  • Bioaccumulation of oil compounds in the high-Arctic copepod Calanus
           hyperboreus
    • Authors: Mette Dalgaard Agersted; Eva Friis Møller; Kim Gustavson
      Pages: 8 - 14
      Abstract: Publication date: February 2018
      Source:Aquatic Toxicology, Volume 195
      Author(s): Mette Dalgaard Agersted, Eva Friis Møller, Kim Gustavson
      Oil and gas exploration in the Arctic will increase the risk for accidental oil spills and thereby have a potential impact on the ecosystem and the organisms inhabiting these areas. Lipid rich copepods are an important food source for higher trophic levels in Arctic marine ecosystems. However, high lipid content and a slower metabolism increase the risk for bioaccumulation in Arctic species. Here we exposed three late development stages of the lipid rich high-Arctic copepod species Calanus hyperboreus to two different 14C-marked crude oil model compounds, the alkane dodecane (log Kow 6.10) and the polycyclic aromatic hydrocarbon (PAH) phenanthrene (log Kow 4.46) on a short-term scale of 4days. Exposure was followed by a depuration phase of 3days. We observed a difference in estimated bioaccumulation of the two model compounds between stages and found a slower depuration of dodecane than of phenanthrene in the two largest and most lipid rich stages. However, depuration of dodecane and phenanthrene was non-significant for all three stages. The results indicate that even short-term exposure may result in long-term bioaccumulation and internal exposure of oil compounds in the lipid rich high-Arctic copepods C. hyperboreus. Slow elimination and depuration of oil components indicate a risk for transfer of oil component up the food web to pelagic fish, seabirds and baleen whales.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.12.001
      Issue No: Vol. 195 (2017)
       
  • Impacts on the seagrass, Zostera nigricaulis, from the herbicide Fusilade
           Forte® used in the management of Spartina anglica infestations
    • Authors: Megan Carve; Timothy L. Coggan; Jackie H. Myers; Bradley Clarke; Dayanthi Nugegoda; Jeff Shimeta
      Pages: 15 - 23
      Abstract: Publication date: February 2018
      Source:Aquatic Toxicology, Volume 195
      Author(s): Megan Carve, Timothy L. Coggan, Jackie H. Myers, Bradley Clarke, Dayanthi Nugegoda, Jeff Shimeta
      The herbicide Fusilade Forte® (FF) is widely applied in agricultural weed management and in the management of the invasive saltmarsh grass, Spartina anglica (ricegrass or cordgrass). FF (active ingredient fluazifop-P acid, FPA) is selective for poaceous grasses. Its primary mode of action is inhibition of the acetyl coenzyme-A carboxylase (ACCase) specific to this taxonomic group, and its secondary mode is by promotion of oxidative stress. FF is applied to S. anglica infestations in the intertidal zone, in proximity to seagrass meadows. Despite the potential for vital seagrass ecosystems to be exposed to FF, there is limited knowledge of any potential impacts. We investigated impacts of FPA on the endemic Australian seagrass, Zostera nigricaulis, measuring ACCase activity and parameters that reflect oxidative stress: photosynthetic performance, lipid peroxidation and photosynthetic pigment content. Seagrass was exposed to FF (0.01–10mgL−1 FPA and a control) for 7d, followed by a 7-d recovery in uncontaminated seawater. An enzyme assay demonstrated that FPA ≤10mgL−1 did not inhibit the activity of ACCase isolated from Z. nigricaulis, demonstrating that this seagrass is resistant to FF's primary mode of action. However, physiological impacts occurred following 7 days exposure to ≥0.1mgL−1 FPA, including up to a 72% reduction in photosynthetic pigment concentration. After 7-d recovery, photosynthetic pigment content improved in treatment plants; however, treated plants exhibited higher levels of lipid peroxidation. This study demonstrates that while Z. nigricaulis is resistant to FF's primary mode of action, significant physiological impacts occur following 7 days exposure to ≥0.1mgL−1 FPA. This study provides valuable information on the effects of FF on a non-target species that can better inform approaches to Spartina management in coastal seagrass ecosystems.

      PubDate: 2017-12-23T11:42:57Z
      DOI: 10.1016/j.aquatox.2017.11.021
      Issue No: Vol. 195 (2017)
       
  • Effects of triphenyl phosphate on growth, reproduction and transcription
           of genes of Daphnia magna
    • Authors: Siliang Yuan; Han Li; Yao Dang; Chunsheng Liu
      Pages: 58 - 66
      Abstract: Publication date: February 2018
      Source:Aquatic Toxicology, Volume 195
      Author(s): Siliang Yuan, Han Li, Yao Dang, Chunsheng Liu
      The additive flame retardant triphenyl phosphate (TPHP) has been frequently detected in environments and biota. Evidences indicate that TPHP has potential risks to aquatic organisms. Seldom has been reported about its chronic effects to aquatic organism at low trophic levels, such as Cladocera. In the present study, <12 h old Daphnia magna (D. magna) were exposed to 0, 5, 50 or 500 μg/L TPHP for 21 days to investigate the chronic effects of TPHP on body length, fecundity and survival. Meanwhile, D. magna PCR arrays were used to evaluate the transcriptional responses of 155 genes involved in 40 pathways. Exposure to 500 μg/L TPHP for 21 days significantly decreased the body lengths of both F0 and F1 generation and inhibited the fecundity of F0 generation. Results of RT-qPCR showed that the expressions of 76 genes involved in 15 pathways were significantly altered after exposure to 500 μg/L TPHP for 21 days. The significantly altered pathways related to genetic information processing, cellular process and metabolism might be responsible for the observed effects of TPHP. Overall, our results showed that chronic exposure to TPHP caused developmental and reproductive toxicities to D. magna.

      PubDate: 2017-12-27T11:50:31Z
      DOI: 10.1016/j.aquatox.2017.12.009
      Issue No: Vol. 195 (2017)
       
  • Effects of waterborne cadmium on metabolic rate, oxidative stress, and ion
           regulation in the freshwater fish, inanga (Galaxias maculatus)
    • Authors: Nicole K. McRae; Sally Gaw; Chris N. Glover
      Pages: 1 - 9
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Nicole K. McRae, Sally Gaw, Chris N. Glover
      The freshwater fish Galaxias maculatus (inanga) is a widespread Southern hemisphere species, but despite its habitation of lowland near-coastal waters with a high potential for cadmium contamination, nothing is known regarding its sensitivity to this toxic trace metal. Acute (96h) exposures were therefore performed to determine sublethal responses of inanga to waterborne cadmium at a regulatory trigger value (nominally 0.2μgL−1; measured 1μgL−1), an environmental level (measured at 2.5μgL−1), and an effect level (measured at 10μgL−1). Whole body (tissue remaining following excision of kidney and liver) cadmium burden remained constant up until an exposure concentration of 10μgL−1, at which point cadmium concentration increased significantly. A transient effect of cadmium on metabolic rate was observed, with an impaired oxygen consumption noted at 2.5, but not 1 or 10, μg L−1. Cadmium did not impair influx rates of either sodium or calcium, and no effects of cadmium on oxidative stress parameters (catalase activity, lipid peroxidation) were noted in the kidney. However, at cadmium concentrations of 2.5 and 10μgL−1, lipid peroxidation in the liver increased, concomitant with a decline in hepatic catalase activity. These data indicate that there are significant differences in the mechanisms of cadmium toxicity in inanga, relative to better-studied Northern hemisphere species, especially with respect to ionoregulatory impacts. However, effects were induced at cadmium concentrations unlikely to be encountered in any but the most highly contaminated waterways, and thus our data suggest that current trigger values for cadmium concentrations in Australian and New Zealand waters are likely to be protective of inanga.

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.10.027
      Issue No: Vol. 194 (2017)
       
  • Antioxidant responses and oxidative stress in sheepshead minnow larvae
           exposed to Corexit 9500® or its component surfactant, DOSS
    • Authors: Subham Dasgupta; Sarah Choyke; P. Lee Ferguson; Anne E. McElroy
      Pages: 10 - 17
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Subham Dasgupta, Sarah Choyke, P. Lee Ferguson, Anne E. McElroy
      Large-scale use of dispersants to remediate oil spills has raised concerns about their toxicity to marine organisms. Of particular concern is oxidative stress and resulting membrane damage due to exposure to surfactants in dispersant mixtures. We investigated the potential of the dispersant Corexit 9500® and one of its major components, the anionic surfactant dioctyl sodium sulfosuccinate (DOSS), to induce oxidative stress in larval sheepshead minnows after 24 and 96h exposures, at two sublethal concentrations, the lesser being environmentally realistic for each compound. Corexit exposures elicited only minimal antioxidant responses for most antioxidant components tested, with increased glutathione peroxidase (GPx) and glutathione S-transferase (GST) activities observed only after 96h and at the higher exposure concentration. In contrast, DOSS induced statistically significant increases in the levels of reactive oxygen species (ROS), GPx, and lipid peroxidation, as well as depleted reduced glutathione (GSH) levels at both time points and concentrations. These data indicate that short-term and environmentally realistic exposures to DOSS can impact antioxidant response capabilities, raising concern about its use in oil dispersants and other high volume use products where environmental releases are likely.

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.10.010
      Issue No: Vol. 194 (2017)
       
  • Effects of Microcystis on development of early life stage Japanese medaka
           (Oryzias latipes): Comparative toxicity of natural blooms, cultured
           Microcystis and microcystin-LR
    • Authors: Spencer R. Saraf; Amy Frenkel; Matthew J. Harke; Jennifer G. Jankowiak; Christopher J. Gobler; Anne E. McElroy
      Pages: 18 - 26
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Spencer R. Saraf, Amy Frenkel, Matthew J. Harke, Jennifer G. Jankowiak, Christopher J. Gobler, Anne E. McElroy
      Freshwater cyanobacterial harmful algal blooms (CyanoHABs) caused by algae in the genus Microcystis have been increasing in frequency and severity in recent decades. Microcystis blooms threaten aquatic organisms through effects associated with the rapid increase of biomass and the production of the hepatotoxin microcystin (MC) by toxic strains. Among fish, effects of blooms are likely to be more severe for early life stages, and physiological impacts on this life stage could significantly impact recruitment and fish populations. This study explores the effects of Microcystis blooms on the development of fish using the model organism, the Japanese medaka (Oryzias latipes), under realistic exposure conditions. Medaka embryos were exposed to natural blooms collected from New York City (USA) lakes, lab cultures of Microcystis, and MC-LR solutions. Field collected samples were more toxic than lab cultures (even when compared at the same algal density or MC concentration), causing decreased survival, premature time to hatch, reduced body length, yolk sac edema, and decreased heart rate, while lab culture exposures only resulted in bradycardia. Heart rate was the most sensitive endpoint measured, being depressed in embryos exposed to both lab cultures and field collected blooms. Generalized linear model analysis indicated bradycardia was statistically associated with both cell densities of blooms and MC concentrations, while single factor analysis indicated that MC concentrations had a stronger correlation compared to cell densities. However, MC exposure could not fully explain the effects observed, as exposures to MC-LR solutions alone were not able to reduce heart rate as severely as algal exposures. Collectively, these experiments indicate that factors beyond exposure to MC or even isolated Microcystis strains influence heart rate of fish exposed to Microcystis blooms. Enhanced mortality, depressed heart rate, and abnormal development observed in response to environmentally realistic exposures of Microcystis blooms could affect success of fish at both individual or population levels.

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.10.026
      Issue No: Vol. 194 (2017)
       
  • Influence of body size, metabolic rate and life history stage on the
           uptake and excretion of the lampricide 3-trifluoromethyl-4-nitrophenol
           (TFM) by invasive sea lampreys (Petromyzon marinus)
    • Authors: Laura R. Tessier; Tristan A.F. Long; Michael P. Wilkie
      Pages: 27 - 36
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Laura R. Tessier, Tristan A.F. Long, Michael P. Wilkie
      Invasive sea lamprey (Petromyzon marinus) are controlled in the Great Lakes using the lampricide 3-trifluoromethyl-4-nitrophenol (TFM), which is applied to streams infested with larval lamprey. However, lamprey that survive treatments (residuals) remain a challenge because they may subsequently undergo metamorphosis into parasitic juvenile animals that migrate downstream to the Great Lakes, where they feed on important sport and commercial fishes. The goal of this study was to determine if body size and life stage could potentially influence sea lamprey tolerance to TFM by influencing patterns of TFM uptake and elimination. Because mass specific rates of oxygen consumption ( M ˙ O 2 ) are lower in larger compared to smaller lamprey, we predicted that TFM uptake would be negatively correlated to body size, suggesting that large larvae would be more tolerant to TFM exposure. Accordingly, TFM uptake and M ˙ O 2 were measured in larvae ranging in size from 0.2–4.2g using radio-labelled TFM (14C-TFM) and static respirometry. Both were inversely proportional to wet mass (M), and could be described usingthe allometric power relationship: Y = aMb , in which M ˙ O 2 = 1.86M0.53 and TFM Uptake = 7.24M0.34. We also predicted that body size would extend to rates of TFM elimination, which was measured following the administration of 14C-TFM (via intraperitoneal injection). However, there were no differences in the half-lives of elimination of TFM (T 1/2-TFM). There were also no differences in M ˙ O 2 or TFM uptake amongst size-matched larval, metamorphosing (stages 6–7), or post-metamorphic (juvenile) sea lamprey. However, the T1/2-TFM was significantly lower in larval than post-metamorphic lamprey (juvenile), indicating the larval lamprey cleared TFM more efficiently than juvenile lamprey. We conclude that larger larval sea lamprey are more likely to survive TFM treatments suggesting that body size might be an important variable to consider when treating streams with TFM to control these invasive species.

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.10.020
      Issue No: Vol. 194 (2017)
       
  • Cyanobacteria blooms induce embryonic heart failure in an endangered fish
           species
    • Authors: Jinmei Zi; Xiaofu Pan; Hugh J. MacIsaac; Junxing Yang; Runbing Xu; Shanyuan Chen; Xuexiu Chang
      Pages: 78 - 85
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Jinmei Zi, Xiaofu Pan, Hugh J. MacIsaac, Junxing Yang, Runbing Xu, Shanyuan Chen, Xuexiu Chang
      Cyanobacterial blooms drive water-quality and aquatic-ecosystem deterioration in eutrophic lakes worldwide, mainly owing to their harmful, secondary metabolites. The response of fish exposed to these cyanobacterial chemicals, however, remains largely unknown. In this paper, we employed an endangered fish species (Sinocyclocheilus grahami) in Dianchi Lake, China to evaluate the risks of cell-free exudates (MaE) produced by a dominant cyanobacterium (Microcystis aeruginosa) on embryo development, as well as the molecular mechanisms responsible. MaE (3d cultured) caused a reduction of fertilization (35.4%) and hatching (15.5%) rates, and increased mortality rates (≤90.0%) and malformation rate (27.6%), typically accompanied by heart failure. Proteomics analysis revealed that two greatest changed proteins – protein S100A1 (over-expressed 26 times compared with control) and myosin light chain (under-expressed 25 fold) – are closely associated with heart function. Further study revealed that heart failure was due to calcium ion imbalance and malformed cardiac structure. We conclude that harmful secondary metabolites from cyanobacteria may adversely affect embryo development in this endangered fish, and possibly contribute to its disappearance and unsuccessful recovery in Dianchi Lake. Hazardous consequences of substances released by cyanobacteria should raise concerns for managers addressing recovery of this and other imperiled species in affected lakes.
      Graphical abstract image

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.007
      Issue No: Vol. 194 (2017)
       
  • Multigenerational effects of 4-methylbenzylidene camphor (4-MBC) on the
           survival, development and reproduction of the marine copepod Tigriopus
           japonicus
    • Authors: Leyun Chen; Xiaolin Li; Haizheng Hong; Dalin Shi
      Pages: 94 - 102
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Leyun Chen, Xiaolin Li, Haizheng Hong, Dalin Shi
      One of the most widely used organic UV filters, 4-methylbenzylidene camphor (4-MBC), is present at high concentrations in offshore waters. The marine copepod Tigriopus japonicus was exposed to different concentrations of 4-MBC (i.e., 0, 0.5, 1, 5 and 10μgL−1) for 4 consecutive generations (F0-F3) to evaluate the impact of 4-MBC on marine ecosystems. The results showed that in the F0 generation, 4-MBC caused significant lethal toxicity in T. japonicas at concentrations of 5 and 10μgL−1 and the nauplii were more sensitive to 4-MBC toxicity than the adults. However in the F1-F3 generations, 4-MBC exposure did not affect the survival rate. The hatching rate and the developmental duration from the nauplii to the copepodite (N-C) and from the nauplii to adult (N-A) decreased significantly in the F1-F2 generations and in the F2-F3 generations, respectively, even at the lowest exposure concentration (0.5μgL−1). In the subsequent two generations (i.e., the F4-F5 generations) of recovery exposure in clean seawater, the growth rates of the original 4-MBC exposure groups were still faster than the control in both the N-C and N-A stages, suggesting possible transgenerational genetic and/or epigenetic changes upon chronic 4-MBC exposure. The expression of the ecdysone receptor gene was up-regulated by 4-MBC, which was consistent with the decrease of the N-C/N-A duration. In addition, 4-MBC may induce oxidative stress and trigger apoptosis in T. japonicas, resulting in developmental, reproductive and even lethal toxicity. A preliminary risk assessment suggested that under environmentally realistic concentrations, 4-MBC had significant potential to pose a threat to marine crustaceans and marine ecosystems.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.008
      Issue No: Vol. 194 (2017)
       
  • Effects of two-hour exposure to environmental and high concentrations of
           methylmercury on the transcriptome of the macrophyte Elodea nuttallii
    • Authors: Rebecca Beauvais-Flück; Vera I. Slaveykova; Claudia Cosio
      Pages: 103 - 111
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Rebecca Beauvais-Flück, Vera I. Slaveykova, Claudia Cosio
      The effects of two methylmercury (CH3Hg+, MeHg) concentrations, representative of environmental level and extreme contamination, were investigated on the macrophyte Elodea nuttallii during a 2h-exposure combining transcriptomic (RNA-Seq), physiological endpoints (pigment contents, activity of anti-oxidative stress enzymes) and bioaccumulation. Exposure to MeHg induced the up- and down-regulation of numerous genes (4389 and 16853 for 10ngL−1 and 10μgL−1 MeHg exposure, respectively) involved in sugar, amino acid and secondary metabolism (e.g. cinnamic acid, flavonoids) at both concentrations. Genes coding for photosynthesis, membrane integrity, metal homeostasis, water transport and anti-oxidative enzymes were additionally up- and down-regulated at the higher concentration. At the physiological level, exposure to both MeHg concentrations resulted in a strong increase of anthocyanin content in shoots. Chlorophyll content and antioxidant enzyme activities were unchanged. The data suggest that the macrophyte was able to efficiently cope with the stress resulting from MeHg exposure, possibly by using anthocyanin as anti-oxidant and S-rich amino acids (such as cysteine and methionine) as chelators. Transcriptomics analysis enabled gaining novel insights on molecular effects of MeHg in primary producers, which are one of the main entry pathway of hazardous MeHg in aquatic food webs.
      Graphical abstract image

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.010
      Issue No: Vol. 194 (2017)
       
  • Metabolomics and transcriptomics reveal the toxicity of difenoconazole to
           the early life stages of zebrafish (Danio rerio)
    • Authors: Miaomiao Teng; Wentao Zhu; Dezhen Wang; Suzhen Qi; Yao Wang; Jin Yan; Kai Dong; Mingqi Zheng; Chengju Wang
      Pages: 112 - 120
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Miaomiao Teng, Wentao Zhu, Dezhen Wang, Suzhen Qi, Yao Wang, Jin Yan, Kai Dong, Mingqi Zheng, Chengju Wang
      Difenoconazole is widely used to inhibit the growth of fungi, but its residue in the water environment may threaten ecosystem and human health. Here, 1H nuclear magnetic resonance (NMR) and LC–MS/MS based metabolomics and transcriptomics approaches were used to assess the response of zebrafish to difenoconazole exposure. Early life stages of zebrafish were exposed to difenoconazole at environmentally relevant concentrations for 168h. Their comparison with the control group suggested an adverse development and disturbance of steroid hormones and VTG. KEGG pathway analysis identified five biological processes on the basis of differentially expressed genes (DEGs), as well as altered metabolites and amino acids in zebrafish following difenoconazole exposure. These affected processes included energy metabolism, amino acids metabolism, lipid metabolism, nucleotide metabolism, and an immune-related pathway. Collectively, these results bring us closer to an incremental understanding of the toxic effects of difenoconazole on zebrafish in its early development, and lend support to the continued use of the early life stages of zebrafish as a classical model to evaluate underlying environmental risks of xenobiotics in aquatic organisms.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.009
      Issue No: Vol. 194 (2017)
       
  • Digital gene expression analysis in the gills of Ruditapes philippinarum
           exposed to short- and long-term exposures of ammonia nitrogen
    • Authors: Ming Cong; Huifeng Wu; Tengfei Cao; Jiasen Lv; Qing Wang; Chenglong Ji; Chenghua Li; Jianmin Zhao
      Pages: 121 - 131
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Ming Cong, Huifeng Wu, Tengfei Cao, Jiasen Lv, Qing Wang, Chenglong Ji, Chenghua Li, Jianmin Zhao
      Previous study revealed severe toxic effects of ammonia nitrogen on Ruditapes philippinarum including lysosomal instability, disturbed metabolic profiles, gill tissues with damaged structure, and variation of neurotransmitter concentrations. However, the underlying molecular mechanism was not fully understood yet. In the present study, digital gene expression technology (DGE) was applied to globally screen the key genes and pathways involved in the responses to short- and long-term exposures of ammonia nitrogen. Results of DGE analysis indicated that short-term duration of ammonia exposure affected pathways in Dorso-ventral axis formation, Notch signaling, thyroid hormone signaling and protein processing in endoplasmic reticulum. The long-term exposure led to DEGs significantly enriched in gap junction, immunity, signal and hormone transduction, as well as key substance metabolism pathways. Functional research of significantly changed DEGs suggested that the immunity of R. philippinarum was weakened heavily by toxic effects of ammonia nitrogen, as well as neuro-transduction and metabolism of important substances. Taken together, the present study provides a molecular support for the previous results of the detrimental toxicity of ammonia exposure in R. philippinarum, further work will be performed to investigate the specific genes and their certain functions involved in ammonia toxicity to molluscs.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.012
      Issue No: Vol. 194 (2017)
       
  • Systemic response of the stony coral Pocillopora damicornis against acute
           cadmium stress
    • Authors: Zhi Zhou; Xiaopeng Yu; Jia Tang; Yibo Wu; Lingui Wang; Bo Huang
      Pages: 132 - 139
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Zhi Zhou, Xiaopeng Yu, Jia Tang, Yibo Wu, Lingui Wang, Bo Huang
      Heavy metals have become one of the main pollutants in the marine environment and a major threat to the growth and reproduction of stony corals. In the present study, the density of symbiotic zooxanthellae, levels of crucial physiological activities and the transcriptome were investigated in the stony coral Pocillopora damicornis after the acute exposure to elevated cadmium concentration. The density of symbiotic zooxanthellae decreased significantly during 12–24h period, and reached lowest at 24h after acute cadmium stress. No significant changes were observed in the activity of glutathione S-transferase during the entire stress exposure. The activities of superoxide dismutase and catalase, and the concentration of glutathione decreased significantly, but the activation level of caspase3 increased significantly after cadmium exposure. Furthermore, transcriptome sequencing and bioinformatics analysis revealed 3538 significantly upregulated genes and 8048 significantly downregulated genes at 12h after the treatment. There were 12 overrepresented GO terms for significantly upregulated genes, mostly related to unfolded protein response, endoplasmic reticulum stress and apoptosis. In addition, a total of 32 GO terms were overrepresented for significantly downregulated genes, and mainly correlated with macromolecular metabolic processes. These results collectively suggest that acute cadmium stress could induce apoptosis by repressing the production of the antioxidants, elevating oxidative stress and activating the unfolded protein response. This cascade of reactions would result to the collapse of the coral-zooxanthella symbiosis and the expulsion of symbiotic zooxanthellae in the stony coral P. damicornis, ultimately leading to coral bleaching.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.013
      Issue No: Vol. 194 (2017)
       
  • Differential response between histological and biochemical biomarkers in
           the apple snail Pomacea canaliculata (Gasteropoda: Amullariidae) exposed
           to cypermethrin
    • Authors: F. Arrighetti; E. Ambrosio; M. Astiz; A. Rodrigues Capítulo; S. Lavarías
      Pages: 140 - 151
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): F. Arrighetti, E. Ambrosio, M. Astiz, A. Rodrigues Capítulo, S. Lavarías
      To develop effective programs to monitor water quality is necessary to identify sensitive biomarkers in indicator species. The aim of this study was to evaluate different biomarkers in the apple snail Pomacea canaliculata exposed to the insecticide Cypermethrin (CYP). Adult male and female snails were exposed to sublethal CYP concentrations (10, 25 and 100μgl−1) for 1, 4, 7 and 14days. The recovery of the exposed snails was also studied by a post-exposure assay. The activities of the enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST), the levels of lipid peroxidation (LPO) and protein oxidation (PC) in digestive gland and gills were studied as biomarkers of exposure. Histopathological changes in target tissues were also evaluated. In digestive gland, CYP caused a significant increase in SOD, CAT and GST activities compared to control (p< 0.05) as well as in LPO and PC levels (p< 0.05). However, such biochemical effects were neither concentration nor time dependent. Histopatological changes were observed in the exposed groups, such as an increase in the number of basophilic cells, hemocytic infiltration and epithelia atrophy. Additionally, a positive correlation between the surface occupied by pigmented corpuscles and CYP concentrations was observed at all exposure periods. Gills showed greater sensitivity to oxidative damage than digestive gland. CYP caused an acute toxic effect in LPO levels in this respiratory organ. The gill filament of exposed snails, exhibited a reduction or loss of cilia, vacuolization of the columnar cells and an increase in haemocyte content irrespective of the concentration. High concentrations of CYP caused disruptions in the columnar muscle fibers. In general, snails did not show an improvement in their basal state during post-exposure treatment. Apparently, males and females do not have differential sensitivity to the pesticide. The results of this study suggest that histopathological changes are the most sensitive time- and dose-dependent biomarkers of toxicity induced by CYP in P. canaliculata.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.014
      Issue No: Vol. 194 (2017)
       
  • Uniquely high turnover of nickel in contaminated oysters Crassostrea
           hongkongensis: Biokinetics and subcellular distribution
    • Authors: Qijun Yin; Wen-Xiong Wang
      Pages: 159 - 166
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Qijun Yin, Wen-Xiong Wang
      Despite the environmental concerns regarding nickel (Ni) especially in China, it has received little attention in aquatic animals due to its comparatively weak toxicity. In the present study, we explored the bioaccumulation, biokinetics, and subcellular distribution of Ni in an estuarine oyster Crassostrea hongkongensis. We demonstrated that Ni represented a new pattern of bioaccumulation in oysters characterized by rapid elimination and low dissolved uptake. The waterborne uptake rate constant and dietary assimilation efficiency were 0.036L/g/h and 28%, respectively, and dissolved uptake was the predominant exposure route. The efflux rate constant was positively related to tissue Ni concentration, with the highest efflux of 0.155d−1. Such high elimination resulted in a high Ni turnover and steady-state condition reached rapidly, as shown with a 4-week waterborne exposure experiment at different Ni concentrations. Ni in oysters was mainly sequestered in metallothionein-like protein (MTLP), metal-rich granule, and cellular debris. MTLP was the most important binding fraction during accumulation and depuration, and played a dynamic role leading to rapid Ni elimination. Pre-exposure to Ni significantly reduced the dissolved uptake, probably accompanied by depressed filtration activity. Overall, the high turnover and regulation of Ni in oysters were achieved by enhanced efflux, suppressed uptake, and sequestration of most Ni into the detoxified pool.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.018
      Issue No: Vol. 194 (2017)
       
  • Role of neurexin2a in lead-induced locomotor defect in developing
           zebrafish
    • Authors: Hongwei Tu; Tao Peng; Jiaxian Liu; Xiaohui Chen; Chengji Fan; Zhibin Huang; Yiyue Zhang; Fei Zou; Xiaojing Meng
      Pages: 167 - 175
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Hongwei Tu, Tao Peng, Jiaxian Liu, Xiaohui Chen, Chengji Fan, Zhibin Huang, Yiyue Zhang, Fei Zou, Xiaojing Meng
      Low-dose chronic lead (Pb) exposure interferes with the development of the nervous system, which may lead to learning disabilities, behavioral abnormalities, and mental retardation. Neurexins (Nrxns) are synaptic cell-adhesion molecules associated with neurological disorders. We hypothesized that Pb can affect the expression of nrxns during synapse formation and alter the phenotype behavior. Here, apoptosis, nrxns mRNA expression, and alterations of locomotion were examined after exposure to Pb in zebrafish embryos/larvae. To confirm the function of nrxn2a, rescue experiments were performed using β-nrxn2a mRNA microinjection. Pb exposure increased apoptosis and altered locomotor behavior in zebrafish larvae. Quantitative PCR showed that among several synaptic adhesion molecules, only nrxn2a were affected by Pb exposure. Moreover, exposure to Pb at 10μmol/L upregulated mRNA expression of nrxn1a and nrxn3a at 24h post fertilization (hpf) and downregulated expression at 48 hpf, whereas the expression remained unchanged at 72 hpf. Only the two isoforms of nrxn2a were downregulated by Pb at 10μmol/L at all three time points. Rescue experiments showed that β-nrxn2a mRNA injection recovered the decreased locomotor activity and the increased apoptosis induced by Pb. In addition, overexpression of β-nrxn2a mRNA upregulated α-nrxn2a. These data indicated that Pb inhibited the expression of nrxn2a genes, which play a critical role in neural development, and further altered the behavior of zebrafish embryos/larvae.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.011
      Issue No: Vol. 194 (2017)
       
  • Uptake and effects of 2, 4, 6 - trinitrotoluene (TNT) in juvenile Atlantic
           salmon (Salmo salar)
    • Authors: Espen Mariussen; Siv Marie Stornes; Kari Oline Bøifot; Bjørn Olav Rosseland; Brit Salbu; Lene Sørlie Heier
      Pages: 176 - 184
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Espen Mariussen, Siv Marie Stornes, Kari Oline Bøifot, Bjørn Olav Rosseland, Brit Salbu, Lene Sørlie Heier
      Organ specific uptake and depuration, and biological effects in Atlantic salmon (Salmo salar) exposed to 2, 4, 6-trinitrotoluene (TNT) were studied. Two experiments were conducted, the first using radiolabeled TNT (14C-TNT, 0.16mg/L) to study uptake (48h) and depuration (48h), while the second experiment focused on physiological effects in fish exposed to increasing concentrations of unlabeled TNT (1μg–1mg/L) for 48h. The uptake of 14C-TNT in the gills and most of the organs increased rapidly during the first 6h of exposure (12h in the brain) followed by a rapid decrease even though the fish were still exposed to TNT in the water. The radioactivity in the gall bladder reached a maximum after 55h, 7h after the transfer to the clean water. A high concentration of 14C-TNT in the gall bladder indicates that TNT is excreted through the gall bladder. Mortality (2 out of 14) was observed at a concentration of 1mg/L, and the surviving fish had hemorrhages in the dorsal muscle tissue near the spine. Analysis of the physiological parameters in blood from the high exposure group revealed severe effects, with an increase in the levels of glucose, urea and HCO3, and a decrease in hematocrit and the levels of Cl and hemoglobin. No effects on blood physiology were observed in fish exposed to the lower concentrations of TNT (1–100μg/L). TNT and the metabolites 2-amino-4,6-dinitrotoluene (2-ADNT) and 4-amino-2,6-dinitrotoluene (4-ADNT) were found in the muscle tissue, whereas only 2-ADNT and 4-ADNT were found in the bile. The rapid excretion and estimated bioconcentration factors (range of 2–18 after 48h in gills, blood, liver, kidney, muscle and brain) indicated a low potential for bioaccumulation of TNT.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.016
      Issue No: Vol. 194 (2017)
       
  • Uptake, tissue distribution, and toxicity of polystyrene nanoparticles in
           developing zebrafish (Danio rerio)
    • Authors: Jordan A. Pitt; Jordan S. Kozal; Nishad Jayasundara; Andrey Massarsky; Rafael Trevisan; Nick Geitner; Mark Wiesner; Edward D. Levin; Richard T. Di Giulio
      Pages: 185 - 194
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Jordan A. Pitt, Jordan S. Kozal, Nishad Jayasundara, Andrey Massarsky, Rafael Trevisan, Nick Geitner, Mark Wiesner, Edward D. Levin, Richard T. Di Giulio
      Plastic pollution is a critical environmental concern and comprises the majority of anthropogenic debris in the ocean, including macro, micro, and likely nanoscale (less than 100nm in at least one dimension) plastic particles. While the toxicity of macroplastics and microplastics is relatively well studied, the toxicity of nanoplastics is largely uncharacterized. Here, fluorescent polystyrene nanoparticles (PS NPs) were used to investigate the potential toxicity of nanoplastics in developing zebrafish (Danio rerio), as well as to characterize the uptake and distribution of the particles within embryos and larvae. Zebrafish embryos at 6h post-fertilization (hpf) were exposed to PS NPs (0.1, 1, or 10ppm) until 120 hpf. Our results demonstrate that PS NPs accumulated in the yolk sac as early as 24 hpf and migrated to the gastrointestinal tract, gallbladder, liver, pancreas, heart, and brain throughout development (48–120 hpf). Accumulation of PS NPs decreased during the depuration phase (120–168 hpf) in all organs, but at a slower rate in the pancreas and gastrointestinal tract. Notably, exposure to PS NPs did not induce significant mortality, deformities, or changes to mitochondrial bioenergetics, but did decrease the heart rate. Lastly, exposure to PS NPs altered larval behavior as evidenced by swimming hypoactivity in exposed larvae. Taken together, these data suggest that at least some nanoplastics can penetrate the chorion of developing zebrafish, accumulate in the tissues, and affect physiology and behavior, potentially affecting organismal fitness in contaminated aquatic ecosystems.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.017
      Issue No: Vol. 194 (2017)
       
  • Microbiota and environmental stress: how pollution affects microbial
           communities in Manila clams
    • Authors: M. Milan; L. Carraro; P. Fariselli; M.E. Martino; D. Cavalieri; F. Vitali; L. Boffo; T. Patarnello; L. Bargelloni; B. Cardazzo
      Pages: 195 - 207
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): M. Milan, L. Carraro, P. Fariselli, M.E. Martino, D. Cavalieri, F. Vitali, L. Boffo, T. Patarnello, L. Bargelloni, B. Cardazzo
      Given the crucial role of microbiota in host development, health, and environmental interactions, genomic analyses focusing on host-microbiota interactions should certainly be considered in the investigation of the adaptive mechanisms to environmental stress. Recently, several studies suggested that microbiota associated to digestive tract is a key, although still not fully understood, player that must be considered to assess the toxicity of environmental contaminants. Bacteria-dependent metabolism of xenobiotics may indeed modulate the host toxicity. Conversely, environmental variables (including pollution) may alter the microbial community and/or its metabolic activity leading to host physiological alterations that may contribute to their toxicity. Here, 16s rRNA gene amplicon sequencing has been applied to characterize the hepatopancreas microbiota composition of the Manila clam, Ruditapes philippinarum. The animals were collected in the Venice lagoon area, which is subject to different anthropogenic pressures, mainly represented by the industrial activities of Porto Marghera (PM). Seasonal and geographic differences in clam microbiotas were explored and linked to host response to chemical stress identified in a previous study at the transcriptome level, establishing potential interactions among hosts, microbes, and environmental parameters. The obtained results showed the recurrent presence of putatively detoxifying bacterial taxa in PM clams during winter and over-representation of several metabolic pathways involved in xenobiotic degradation, which suggested the potential for host-microbial synergistic detoxifying actions. Strong interaction between seasonal and chemically-induced responses was also observed, which partially obscured such potentially synergistic actions. Seasonal variables and exposure to toxicants were therefore shown to interact and substantially affect clam microbiota, which appeared to mirror host response to environmental variation. It is clear that understanding how animals respond to chemical stress cannot ignore a key component of such response, the microbiota.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.019
      Issue No: Vol. 194 (2017)
       
  • Fish as a model to assess chemical toxicity in bone
    • Authors: Ignacio Fernández; Paulo J. Gavaia; Vincent Laizé; M. Leonor Cancela
      Pages: 208 - 226
      Abstract: Publication date: January 2018
      Source:Aquatic Toxicology, Volume 194
      Author(s): Ignacio Fernández, Paulo J. Gavaia, Vincent Laizé, M. Leonor Cancela
      Environmental toxicology has been expanding as growing concerns on the impact of produced and released chemical compounds over the environment and human health are being demonstrated. Among the toxic effects observed in organisms exposed to pollutants, those affecting skeletal tissues (osteotoxicity) have been somehow overlooked in comparison to hepato-, immune-, neuro- and/or reproductive toxicities. Nevertheless, sub-lethal effects of toxicants on skeletal development and/or bone maintenance may result in impaired growth, reduced survival rate, increased disease susceptibility and diminished welfare. Osteotoxicity may occur by acute or chronic exposure to different environmental insults. Because of biologically and technically advantagous features – easy to breed and inexpensive to maintain, external and rapid rate of development, translucent larvae and the availability of molecular and genetic tools – the zebrafish (Danio rerio) has emerged in the last decade as a vertebrate model system of choice to evaluate osteotoxicity. Different experimental approaches in fish species and analytical tools have been applied, from in vitro to in vivo systems, from specific to high throughput methodologies. Current knowledge on osteotoxicity and underlying mechanisms gained using fish, with a special emphasis on zebrafish systems, is reviewed here. Osteotoxicants have been classified into four categories according to the pathway involved in the transduction of the osteotoxic effects: activation/inhibition of membrane and/or nuclear receptors, alteration of redox condition, mimicking of bone constituents and unknown pathways. Knowledge on these pathways is also reported here as it may provide critical insights into the development, production and release of future chemical compounds with none or low osteotoxicity, thus promoting the green/environmental friendly chemistry.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.11.015
      Issue No: Vol. 194 (2017)
       
  • Microplastics have a more profound impact than elevated temperatures on
           the predatory performance, digestion and energy metabolism of an Amazonian
           cichlid
    • Authors: Bin Wen; Nan Zhang Shi-Rong Jin Zai-Zhong Chen Jian-Zhong Gao
      Abstract: Publication date: Available online 26 December 2017
      Source:Aquatic Toxicology
      Author(s): Bin Wen, Nan Zhang, Shi-Rong Jin, Zai-Zhong Chen, Jian-Zhong Gao, Ying Liu, Han-Peng Liu, Zhe Xu
      Knowledge on the impacts of microplastics (MPs) pollution on freshwater environments and biota remains limited. Meanwhile, freshwater ecosystems have been threatened by elevated temperatures caused by climate change. To date, no information exists on how MPs—especially under elevated temperature conditions—affect predatory performance, digestive processes and metabolic pathways in freshwater organisms. Here, we examined MPs, elevated temperature and their combined effects on juveniles (0+ group) of an Amazonian cichlid, the discus fish (Symphysodon aequifasciatus). For 30 days, fish were exposed to ambient or elevated temperatures (i.e., 28 or 31 °C) in the absence or presence of MPs (i.e., 0 or 200 μg/L). The following metrics were quantified: MPs accumulation; predatory performance; and biomarkers involved in neurotransmission, digestion and energy production. The results showed that survival rate and body length were not affected by MPs, elevated temperatures or their combination. Elevated temperatures resulted in an increase in MP concentrations in fish bodies. Exposure to MPs decreased the post-exposure predatory performance (PEPP) at ambient temperatures but not at elevated temperatures. Elevated temperatures, however, had no effect on the PEPP but antagonistically interacted with MPs, leading to similar predatory performances under present and future conditions. Acetylcholinesterase (AChE) activity was only affected by MPs and decreased in the presence of MPs, indicating adverse effects in nervous and neuromuscular function and, thus, potentially in predatory performance. Trypsin activity was only influenced by MPs and decreased during exposure to MPs. Elevated temperatures or MPs alone increased the amylase activity but interacted antagonistically. Lipase activity was not influenced by either of the two stressors. In contrast, alkaline phosphatase (ALP) activity was affected by MPs or elevated temperatures alone and decreased with both stressors. Such results indicate deficits in the digestive capabilities of early-stage S. aequifasciatus under elevated temperature conditions and especially during exposure to MPs. Electron transport system (ETS) activity was not influenced by either of the two stressors. Both elevated temperatures and MPs alone increased LDH activity; however, the interaction between the two stressors cancelled activity but was still higher than activity in present conditions. Citrate synthase (CS) activity decreased with elevated temperature but increased during exposure to MPs. Cytochrome c oxidase (COX) activity was only influenced by MPs and increased in the presence of MPs. Thus, S. aequifasciatus juveniles exposed to elevated temperatures and MPs not only relied on anaerobic glycolysis for energy production but also depended on aerobic metabolism in the presence of MPs. Overall, these findings suggested that MPs showed a greater impact than elevated temperatures on the predatory performance, digestion and energy production of S. aequifasciatus. Nevertheless, juvenile survival and growth were minimally impacted, and thus, S. aequifasciatus could cope with near-future temperature increases and MP exposure.

      PubDate: 2017-12-27T11:50:31Z
       
  • A glyphosate micro-emulsion formulation displays teratogenicity in Xenopus
           laevis
    • Authors: P. Bonfanti; M. Saibene; R. Bacchetta; P. Mantecca; A. Colombo
      Abstract: Publication date: Available online 24 December 2017
      Source:Aquatic Toxicology
      Author(s): P. Bonfanti, M. Saibene, R. Bacchetta, P. Mantecca, A. Colombo
      Glyphosate is the active ingredient in broad-spectrum herbicide formulations used in agriculture, domestic area and aquatic weed control worldwide. Its market is growing steadily concurrently with the cultivation of glyphosate-tolerant transgenic crops and emergence of weeds less sensitive to glyphosate. Ephemeral and lentic waters near to agricultural lands, representing favorite habitats for amphibian reproduction and early life-stage development, may thus be contaminated by glyphosate based herbicides (GBHs) residues. Previous studies on larval anuran species highlighted increased mortality and growth effects after exposure to different GBHs in comparison to glyphosate itself, mainly because of the surfactants such as polyethoxylated tallow amine present in the formulations. Nevertheless, these conclusions are not completely fulfilled when the early development, characterized by primary organogenesis events, is considered. In this study, we compare the embryotoxicity of Roundup® Power 2.0, a new GBH formulation currently authorized in Italy, with that of technical grade glyphosate using the Frog Embryo Teratogenesis Assay–Xenopus (FETAX). Our results evidenced that glyphosate was not embryolethal and only at the highest concentration (50 mg a.e./L) caused edemas. Conversely, Roundup® Power 2.0 exhibited a 96 h LC50 of 24.78 mg a.e./L and a 96 h EC50 of 7.8 mg a.e./L. A Teratogenic Index of 3.4 was derived, pointing out the high teratogenic potential of the Roundup® Power 2.0. Specific concentration-dependent abnormal phenotypes, such as craniofacial alterations, microphthalmia, narrow eyes and forebrain regionalization defects were evidenced by gross malformation screening and histopathological analysis. These phenotypes are coherent with those evidenced in Xenopus laevis embryos injected with glyphosate, allowing us to hypothesize that the teratogenicity observed for Roundup® Power 2.0 may be related to the improved efficacy in delivering glyphosate to cells, guaranteed by the specific surfactant formulation. In conclusion, the differences in GBH formulations should be carefully considered by the authorities, since sub-lethal and/or long-term effects (e.g. teratogenicity) can be significantly modulated by the active ingredient salt type and concentration of the adjuvants. Finally, the mechanistic toxicity of glyphosate and GBHs are worthy of further research.

      PubDate: 2017-12-27T11:50:31Z
      DOI: 10.1016/j.aquatox.2017.12.007
       
  • Microplastics cause neurotoxicity, oxidative damage and energy-related
           changes and interact with the bioaccumulation of mercury in the European
           seabass, Dicentrarchus labrax (Linnaeus, 1758)
    • Authors: Luís Gabriel Antão Barboza; Luís Russo Vieira; Vasco Branco; Neusa Figueiredo; Felix Carvalho; Cristina Carvalho; Lúcia Guilhermino
      Abstract: Publication date: Available online 20 December 2017
      Source:Aquatic Toxicology
      Author(s): Luís Gabriel Antão Barboza, Luís Russo Vieira, Vasco Branco, Neusa Figueiredo, Felix Carvalho, Cristina Carvalho, Lúcia Guilhermino
      Microplastics pollution is a global paradigm that raises concern in relation to environmental and human health. This study investigated toxic effects of microplastics and mercury in the European seabass (Dicentrarchus labrax), a marine fish widely used as food for humans. A short-term (96 h) laboratory bioassay was done by exposing juvenile fish to microplastics (0.26 and 0.69 mg/L), mercury (0.010 and 0.016 mg/L) and binary mixtures of the two substances using the same concentrations, through test media. Microplastics alone and mercury alone caused neurotoxicity through acetylcholinesterase (AChE) inhibition, increased lipid oxidation (LPO) in brain and muscle, and changed the activities of the energy-related enzymes lactate dehydrogenase (LDH) and isocitrate dehydrogenase (IDH). All the mixtures caused significant inhibition of brain AChE activity (64–76%), and significant increase of LPO levels in brain (2.9–3.4 fold) and muscle (2.2–2.9 fold) but not in a concentration-dependent manner; mixtures containing low and high concentrations of microplastics caused different effects on IDH and LDH activity. Mercury was found to accumulate in the brain and muscle, with bioaccumulation factors of 4–7 and 25–40, respectively. Moreover, in the analysis of mercury concentrations in both tissues, a significant interaction between mercury and microplastics was found. The decay of mercury in the water increased with microplastics concentration, and was higher in the presence of fish than in their absence. Overall, these results indicate that: microplastics influence the bioaccumulation of mercury by D. labrax juveniles; microplastics, mercury and their mixtures (ppb range concentrations) cause neurotoxicity, oxidative stress and damage, and changes in the activities of energy-related enzymes in juveniles of this species; mixtures with the lowest and highest concentrations of their components induced different effects on some biomarkers. These findings and other published in the literature raise concern regarding high level predators and humans consuming fish being exposed to microplastics and heavy metals, and highlight the need of more research on the topic.

      PubDate: 2017-12-23T11:42:57Z
      DOI: 10.1016/j.aquatox.2017.12.008
       
  • The effects of high environmental ammonia on the structure of rainbow
           trout hierarchies and the physiology of the individuals therein
    • Authors: Josias M.B. Grobler; Chris M. Wood
      Abstract: Publication date: Available online 19 December 2017
      Source:Aquatic Toxicology
      Author(s): Josias M.B. Grobler, Chris M. Wood
      Our goals were: (i) to determine whether sublethal concentrations of water-borne ammonia would prevent the formation of a dominance hierarchy, or alter its structure, in groups of 4 juvenile trout; (ii) to investigate the behavioral and physiological responses of individuals of different social rank exposed to a concentration of ammonia that still allowed hierarchy formation. Social hierarchies were created by using a technique in which a food delivery system that created competition also served to isolate individual fish for respirometry. Groups of 4 fish were exposed to elevated ammonia (NH4HCO3) 12 h before first feeding; aggression was recorded by video camera during morning feedings. Experimental ammonia concentrations were 700, 1200 and 1500 μmol L−1 at pH 7.3, 12 °C (9.8, 16.8, and 21.0 mg L−1 as total ammonia-N, or 0.0515, 0.0884, and 0.1105 mg L−1 as NH3 N). Aggression was severely reduced by 1200 and abolished by 1500 μmol L−1 total ammonia, such that hierarchies did not form. However, groups exposed to 700 μmol L−1 total ammonia still formed stable hierarchies but displayed lower levels of aggression in comparison to control hierarchies. Exposure continued for 11 days. Physiological parameters were recorded on day 5 (end of period 1) and day 10 (end of period 2), while feeding and plasma cortisol were measured on day 11. In control hierarchies, dominant (rank 1) trout generally exhibited higher growth rates, greater increases in condition factor, higher food consumption, and lower cortisol levels than did fish of ranks 2, 3, and 4. In comparison to controls, the 700 μmol L−1 total ammonia hierarchies generally displayed lower growth, lower condition factor increases, lower O2 consumption, lower cortisol levels, but similar feeding patterns, with smaller physiological differences amongst ranks during period 1. Effects attenuated during period 2, as aggression and physiological measures returned towards control levels, indicating both behavioral and physiological acclimation to ammonia. These disturbances in social behavior and associated physiology occurred at an ammonia concentration in the range of regulatory significance and relevance to aquaculture.

      PubDate: 2017-12-23T11:42:57Z
      DOI: 10.1016/j.aquatox.2017.12.006
       
  • Transcriptomic analysis reveals transgenerational effect of hypoxia on the
           neural control of testicular functions
    • Authors: Keng Lai; Jing Woei Simon Yuan Wang Miles Teng Wan
      Abstract: Publication date: Available online 16 December 2017
      Source:Aquatic Toxicology
      Author(s): Keng Po Lai, Jing Woei Li, Simon Yuan Wang, Miles Teng Wan, Ting Fung Chan, Wing Yee Lui, Doris Wai-Ting Au, Rudolf Shiu-Sun Wu, Richard Yuen-Chong Kong
      There are over 400 hypoxic zones in the ocean worldwide. Both laboratory and field studies have shown that hypoxia causes endocrine disruption and reproductive impairments in vertebrates. More importantly, our recent study discovered that parental (F0) hypoxia exposure resulted in the transgenerational impairment of sperm quality in the F2 generation through the epigenetic regulation of germ cells. In the present study, we aim to test the hypothesis that the brain, as the major regulator of the brain-pituitary-gonad (BPG) axis, is also involved in the observed transgenerational effect. Using comparative transcriptomic analysis on brain tissues of marine medaka Oryzias melastigma, 45 common differentially expressed genes caused by parental hypoxia exposure were found in the hypoxic group of the F0 and F2 generations, and the transgenerational groups of the F2 generation. The bioinformatic analysis on this deregulated gene cluster further highlighted the possible involvement of the brain in the transgenerational effect of hypoxia on testicular structure, including abnormal morphologies of the epididymis and the seminal vesicle, and degeneration of the seminiferous tubule. This finding is concordant to the result of hematoxylin and eosin staining, which showed the reduction of testicular lobular diameter in the F0 and F2 generations. Our study demonstrated for the first time the involvement of the brain in the transgenerational effect of hypoxia.

      PubDate: 2017-12-23T11:42:57Z
       
  • Induction of oxidative stress by chlorothalonil in the estuarine
           polychaete Laeonereis acuta
    • Authors: Juliano da Silva Barreto; Fabio de Melo Tarouco; Filipe Guilherme Andrade de Godoi; Márcio Alberto Geihs; Fiamma Eugenia Lemos Abreu; Gilberto Fillmann; Juliana Zomer Sandrini; Carlos Eduardo da Rosa
      Abstract: Publication date: Available online 15 December 2017
      Source:Aquatic Toxicology
      Author(s): Juliano da Silva Barreto, Fabio de Melo Tarouco, Filipe Guilherme Andrade de Godoi, Márcio Alberto Geihs, Fiamma Eugenia Lemos Abreu, Gilberto Fillmann, Juliana Zomer Sandrini, Carlos Eduardo da Rosa
      Chlorothalonil is an active biocide applied in antifouling paints, and also used as fungicide in agricultural activities with the purpose to protect plants from foliar and seed diseases. Thus, the aim of this study was to evaluate the effects of chlorothalonil exposure on biochemical biomarkers of oxidative metabolism as well as on cholinesterases in the estuarine polychaete Laeonereis acuta. Animals were exposed for 24 and 96 h to the following nominal concentrations of chlorothalonil: 0.1, 10.0 and 100.0 μg/L. The antioxidant capacity against peroxyl radicals (ACAP) and the activity of the enzymes catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), glutamate cysteine ligase (GCL), acetylcholinesterase (AChE) and propionylcholinesterase (PChE) were evaluated in whole-body tissue. In addition, the levels of reduced glutathione (GSH), lipid peroxidation (LPO), glycogen and lactate levels were also analyzed. A reduction in ACAP levels was observed in animals exposed to the higher chlorothalonil concentration, concomitantly with an induction of GST activity as well as diminution in GSH content in these animals. This disturbance in the redox state of animal tissues leads to an oxidative stress situation, resulting in an induction in LPO levels. It was also demonstrated that chlorothalonil exposure causes alteration in AChE activity, possibly related to damage to membrane lipids. These results demonstrated that chlorothalonil possesses harmful effects to estuarine animals and its use as antifouling biocide has to be carefully reconsidered in risk analysis studies.

      PubDate: 2017-12-23T11:42:57Z
      DOI: 10.1016/j.aquatox.2017.12.004
       
  • Low-dose metformin exposure causes changes in expression of endocrine
           disruption-associated genes
    • Authors: Nicholas J. Niemuth; Rebecca D. Klaper
      Abstract: Publication date: Available online 8 December 2017
      Source:Aquatic Toxicology
      Author(s): Nicholas J. Niemuth, Rebecca D. Klaper
      The presence of intersex fish in watersheds around the world is a warning of the presence of anthropogenic endocrine-disrupting compounds (EDCs) being deposited into the aquatic environment. The anti-diabetic drug metformin is among the most prevalent and ubiquitous of the myriad pharmaceuticals found in wastewater effluent and watersheds worldwide. In addition to its prescription for type-2 diabetes, metformin is indicated as a treatment in cancers and the endocrine disorder polycystic ovarian syndrome (PCOS). Our previous research found evidence of endocrine-disruption following Pimephales promelas (fathead minnow) exposure to metformin at an environmentally relevant concentration. However, the mechanism of action leading to these impacts is unknown. Although metformin does not structurally resemble classical EDCs, there’s an increasing recognition that endocrine disruption may occur by mechanisms other than classical endocrine receptor binding, and metformin’s off-label use for treating endocrine-related disorders such as PCOS indicates its potential interaction with the endocrine system. To further explore metformin’s mechanism of action as an EDC, we measured expression of numerous endocrine-related genes in male fathead minnows exposed to metformin at a low-dose similar to that found in wastewater effluent and the environment (40μgL−1) for a full year (early development to adulthood) and discovered significant upregulation of the AR (3.6±0.9-fold), 3β-HSD (3.9±0.8-fold), 17β-HSD (17±4-fold), CYP19A1 (40±20-fold), and SULT2A1 (2.3±0.4-fold) genes in exposed male gonad. We also found a significant correlation between expression of 3β-HSD, 17β-HSD, and CYP19A1 in testis of metformin-treated male fish and the degree of intersex occurring in their gonads. These results provide additional evidence of the endocrine disrupting impact of the drug metformin and insight into the potential mechanisms by which metformin may influence the endocrine system in aquatic organisms.

      PubDate: 2017-12-12T19:47:48Z
      DOI: 10.1016/j.aquatox.2017.12.003
       
  • 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB), a novel
           perfluorooctane sulfonate alternative, induced developmental toxicity in
           zebrafish embryos
    • Authors: Guohui Shi; Xie Yong Guo Jiayin Dai
      Abstract: Publication date: Available online 7 December 2017
      Source:Aquatic Toxicology
      Author(s): Guohui Shi, Yu Xie, Yong Guo, Jiayin Dai
      6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB) is a major component of Forafac®1157, a novel perfluorooctane sulfonate (PFOS) alternative used globally in aqueous film forming foams (AFFFs). Although 6:2 FTAB has been recently detected in the aquatic environment, its toxic effects on aquatic organisms remain unclear. Here, zebrafish embryos were exposed to various concentrations of 6:2 FTAB (0, 5, 10, 20, 40, 60, 80, and 100mg/L) from 6 to 120h post-fertilization (hpf) to investigate its developmental toxicity and possible mechanism of action. Results showed that exposure to 40mg/L or higher concentrations of 6:2 FTAB significantly decreased the survival percentage and increased the malformation percentage. The median lethal concentration (LC50) at 120 hpf was 43.73±3.24mg/L, and the corresponding benchmark dose lower limit (BMDL) of lethal effect was 33.79mg/L. These values were both higher than those for PFOS, supporting the notion that 6:2 FTAB is less toxic than PFOS to zebrafish embryos. The most common developmental defect in 6:2 FTAB-treated embryos was rough-edged skin/fins. TUNEL assay showed that 6:2 FTAB exposure induced cell apoptosis in the tail region compared with that of the control, which might explain the rough-edged skin/fins. The increased transcriptional levels of p53, bax, and apaf1 and the increased activities of caspase-3, −8, and −9 provided further evidence of 6:2 FTAB-induced apoptosis. We also analyzed the effects of 6:2 FTAB on oxidative stress and the immune system. Results showed that reactive oxygen species and malondialdehyde accumulated in concentration-dependent manners after exposure to 6:2 FTAB, and antioxidant enzyme activities (catalase and glutathione peroxidase) also changed. Exposure to 6:2 FTAB also altered the transcriptional levels of ccl1, il-1β, il-8, tnfα, ifn, and cxcl-c1c, which play important roles in the innate immune system. Collectively, our data suggest that 6:2 FTAB exposure can induce cell apoptosis, oxidative stress, and immunotoxicity, thus highlighting the developmental toxicity of 6:2 FTAB in zebrafish embryos.

      PubDate: 2017-12-12T19:47:48Z
       
  • Estrogenic and anti-androgenic effects of the herbicide tebuthiuron in
           male Nile tilapia (Oreochromis niloticus)
    • Authors: Milena Devechi; Almeida Thiago Scremin Boscolo Pereira Sergio Ricardo Batlouni
      Abstract: Publication date: Available online 14 November 2017
      Source:Aquatic Toxicology
      Author(s): Milena Devechi de Almeida, Thiago Scremin Boscolo Pereira, Sergio Ricardo Batlouni, Camila Nomura Pereira Boscolo, Eduardo Alves de Almeida
      Tebuthiuron is a phenylurea herbicide widely used in agriculture that can reach the aquatic environments, possibly posing negative effects to the aquatic biota. Phenylurea herbicides, such as diuron, are known to cause estrogenic and anti-androgenic effects in fish, but no such effects were yet reported for tebuthiuron exposure. Thus, the aim of this study was to evaluate if tebuthiuron, at environmentally relevant concentrations (100 and 200ng/L) and after 25days of exposure have estrogenic and/or anti-androgenic effects on male of Nile tilapia (Oreochromis niloticus), through the evaluation of plasmatic testosterone (T) and estradiol (E2) levels, brain aromatase (CYP19) levels (western-blot), and by evaluating the histology of the testicles. When compared to the control group, plasmatic T levels decreased about 76% in the animals exposed to 200ng/L of tebuthiuron, while E2 levels increased about 94%, which could be related to a significant increase (77%) in CYP19A1 levels, an enzyme that catalyzes the conversion of androgens into estrogens. Histological analyses of the testicles also demonstrated that tebuthiuron at both tested concentrations caused a decrease in the diameter of the seminiferous tubules and in the diameter of the lumen. Therefore, the gonadosomatic index (GSI) was reduced by 36% % in the animals exposed 200ng/L to tebuthiuron. Indeed, the relative frequency of spermatocytes and spermatids increased respectively 73% (200ng/L) and 61% (100ng/L) in the tebuthiuron exposed animals, possibly due to the impairment of sperm release into the lumen, that was decreased 93% (200ng/L) in the treated animals compared to the control. These results confirm that tebuthiuron causes estrogenic and anti-androgenic effects in Nile tilapias at environmentally relevant concentrations.

      PubDate: 2017-11-19T02:07:15Z
       
  • Effect of Imidacloprid on the Survival of Xenopus Tadpoles Challenged with
           Wild Type Frog Virus 3
    • Authors: Morgan A. Hrynyk; Craig Brunetti; Leslie Kerr; Chris D. Metcalfe
      Abstract: Publication date: Available online 12 November 2017
      Source:Aquatic Toxicology
      Author(s): Morgan A. Hrynyk, Craig Brunetti, Leslie Kerr, Chris D. Metcalfe
      The sensitivity of amphibians to Ranavirus may be increased by exposure to other environmental stressors, including chemical contaminants. Neonicotinoid insecticides comprise 27% of the global insecticide market and have been detected in wetlands and other aquatic habitats. The present study focused on the effects of exposure of pre-metamorphic Xenopus laevis to the neonicotinoid, imidacloprid (IMI) on sensitivity to frog virus 3 (FV3) infection. It was hypothesized that exposure of tadpoles to IMI at sublethal concentrations of 1 and 500μgL−1 would increase FV3 related mortalities relative to tadpole mortalities in a control treatment with only the virus. However, contrary to the predicted outcome, IMI reduced the rates of mortality following viral challenge, although the total mortalities by the 25th day after infection did not differ among the treatments. These results should not be interpreted as an indication that neonicotinoid insecticides are beneficial to aquatic ecosystems, since these insecticides cause toxic responses at low concentrations to other non-target aquatic organisms.

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.11.005
       
  • Gadolinium perturbs expression of skeletogenic genes, calcium uptake and
           larval development in phylogenetically distant sea urchin species
    • Authors: Chiara Martino; Caterina Costa; Maria Carmela Roccheri; Demian Koop; Rosaria Scudiero; Maria Byrne
      Abstract: Publication date: Available online 11 November 2017
      Source:Aquatic Toxicology
      Author(s): Chiara Martino, Caterina Costa, Maria Carmela Roccheri, Demian Koop, Rosaria Scudiero, Maria Byrne
      Chelates of Gadolinium (Gd), a lanthanide metal, are employed as contrast agents for magnetic resonance imaging and are released into the aquatic environment where they are an emerging contaminant. We studied the effects of environmentally relevant Gd concentrations on the development of two phylogenetically and geographically distant sea urchin species: the Mediterranean Paracentrotus lividus and the Australian Heliocidaris tuberculata. We found a general delay of embryo development at 24hours post-fertilization, and a strong inhibition of skeleton growth at 48h. Total Gd and Ca content in the larvae showed a time- and concentration-dependent increase in Gd, in parallel with a reduction in Ca. To investigate the impact of Gd on the expression of genes involved in the regulation of skeletogenesis, we performed comparative RT-PCR analysis and found a misregulation of several genes involved in the skeletogenic and left-right axis specification gene regulatory networks. Species-specific differences in the biomineralization response were evident, likely due to differences in the skeletal framework of the larvae and the amount of biomineral produced. Our results highlight the hazard of Gd for marine organisms.

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.11.004
       
  • Evaluating features of periphytic diatom communities as biomonitoring
           tools in fresh, brackish and marine waters
    • Authors: Lalit K. Pandey; Yogesh Chandra Sharma; Jihae Park; Soyeon Choi; Hojun Lee; Jie Lyu; Taejun Han
      Abstract: Publication date: Available online 10 November 2017
      Source:Aquatic Toxicology
      Author(s): Lalit K. Pandey, Yogesh Chandra Sharma, Jihae Park, Soyeon Choi, Hojun Lee, Jie Lyu, Taejun Han
      The aims of this study were to assess the biodiversity of periphytic diatom assemblages in fresh, brackish and marine waterbodies of Korea, and to assess the effect of environmental and anthropogenic factors on parameters such as the quantity and biovolume of lipid bodies and deformations of diatoms as early warning measures of anthropogenic impact. Diatom samples were collected from 31 sites (14 freshwater, 10 brackish and 7 marine), which included less impacted (upstream) and impacted (downstream) sites in each water type. Our results showed higher abundance and biodiversity of periphytic diatoms at the less impacted sites in terms of species richness, Shannon index, cell count and biovolume of the communities than at the impacted sites for freshwater and estuarine sites, but not for marine sites. 84 diatom species were noted in freshwater, 80 in brackish water and 40 in marine waters. In comparison to diatoms of the impacted sites, those of less impacted freshwater, brackish and marine sites had less lipid bodies (also less biovolume) and a lower percentage of teratological frustules, and showed more mobile forms in the community. Principal component analysis (PCA) also showed clear segregation of impacted from less impacted sites by the extent of the presence of lipid bodies (higher both in number and biovolume) and deformities in diatom frustules. Pearson correlation analysis revealed that lipid body induction and deformities were positively correlated with metals (Cd, Co, Cr, Cu, Fe, Pb and Zn) and nutrients (total phosphorus and total nitrogen), whereas they showed negative correlation with salinity, dissolved oxygen, suspended solutes and pH. Life-forms, lipid bodies and deformities in diatoms may be an effective biomonitoring tool for assessing biological effects of pollutants in non-marine aquatic ecosystems in Korea.
      Graphical abstract image

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.11.003
       
  • The role of the p38-activated protein kinase signaling pathway-mediated
           autophagy in cadmium-exposed monogonont rotifer Brachious koreanus
    • Authors: Hye-Min Kang; Chang-Bum Jeong; Min-Sub Kim; Jin-Sol Lee; Jiaying Zhou; Young Hwan Lee; Duck-Hyun Kim; Eunyoung Moon; Hee-Seok Kweon; Su-Jae Lee; Jae-Seong Lee
      Abstract: Publication date: Available online 10 November 2017
      Source:Aquatic Toxicology
      Author(s): Hye-Min Kang, Chang-Bum Jeong, Min-Sub Kim, Jin-Sol Lee, Jiaying Zhou, Young Hwan Lee, Duck-Hyun Kim, Eunyoung Moon, Hee-Seok Kweon, Su-Jae Lee, Jae-Seong Lee
      Autophagy is a ‘self-eating’ system that regulates the degradation of cellular components and is involved in various biological processes including survival and development. However, despite its crucial role in organisms the regulatory mechanism of autophagy remains largely unclear, particularly in invertebrates. In this study, conserved autophagy in the rotifer Brachionus koreanus in response to cadmium (Cd) exposure was verified by measuring acidic vesicle organelles using acridine orange (AO) and neutral red (NR) staining, and by detecting LC3 I/II on Western blot and immunofluorescence. We also demonstrated activation of p38 mitogen-activated protein kinase (MAPK) in response to Cd-induced oxidative stress, leading to the induction of autophagy in B. koreanus. This was further verified by analysis of MAPK protein levels and immunofluorescence of LC3 I/II after treatment with reactive oxygen species scavengers and inhibitors specific to MAPKs. We propose a p38 MAPK-mediated regulatory mechanism of autophagy in B. koreanus in response to Cd-induced oxidative stress. This study will contribute to a better understanding of autophagic processes in invertebrates and its modulation by environmental stressors.

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.11.002
       
  • Oxidative stress, cell cycle arrest, DNA damage and apoptosis in adult
           zebrafish (Danio rerio) induced by tris(1,3-dichloro-2-propyl) phosphate
    • Authors: Hanyan Chen; Pingping Wang; Zhongkun Du; Guowei Wang; Shixiang Gao
      Abstract: Publication date: Available online 10 November 2017
      Source:Aquatic Toxicology
      Author(s): Hanyan Chen, Pingping Wang, Zhongkun Du, Guowei Wang, Shixiang Gao
      Tris(1,3-dichloro-2-propyl)phosphate (TDCPP) is an additive flame retardant of high production volume, and frequently detected in biota and environment. However, knowledge on its potential risk and toxicological mechanism still remains limited. In this study, DNA damage, transcriptomic responses and biochemical changes in the liver of zebrafish (Danio rerio) induced by TDCPP were investigated. Zebrafish were exposed to 45.81μg/L (1/100 (96h-LC50)) and 229.05μg/L (1/20 (96h-LC50)) TDCPP for 7 d. The reactive oxygen species (ROS) and GSH contents, in addition to antioxidant enzyme activities in the liver changed significantly, and the mRNA levels of genes related to oxidative stress were alerted in a dose-dependent and/or sex-dependent manner after exposure to TDCPP. Significant DNA damage in zebrafish liver was found, and olive tail moment increased in a concentration-dependent manner. Moreover, exposure of TDCPP at 45.81μg/L level activated the cell cycle arrest, DNA repair system and apoptosis pathway in male zebrafish, and 229.05μg/L TDCPP exposure inhibited those pathways in both male and female zebrafish. The cell apoptosis was confirmed in TUNEL assay as higher incidence of TUNEL-positive cells were observed in zebrafish exposed to 229.05μg/L TDCPP. Our results also indicated that males were more sensitive to TDCPP exposure compared with females. Taken together, our results showed that TDCPP could induce oxidative stress, cell cycle arrest, DNA damage and apoptosis in adult zebrafish liver in sex- and concentration-dependent manners.

      PubDate: 2017-11-13T14:06:04Z
      DOI: 10.1016/j.aquatox.2017.11.001
       
 
 
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