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  Subjects -> BIOLOGY (Total: 3003 journals)
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BIOLOGY (1427 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 1720 Journals sorted alphabetically
AAPS Journal     Hybrid Journal   (Followers: 20)
Achievements in the Life Sciences     Open Access   (Followers: 4)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 21)
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: 25)
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: 18)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 6)
Advances in Cell Biology     Open Access   (Followers: 24)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Ecological Research     Full-text available via subscription   (Followers: 41)
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: 7)
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: 1)
Advances in Life Science and Technology     Open Access   (Followers: 14)
Advances in Life Sciences     Open Access   (Followers: 4)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 22)
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3)
Advances in Regenerative Biology     Open Access   (Followers: 1)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Virus Research     Full-text available via subscription   (Followers: 5)
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: 8)
Aging Cell     Open Access   (Followers: 10)
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: 13)
AJP Endocrinology and Metabolism     Full-text available via subscription   (Followers: 22)
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 Biostatistics     Open Access   (Followers: 9)
American Journal of Human Biology     Hybrid Journal   (Followers: 12)
American Journal of Medical and Biological Research     Open Access   (Followers: 6)
American Journal of Plant Sciences     Open Access   (Followers: 19)
American Journal of Primatology     Hybrid Journal   (Followers: 15)
American Malacological Bulletin     Full-text available via subscription   (Followers: 3)
American Naturalist     Full-text available via subscription   (Followers: 69)
Amphibia-Reptilia     Hybrid Journal   (Followers: 6)
Anaerobe     Hybrid Journal   (Followers: 4)
Analytical Methods     Full-text available via subscription   (Followers: 9)
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: 17)
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: 38)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 15)
Annual Review of Genomics and Human Genetics     Full-text available via subscription   (Followers: 19)
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: 30)
Aquatic Ecosystem Health & Management     Hybrid Journal   (Followers: 13)
Aquatic Science and Technology     Open Access   (Followers: 3)
Aquatic Toxicology     Hybrid Journal   (Followers: 19)
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: 7)
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: 2)
Artificial Photosynthesis     Open Access   (Followers: 1)
Asian Bioethics Review     Full-text available via subscription   (Followers: 1)
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: 4)
Avian Conservation and Ecology     Open Access   (Followers: 12)
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: 1)
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)
Biodiversidad Colombia     Open Access  
Biodiversity : Research and Conservation     Open Access   (Followers: 26)
Biodiversity and Natural History     Open Access   (Followers: 5)
Biodiversity Data Journal     Open Access   (Followers: 3)
Biodiversity Informatics     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: 310)
Bioinformatics and Biology Insights     Open Access   (Followers: 15)
Bioinspiration & Biomimetics     Hybrid Journal   (Followers: 6)
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: 16)
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: 42)
Biological Psychology     Hybrid Journal   (Followers: 6)
Biological Research     Open Access  
Biological Rhythm Research     Hybrid Journal   (Followers: 2)
Biological Theory     Hybrid Journal   (Followers: 1)
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: 42)
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  
Biology Direct     Open Access   (Followers: 7)
Biology Letters     Full-text available via subscription   (Followers: 36)

        1 2 3 4 5 6 7 8 | Last

Journal Cover Aquatic Toxicology
  [SJR: 1.671]   [H-I: 105]   [19 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0166-445X - ISSN (Online) 1879-1514
   Published by Elsevier Homepage  [3043 journals]
  • Paternal exposure to environmental 17-alpha-ethinylestradiol
           concentrations modifies testicular transcription, affecting the sperm
           transcript content and the offspring performance in zebrafish
    • Authors: David G. Valcarce; Elena Vuelta; Vanesa Robles; M.Paz Herráez
      Abstract: Publication date: December 2017
      Source:Aquatic Toxicology, Volume 193
      Author(s): David G. Valcarce, Elena Vuelta, Vanesa Robles, Maria Paz Herráez
      The synthetic estrogen 17-α-ethinylestradiol (EE2), a major constituent in contraceptive pills, is an endocrine disrupting chemical (EDC) present in the aquatic environment at concentrations of ng/L. Developmental exposure to these low concentrations in fish can induce several disorders. Zebrafish (Danio rerio) is a perfect organism for monitoring the effects of environmental contaminants. Our hypothesis is that changes promoted by EE2 in the germ line of male adults could be transmitted to the unexposed progeny. We exposed male zebrafish to 2.5, 5 and 10ng/L of EE2 during spermatogenesis and mated them with untreated females. Detailed progeny development was studied concentrating to survival, hatching and malformations. Due to the high incidence of lymphedemas within larvae, we performed qPCR analysis of genes involved in lymphatic development (vegfc and vegfr3) and endothelial cell migration guidance (cxcr4a and cxcl12b). Estrogen receptor (ER) transcript presence was also evaluated in sperm, testis and embryos. Progenies showed a range of disorders although at a low incidence: skeletal distortions, uninflated swimbladder, lymphedema formation, cartilage deformities and otolith tethering. Swimming evaluation revealed less active locomotion. All these processes are related to pathways involving ERs (esr1, esr2a and esr2b). mRNA analysis revealed that environmental EE2 causes the up-regulation of esr1 an esr2b in testis and the increase of esr2b transcripts in sperm pointing to a link between lymphedema in embryos and ER expression impairment. We demonstrate that the effects induced by environmental toxicants can be paternally inherited and point to the changes on the sperm transcriptome as the responsible mechanism.

      PubDate: 2017-10-12T04:47:33Z
      DOI: 10.1016/j.aquatox.2017.09.025
      Issue No: Vol. 193 (2017)
       
  • Variable silver nanoparticle toxicity to Daphnia in boreal lakes
    • Authors: Andrea L. Conine; Daniel C. Rearick; Marguerite A. Xenopoulos; Paul C. Frost
      Pages: 1 - 6
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Andrea L. Conine, Daniel C. Rearick, Marguerite A. Xenopoulos, Paul C. Frost
      Variable sensitivity of organisms to silver nanoparticles (AgNPs) caused by changes in physico-chemical variables in aquatic ecosystems is receiving increasing attention. Variables such as dissolved organic carbon, pH, light, the presence of algae and bacteria, dissolved oxygen and different ions have all been studied individually, but it is still unclear how these variables in combination alter AgNP toxicity in natural ecosystems. Here we examined AgNP toxicity on survival of wild-caught Daphnia using AgNP suspensions placed in water from several different lakes at the IISD-Experimental Lakes Area, which span a gradient of water quality parameters. The partitioning of AgNPs between particulate and dissolved organic matter fractions was also assessed due to the potential for algal sequestration and detoxification of AgNPs. We found that toxicity varied between lakes with LC50 values ranging between 34 and 292μg AgL−1. Time of year in terms of days since ice-off and carbon to nitrogen ratios of particulate matter were the major predictors of toxicity between ecosystems. Total dissolved phosphorus, dissolved organic carbon, and particulate carbon to phosphorus ratios also played minor roles in influencing survival of Daphnia between water types. We found variable partitioning of silver into the particulate fraction within lakes and no significant differences between lakes. Silver associated with particulate organic matter increased with increasing concentrations of AgNPs in the ecosystem. Overall, we found strong evidence that AgNP toxicity is highly context dependent in natural lake ecosystems.

      PubDate: 2017-09-10T21:34:21Z
      DOI: 10.1016/j.aquatox.2017.09.004
      Issue No: Vol. 192 (2017)
       
  • Effects of triphenyltin on reproduction in Japanese medaka (Oryzias
           latipes) across two generations
    • Authors: Yoshifumi Horie; Haruna Watanabe; Hitomi Takanobu; Yoshiko Shigemoto; Takahiro Yamagishi; Taisen Iguchi; Norihisa Tatarazako
      Pages: 16 - 23
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Yoshifumi Horie, Haruna Watanabe, Hitomi Takanobu, Yoshiko Shigemoto, Takahiro Yamagishi, Taisen Iguchi, Norihisa Tatarazako
      Triphenyltin (TPT) is an organotin compound used in marine anti-fouling coatings to prevent the attachment and growth of marine organisms, and it has negative effects on aquatic organisms. TPT is still detected at low concentrations, although its use has been prohibited at least in the European Community and is restricted in Japan as well. Studies using Japanese medaka (Oryzias latipes) indicate that TPT has the potential to inhibit reproduction. Although TPT is detected in many aquatic ecosystems, the multi-generational impact of TPT remains unknown. We investigated the two-generational effects of TPT on Japanese medaka and examined the relationships of several such effects between the F0 and F1 generations. Suppression of fecundity was observed in both generations, and fertility and growth were inhibited in the F1 generation. Moreover, delayed hatching and lower hatchability were observed in F1 embryos. Importantly, the value of the lowest observed effect concentration (LOEC) for these influences in F1 was lower than that in F0: that is, the LOEC values of fecundity and mortality were 3.2μg/L in the F0 generation and 1.0μg/L in the F1 generation. Fertility was not affected by TPT in F0, whereas it was significantly suppressed in the 1.0μg/L-exposure group of the F1 generation. Our results provide the first evidence of the effects of TPT on reproduction in a teleost fish across two generations, highlighting the concern that TPT could affect reproduction and mortality at decreasing concentrations in temporally overlapping generations.

      PubDate: 2017-09-17T01:39:55Z
      DOI: 10.1016/j.aquatox.2017.08.016
      Issue No: Vol. 192 (2017)
       
  • Toxic responses of Perna viridis hepatopancreas exposed to DDT,
           benzo(a)pyrene and their mixture uncovered by iTRAQ-based proteomics and
           NMR-based metabolomics
    • Authors: Qinqin Song; Hailong Zhou; Qian Han; Xiaoping Diao
      Pages: 48 - 57
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Qinqin Song, Hailong Zhou, Qian Han, Xiaoping Diao
      Dichlorodiphenyltrichloroethane (DDT) and benzo(a)pyrene (BaP) are environmental estrogens (EEs) that are ubiquitous in the marine environment. In the present study, we integrated isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic and nuclear magnetic resonance (NMR)-based metabolomic approaches to explore the toxic responses of green mussel hepatopancreas exposed to DDT (10μg/L), BaP (10μg/L) and their mixture. The metabolic responses indicated that BaP primarily disturbed energy metabolism and osmotic regulation in the hepatopancreas of the male green mussel P. viridis. Both DDT and the mixture of DDT and BaP perturbed the energy metabolism and osmotic regulation in P. viridis. The proteomic responses revealed that BaP affected the proteins involved in energy metabolism, material transformation, cytoskeleton, stress responses, reproduction and development in green mussels. DDT exposure could change the proteins involved in primary metabolism, stress responses, cytoskeleton and signal transduction. However, the mixture of DDT and BaP altered proteins associated with material and energy metabolism, stress responses, signal transduction, reproduction and development, cytoskeleton and apoptosis. This study showed that iTRAQ-based proteomic and NMR-based metabolomic approaches could effectively elucidate the essential molecular mechanism of disturbances in hepatopancreas function of green mussels exposed to environmental estrogens.

      PubDate: 2017-09-17T01:39:55Z
      DOI: 10.1016/j.aquatox.2017.09.010
      Issue No: Vol. 192 (2017)
       
  • The impact of acute PAH exposure on the toadfish glucocorticoid stress
           response
    • Authors: Aalekhya Reddam; Edward M. Mager; Martin Grosell; M. Danielle McDonald
      Pages: 89 - 96
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Aalekhya Reddam, Edward M. Mager, Martin Grosell, M. Danielle McDonald
      The objective of the present study was to determine whether the polycyclic aromatic hydrocarbons (PAHs) associated with the Deepwater Horizon (DWH) oil spill impacted the stress response of teleost fish. The hypothesis was that intraperitoneal (IP) treatment with PAHs associated with the DWH oil spill or waterborne exposure to DWH oil high energy water-accommodated fraction (HEWAF) would result in the downregulation of the stress response of Gulf toadfish, Opsanus beta, a benthic marine teleost fish that resides in the Gulf of Mexico. In vivo plasma cortisol levels and adrenocorticotropic hormone (ACTH)-mediated cortisol secretion by in vitro isolated kidney tissue were measured. Toadfish at rest IP-treated with naphthalene had higher plasma cortisol compared to fluorene-treated and control fish; phenanthrene-treated fish tended to have higher plasma cortisol levels that fluorene-treated and controls. When subjected to an additional crowding stress, naphthalene and phenanthrene-treated fish were no longer able to mount a stress response compared to fluorene-treated and control fish, suggesting exhaustion of the stress response. Supporting this in vivo data, there tended to be less cortisol released by the kidney in vitro from naphthalene and phenanthrene-treated fish in response to ACTH compared to controls. In contrast, toadfish at rest exposed to 3% Slick A HEWAF did not have significantly different plasma cortisol levels compared to controls. But, exposed fish did have significantly less cortisol released by the kidney in vitro in response to ACTH. When toadfish were subjected to an additional stress, there were no significant differences in plasma cortisol or ACTH, suggesting the action of a secondary secretagogue to maintain plasma cortisol in vivo. Combined, these data suggest that in response to acute PAH exposure, there may be internalization or downregulation of the melanocortin 2 receptor (MC2R) that mediates the action of ACTH.

      PubDate: 2017-09-22T01:48:55Z
      DOI: 10.1016/j.aquatox.2017.08.014
      Issue No: Vol. 192 (2017)
       
  • Sensitivity and toxic mode of action of dietary organic and inorganic
           selenium in Atlantic salmon (Salmon salar)
    • Authors: M.H.G. Berntssen; T.K. Sundal; P.A. Olsvik; H. Amlund; J.D. Rasinger; V. Sele; K. Hamre; M. Hillestad; L. Buttle; R. Ørnsrud
      Pages: 116 - 126
      Abstract: Publication date: Available online 18 September 2017
      Source:Aquatic Toxicology
      Author(s): M.H.G. Berntssen, T.K. Sundal, P.A. Olsvik, H. Amlund, J.D. Rasinger, V. Sele, K. Hamre, M. Hillestad, L. Buttle, R. Ørnsrud
      Depending on its chemical form, selenium (Se) is a trace element with a narrow range between requirement and toxicity for most vertebrates. Traditional endpoints of Se toxicity include reduced growth, feed intake, and oxidative stress, while more recent finding describe disturbance in fatty acid synthesis as underlying toxic mechanism. To investigate overall metabolic mode of toxic action, with emphasis on lipid metabolism, a wide scope metabolomics pathway profiling was performed on Atlantic salmon (Salmo salar) (572±7g) that were fed organic and inorganic Se fortified diets. Atlantic salmon were fed a low natural background organic Se diet (0.35mg Se kg−1, wet weight (WW)) fortified with inorganic sodium selenite or organic selenomethionine-yeast (SeMet-yeast) at two levels (∼1–2 or 15mgkg−1, WW), in triplicate for 3 months. Apparent adverse effects were assessed by growth, feed intake, oxidative stress as production of thiobarbituric acid-reactive substances (TBARS) and levels of tocopherols, as well as an overall metabolomic pathway assessment. Fish fed 15mgkg−1 selenite, but not 15mgkg−1 SeMet-yeast, showed reduced feed intake, reduced growth, increased liver TBARS and reduced liver tocopherol. Main metabolic pathways significantly affected by 15mgkg−1 selenite, and to a lesser extent 15mgkg−1 SeMet-yeast, were lipid catabolism, endocannabinoids synthesis, and oxidant/glutathione metabolism. Disturbance in lipid metabolism was reflected by depressed levels of free fatty acids, monoacylglycerols and diacylglycerols as well as endocannabinoids. Specific for selenite was the significant reduction of metabolites in the S-Adenosylmethionine (SAM) pathway, indicating a use of methyl donors that could be allied with excess Se excretion. Dietary Se levels to respectively 1.1 and 2.1mgkg−1 selenite and SeMet-yeast did not affect any of the above mentioned parameters. Apparent toxic mechanisms at higher Se levels (15mgkg−1) included oxidative stress and altered lipid metabolism for both inorganic and organic Se, with higher toxicity for inorganic Se.

      PubDate: 2017-09-22T01:48:55Z
      DOI: 10.1016/j.aquatox.2017.09.014
      Issue No: Vol. 192 (2017)
       
  • Salt and cadmium stress tolerance caused by overexpression of the Glycine
           Max Na+/H+ Antiporter (GmNHX1) gene in duckweed (Lemna turionifera 5511)
    • Authors: Lin Yang; Yujie Han; Di Wu; Wang Yong; Miaomiao Liu; Sutong Wang; Wenxin Liu; Meiyi Lu; Ying Wei; Jinsheng Sun
      Pages: 127 - 135
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Lin Yang, Yujie Han, Di Wu, Wang Yong, Miaomiao Liu, Sutong Wang, Wenxin Liu, Meiyi Lu, Ying Wei, Jinsheng Sun
      Cadmium (Cd) pollution has aroused increasing attention due to its toxicity. It has been proved that Na+/H+ Antiporter (NHX1) encodes a well-documented protein in Na+/H+ trafficking, which leads to salt tolerance. This study showed that Glycine max Na+/H+ Antiporter (GmNHX1) improved short-term cadmium and salt resistance in Lemna turionifera 5511. Expression of GmNHX1 prevented root from abscission and cell membrane damage, which also can enhance antioxidant system, inhibited of reactive oxygen species (ROS) accumulation and cause a less absorption of Cd under cadmium and salt stress. The cadmium tolerance suggested that NHX1 was involved under the cadmium stress.

      PubDate: 2017-09-28T10:07:11Z
      DOI: 10.1016/j.aquatox.2017.08.010
      Issue No: Vol. 192 (2017)
       
  • Developmental toxicity and cardiac effects of butyl benzyl phthalate in
           zebrafish embryos
    • Authors: Guijin Sun; Kechun Liu
      Pages: 165 - 170
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Guijin Sun, Kechun Liu
      Phthalic acid esters (PAEs), commonly called phthalates, have become ubiquitous environment pollutants. Studies have focused on reproductive toxicity, neurotoxicity, teratogenicity, tumourigenesis, and mutagenesis of phthalates. However, relatively little is known about the phthalates effects on the heart. Butyl benzyl phthalate (BBP), a member of PAEs, is classified by the US Environmental Protection Agency as a priority environmental pollutant. We studied the developmental toxicity of BBP, especially its effects on the heart development, in zebrafish (Danio rerio) embryos. Embryos at 4hr post-fertilization (hpf) were exposed to 0, 0.1, 0.6 and 1.2mg/L BBP until 72hpf. BBP caused abnormalities in embryo morphology, including yolk-sac edema, spinal curvature, tail deformity, uninflated swim bladder and cardiac defects. Exposure to 0.6mg/L BBP significantly increased the malformation rate, caused growth inhibition, increased the cardiac malformation rate as well as the distance between the sinus venosus (SV) and bulbus arteriosus (BA), and reduced the heart rate of embryos. Exposure to 1.2mg/L BBP significantly affected all endpoints, except survival rate at 24hpf. To preliminarily elucidate the potential mechanism of heart developmental toxicity caused by BBP, we examined the expression of two genes related to heart development, Nkx2.5 and T-box transcription factor 5, by real-time quantitative PCR. The expression of the two genes was dose-dependently downregulated with BBP. BBP could induce developmental toxicity, with adverse effects on the heart development in zebrafish embryos, and alter the expression of genes related to heart development.

      PubDate: 2017-09-28T10:07:11Z
      DOI: 10.1016/j.aquatox.2017.09.020
      Issue No: Vol. 192 (2017)
       
  • Experimentally derived acute and chronic copper Biotic Ligand Models for
           rainbow trout
    • Authors: Anne Crémazy; Chris M. Wood; Tania Y.-T. Ng; D. Scott Smith; M. Jasim Chowdhury
      Pages: 224 - 240
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Anne Crémazy, Chris M. Wood, Tania Y.-T. Ng, D. Scott Smith, M. Jasim Chowdhury
      We evaluated the effects of varying water chemistry ([Ca2+]=0.2–3mM, [Mg2+]=0.05–3mM, dissolved organic matter (DOM, natural, from maple leaves)=0.3–10mg of CL−1, pH=5.0–8.5) on the acute (96-h, unfed fish) and chronic (30-d, fed fish) toxicity of waterborne Cu to juvenile rainbow trout (Oncorhynchus mykiss) exposed in flow-through conditions. Acute and chronic Biotic Ligand Models (BLMs) were developed from the obtained toxicity data-sets, using the Visual MINTEQ software. Our results indicate that Cu is predominantly an acute toxicant to rainbow trout, as there were no observable growth effects and the 96-h and 30-d LC50 values were similar, with mortality mostly occurring within the first few days of exposure. Calcium and DOM were greatly protective against both acute and chronic Cu toxicity, but Mg seemed to only protect against chronic toxicity. Additional protection by pH 5.0 in acute exposure and by pH 8.5 in chronic exposure occurred. In the range of conditions tested, the observed 96-h LC50 and 30-d LC20 values varied by a factor of 39 and 27 respectively. The newly developed acute and chronic BLMs explained these variations reasonably well (i.e. within a 2-fold error), except at pH≥8 where the high observed acute toxicity could not be explained, even by considering an equal contribution of CuOH+ and Cu2+ to the overall Cu toxicity. The 96-h LC50 values of 59% of 90 toxicity tests from 19 independent studies in the literature were reasonably well predicted by the new acute BLM. The LC20 predictions from the new chronic BLM were reasonable for 7 out of 14 toxicity tests from 6 independent chronic studies (with variable exposure durations). The observed deviations from BLM predictions may be due to uncertainties in the water chemistry in these literature studies and/or to differences in fish sensitivity. A residual pH effect was also observed for both the acute and the chronic data-sets, as the ratio of predicted vs. observed LC values generally increased with the pH. Additional mechanistic studies are required to understand the influence of pH, Na, and Mg on Cu toxicity to trout. The present study presents the first experimentally developed chronic Cu BLM for the rainbow trout. To the best of our knowledge, it also presents the first acute Cu BLM that is based on a published data-set for trout. These newly developed BLMs should contribute to improving the risk assessment of Cu to fish in freshwater.

      PubDate: 2017-10-05T10:16:09Z
      DOI: 10.1016/j.aquatox.2017.07.013
      Issue No: Vol. 192 (2017)
       
  • Phytoplankton growth and PSII efficiency sensitivity to a glyphosate-based
           herbicide (Factor 540®)
    • Authors: Élise Smedbol; Marc Lucotte; Michel Labrecque; Laurent Lepage; Philippe Juneau
      Pages: 265 - 273
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Élise Smedbol, Marc Lucotte, Michel Labrecque, Laurent Lepage, Philippe Juneau
      The use of glyphosate-based herbicides in agriculture has increased steadily since the mid 90’s and there is now evidence of glyphosate leaching and contamination of aquatic ecosystems. The aim of this study was to evaluate the effects of a glyphosate-based herbicide (Factor 540®) on growth and photosynthetic capacity of algae and cyanobacteria. Six algal and three cyanobacterial species/strains, of three different taxonomic groups, were exposed to five glyphosate concentrations (10, 50, 100, 500 and 1000μgl−1) during 48h. All species have significant growth inhibition at concentrations varying between 50 and 500μgl−1. The photosynthetic response, after glyphosate exposure, varied among species, but a general pattern has emerged. There was an increase in the amount of photons absorbed (ABS/RC), in dissipated (DIO/RC) and trapped (TRO/RC) energy in the photosystem II reaction centers, along with a decreased of the maximum photosystem II quantum yield (FV/FM) and electron transport per reaction center (ETO/RC). The EC50 and LOEC values for growth and photosynthesis were calculated and established that growth was the most affected parameter by glyphosate-based herbicide, while parameter TRO/RC was the least affected. All species showed reduced growth at glyphosate concentrations lower than the Canadian standard for the protection of aquatic life, set at 800μgl−1 or the American aquatic life benchmark for acute toxicity in non vascular plants of 12 100μgl−1 questioning the validity of these thresholds in assessing the risks related to the presence of glyphosate and glyphosate-based herbicides in aquatic systems.

      PubDate: 2017-10-12T04:47:33Z
      DOI: 10.1016/j.aquatox.2017.09.021
      Issue No: Vol. 192 (2017)
       
  • Global transcriptomic analysis of zebrafish in response to embryonic
           exposure to three antidepressants, amitriptyline, fluoxetine and mianserin
           
    • Authors: Minghong Wu; Shuai Liu; Lei Hu; Haidong Qu; Chenyuan Pan; Penghui Lei; Yingjia Shen; Ming Yang
      Pages: 274 - 283
      Abstract: Publication date: November 2017
      Source:Aquatic Toxicology, Volume 192
      Author(s): Minghong Wu, Shuai Liu, Lei Hu, Haidong Qu, Chenyuan Pan, Penghui Lei, Yingjia Shen, Ming Yang
      Antidepressants are among the most commonly detected pharmaceuticals in aqueous systems, and, as emerging organic pollutants, may exert negative effects on non-target aquatic organisms. Previously, it has been revealed that antidepressant exposure significantly inhibits the growth and development of fish during their early developmental stages. Thus, in the present study, we aimed to identify and compare the underlying mechanisms of action of different antidepressants at the transcriptional level using zebrafish (Danio rerio) embryos. Through high-throughput RNA sequencing (RNA-Seq) data analysis, 32, 34, and 130 differentially expressed genes (DEGs) were obtained from zebrafish larvae after 120h of embryonic exposure to sublethal concentrations of amitriptyline, fluoxetine, and mianserin, respectively. The expression profiles of the identified DEGs showed similar trends in response to the three antidepressant treatments, suggesting consistent toxic effects of low concentrations of these three drugs on the regulation of gene expression in fish. Several metabolic and signaling pathways, including glycolysis/gluconeogenesis and the insulin pathway, were affected in the exposed fish larvae. The expression profiles of selected DEGs were then verified by the qRT-PCR method, which indicated significant positive correlations with the RNA-Seq results. Next, we determined the concentration-dependent expression patterns of 6 selected DEGs in fish larvae exposed to three antidepressants at a series of environmentally relevant concentrations. The results revealed a significant concentration-dependent reduction in the levels of dual-specificity phosphatase 5 (dusp5) mRNA, as well as a non-concentration-dependent gene expression inhibition of prostaglandin D2 synthase b (ptgdsb); the circadian rhythm-related genes, i.e. those encoding nuclear receptor subfamily 1, group D, member 1 (nr1d1) and period 2 (per2); and genes encoding early growth response factors (egr1 and egr4), in the antidepressant-treated fish larvae. In summary, to our knowledge, our findings demonstrate, for the first time, that the three different categories of antidepressants have common effects on the gene expression involved in multiple biological processes and signaling pathways during the early development of fish and thus provide information for characterizing the adverse outcome pathways and on the ecological risk assessment of these pharmaceutical pollutants in the aquatic environment.

      PubDate: 2017-10-12T04:47:33Z
      DOI: 10.1016/j.aquatox.2017.09.027
      Issue No: Vol. 192 (2017)
       
  • A comparative experimental approach to ecotoxicology in shallow-water and
           deep-sea holothurians suggests similar behavioural responses
    • Authors: Alastair Brown; Roseanna Wright; Lisa Mevenkamp; Chris Hauton
      Pages: 10 - 16
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Alastair Brown, Roseanna Wright, Lisa Mevenkamp, Chris Hauton
      Exploration of deep-sea mineral resources is burgeoning, raising concerns regarding ecotoxicological impacts on deep-sea fauna. Assessing toxicity in deep-sea species is technologically challenging, which promotes interest in establishing shallow-water ecotoxicological proxy species. However, the effects of temperature and hydrostatic pressure on toxicity, and how adaptation to deep-sea environmental conditions might moderate these effects, are unknown. To address these uncertainties we assessed behavioural and physiological (antioxidant enzyme activity) responses to exposure to copper-spiked artificial sediments in a laboratory experiment using a shallow-water holothurian (Holothuria forskali), and in an in situ experiment using a deep-sea holothurian (Amperima sp.). Both species demonstrated sustained avoidance behaviour, evading contact with contaminated artificial sediment. However, A. sp. demonstrated sustained avoidance of 5mgl−1 copper-contaminated artificial sediment whereas H. forskali demonstrated only temporary avoidance of 5mgl−1 copper-contaminated artificial sediment, suggesting that H. forskali may be more tolerant of metal exposure over 96h. Nonetheless, the acute behavioural response appears consistent between the shallow-water species and the deep-sea species, suggesting that H. forskali may be a suitable ecotoxicological proxy for A. sp. in acute (≤24h) exposures, which may be representative of deep-sea mining impacts. No antioxidant response was observed in either species, which was interpreted to be the consequence of avoiding copper exposure. Although these data suggest that shallow-water taxa may be suitable ecotoxicological proxies for deep-sea taxa, differences in methodological and analytical approaches, and in sex and reproductive stage of experimental subjects, require caution in assessing the suitability of H. forskali as an ecotoxicological proxy for A. sp. Nonetheless, avoidance behaviour may have bioenergetic consequences that affect growth and/or reproductive output, potentially impacting fecundity and/or offspring fitness, and thus influencing source-sink dynamics and persistence of wider deep-sea populations.

      PubDate: 2017-09-17T01:39:55Z
      DOI: 10.1016/j.aquatox.2017.06.028
      Issue No: Vol. 191 (2017)
       
  • Acute exposure to tris (2-butoxyethyl) phosphate (TBOEP) affects growth
           and development of embryo-larval zebrafish
    • Authors: Yiran Liu; Ding Wu; Qinglong Xu; Liqin Yu; Chunsheng Liu; Jianghua Wang
      Pages: 17 - 24
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Yiran Liu, Ding Wu, Qinglong Xu, Liqin Yu, Chunsheng Liu, Jianghua Wang
      Tris (2-butoxyethyl) phosphate (TBOEP), is used as a flame retardant worldwide. It is an additive in materials and can be easily discharged into the surrounding environment. There is evidence linking TBOEP exposure to abnormal development and growth in zebrafish embryos/larvae. Here, using zebrafish embryo as a model, we investigated toxicological effects on developing zebrafish (Danio rerio) caused by TBOEP at concentrations of 0, 20, 200, 1000, 2000μg/L starting from 2h post-fertilization (hpf). Our findings revealed that TBOEP exposure caused developmental toxicity, such as malformation, growth delay and decreased heart rate in zebrafish larvae. Correlation analysis indicated that inhibition of growth was possibly due to down-regulation of expression of genes related to the growth hormone/insulin-like growth factor (GH/IGF) axis. Furthermore, exposure to TBOEP significantly increased thyroxine (T4) and 3,5,3′-triiodothyronine (T3) in whole larvae. In addition, changed expression of genes involved in the hypothalamic-pituitary-thyroid (HPT) axis was observed, indicating that perturbation of HPT axis might be responsible for the developmental damage and growth delay induced by TBOEP. The present study provides a new set of evidence that exposure of embryo-larval zebrafish to TBOEP can cause perturbation of GH/IGF axis and HPT axis, which could result in developmental impairment and growth inhibition.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.07.015
      Issue No: Vol. 191 (2017)
       
  • Effect of UVB radiation exposure in the expression of genes and proteins
           related to apoptosis in freshwater prawn embryos
    • Authors: Heloísa Schramm; Michael L. Jaramillo; Thaline de Quadros; Eliane C. Zeni; Yara M.R. Müller; Dib Ammar; Evelise M. Nazari
      Pages: 25 - 33
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Heloísa Schramm, Michael L. Jaramillo, Thaline de Quadros, Eliane C. Zeni, Yara M.R. Müller, Dib Ammar, Evelise M. Nazari
      Our previous studies showed that embryos of the freshwater prawn Macrobrachium olfersii exposed to ultraviolet B (UVB) radiation exhibited DNA damage, excessive ROS production, mitochondrial dysfunction and increased hsp70 expression, which are able, independently or together, to induce apoptosis. Thus, we attempted to elucidate some key apoptosis-related genes (ARG) and apoptosis-related proteins (ARP) and their expression during different stages of embryonic development, as well as to characterize the chronology of ARG expression and ARP contents after UVB radiation insult. We demonstrate that p53, Bax and Caspase3 genes are active in the embryonic cells at early embryonic developmental stages, and that the Bcl2 gene is active from the mid-embryonic stage. After UVB radiation exposure, we found an increase in ARP such as p53 and Bak after 3h of exposure. Moreover, an increase in ARG transcript levels for p53, Bax, Bcl2 and Caspase3 was observed at 6h after UVB exposure. Then, after 12h of UVB radiation exposure, an increase in Caspase3 gene expression and protein was observed, concomitantly with an increased number of apoptotic cells. Our data reveal that ARG and ARP are developmentally regulated in embryonic cells of M. olfersii and that UVB radiation causes apoptosis after 12h of exposure. Overall, we demonstrate that embryonic cells of M. olfersii are able to active the cell machinery against environmental changes, such as increased incidence of UVB radiation in aquatic ecosystems.
      Graphical abstract image

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.07.014
      Issue No: Vol. 191 (2017)
       
  • Respiration disruption and detoxification at the protein expression levels
           in the Pacific oyster (Crassostrea gigas) under zinc exposure
    • Authors: Jie Meng; Wen-Xiong Wang; Li Li; Guofan Zhang
      Pages: 34 - 41
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Jie Meng, Wen-Xiong Wang, Li Li, Guofan Zhang
      The Pacific oyster (Crassostrea gigas) can accumulate high levels of zinc (Zn) without obvious toxicity, but the related molecular mechanisms are largely unknown. In the present study, C. gigas were exposed to excess Zn for 9days and the differentially expressed proteins (DEPs) were examined using the isobaric tags for relative and absolute quantitation (iTRAQ) method. In total, 2667 proteins containing at least two peptides and detected in both replicates were used for proteomic analysis. Among these DEPs, 332 were up-regulated and 282 were down-regulated. KEGG enrichment analysis of DEPs revealed that Zn exposure mainly distrubed ‘tricarboxylic acid (TCA) cycle’, ‘electron transport chain (ETC)’ and ‘glutathione (GSH) metabolism’ processes in oysters. Further key protein expressions enriched in these metabolism pathways were analyzed. In TCA cycle, Zn inhibited the Fe-containing protein expressions, which may lead to the accumulation of succinate and induce anaerobiosis. In ETC metabolism process, Zn inhibited ETC complex protein expressions, including complex I–IV, which may affect the electron transport process. Furthermore, Zn induced phytochelatin (PC) and glutathione peroxidase (GPX) expression in GSH catabolism. The proteins play important roles in Zn detoxification and ROS elimination process. The transcriptional expressions of genes encoding these proteins were observed using real-time PCR analysis, and there was good consistency between these two datasets. Overall, we provide direct evidence for Zn toxicity and detoxification mechanisms at protein level.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.07.011
      Issue No: Vol. 191 (2017)
       
  • Chronic endosulfan exposure impairs immune response rendering Clarias
           gariepinus susceptible to microbial infection
    • Authors: Usha Kumari; Rashmi Singh; Shibnath Mazumder
      Pages: 42 - 49
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Usha Kumari, Rashmi Singh, Shibnath Mazumder
      Endosulfan, a persistent organochlorine insecticide affects several off-target organisms including fish though the underlying mechanisms remain obscure. In the present study, we monitored the effect of chronic endosulfan exposure on headkidney (HK), an important immune organ in fish and on fish immune system thereof. Clarias gariepinus were exposed to a non-lethal concentration of endosulfan 2.884ppb (1/10th LC50) for 30 d which resulted in suppressed phagocytosis and bactericidal potential of headkidney macrophages (HKM). The same non-lethal concentration of endosulfan also interfered with T-cell proliferation and serum antibody titer in fish. Endosulfan-exposed fish were challenged with non-lethal dose of fish pathogenic bacteria Aeromonas hydrophila and the ‘exposure-challenge’ study revealed endosulfan-exposed C. gariepinus severely immunocompromised and prone to bacterial infections. Depuration for 30 d suggested that except for phagocytosis and serum agglutination titer other endosulfan-induced immune aberrations could not be restored significantly. Nonetheless, compared to exposed-challenged fish the depurated fish showed significant improvement in viability on challenge with A. hydrophila. Collectively, these findings suggest chronic endosulfan exposure has prolonged effect on fish making them prone to microbial infections.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.07.018
      Issue No: Vol. 191 (2017)
       
  • Effects of phenanthrene on early development of the Pacific oyster
           Crassostrea gigas (Thunberg, 1789)
    • Authors: Diego J. Nogueira; Jacó J. Mattos; Patrick R. Dybas; Fabrıcio Flores-Nunes; Silvio Tarou Sasaki; Satie Taniguchi; Éder C. Schmidt; Zenilda L. Bouzon; Márcia C. Bícego; Claudio M.R. Melo; Guilherme Toledo-Silva; Afonso C.D. Bainy
      Pages: 50 - 61
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Diego J. Nogueira, Jacó J. Mattos, Patrick R. Dybas, Fabrıcio Flores-Nunes, Silvio Tarou Sasaki, Satie Taniguchi, Éder C. Schmidt, Zenilda L. Bouzon, Márcia C. Bícego, Claudio M.R. Melo, Guilherme Toledo-Silva, Afonso C.D. Bainy
      Phenanthnere (PHE) is a polycyclic aromatic hydrocarbon continuously discarded in the marine environment and bioavailable to many aquatic species. Although studies about PHE toxicity have been documented for adult oysters, the effects on early developmental stages are poorly characterized in bivalves. In this study, the effects of PHE (0.02 and 2.0μg.L−1) were evaluated on the embryogenesis and larval development of Crassostrea gigas. Toxicity bioassays, growth and deformities assessment, analysis of shell calcium abundance and transcript levels of genes related to xenobiotic biotransformation (CYP2AU2, CYP30C1), immune system (Cg-Tal) and tissue growth and shell formation (Ferritin, Insulin-like, Cg-Try, Calmodulin and Nacrein) were assayed in D-shape larvae after 24h of PHE exposure. At the highest concentration (2.0μg.L−1), PHE decreased the frequency of normal development (19.7±2.9%) and shell size (53.5±2.8mm). Developmental deformities were mostly related to abnormal mantle and shell formation. Lower calcium levels in oyster shells exposed to PHE 2.0μg.L−1 were observed, suggesting effects on shell structure. At this same PHE concentration, CYP30C1, Cg-Tal, Cg-Tyr, Calmodulin were upregulated and CYP2AU2, Ferritin, Nacrein, and Insulin-Like were downregulated compared to control larvae. At the lowest PHE concentration (0.02μg.L−1), it was observed a minor decrease in normal larval development (89,6±6%) and the remaining parameters were not affected. This is the first study to provide evidences that exposure to PHE can affect early oyster development at the molecular and morphological levels, possibly threatening this bivalve species.

      PubDate: 2017-08-18T13:16:24Z
      DOI: 10.1016/j.aquatox.2017.07.022
      Issue No: Vol. 191 (2017)
       
  • Cytotoxic effects of the proton pump inhibitor omeprazole on the
           non-target marine microalga Tetraselmis suecica
    • Authors: Marta Seoane; Marta Esperanza; Ángeles Cid
      Pages: 62 - 72
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Marta Seoane, Marta Esperanza, Ángeles Cid
      Omeprazole (OMP) is one of the most commonly used drugs for the treatment of gastro-intestinal disorders. Although it is daily consumed in high quantities and commonly detected in waters worldwide, relatively little is known about its ecotoxicity. The aim of this study was to evaluate the potential acute toxicity of increasing concentrations of OMP on the marine microalga Tetraselmis suecica analysing several cytotoxicity biomarkers by flow cytometry after 24h of exposure. Results showed that OMP caused a decrease in growth and autofluorescence, an increase in cellular volume and intracellular complexity, hyperpolarization of cytoplasmic and mitochondrial membranes and intracellular acidification. In addition, large amounts of reactive oxygen species (ROS) were generated which resulted in a decrease in the percentage of the viable population. However, the viable population showed an increase in their metabolic activity as an early response to overcome the stress. In conclusion, OMP may affect proton pumps in non-target organisms such as microalgae; it disturbed pH homeostasis and provoked an early accumulation of ROS that resulted in a rapid cell death in cells exposed to the highest concentration assayed.

      PubDate: 2017-09-17T01:39:55Z
      DOI: 10.1016/j.aquatox.2017.08.001
      Issue No: Vol. 191 (2017)
       
  • Exposure of European sea bass (Dicentrarchus labrax) to chemically
           dispersed oil has a chronic residual effect on hypoxia tolerance but not
           aerobic scope
    • Authors: Yangfan Zhang; Florian Mauduit; Anthony P. Farrell; Denis Chabot; Hélène Ollivier; Adrien Rio-Cabello; Stéphane Le Floch; Guy Claireaux
      Pages: 95 - 104
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Yangfan Zhang, Florian Mauduit, Anthony P. Farrell, Denis Chabot, Hélène Ollivier, Adrien Rio-Cabello, Stéphane Le Floch, Guy Claireaux
      We tested the hypothesis that the chronic residual effects of an acute exposure of European sea bass (Dicentrarchus labrax) to chemically dispersed crude oil is manifest in indices of hypoxic performance rather than aerobic performance. Sea bass were pre-screened with a hypoxia challenge test to establish their incipient lethal oxygen saturation (ILOS), but on discovering a wide breadth for individual ILOS values (2.6–11.0% O2 saturation), fish were subsequently subdivided into either hypoxia sensitive (HS) or hypoxia tolerant (HT) phenotypes, traits that were shown to be experimentally repeatable. The HT phenotype had a lower ILOS and critical oxygen saturation (O2crit) compared with the HS phenotype and switched to glycolytic metabolism at a lower dissolved oxygen, even though both phenotypes accumulated lactate and glucose to the same plasma concentrations at ILOS. As initially hypothesized, and regardless of the phenotype considered, we found no residual effect of oil on any of the indices of aerobic performance. Contrary to our hypothesis, however, oil exposure had no residual effect on any of the indices of hypoxic performance in the HS phenotype. In the HT phenotype, on the other hand, oil exposure had residual effects as illustrated by the impaired repeatability of hypoxia tolerance and also by the 24% increase in O2crit, the 40% increase in scope for oxygen deficit, the 17% increase in factorial scope for oxygen deficit and the 57% increase in accumulated oxygen deficit. Thus, sea bass with a HT phenotype remained chronically impaired for a minimum of 167days following an acute 24-h oil exposure while the HS phenotypes did not. We reasoned that impaired oxygen extraction at gill due to oil exposure activates glycolytic metabolism at a higher dissolved oxygen, conferring on the HT phenotype an inferior hypoxia resistance that might eventually compromise their ability to survive hypoxic episodes.

      PubDate: 2017-08-18T13:16:24Z
      DOI: 10.1016/j.aquatox.2017.07.020
      Issue No: Vol. 191 (2017)
       
  • Time-gated luminescence imaging of singlet oxygen photoinduced by
           fluoroquinolones and functionalized graphenes in Daphnia magna
    • Authors: Tianlie Luo; Jingwen Chen; Bo Song; Hua Ma; Zhiqiang Fu; Willie J.G.M. Peijnenburg
      Pages: 105 - 112
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Tianlie Luo, Jingwen Chen, Bo Song, Hua Ma, Zhiqiang Fu, Willie J.G.M. Peijnenburg
      Singlet oxygen (1O2) can be photogenerated by photoactive xenobiotics and is capable of causing adverse effects due to its electrophilicity and its high reactivity with biological molecules. Detection of the production and distribution of 1O2 in living organisms is therefore of great importance. In this study, a luminescent probe ATTA-Eu3+ combined with time-gated luminescence imaging was adopted to detect the distribution and temporal variation of 1O2 photoinduced by fluoroquinolone antibiotics and carboxylated/aminated graphenes in Daphnia magna. Results show that the xenobiotics generate 1O2 in living daphnids under simulated sunlight irradiation (SSR). The photogeneration of 1O2 by carboxylated/aminated graphenes was also confirmed by electron paramagnetic resonance spectroscopy. The strongest luminescence signals of 1O2 were observed in the hindgut of daphnids, and the signals in different areas of the daphnids (gut, thoracic legs and post-abdominal claw) displayed a similar trend of enhancement over irradiation time. Mean 1O2 concentrations at different regions of daphnids within one hour of SSR irradiation were estimated to be in the range of 0.5∼4.8μM. This study presented an efficient method for visualizing and quantifying the temporal and spatial distribution of 1O2 photogenerated by xenobiotics in living organisms, which can be employed for phototoxicity evaluation of xenobiotics.
      Graphical abstract image

      PubDate: 2017-08-18T13:16:24Z
      DOI: 10.1016/j.aquatox.2017.07.016
      Issue No: Vol. 191 (2017)
       
  • Omics tools: New challenges in aquatic nanotoxicology'
    • Authors: Messika Revel; Amélie Châtel; Catherine Mouneyrac
      Abstract: Publication date: Available online 12 October 2017
      Source:Aquatic Toxicology
      Author(s): Messika Revel, Amélie Châtel, Catherine Mouneyrac
      In recent years, the implication of genomics into ecotoxicological studies has been studied closely to allow a better understanding of organism’s responses to environmental contaminants including engineering nanomaterials (ENMs). ENMs are increasingly produced for various applications including cosmetics, electronics, sports equipment, biomedicine and agriculture. Because of their small size, ENMs possess chemical or physical characteristics improved compared to the corresponding macro-sized material. As their application expend, the release of manufactured ENMs into the environment is likely to increase and concern over impacts for the aquatic ecosystem is growing. Several studies reported deleterious effect of ENMs to aquatic organisms, but there is little information about the molecular mechanisms of toxicity. The development of ecotoxicogenomic approaches will improve the characterization of cellular and molecular modes of action of ENMs to aquatic organisms and allow a better prediction of contaminants toxicity. This paper presents an overview of transciptomic/proteomic studies in freshwater and marine organisms exposed to ENMs. Overall, induction of gene expression in relations to defense mechanisms, immune responses, growth and reproduction were measured after ENMs exposures of organisms, but with different patterns depending on exposure duration and concentrations used. In addition, some studies reported a positive correlation between gene expression and cellular modifications, but not at the individual level.

      PubDate: 2017-10-14T04:48:31Z
      DOI: 10.1016/j.aquatox.2017.10.005
       
  • mPhysiological impacts of acute Cu exposure on deep-sea vent mussel
           Bathymodiolus azoricus under a deep-sea mining activity scenario
    • Authors: Inês Martins; Joana Goulart; Eva Martins; Rosa Morales-Román; Sergio Marín; Virginie Riou; Ana Colaço; Raul Bettencourt
      Abstract: Publication date: Available online 9 October 2017
      Source:Aquatic Toxicology
      Author(s): Inês Martins, Joana Goulart, Eva Martins, Rosa Morales-Román, Sergio Marín, Virginie Riou, Ana Colaço, Raul Bettencourt
      Over the past years, several studies have been dedicated to understanding the physiological ability of the vent mussel Bathymodiolus azoricus to overcome the high metal concentrations present in their surrounding hydrothermal environment. Potential deep-sea mining activities at Azores Triple junction hydrothermal vent deposits would inevitably lead to the emergence of new fluid sources close to mussel beds, with consequent emission of high metal concentrations and potential resolubilization of Cu from minerals formed during the active phase of the vent field. Copper is an essential metal playing a key role in the activation of metalloenzymes and metalloproteins responsible for important cellular metabolic processes and tissue homeostasis. However, excessive intracellular amounts of reactive Cu ions may cause irreversible damages triggering possible cell apoptosis. In the present study, B. azoricus was exposed to increasing concentrations of Cu for 96h in conditions of temperature and hydrostatic pressure similar to those experienced at the Lucky Strike hydrothermal vent field. Specimens were kept in 1L flasks, exposed to four Cu concentrations: 0μg/L (control), 300, 800 and 1600μg/L and pressurized to 1750bar. We addressed the question of how increased Cu concentration would affect the function of antioxidant defense proteins and expression of antioxidant and immune-related genes in B. azoricus. Both antioxidant enzymatic activities and gene expression were examined in gills, mantle and digestive gland tissues of exposed vent mussels. Our study reveals that stressful short-term Cu exposure has a strong effect on molecular metabolism of the hydrothermal vent mussel, especially in gill tissue. Initially, both the stress caused by unpressurization or by Cu exposure was associated with high antioxidant enzyme activities and tissue-specific transcriptional up-regulation. However, mussels exposed to increased Cu concentrations showed both antioxidant and immune-related gene suppression. Under a mining activity scenario, the release of an excess of dissolved Cu to the vent environment may cause serious changes in cellular defense mechanisms of B. azoricus. This outcome, while adding to our knowledge of Cu toxicity, highlights the potentially deleterious impacts of mining activities on the physiology of deep-sea organisms.

      PubDate: 2017-10-12T04:47:33Z
      DOI: 10.1016/j.aquatox.2017.10.004
       
  • Alterations to Juvenile Zebrafish (Danio rerio) Swim Performance after
           Acute Embryonic Exposure to Sub-lethal Exposures of Hydraulic Fracturing
           Flowback and Produced Water
    • Authors: Erik J. Folkerts; Tamzin A. Blewett; Yuhe He; Greg G. Goss
      Abstract: Publication date: Available online 7 October 2017
      Source:Aquatic Toxicology
      Author(s): Erik J. Folkerts, Tamzin A. Blewett, Yuhe He, Greg G. Goss
      Hydraulic fracturing flowback and produced water (FPW) is a wastewater produced during fracturing activities in an operating well which is hyper saline and chemically heterogeneous in nature, containing both anthropogenic and petrogenic chemicals. Determination of FPW associated toxicity to embryonic fish is limited, while investigation into how embryonic exposures may affect later life stages is not yet studied. Juvenile zebrafish embryos (24hrs post fertilization) were acutely exposed to 2.5% and 5% FPW fractions for either 24 or 48hrs and returned to freshwater. After either 24 or 48h exposures, embryos were examined for expression of 3 hypoxia related genes. Erythropoietin (epoa) but not hypoxia inducible factor (hif1aa) nor hemoglobin −ß chain (hbbe1.1) was up-regulated after either 24 or 48h FPW exposure. Surviving embryos were placed in freshwater and grown to a juvenile stage (60days post fertilization). Previously exposed zebrafish were analyzed for both swim performance (Ucrit and Umax ) and aerobic capacity. Fish exposed to both sediment containing (FPW-S) or sediment free (FPW-SF) FPW displayed significantly reduced aerobic scope and Ucrit /Umax values compared to control conditions. Our results collectively suggest that organics present in our FPW sample may be responsible for sub-lethal fitness and metabolic responses. We provide evidence supporting the theory that the cardio-respiratory system is impacted by FPW exposure. This is the first known research associating embryonic FPW exposures to sub-lethal performance related responses in later life fish stages.

      PubDate: 2017-10-12T04:47:33Z
      DOI: 10.1016/j.aquatox.2017.10.003
       
  • Endocrine disruptors affect larval zebrafish behavior: Testing potential
           mechanisms and comparisons of behavioral sensitivity to alternative
           biomarkers
    • Authors: Thomas W.K. Fraser; Abdolrahman Khezri; Anna M. Lewandowska-Sabat; Theodore Henry; Erik Ropstad
      Abstract: Publication date: Available online 6 October 2017
      Source:Aquatic Toxicology
      Author(s): Thomas W.K. Fraser, Abdolrahman Khezri, Anna M. Lewandowska-Sabat, Theodore Henry, Erik Ropstad
      Larval zebrafish (Danio rerio) are a tool for assessing endocrine disruption during early development. Here, we investigated the extent to which a simple light/dark behavioral test at five days post fertilization could compliment current methods within the field. We exposed fertilized embryos to hormones (17β-estradiol, testosterone, dihydrotestosterone, 11-ketotestosterone, thyroxine, triiodothyronine, progesterone, and hydrocortisone) and other relevant compounds (17α ethinylestradiol, bisphenol A, bisphenol S, nonylphenol, flutamide, nilutamide, linuron, drospirenone, potassium perchlorate, mifepristone, and fadrozole) to screen for behavioral effects between 96 and 118hours post fertilization (hpf). With the exception of progesterone, all the hormones tested resulted in altered behaviors. However, some inconsistencies were observed regarding the age of the larvae at testing. For example, the xenoestrogens 17α- ethinylestradiol and nonylphenol had behavioral effects at 96 hpf, but not at 118 hpf. Furthermore, although thyroxine exposure had pronounced effects on behavior, the thyroid disruptor potassium perchlorate did not. Finally, we were unable to demonstrate a role of nuclear receptors following testosterone and 17α- ethinylestradiol exposure, as neither the androgen receptor antagonist flutamide nor the general estrogen receptor inhibitor fulvestrant (ICI) could rescue the observed behavioral effects, respectively. Similarly, molecular markers for androgen and estrogen disruption were upregulated at concentrations below which behavioral effects were observed. These results demonstrate hormones and endocrine disruptors can alter the behavior of larval zebrafish, but the mechanistic pathways remain unclear.

      PubDate: 2017-10-12T04:47:33Z
      DOI: 10.1016/j.aquatox.2017.10.002
       
  • Combinatory effects of low concentrations of 17α-etinylestradiol and
           citalopram on non-reproductive behavior in adult zebrafish (Danio rerio)
    • Authors: Tove Porseryd; Martin Kellner Nasim Reyhanian Caspillo Kristina Volkova Lubna
      Abstract: Publication date: Available online 4 October 2017
      Source:Aquatic Toxicology
      Author(s): Tove Porseryd, Martin Kellner, Nasim Reyhanian Caspillo, Kristina Volkova, Lubna Elabbas, Shahid Ullah, Håkan Olsén, Patrik Dinnétz, Inger Porsch Hällström
      Sewage effluents contain pharmaceuticals, personal care products and industrial chemicals, exposing aquatic organisms to complex mixtures. The consequences of exposure to combinations of different classes of drugs in fish are largely unknown. In this study, we exposed adult zebrafish (Danio rerio) males and females for two weeks to low, environmentally relevant concentrations of the endocrine disrupting chemical 17α-etinylestradiol (EE2) and the selective serotonin re-uptake inhibitor (SSRI) citalopram, alone and in combination, and analyzed behaviors of importance for population fitness, scototaxis (light/dark preference), the novel tank test and shoal cohesion. Control water contained 0.4ng/L EE2 and the measured exposure concentrations were 0.9ng/L EE2 (nominal 0.1) and 1ng/L EE2 (nominal 0.5). The measured concentrations of citalopram were 0.1 (nominal 0.1) and 0.4μg/L (nominal 0.5). Both EE2 exposures increased anxiety in males in the scototaxis test, with significantly longer latency periods before entering and fewer visits to the white zone of the tank. The combined exposures (0.9ng/L EE2 +0.1μg/L citalopram and 1ng/L EE2 +0.4μg/L citalopram) resulted in abolishment of effects of EE2, with shorter latency period and more transitions to white than for fish exposed to EE2 alone. In the novel tank test, the results surprisingly indicated lower anxiety after both EE2 and citalopram exposure. Significantly more transitions to the upper half of the tank observed in males exposed to 0.1μg/L citalopram alone compared to control males. Males exposed to EE2 (0.9ng/L) had shorter latency period to the upper half. Combination exposure resulted in a longer latency and fewer transitions to the upper half compared to both control, EE2- and citalopram-exposed males. Males exposed to the combination spent significantly less time in the upper half than males EE2 or citalopram-exposed males. Females exposed to 1ng/L EE2 had fewer transitions to the upper half than the control group and females exposed to 0.4μg/L citalopram. In the shoaling test, males exposed to 0.1μg/L citalopram+0.9ng/l EE2 showed more transitions away from peers than males exposed to 0.1μg/L citalopram alone. In conclusion, low concentrations of EE2, closely above the predicted no effect concentration (NOEC) of 0.1ng/L, created anxiety-like behavior in zebrafish males. Citalopram showed marginal effects at these low concentrations but in the combination exposure the behavioral effects of EE2 were abolished. This is an initial effort to understand the effects of cocktails of anthropogenic substances contaminating aquatic environments.

      PubDate: 2017-10-05T10:16:09Z
       
  • Combined Toxicity of Prevalent Mycotoxins Studied in Fish Cell Line and
           Zebrafish Larvae Revealed that Type of Interactions is Dose-dependent
    • Authors: Hongyuan Zhou; Saji George; Caixia Li; Subramaniam Gurusamy; Xiulan Sun; Zhiyuan Gong; He Qian
      Abstract: Publication date: Available online 3 October 2017
      Source:Aquatic Toxicology
      Author(s): Hongyuan Zhou, Saji George, Caixia Li, Subramaniam Gurusamy, Xiulan Sun, Zhiyuan Gong, He Qian
      While, Aflatoxin B1 (AFB1), deoxynivalenol (DON) and zearalenone (ZEN) are the most prevalent mycotoxins co-existing in grain products and animal feeds, little is known about their combinatorial toxicities on aquatic life-forms. We studied the individual and combined effects of these mycotoxins in a fish cell line (BF-2) and zebrafish larvae (wild-type and transgenic). The types of interactions in mycotoxins combinations on cell viability were determined by using Chou-Talalay model. Induction of oxidative stress pathway in mycotoxins-exposed BF-2 cells was assessed using high content screening (HCS). Mycotoxin-exposed wild-type zebrafish larvae were examined for mortality and morphological abnormalities and transgenic zebrafish larvae (expressing DsRed in the liver) were imaged using HCS and examined for liver abnormalities. Results showed that the cytotoxicity of mycotoxins in a decreasing order was AFB1 >DON>ZEN, however, the highest mortality rate and liver damage in zebrafish were observed for AFB1 followed by ZEN. AFB1 +DON and AFB1 +ZEN synergistically enhanced the toxic effects on BF-2 cells and zebrafish while DON+ZEN showed antagonism. Interestingly, in the tertiary combination, the synergism seen at lower individual concentrations of mycotoxins progressively turned to an overall antagonism at higher doses. The results provide a scientific basis for the necessity to consider co-exposure when formulating risk-management strategies.

      PubDate: 2017-10-05T10:16:09Z
      DOI: 10.1016/j.aquatox.2017.09.030
       
  • Effects of benzophenone-3 on the green alga Chlamydomonas reinhardtii and
           the cyanobacterium Microcystis aeruginosa
    • Authors: Feijian Mao; Yiliang He; Ariel Kushmaro; Karina Yew-Hoong Gin
      Abstract: Publication date: Available online 2 October 2017
      Source:Aquatic Toxicology
      Author(s): Feijian Mao, Yiliang He, Ariel Kushmaro, Karina Yew-Hoong Gin
      Effects of benzophenone-3 (BP-3) on the green alga, Chlamydomonas reinhardtii, and the cyanobacterium, Microcystis aeruginosa, were investigated. The tested organisms were exposed to environmental levels of BP-3 for 10 days, at nominal concentrations from 0.01 to 5000μgL−1. Specific growth rate and photosynthetic pigments were employed to evaluate the toxic responses. The two tested algae had distinct toxic responses towards BP-3 stress, with the green alga C. reinhardtii being more sensitive than the cyanobacterium M. aeriginosa, based on EC20 and EC50 values. Uptake of BP-3 from the medium occurred in both species, with M. aeruginosa showing greater overall uptake (27.2-77.4%) compared to C. reinhardtii (1.1-58.4%). The effects of BP-3 on C. reinhardtii were variable at concentrations lower than 100μgL−1. At higher concentrations, the specific growth rate of C. reinhardtii decreased following a reduction in chlorophyll a (chl-a) content. Further experiments showed that BP-3 regulated the growth of C. reinhardtii by affecting the production of chl-a, chlorophyll b and carotenoids. In M. aeruginosa, specific growth rate was only moderately affected by BP-3. Additionally, the production of chl-a was significantly inhibited over the different exposure concentrations, while the production of carotenoids was stimulated. These results indicate a potential detrimental effect on prokaryotes and eukaryotes and that the mechanism of action varies with species.

      PubDate: 2017-10-05T10:16:09Z
      DOI: 10.1016/j.aquatox.2017.09.029
       
  • Inter- and intra-specific competition of duckweed under multiple heavy
           metal contaminated water
    • Authors: Zhao Zhao; Huijuan Shi; Xianjiang Kang; Cunqi Liu; Lingci Chen; Xiaofei Liang; Lei Jin
      Abstract: Publication date: Available online 27 September 2017
      Source:Aquatic Toxicology
      Author(s): Zhao Zhao, Huijuan Shi, Xianjiang Kang, Cunqi Liu, Lingci Chen, Xiaofei Liang, Lei Jin
      The influences of intra- and inter-species competition on ecosystems are poorly understood. Lemna aequinoctialis and Spirodela polyrhiza were used to assess the effects of exposure to different concentrations of multiple heavy metals (copper-cadmium-zinc), when the plants were grown in mixed- or mono-culture. Parameters assessed included relative growth rate (RGR), content of chlorophyll, glutathione (GSH), malondialdehyde (MDA), as well as the activity of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD). Inter-specific competition was affected by metal concentration, with results indicating that inter-specific competition significantly affected duckweed growth and metal uptake in different heavy metal exposure conditions. Inter-specific competition increased growth rate of duckweed under high metal concentrations, although when compared with intra-specific competition, it caused no obvious differences under low metal concentrations. The growth of L. aequinoctialis was further increased in mixed culture when exposed to high metal concentrations, with inter-specific competition increasing the content of cadmium and zinc, while decreasing copper content of L. aequinoctialis compared with under intra-specific conditions. Conversely, inter-specific competition increased the content of copper and cadmium of S. polyrhiza, without causing obvious differences in zinc accumulation under high ambient concentrations. Under high metal conditions, inter-specific competition increased antioxidant enzyme activities in duckweed species, increasing resistance to heavy metals. Results show that inter-specific competition makes duckweed develop mechanisms to increase fitness and survival, such as enhancement of antioxidant enzyme activities, rather than limiting metal uptake when exposed to high concentrations of multiple metals.

      PubDate: 2017-09-28T10:07:11Z
      DOI: 10.1016/j.aquatox.2017.09.023
       
  • Effect of cadmium on oxidative stress and immune function of common carp
           (Cyprinus carpio L.) by transcriptome analysis
    • Authors: Ziwei Zhang; Zhi Zheng; Jingzeng Cai; Qi Liu; Jie Yang; Yafan Gong; Meishan Wu; Qiang Shen; Shiwen Xu
      Abstract: Publication date: Available online 23 September 2017
      Source:Aquatic Toxicology
      Author(s): Ziwei Zhang, Zhi Zheng, Jingzeng Cai, Qi Liu, Jie Yang, Yafan Gong, Meishan Wu, Qiang Shen, Shiwen Xu
      Cadmium (Cd) is an increasingly important environmental pollutant which causes irreversible toxicity to fish. To understand how Cd impacts the immune response and oxidative stress in common carp, we performed transcriptomic profiles for head kidney, the immune organ of common carp which were underwent Cd exposure. Totally there are 42,489,124 and 48,562,526 high quality clean reads obtained from the Cd exposure groups, and 44,677,578 and 44,106,696 clean reads from the control groups. Among them, 308 genes were differently expressed, including 101 upregulated and 207 down-regulated genes. The identified genes were enriched using databases of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Antioxidant systems and immune function genes and pathways were identified and validated by quantitative real-time RT-PCR. Our results showed that Cd exposure leads to oxidative stress and immunosuppression in head kidney of common carp. These results provide new insights for unveiling the biological effects of Cd in common carp.

      PubDate: 2017-09-28T10:07:11Z
      DOI: 10.1016/j.aquatox.2017.09.022
       
  • Does wastewater treatment plant upgrading with activated carbon result in
           an improvement of fish health'
    • Authors: Sabrina Wilhelm; Anja Henneberg; Heinz-R. Köhler; Magali Rault; Doreen Richter; Marco Scheurer; Séverine Suchail; Rita Triebskorn
      Abstract: Publication date: Available online 21 September 2017
      Source:Aquatic Toxicology
      Author(s): Sabrina Wilhelm, Anja Henneberg, Heinz-R. Köhler, Magali Rault, Doreen Richter, Marco Scheurer, Séverine Suchail, Rita Triebskorn
      In the present study, the efficiency of a wastewater treatment plant (WWTP) upgraded with a powdered activated carbon unit for the reduction of micropollutants and the related advantages for fish health have been analyzed by means of different biomarkers, i.e. histopathological investigations, analyses of glycogen content and stress proteins, as well as by chemical analyses in different matrices. Comparative analyses were conducted prior and subsequent to the installation of the additional purification unit. Chemical analyses revealed a significant reduction of several pharmaceuticals, including diclofenac, carbamazepine and metoprolol, in samples of effluent and surface water downstream of the WWTP after its upgrade. In addition, diminished concentrations of diclofenac and PFOS were detected in tissues of analyzed fish. Histopathological investigations of fish liver, gills, and kidney revealed improved tissue integrity in fish after improved wastewater treatment. In parallel, biochemical measurements of glycogen revealed increased energy resources in fish liver and, furthermore, hsp70 levels in livers of exposed rainbow trout and in kidneys of exposed brown trout were lower after than before the WWTP upgrade. In summary, additional treatment with powdered activated carbon led to a reduction of potentially hazardous chemicals in the effluent and the adjacent river and, consequently, to an improvement of fish health in the receiving water course.

      PubDate: 2017-09-22T01:48:55Z
      DOI: 10.1016/j.aquatox.2017.09.017
       
  • Copper Impairs Zebrafish Swimbladder Development by Down-regulating Wnt
           Signaling
    • Authors: JiangPing Xu; RuiTao Zhang; Ting Zhang; Guang Zhao; Yan Huang; HuanLing Wang; Jing-Xia Liu
      Abstract: Publication date: Available online 21 September 2017
      Source:Aquatic Toxicology
      Author(s): JiangPing Xu, RuiTao Zhang, Ting Zhang, Guang Zhao, Yan Huang, HuanLing Wang, Jing-Xia Liu
      Copper nanoparticles (CuNPs) are used widely in different fields due to their attractive and effective abilities in inhibiting bacteria and fungi, but little information is available about their biological effects and potential molecular mechanisms on fish development. Here, CuNPs and copper (II) ions (Cu2+) were revealed to inhibit the specification and formation of three layers of zebrafish embryonic posterior swimbladder and impair its inflation in a stage-specific manner. CuNPs and Cu2+ were also revealed to down-regulate Wnt signaling in embryos. Furthermore, Wnt agonist 6-Bromoindirubin-3′-oxime (BIO) was found to neutralize the inhibiting effects of CuNPs or Cu2+ or both on zebrafish swimbladder development. The integrated data here provide the first evidence that both CuNPs and Cu2+ act on the specification and growth of the three layers of swimbladder and inhibit its inflation by down-regulating Wnt signaling in a stage-specific manner during embryogenesis.

      PubDate: 2017-09-22T01:48:55Z
      DOI: 10.1016/j.aquatox.2017.09.018
       
  • Relationship between genotoxicity and oxidative stress induced by mercury
           on common carp (Cyprinus carpio) tissues
    • Authors: Sandra García-Medina; Marcela Galar-Martínez; Leobardo Manuel Gómez-Oliván; Karina Ruiz-Lara; Hariz Islas-Flores; Eloy Gasca-Pérez
      Abstract: Publication date: Available online 21 September 2017
      Source:Aquatic Toxicology
      Author(s): Sandra García-Medina, Marcela Galar-Martínez, Leobardo Manuel Gómez-Oliván, Karina Ruiz-Lara, Hariz Islas-Flores, Eloy Gasca-Pérez
      Mercury is one of the most toxic metals in aquatic systems since it is able to induce neurobehavioral disorders as well as renal and gastrointestinal tract damage. The common carp Cyprinus carpio is an important species from both an ecological and economic viewpoint as it is consumed in many countries, the top producers being Mexico, China, India and Japan. The present study aimed to evaluate the relation between Hg-induced oxidative stress and genotoxicity in diverse tissues of C. carpio. Specimens were exposed to 0.01mg Hg/L (the maximum permissible limit for aquatic life protection), and lipid peroxidation, protein carbonyl content and the activity of antioxidant enzymes were evaluated at 96h. Micronuclei frequency and DNA damage by comet assay were determined at 12, 24, 48, 72 and 96h. Hg induced oxidative stress and genotoxicity on exposed fish, since inhibition of antioxidant enzymes activity and increases in lipid peroxidation, DNA damage and micronuclei frequency occurred. Blood, gill and liver were more susceptible to oxidative stress, while blood were more sensitive to genotoxicity. In conclusion, Hg at concentrations equal to the maximum permissible limit for aquatic life protection induced oxidative stress and genotoxicity on C. carpio, and these two effects prove to be correlated.
      Graphical abstract image

      PubDate: 2017-09-22T01:48:55Z
      DOI: 10.1016/j.aquatox.2017.09.019
       
  • Toxicological effects of paracetamol on the clam Ruditapes philippinarum:
           exposure vs recovery
    • Authors: Bruno Nunes; Joana Nunes; Amadeu M.V.M. Soares; Etelvina Figueira; Rosa Freitas
      Abstract: Publication date: Available online 20 September 2017
      Source:Aquatic Toxicology
      Author(s): Bruno Nunes, Joana Nunes, Amadeu M.V.M. Soares, Etelvina Figueira, Rosa Freitas
      Exposure of wild organisms to anthropogenic substances never follows a definite time-course and pulsed events can often determine biological responses to such chemicals, confounding the interpretation of toxicological data. This is the case of specific chemicals such as pharmaceutical drugs, which are commonly released by sewage systems into sensitive areas, including estuaries. The presence and amount of these chemicals in the wild can be modulated by events such as dilution due to heavy rain, floods, or by varying patterns of domestic water use (daily vs. seasonal). The present study aimed to obtain additional data about the toxicity of paracetamol towards the marine clam species Ruditapes philippinarum, following realistic modes of exposure. Thus, the toxicity assessment was made after an acute exposure to different concentrations of paracetamol, followed by a recovery period. The adopted toxicological endpoints included energy-related parameters (glycogen content, GLY; protein content, PROT; electron transport system activity, ETS), activity of antioxidant and biotransformation enzymes (superoxide dismutase, SOD; glutathione peroxidase, GPx; Glutathione-S-transferases, GSTs), levels of reduced glutathione (GSH), neurotoxicity (cholinesterase activity, ChE), and indicators of oxidative damage (lipid peroxidation, LPO). The here obtained results showed an increase in SOD and GPx activities after exposure. In organisms exposed to the highest concentration tested it was also possible to observe a significant increase in GST activity. However, these alterations in the antioxidant defence system were not able to prevent the occurrence of oxidative stress in exposed organisms. Furthermore, exposure to paracetamol induced neurotoxicity in clams, with a concentration-dependent ChE inhibition along the exposure concentrations. Exposure to paracetamol also led to an increase of GLY content which resulted from metabolic activity depression along the increasing exposure gradient. In recovering organisms the activities of SOD, GPx and GSTs decreased back towards control values presenting lower values than the ones observed in organisms after acute exposure to paracetamol. No LPO was registered in organisms after the recovery period. In addition, after recovery, clams showed no signs of neurotoxicity, with ChE activities in previously exposed organisms similar to control clams. After recovery clams seemed to re-establish their metabolic capacity, especially evidenced in clams previously exposed to the highest paracetamol concentration as demonstrated by the increase of ETS activity up to control values. Furthermore, the decrease of GLY content after recovery may indicate that clams increase their metabolic activity and started to use their energetic reserves to re-establish their oxidative status. This set of data shows that an acute exposure to paracetamol can exert deleterious effects that may compromise specific biochemical pathways in sensitive aquatic species, such as R. philippinarum, but organisms can re-establish their biochemical status to control levels after a recovery period.

      PubDate: 2017-09-22T01:48:55Z
      DOI: 10.1016/j.aquatox.2017.09.015
       
  • Hydrostatic pressure and temperature affect the tolerance of the
           free-living marine nematode Halomonhystera disjuncta to acute copper
           exposure
    • Authors: Lisa Mevenkamp; Alastair Brown; Chris Hauton; Anna Kordas; Sven Thatje; Ann Vanreusel
      Abstract: Publication date: Available online 20 September 2017
      Source:Aquatic Toxicology
      Author(s): Lisa Mevenkamp, Alastair Brown, Chris Hauton, Anna Kordas, Sven Thatje, Ann Vanreusel
      Potential deep-sea mineral extraction poses new challenges for ecotoxicological research since little is known about effects of abiotic conditions present in the deep sea on the toxicity of heavy metals. Due to the difficulty of collecting and maintaining deep-sea organisms alive, a first step would be to understand the effects of high hydrostatic pressure and low temperatures on heavy metal toxicity using shallow-water relatives of deep-sea species. Here, we present the results of acute copper toxicity tests on the free-living shallow-water marine nematode Halomonhystera disjuncta, which has close phylogenetic and ecological links to the bathyal species Halomonhystera hermesi. Copper toxicity was assessed using a semi-liquid gellan gum medium at two levels of hydrostatic pressure (0.1MPa and 10MPa) and temperature (10°C and 20°C) in a fully crossed design. Mortality of nematodes in each treatment was assessed at 4 time intervals (24 and 48h for all experiments and additionally 72 and 96h for experiments run at 10°C). LC50 values ranged between 0.561 and 1.864mg Cu2+ L−1 and showed a decreasing trend with incubation time. Exposure to high hydrostatic pressure significantly increased sensitivity of nematodes to copper, whereas lower temperature resulted in an apparently increased copper tolerance, possibly as a result of a slower metabolism under low temperatures. These results indicate that hydrostatic pressure and temperature significantly affect metal toxicity and therefore need to be considered in toxicity assessments for deep-sea species. Any application of pollution limits derived from studies of shallow-water species to the deep-sea mining context must be done cautiously, with consideration of the effects of both stressors.

      PubDate: 2017-09-22T01:48:55Z
      DOI: 10.1016/j.aquatox.2017.09.016
       
  • Inside Front Cover - Editorial Board Page
    • Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191


      PubDate: 2017-09-17T01:39:55Z
       
  • Mercury (II) impairs nucleotide excision repair (NER) in zebrafish (Danio
           rerio) embryos by targeting primarily at the stage of DNA incision
    • Authors: Yung Chang; Wei-Yuan Lee; Yu-Jie Lin; Todd Hsu
      Abstract: Publication date: Available online 14 September 2017
      Source:Aquatic Toxicology
      Author(s): Yung Chang, Wei-Yuan Lee, Yu-Jie Lin, Todd Hsu
      Mercuric ion (Hg2+) is the most prevalent form of inorganic Hg found in polluted aquatic environment. As inhibition of DNA damage repair has been proposed as one of the mechanisms of Hg2+-induced genotoxicity in aquatic animals and mammalian cells, this study explored the susceptibility of different stages of nucleotide excision repair (NER) in zebrafish (Danio rerio) embryos to Hg2+ using UV-damaged DNA as the repair substrate. Exposure of embryos at 1h post fertilization (hpf) to HgCl2 at 0.1–2.5μM for 9h caused a concentration-dependent inhibition of NER capacity monitored by a transcription-based DNA repair assay. The extracts of embryos exposed to 2.5μM Hg2+ almost failed to up-regulate UV-suppressed marker cDNA transcription. No inhibition of ATP production was observed in all Hg2+-exposed embryos. Hg2+ exposure imposed either weak inhibitory or stimulating effects on the gene expression of NER factors, while band shift assay showed the inhibition of photolesion binding activities to about 40% of control in embryos treated with 1 to 2.5μM HgCl2. The damage incision stage of NER in zebrafish embryos was found to be more sensitive to Hg2+ than photolesion binding capacity due to the complete loss of damage incision activity in the extracts of embryos exposed to 1–2.5μM Hg2+. NER-related DNA incision was induced in UV-irradiated embryos based on the production of short DNA fragments matching the sizes of excision products generated by eukaryotic NER. Pre-exposure of embryos to Hg2+ at 0.1–2.5μM all suppressed DNA incision/excision in UV-irradiated embryos, reflecting a high sensitivity of DNA damage incision/excision to Hg2+. Our results showed the potential of Hg2+ at environmental relevant levels to disturb NER in zebrafish embryos by targeting primarily at the stage of DNA incision/excision.

      PubDate: 2017-09-17T01:39:55Z
      DOI: 10.1016/j.aquatox.2017.09.001
       
  • Short-term and persistent impacts on behaviors related to locomotion,
           anxiety, and startle responses of Japanese medaka (Oryzias latipes)
           induced by acute, sublethal exposure to chlorpyrifos
    • Authors: Xuchun Qiu; Sayaka Nomichi; Kun Chen; Masato Honda; Ik Joon Kang; Yohei Shimasaki; Yuji Oshima
      Abstract: Publication date: Available online 14 September 2017
      Source:Aquatic Toxicology
      Author(s): Xuchun Qiu, Sayaka Nomichi, Kun Chen, Masato Honda, Ik Joon Kang, Yohei Shimasaki, Yuji Oshima
      Although most exposures to chlorpyrifos (CPF) in natural flowing waters are brief and episodic, there have been a few reports of the persistence of abnormal fish behaviors caused by such acute exposure. The present study focused on the behavioral and biochemical responses of Japanese medaka (Oryzias latipes) to acute, sublethal exposure to CPF, as well as the persistence of the effects during a 3-week recovery test in CPF-free water. The medaka became hyperactive and exhibited an elevated anxiety state after a 4-day exposure to 0.024mg/L of CPF, but they recovered from these abnormal behavioral responses within 7days of recovery treatment. In contrast, persistent impacts on some startle responses to a sudden stimulation (induced by a ball drop) were observed in medaka exposed to CPF. The reaction latency did not change immediately after the 4-day exposure, but was significantly prolonged by as much as 21days after the termination of exposure. The post-stimulus swimming distance within 5s significantly decreased on the day immediately after the 4-day exposure, but it significantly increased after 7days of recovery treatment. The activity of acetylcholinesterase (AChE) in the brains of medaka was significantly inhibited on the day immediately after the 4-day exposure, but it returned to 80% and 110% of that in control fish on days 7 and 21 of the recovery period, respectively. However, AChE activities in the eyes of exposed medaka were persistently inhibited and declined to 33%, 71%, and 72% of that in control fish on days 0 (immediately after the 4-day exposure), 7, and 21 of recovery, respectively. Correlation analysis suggested that the changes of AChE activities in the brains of medaka may underlie some of the observed acute behavioral changes, and the changes of AChE activities in the eyes may contribute to the persistence of the abnormalities in the reaction latency of the startle response. Our findings suggest that medaka need a long time to recover from acute, sublethal exposure to CPF, and the persistence of the behavioral abnormalities might affect their fitness in natural habitats.

      PubDate: 2017-09-17T01:39:55Z
      DOI: 10.1016/j.aquatox.2017.09.012
       
  • Physiological responses and gene expression changes in the western
           mosquitofish (Gambusia affinis) exposed to progesterone at environmentally
           relevant concentrations
    • Authors: Liping Hou; Hongyan Xu; Guangguo Ying; Yang Yang; Hu Shu; Jianliang Zhao; Xuemei Cheng
      Abstract: Publication date: Available online 14 September 2017
      Source:Aquatic Toxicology
      Author(s): Liping Hou, Hongyan Xu, Guangguo Ying, Yang Yang, Hu Shu, Jianliang Zhao, Xuemei Cheng
      Progesterone (P4) is a natural and synthetic steroid, widely distributed in the aquatic environments. It can lead to adverse effects on the endocrine system in aquatic organisms. This study investigated the toxicological effects of exposure to environmentally relevant concentrations (4, 44, and 410ng/L) of progesterone for 42 d on adult female mosquitofish, Gambusia affinis. We performed morphological and histological analyses on gonads, anal fins, liver, and gills after the exposure of mosquito fish to P4. The expression levels of genes (vtg, er, and ar isoforms) related to fish reproduction and detoxification (cyp1a) in the liver were quantified by quantitative real-time polymerase chain reaction. The results showed that the progesterone exposure induced slight masculinization in female mosquitofish, influenced the oocyte maturation as revealed by histology of the ovaries, and caused severe damages to the liver and gills of adult female mosquitofish. It also suppressed the mRNAs expression of vtg, er, cyp1a, and significantly enhanced the expression of ar mRNA in the liver. This study reveals the molecular and physiological effects of progesterone at environmentally relevant concentrations, which might further be translated to alterations in the reproduction of mosquitofish.

      PubDate: 2017-09-17T01:39:55Z
      DOI: 10.1016/j.aquatox.2017.09.011
       
  • Tetrabromoethylcyclohexane affects gonadal differentiation and development
           in the frog Pelophylax nigromaculatus
    • Authors: Peng-Yan Liu; Tan Meng; Yuan-Yuan Li; Man Cai; Xing-Hong Li; Juan Chen; Zhan-Fen Qin
      Abstract: Publication date: Available online 9 September 2017
      Source:Aquatic Toxicology
      Author(s): Peng-Yan Liu, Tan Meng, Yuan-Yuan Li, Man Cai, Xing-Hong Li, Juan Chen, Zhan-Fen Qin
      Tetrabromoethylcyclohexane (TBECH), an additive brominated flame retardant, has been shown to have an androgenic activity in vitro. In the present study, we aimed to investigate the effects of TBECH on gonadal differentiation and development in the frog Pelophylax nigromaculatus, an amphibian species sensitive to androgenic chemicals, and to assess the androgenic activity of TBECH in vivo. P. nigromaculatus tadpoles were exposed to TBECH (1, 10, 100nM) from Gosner stage 24 to complete metamorphosis, and to 5α-dihydrotestosterone (DHT) as a positive control. We found that 1nM DHT resulted in 100% males, while the sex ratio in the solvent control group was close to 1:1. In all the TBECH treatment groups, sexually ambiguous gonads based on gross morphology and intersexualities with testicular and ovarian histological structures were found, but no abnormality occurred in the solvent control. In the 1, 10, 100nM TBECH treatment groups, the female percentages were 52%, 31%, 17%, with 36%, 56%, 66% for males and 12%, 13%, 17% for abnormal sexes, respectively. X2 -test revealed significant differences in sex ratios between the three TBECH groups and the solvent control group, and the sex ratios in the two higher concentration groups were male-biased. These observations show that TBECH has a masculinizing effect on gonadal differentiation and development in P. nigromaculatus, suggesting an androgenic activity of TBECH in vivo. To our knowledge, this is the first study demonstrating that TBECH could induce gonadal masculinization in an animal, which raises new concerns for reproductive risk of TBECH exposure.

      PubDate: 2017-09-10T21:34:21Z
      DOI: 10.1016/j.aquatox.2017.09.009
       
  • Cellular uptake and intracellular localization of poly (acrylic acid)
           nanoparticles in a rainbow trout (Oncorhynchus mykiss) gill epithelial
           cell line, RTgill-W1
    • Authors: Lindsey C. Felix; Van A. Ortega; Greg G. Goss
      Abstract: Publication date: Available online 7 September 2017
      Source:Aquatic Toxicology
      Author(s): Lindsey C. Felix, Van A. Ortega, Greg G. Goss
      The ever-growing production of engineered nanoparticles (NPs) for use in many agricultural, commercial, consumer, and industrial applications will lead to their accidental or intentional release into the environment. Potential routes of environmental exposure include manufacturing or transport spills, disposal of NP‐containing products down the drain and/or in landfills, as well as direct usage on agricultural land. Therefore, NPs will inevitably contaminate aquatic environments and interact with resident organisms. However, there is limited information regarding the mechanisms that regulate NP transport into fish from the environment. Thus, our primary objective was to elucidate the mechanism(s) underlying cellular uptake and intracellular fate of 3–9nm poly (acrylic acid) NPs loaded with the fluorescent dye Nile red using a rainbow trout (Oncorhynchus mykiss) gill epithelial cell line (RTgill‐W1). In vitro measurements with NP‐treated RTgill-W1 cells were carried out using a combination of laser scanning confocal microscopy, flow cytometry, fluorescent biomarkers (transferrin, cholera toxin B subunit, and dextran), endocytosis inhibitors (chlorpromazine, genistein, and wortmannin), and stains (4′, 6‐diamidino-2-phenylindole, Hoechst 33342, CellMask Deep Red, and LysoTracker Yellow). Clathrin-mediated endocytosis (CME), caveolae‐mediated endocytosis and macropinocytosis pathways were active in RTgill‐W1 cells, and these pathways were exploited by the non-cytotoxic NPs to enter these cells. We have demonstrated that NP uptake by RTgill‐W1 cells was impeded when clathrin-coated pit formation was blocked by chlorpromazine. Furthermore, colocalization analysis revealed a moderate positive relationship between NPs and LysoTracker Yellow-positive lysosomal compartments indicating that CME was the dominant operative mechanism involved in NP internalization by RTgill-W1 cells. Overall, our results clearly show that fish gill epithelial cells internalized NPs via energy‐dependent endocytotic processes. This study enhances our understanding of complex NP‐cell interactions and the results obtained in vitro imply a potential risk to aquatic organisms.

      PubDate: 2017-09-10T21:34:21Z
      DOI: 10.1016/j.aquatox.2017.09.008
       
  • Oxidative damage of 18S and 5S ribosomal RNA in digestive gland of mussels
           exposed to trace metals
    • Authors: Georgia G. Kournoutou; Panagiota C. Giannopoulou; Eleni Sazakli; Michel Leotsinidis; Dimitrios L. Kalpaxis
      Abstract: Publication date: Available online 6 September 2017
      Source:Aquatic Toxicology
      Author(s): Georgia G. Kournoutou, Panagiota C. Giannopoulou, Eleni Sazakli, Michel Leotsinidis, Dimitrios L. Kalpaxis
      Numerous studies have shown the ability of trace metals to accumulate in marine organisms and to cause oxidative stress that leads to perturbations in many important intracellular processes, including protein synthesis. This study is mainly focused on the exploration of structural changes, like base modifications, scissions, and conformational changes, caused in 18S and 5S ribosomal RNA (rRNA) isolated from the mussel Mytilus galloprovincialis exposed to 40μg/L Cu, 30μg/L Hg, or 100μg/L Cd, for 5 or 15 days. 18S rRNA and 5S rRNA are components of the small and large ribosomal subunit, respectively, found in complex with ribosomal proteins, translation factors and other auxiliary components (metal ions, toxins etc). 18S rRNA plays crucial roles in all stages of protein synthesis, while 5S rRNA serves as a master signal transducer between several functional regions of 28S rRNA. Therefore, structural changes in these ribosomal constituents could affect the basic functions of ribosomes and hence the normal metabolism of cells. Especially, 18S rRNA along with ribosomal proteins forms the decoding centre that ensures the correct codon-anticodon pairing. As exemplified by ELISA, primer extension analysis and DMS footprinting analysis, each metal caused oxidative damage to rRNA, depending on the nature of metal ion and the duration of exposure. Interestingly, exposure of mussels to Cu or Hg caused structural alterations in 5S rRNA, localized in paired regions and within loops A, B, C, and E, leading to a continuous progressive loss of the 5S RNA structural integrity. In contrast, structural impairments of 5S rRNA in mussels exposed to Cd were accumulating for the initial 5 days, and then progressively decreased to almost the normal level by day 15, probably due to the parallel elevation of metallothionein content that depletes the pools of free Cd. Regions of interest in 18S rRNA, such as the decoding centre, sites implicated in the binding of tRNAs (A- and P-sites) or translation factors, and areas related t○ translation fidelity, were found to undergo significant metal-induced conformational alterations, leading either to loosening of their structure or to more compact folding. These modifications were associated with parallel alterations in the translation process at multiple levels, a fact suggesting that structural perturbations in ribosomes, caused by metals, pose significant hurdles in translational efficiency and fidelity.

      PubDate: 2017-09-10T21:34:21Z
      DOI: 10.1016/j.aquatox.2017.09.007
       
  • Chronic fluoride exposure exacerbates headkidney pathology and causes
           immune commotion in Clarias gariepinus
    • Authors: Rashmi Singh; Md. Arafat Hussain; Jai Kumar; Manmohan Kumar; Usha Kumari; Shibnath Mazumder
      Abstract: Publication date: Available online 6 September 2017
      Source:Aquatic Toxicology
      Author(s): Rashmi Singh, Md. Arafat Hussain, Jai Kumar, Manmohan Kumar, Usha Kumari, Shibnath Mazumder
      The current study was aimed to understand the effects of chronic fluoride exposure on fish immune system. African sharp tooth catfish (Clarias gariepinus) were exposed to 73.45mg/L of fluoride corresponding to 1/10 96h LC50 for 30 d and the effects on general fish health and several immune parameters were studied. Chronic fluoride exposure led to significant alteration in serum biochemical parameters including alkaline phosphatase, alanine transaminase, aspartate transaminase, triglycerides, cholesterol and blood urea nitrogen levels revealing the detrimental effect of fluoride on general fish health. Upregulation in cytochrome P450 1A expression, both at mRNA and protein level suggested that fluoride activates the detoxification machinery in headkidney (HK) of C. gariepinus. Histopathological analysis of HK from exposed fish further revealed fluoride-induced hypertrophy, increase in melano-macrophage centers (MMCs) and the development of cell-depleted regions. Fluoride reduced headkidney somatic index (HKSI) and the phagocytic potential of headkidney macrophages (HKM). It induced caspase-3-dependent headkidney leukocyte (HKL) apoptosis, elevated superoxide generation and production of pro-inflammatory cytokine TNF-α besides suppressed T-cell proliferation in the exposed fish. We surmise the elevation in superoxide levels coupled with increased TNF-α production to be plausible causes of fluoride-induced HKL apoptosis. It is concluded that chronic fluoride exposure induces structure-function alterations in HK, the primary lymphoid organ in fish leading to impairment in immune responses.

      PubDate: 2017-09-10T21:34:21Z
      DOI: 10.1016/j.aquatox.2017.09.006
       
  • Tris(1,3-dichloro-2-propyl) Disrupts Axonal Growth, Cholinergic System and
           Motor Behavior in Early Life Zebrafish
    • Authors: Rui Cheng; Yali Jia; Lili Dai; Chunsheng Liu; Jianghua Wang; Guangyu Li; Liqin Yu
      Abstract: Publication date: Available online 5 September 2017
      Source:Aquatic Toxicology
      Author(s): Rui Cheng, Yali Jia, Lili Dai, Chunsheng Liu, Jianghua Wang, Guangyu Li, Liqin Yu
      TDCIPP could have neurotoxic effects and alter motor behaviors in zebrafish (Danio rerio) larvae, however, the underlying mechanisms are still unknown. In this study, zebrafish embryos were subjected to waterborne exposure of TDCIPP at 100, 300, 600, 900μg/L from 2 to 120-hour post-fertilization (hpf). Behavioral measurements indicate that TDCIPP exposure significantly elevated spontaneous movement, and altered swimming behavior response of larvae to both light and dark stimulation. Interestingly, in accordance with these motor effects, TDCIPP significantly decreased expression of the neuron-specific GFP in transgenic (HuC-GFP) zebrafish larvae as well as decreased expression of the neural marker genes elavl3 and ngn1, inhibited the axonal growth of the secondary motoneurons and altered the expressions of axon-related genes (α1-tubulin, shha and netrin2) in zebrafish larvae. Furthermore, TDCIPP exposure at 900μg/L significantly increased the activity of acetylcholinesterase (AChE) enzyme, and decreased the total acetylcholine (ACh) concentration. Our data indicate that the alteration in motor neuron and inhibition of cholinergic system could together lead to the TDCIPP induced motor behavior alterations in zebrafish larvae.

      PubDate: 2017-09-05T21:31:35Z
      DOI: 10.1016/j.aquatox.2017.09.003
       
  • Toxic effects of Pb2+ entering sperm through Ca2+ channels in the
           freshwater crab Sinopotamon henanense
    • Authors: Na Li; Peng Xu; Wei-xin Jing; Jiang-Shiou Hwang; Lan Wang
      Abstract: Publication date: Available online 4 September 2017
      Source:Aquatic Toxicology
      Author(s): Na Li, Peng Xu, Wei-xin Jing, Jiang-Shiou Hwang, Lan Wang
      Lead (Pb) is a heavy metal that can damage animal sperm. To study the effects of Pb on calcium homeostasis and calcium channel in the sperm of freshwater crab Sinopotamon henanense, the induction of acrosome reaction (AR) and acrosin activity were investigated when crabs were exposed to different Pb concentrations (0, 3.675, 7.35, 14.7, 29.4 and 58.8mg/L) for 3, 5 and 7 d separately. Fluorescent probe Fluo-3/AM was loaded into the sperm, and [Ca2+] in the sperm was measured by fluorescence microscopy and using microplate reader. The calmodulin (CaM) concentration was measured by ELISA method. Verapamil (VRP), a calcium channel blocker, was used to evaluate whether Pb can enter the sperm through calcium channels leading to sperm damage. After sperm were exposed at 50μg/L VRP, 100μg/L Pb, 50μg/L VRP+100μg/L Pb, 1000μg/L Pb and 50μg/L VRP+1000μg/L Pb for 1h in vitro,sperm quality parameters (sperm survival and sperm DNA integrity) and levels of parameters indicating oxidative stress (protein carbonylation [PCO] and malondialdehyde [MDA]) were measured. Our data showed that Pb reduced the induction of acrosome reaction (AR), down-regulated the acrosin activity, decreased the intracellular concentration of Ca2+ and elevated CaM concentration. Compared to controls, Pb alone induced significant stress, as reflected by decreasing sperm survival and sperm DNA integrity, and increasing PCO and MDA contents. In the presence of VRP, 100μg/L Pb-induced stresses were reduced, all the measured parameters in the sperm exposed at 100μg/L Pb returned to control levels. Our results indicate that Pb enters the sperm of the crab S. henanense through calcium channels, the inhibition of which blocks Pb-induced stresses such as sperm quality decline and oxidative damage.

      PubDate: 2017-09-05T21:31:35Z
      DOI: 10.1016/j.aquatox.2017.09.005
       
  • Ryanodine receptor and FK506 binding protein 1 in the Atlantic killifish
           (Fundulus heteroclitus): A phylogenetic and population-based comparison.
    • Authors: Erika B. Holland; Jared V. Goldstone; Isaac N. Pessah; Andrew Whitehead; Noah M. Reid; Sibel I. Karchner; Mark E. Hahn; Diane E. Nacci; Bryan W. Clark; John J. Stegeman
      Abstract: Publication date: Available online 4 September 2017
      Source:Aquatic Toxicology
      Author(s): Erika B. Holland, Jared V. Goldstone, Isaac N. Pessah, Andrew Whitehead, Noah M. Reid, Sibel I. Karchner, Mark E. Hahn, Diane E. Nacci, Bryan W. Clark, John J. Stegeman
      Non-dioxin-like polychlorinated biphenyls (NDL PCBs) activate ryanodine receptors (RyR), microsomal Ca2+ channels of broad significance. Teleost fish may be important models for NDL PCB neurotoxicity, and we used sequencing databases to characterize teleost RyR and FK506 binding protein 12 or 12.6kDa (genes FKBP1A; FKBP1B), which promote NDL PCB-triggered Ca2+ dysregulation. Particular focus was placed on describing genes in the Atlantic killifish (Fundulus heteroclitus) genome and searching available RNA-sequencing datasets for single nucleotide variants (SNV) between PCB tolerant killifish from New Bedford Harbor (NBH) versus sensitive killifish from Scorton Creek (SC), MA. Consistent with the teleost whole genome duplication (tWGD), killifish have six RyR genes, corresponding to a and b paralogs of mammalian RyR1, 2 and 3. The presence of six RyR genes was consistent in all teleosts investigated including zebrafish. Killifish have four FKBP1; one FKBP1b and three FKBP1a named FKBP1aa, FKBP1ab, likely from the tWGD and a single gene duplicate FKBP1a3 suggested to have arisen in Atherinomorphae. The RyR and FKBP1 genes displayed tissue and developmental stage-specific mRNA expression, and the previously uncharacterized RyR3, herein named RyR3b, and all FKBP1 genes were prominent in brain. We identified a SNV in RyR3b encoding missense mutation E1458D. In NBH killifish, 57% were heterozygous and 28% were homozygous for this SNV, whereas almost all SC killifish (94%) lacked the variant (n≥39 per population). The outlined sequence differences between mammalian and teleost RyR and FKBP1 together with outlined population differences in SNV frequency may contribute to our understanding of NDL PCB neurotoxicity.

      PubDate: 2017-09-05T21:31:35Z
      DOI: 10.1016/j.aquatox.2017.09.002
       
  • Zebrafish sex differentiation and gonad development: a review on the
           impact of environmental factors
    • Authors: Dércia Santos; Ana Luzio; Ana M. Coimbra
      Abstract: Publication date: Available online 10 August 2017
      Source:Aquatic Toxicology
      Author(s): Dércia Santos, Ana Luzio, Ana M. Coimbra
      Zebrafish (Danio rerio) is extensively used in research; however the mechanisms that control this species sex determination are still poorly understood. In the latest decades, it has been established that zebrafish sex is determined by genetic factors on a polygenic basis, as various candidate genes with sex dimorphic expression, as well sex-linked loci have been identified in different zebrafish strains. However, it has been evidenced that sex determination in this species is also influenced by environmental factors. For instance, temperature can have a crucial role in zebrafish sex determination. Likewise, the exposure to endocrine disrupting chemicals (EDCs), the most studied zebrafish sex changing factor, can strongly influence the course of sex differentiation and unbalance the sex ratio of zebrafish populations. Despite this, so far the influence of environmental factors is still less understood and only few studies have addressed this topic. Therefore, this review intends to gather current knowledge on the environmental factors involved in sex determination of zebrafish and identify important gaps in this research area. Briefly, the current understanding on zebrafish sex related genetics is also addressed.

      PubDate: 2017-08-18T13:16:24Z
      DOI: 10.1016/j.aquatox.2017.08.005
       
  • Combined Effects of Oil Exposure, Temperature and Ultraviolet Radiation on
           Buoyancy and Oxygen Consumption of Embryonic Mahi-mahi, Coryphaena
           hippurus
    • Authors: Christina Pasparakis; Lauren E. Sweet; John D. Stieglitz; Daniel Benetti; Conrad T. Casente; Aaron P. Roberts; Martin Grosell
      Abstract: Publication date: Available online 5 August 2017
      Source:Aquatic Toxicology
      Author(s): Christina Pasparakis, Lauren E. Sweet, John D. Stieglitz, Daniel Benetti, Conrad T. Casente, Aaron P. Roberts, Martin Grosell
      The Deepwater Horizon oil spill occurred in the summer of 2010 and coincided with the spawning window of the ecologically and economically important pelagic fish mahi-mahi (Coryphaena hippurus). During summer months, early life stage mahi-mahi were likely also exposed to other naturally occurring stressors such as increased temperature and ultraviolet radiation (UV). Previous research has shown that co-exposure to oil and additional natural stressors can affect the timing and duration of negative buoyancy in mahi-mahi embryos. The current study aimed to elucidate the factors affecting the onset of negative buoyancy and to also explore possible mechanisms behind buoyancy change. Embryos co-exposed to oil and/or increased temperature and UV radiation displayed early onset of negative buoyancy with concurrent increases in oxygen consumption and sinking rates, which are normally only seen during the period directly preceding hatch. Results also suggest a behavioral response in which embryos avoid UV radiation by sinking down the water column but reestablish positive buoyancy once the UV radiation is removed. These findings imply that embryos can dynamically change their position in the water column in response to external cues and thus may have much greater control over buoyancy than previously thought.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.07.021
       
  • Influence of sublethal doses of acetamiprid and halosulfuron-methyl on
           metabolites of zebra fish (Brachydanio rerio)
    • Authors: Hong Zhang; Lijuan Zhao
      Abstract: Publication date: Available online 4 August 2017
      Source:Aquatic Toxicology
      Author(s): Hong Zhang, Lijuan Zhao
      Acetamiprid, a neonicotinoid pesticide, is reported to have adverse sublethal effects on non-target beneficial organisms. Halosulfuron-methyl (HM), one of the most widely used herbicides in agriculture, has high ecotoxicity to aquatic plants and animals. In this study, a GC-MS-based metabolomics approach was used to investigate the toxicity of acetamiprid and HM. The Automated Mass Spectral Deconvolution and Identification System (AMDIS) software program and the retention index method were used to identify 51 metabolites in zebra fish (Brachydanio rerio). Changes in metabolites showed that acetamiprid and HM disturbed amino acid (e.g., leucine, valine, serine, glycine, proline, and alanine) metabolism, the TCA cycle (malic acid and fumaric acid), and the balance of neurotransmitters (glutamic acid, taurine, and glycine). The change in metabolites in the liver, head, and blood indicated that metabolites in the liver were more sensitive than those in the head and blood. Overall, on the basis of the change in metabolites, we identified a potential risk to zebra fish exposed to sublethal doses of acetamiprid and/or HM.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.08.002
       
  • Heat indicators of oxidative stress, inflammation and metal transport show
           dependence of cadmium pollution history in the liver of female zebrafish
    • Authors: Qing-Ling Zhu; Sai-Nan Guo; Shuang-Shuang Yuan; Zhen-Ming Lv; Jia-Lang Zheng; Hu Xia
      Abstract: Publication date: Available online 20 July 2017
      Source:Aquatic Toxicology
      Author(s): Qing-Ling Zhu, Sai-Nan Guo, Shuang-Shuang Yuan, Zhen-Ming Lv, Jia-Lang Zheng, Hu Xia
      Environmental stressors such as high temperature and metal exposure may occur sequentially, simultaneously, previously in aquatic ecosystems. However, information about whether responses to high temperature depend on Cd exposure history is still unknown in fish. Zebrafish were exposed to 0 (group 1), 2.5 (group 2) and 5μg/L (group 3) cadmium (Cd) for 10 weeks, and then each group was subjected to Cd-free water maintained at 26°C and 32°C for 7days respectively. 26 indicators were used to compare differences between 26°C and 32°C in the liver of female zebrafish, including 5 biochemical indicators (activity of Cu/Zn-SOD, CAT and iNOS; LPO; MT protein), 8 molecular indicators of oxidative stress (mRNA levels of Nrf2, Cu/Zn-SOD, CAT, HSF1, HSF2, HSP70, MTF-1 and MT), 5 molecular indicators of inflammation (mRNA levels of IL-6, IL-1β, TNF-α, iNOS and NF-κB), 8 molecular indicators of metal transport (mRNA levels of, ZnT1, ZnT5, ZIP8, ZIP10, ATP7A, ATP7B and CTR1). All biochemical indicators were unchanged in group 1 and changed in group 2 and 3. Contrarily, differences were observed in almost all of molecular indicators of inflammation and metal transport in group 1, about half in group 2, and few in group 3. We also found that all molecular indicators of oxidative stress in group 2 and fewer in group 1 and 3 were significantly affected by heat. Our data indicated that heat indicators of oxidative stress, inflammation and metal transport showed dependence of previous cadmium exposure in the liver of zebrafish, emphasizing metal pollution history should be carefully considered when evaluating heat stress in fish.

      PubDate: 2017-07-23T12:38:04Z
      DOI: 10.1016/j.aquatox.2017.07.010
       
 
 
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