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Showing 1 - 200 of 1720 Journals sorted alphabetically
AAPS Journal     Hybrid Journal   (Followers: 22)
Achievements in the Life Sciences     Open Access   (Followers: 5)
ACS Synthetic Biology     Hybrid Journal   (Followers: 24)
Acta Biologica Colombiana     Open Access   (Followers: 7)
Acta Biologica Hungarica     Full-text available via subscription   (Followers: 4)
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acta ethologica     Hybrid Journal   (Followers: 4)
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Acta Neurobiologiae Experimentalis     Open Access  
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AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 1)
Ageing Research Reviews     Hybrid Journal   (Followers: 11)
Aging Cell     Open Access   (Followers: 13)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Agrokreatif Jurnal Ilmiah Pengabdian kepada Masyarakat     Open Access  
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American Biology Teacher     Full-text available via subscription   (Followers: 14)
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American Malacological Bulletin     Full-text available via subscription   (Followers: 3)
American Naturalist     Full-text available via subscription   (Followers: 73)
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Anadolu University Journal of Science and Technology : C Life Sciences and Biotechnology     Open Access  
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Anatomical Science International     Hybrid Journal   (Followers: 2)
Animal Cells and Systems     Hybrid Journal   (Followers: 4)
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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)
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Annual Review of Biomedical Engineering     Full-text available via subscription   (Followers: 14)
Annual Review of Biophysics     Full-text available via subscription   (Followers: 23)
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: 37)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Annual Review of Genomics and Human Genetics     Full-text available via subscription   (Followers: 23)
Annual Review of Phytopathology     Full-text available via subscription   (Followers: 12)
Anthropological Review     Open Access   (Followers: 23)
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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: 10)
Aquaculture Environment Interactions     Open Access   (Followers: 2)
Aquaculture International     Hybrid Journal   (Followers: 23)
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: 34)
Aquatic Ecosystem Health & Management     Hybrid Journal   (Followers: 14)
Aquatic Science and Technology     Open Access   (Followers: 3)
Aquatic Toxicology     Hybrid Journal   (Followers: 22)
Archaea     Open Access   (Followers: 3)
Archiv für Molluskenkunde: International Journal of Malacology     Full-text available via subscription   (Followers: 3)
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Archives of Microbiology     Hybrid Journal   (Followers: 8)
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Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2)
Arid Ecosystems     Hybrid Journal   (Followers: 2)
Arquivos do Instituto Biológico     Open Access   (Followers: 1)
Arquivos do Museu Dinâmico Interdisciplinar     Open Access  
Arthropod Structure & Development     Hybrid Journal   (Followers: 2)
Arthropods     Open Access   (Followers: 1)
Artificial DNA: PNA & XNA     Hybrid Journal   (Followers: 3)
Asian Bioethics Review     Full-text available via subscription   (Followers: 3)
Asian Journal of Biodiversity     Open Access   (Followers: 4)
Asian Journal of Biological Sciences     Open Access   (Followers: 3)
Asian Journal of Cell Biology     Open Access   (Followers: 5)
Asian Journal of Developmental Biology     Open Access   (Followers: 2)
Asian Journal of Medical and Biological Research     Open Access   (Followers: 3)
Asian Journal of Nematology     Open Access   (Followers: 4)
Asian Journal of Poultry Science     Open Access   (Followers: 3)
Atti della Accademia Peloritana dei Pericolanti - Classe di Scienze Medico-Biologiche     Open Access  
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: 11)
Bacteriology Journal     Open Access   (Followers: 1)
Bacteriophage     Full-text available via subscription   (Followers: 3)
Bangladesh Journal of Bioethics     Open Access  
Bangladesh Journal of Plant Taxonomy     Open Access  
Bangladesh Journal of Scientific Research     Open Access   (Followers: 1)
Batman Üniversitesi Yaşam Bilimleri Dergisi     Open Access  
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)
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BioCentury Innovations     Full-text available via subscription   (Followers: 1)
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Biochimie     Hybrid Journal   (Followers: 7)
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BioDiscovery     Open Access   (Followers: 2)
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Biodiversity: Research and Conservation     Open Access   (Followers: 26)
Bioedukasi : Jurnal Pendidikan Biologi FKIP UM Metro     Open Access  
Bioeksperimen : Jurnal Penelitian Biologi     Open Access  
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Biologia     Hybrid Journal  
Biologia on-line : Revista de divulgació de la Facultat de Biologia     Open Access  
Biological Bulletin     Partially Free   (Followers: 6)
Biological Control     Hybrid Journal   (Followers: 4)
Biological Invasions     Hybrid Journal   (Followers: 19)
Biological Journal of the Linnean Society     Hybrid Journal   (Followers: 18)
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Biologicals     Full-text available via subscription   (Followers: 9)

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Journal Cover
Aquatic Toxicology
Journal Prestige (SJR): 1.456
Citation Impact (citeScore): 4
Number of Followers: 22  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0166-445X - ISSN (Online) 1879-1514
Published by Elsevier Homepage  [3159 journals]
  • Growth, energy metabolism and transcriptomic responses in Chinese mitten
           crab (Eriocheir sinensis) to benzo[α]pyrene (BaP) toxicity
    • Abstract: Publication date: Available online 18 August 2018Source: Aquatic ToxicologyAuthor(s): Na Yu, Qingqing Ding, Erchao Li, Jian G. Qin, Liqiao Chen, Xiaodan WangAbstractBenzo(a)pyrene (BaP) is a highly toxic polycyclic aromatic hydrocarbon and has strong affinity to suspended materials and sediments in the aquatic environment. Most crustaceans are benthic species and are easily affected by the pollution in the sediments, but there is little information on the response mechanism of crustaceans to BaP exposure. This study compared the growth and hepatopancreas transcriptomic responses of the Chinse mitten crab (Eriocheir sinensis) exposed to 0, 0.15 (BaP1) and 0.45 μg /L (BaP2) for 28 days. Crab survival and weight gain were reduced in the water born BaP in a dose-dependent way. The contents of hepatopancreas glycogen, triglyceride, total amino acids and lactic acid were all decreased after BaP exposure, indicating possible more energy consumption during detoxification. In the transcriptome analysis, a total of 106.65 million clean reads were obtained and assembled into 81,714 unigenes with an average length of 594 bp and N50 of 808 bp. Under 0.15 or 0.45 μg /L BaP exposure, 922 and 1129 unigenes in crabs were significantly expressed, annotated to 676 and 802 Gene Ontology (GO) terms respectively. The “cellular process” was the leading category for both concentrations. Thirteen significantly changed pathways were identified in both Control vs BaP1 and Control vs BaP2 groups. These pathways were divided into four different parts according to their reported functions, including metabolism, environmental information processing, organismal systems and cellular processes. Nice out of thirteen pathways in BaP1 were related to metabolism, containing amino acid metabolism, phenylpropanoid biosynthesis, monobactam biosynthesis and styrene degradation. Almost all the pathways related with the biosynthesis processes were down-regulated, while the degradation pathways were up-regulated. Seven out of thirteen pathways were classified into metabolism category in BaP2. These pathways were mostly associated with stress resistance rather than supplying energy. This study indicates that both concentrations of BaP disturbed nutrient metabolism, immune response and defense system in the crabs, while exposure to a higher concentration had a greater impact on immunity system than on metabolism. This study provides a better understanding of the underlying molecular and regulatory mechanisms in crustaceans coping with BaP toxicity.
  • UV-B radiation induces DEHP degradation and their combined toxicological
           effects on Scenedesmus acuminatus
    • Abstract: Publication date: Available online 16 August 2018Source: Aquatic ToxicologyAuthor(s): Chao Zhang, Mu Xie, Jing Chen, Yurui Zhang, Sijie Wei, Xinyue Ma, Ling Xiao, Lanzhou ChenAbstractThe co-contamination discharge of Phthalate esters (PAEs) by human activities and the increased UV radiation is increasing in aquatic ecosystems. However, little information is available about the combined detrimental effects of UV and PAEs on phytoplankton. In this study, the combined effects of UV-B irradiation and di-(2-ethylhexyl) phthalate (DEHP) on photosynthesis and antioxidant system of Scenedesmus acuminatus, and the DEHP degradation were investigated. Results showed that UV-B radiation decreased the chlorophyll a fluorescence yield, photosynthetic activity (Fv/Fm), pigment content and superoxide dismutase activity. This radiation also increased the reactive oxygen species (ROS) production and soluble protein and malondialdehyde contents. UV-B radiation with 10 mg L-1 DEHP improved the Fv/Fm and alleviated the cell damage of S. acuminatus, and the addition of high DEHP concentration (≥50 mg L-1) aggravated cell damage. The ROS generation also decreased with the increased DEHP concentration. UV-B radiation can effectively promote the DEHP degradation, with the highest degradation rate of 89.9% at an initial DEHP concentration of 10 mg L-1 within 6 h. This result may be attributed to that UV-B irradiance induced DEHP degradation under the regulation of ROS generated by S. acuminatus. Our findings will contribute to the understanding of the combined toxic mechanisms of UV-B and DEHP and in the evaluation of ecological environment risks for primary producers in aquatic ecosystems.
  • Environmental Risks of ZnO Nanoparticle Exposure on Microcystis
           aeruginosa: Toxic Effects and Environmental Feedback
    • Abstract: Publication date: Available online 16 August 2018Source: Aquatic ToxicologyAuthor(s): Yulin Tang, Huaijia Xin, Shu Yang, Meiting Guo, Tyler Malkoske, Daqiang Yin, Shengji XiaAbstractThe vast majority of studies measure the toxic effect of organisms exposed to nanoparticles (NPs) while there is still a lack of knowledge about the influence of NPs on the aquatic environment. It is unknown whether or not the interaction between NPs and algae will result in the variation of algal organic matter (AOM) and stimulate the production of more algal toxins. In this study, zinc oxide nanoparticles (nano-ZnO) as a typical representative of metal oxide NPs were used to evaluate the toxic effects and environmental feedback of Microcystis aeruginosa. Reactive oxygen species (ROS) and malondialdehyde (MDA) were measured to explain the toxicity mechanism. Changes of AOM, including the production of toxins, the molecular weight distribution and the excitation-emission matrices of algal solution were also studied as environmental feedback indicators after nano-ZnO destroyed the algae. As the nano-ZnO exceeded the comparable critical concentration (1.0 mg/L), the algae were destroyed and intracellular organic matters were released into the aquatic environment, which stimulated the generation of microcystin-LR (MC-LR). However, it is worth noting that the concentration of nano-ZnO would need to be high (at mg/L range) to stimulate more MC-LR production. These findings are expected to be beneficial in interpreting the toxicity and risks of the releasing of NPs through the feedback between algae and the aquatic environment.
  • Oxidative stress responses and cellular energy allocation changes in
           microalgae following exposure to widely used human antibiotics
    • Abstract: Publication date: Available online 15 August 2018Source: Aquatic ToxicologyAuthor(s): Adeolu O. Aderemi, Sara C. Novais, Marco F. Lemos, Luís M. Alves, Colin Hunter, Ole PahlAbstractThe individual effect of four human antibiotics on the microalgae Raphidocelis subcapitata was investigated following a 120-h exposure. The effects were assessed by analyzing growth, and biochemical parameters related with: 1) antioxidant capacity and oxidative damage by measuring superoxide dismutase (SOD) activity and lipid peroxidation (LPO) levels; and 2) cellular energy allocation (CEA) by quantifying the content in energy reserves, which represents the energy available (Ea), and the electron transport system activity that represents a measure of oxygen and cellular energy consumption (Ec). Growth yield inhibitory concentrations of sulfamethoxazole (18-30%), clarithromycin (28.7%), ciprofloxacin (28%) and erythromycin (17-39%) were found to elicit a considerable increase in Ec, thereby causing a significant decrease in the CEA. The elevated Ec can be a result of the need to respond to oxidative stress occurring under those conditions given the significant increase in SOD activity at these levels. For sulfamethoxazole, erythromycin and ciprofloxacin, the antioxidant responses do not seem to be enough to cope with the reactive oxygen species and prevent oxidative damage, given the elevated LPO levels observed. A stimulatory effect on growth yield was observed (up to 16%) at ciprofloxacin lowest concentration, which highly correlated with the increase in CEA. Based on the no observed effect concentration (NOECs) and/or effective concentration (EC10) results, Ec, SOD and CEA were more sensitive than the classical endpoint of growth rate for all the tested antibiotics. By revealing the antibiotic stress effects in R. subcapitata at the cellular level, this study suggests CEA as a more reliable indicator of the organisms’ physiological status.
  • Testing wastewater treatment plant effluent effects on microbial and
           detritivore performance: A combined field and laboratory experiment
    • Abstract: Publication date: Available online 14 August 2018Source: Aquatic ToxicologyAuthor(s): Libe Solagaistua, Ioar de Guzmán, Miren Barrado, Leire Mijangos, Nestor Etxebarria, Gonzalo García-Baquero, Aitor Larrañaga, Daniel von Schiller, Arturo ElosegiABSTRACTThe amount of pollutants and nutrients entering rivers via point sources is increasing along with human population and activity. Although wastewater treatment plants (WWTPs) greatly reduce pollutant loads into the environment, excess nutrient loading is a problem in many streams. Using a Community and Ecosystem Function (CEF) approach, we quantified the effects of WWTP effluent on the performance of microbes and detritivores associated to organic matter decomposition, a key ecosystem process. We measured organic matter breakdown rates, respiration rates and exo-enzymatic activities of aquatic microbes. We also measured food consumption and growth rates and RNA to body-mass ratios (RNA:BM) of a dominant amphipod Echinogammarus berilloni. We predicted responses to follow a subsidy-stress pattern and differences between treatments to increase over time. To examine temporal effects of effluent, we performed a laboratory microcosm experiment under a range of effluent concentrations (0, 20, 40, 60, 80 and 100%), taking samples over time (days 8, 15 and 30; 4 and 10 replicates to assess microbe and detritivore performance respectively, per treatment and day). This experiment was combined with a field in situ Before-After Control-Impact Paired (BACIP) experiment whereby we added WWTP effluent poured (10 L s-1 during 20-40 min every 2 h) into a stream and collected microbial and detritivore samples at days 8 and 15 (5 and 15 replicates to assess the microbe and detritivore performance respectively, per period, reach and sampling day). Responses were clearer in the laboratory experiment, where the effluent caused a general subsidy response. Field measures did not show any significant response, probably because of the high dilution of the effluent in stream water (average of 1.6%). None of the measured variables in any of the experiments followed the predicted subsidy-stress response. Microbial breakdown, respiration rates, exo-enzymatic activities and invertebrate RNA:BM increased with effluent concentrations. Differences in microbial respiration and exo-enzymatic activities among effluent treatments increased with incubation time, whereas microbial breakdown rates and RNA:BM were consistent over time. At the end of the laboratory experiment, microbial respiration rates increased 156% and RN:BM 115% at 100% effluent concentration. Detritivore consumption and growth rates increased asymptotically, and both responses increased with by incubation time. Our results indicate that WWTP effluent stimulates microbial activities and alters detritivore performance, and stream water dilution may mitigate these effects.
  • Impact of multiple stressors on biomarker responses in sympatric
           dreissenid populations
    • Abstract: Publication date: Available online 11 August 2018Source: Aquatic ToxicologyAuthor(s): Marine Potet, Laure Giambérini, Sandrine Pain-Devin, Audrey Catteau, Danièle Pauly, Simon DevinAbstractDreissenid mussels, well-known invaders of the northern hemisphere, also constitute good biomonitors for freshwater quality assessment. Whereas the oldest, Dreissena polymorpha, is relatively well-known, the new invasive, Dreissena rostriformis bugensis, has been very little characterized. The aim of this study was to compare subcellular biomarker responses within these species, by taking into account inter- and intra-specific variability in biomarker responses during a multi-stress assessment. Indeed, due to local environmental conditions and genetic background, biomarker responses can be different between populations of a given species, not only between species. To evaluate these differential responses, we sampled mussels on two sites where they are both present in sympatry (plus another D. r. bugensis population), and we exposed these populations in laboratory to different stressors: thermal stress (12 or 17 °C), dietary stress (fed or unfed), contamination (nickel at 0, 20 and 500 µg.L-1) and exposure duration (0, 4 or 8 days). Results mainly evidenced strong inter-species and inter-population differences, underlining the need to discriminate correctly between the two species and to know well the populations used in biomonitoring. Results also evidenced thermal and food stress-related effects. The numerous data obtained during this multi-stress experiment also highlight the complexity of working on several stressors and analysing the associated results.
  • Effects of nanosilver on Mytilus galloprovincialis hemocytes and
           early embryo development
    • Abstract: Publication date: Available online 7 August 2018Source: Aquatic ToxicologyAuthor(s): M. Auguste, C. Ciacci, T. Balbi, A. Brunelli, V. Caratto, A. Marcomini, R. Cuppini, L. CanesiAbstractSilver nanoparticles (AgNP), one of the main nanomaterials for production and use, are expected to reach the aquatic environment, representing a potential threat to aquatic organisms. In this study, the effects of bare AgNPs (47 nm) on the marine mussel Mytilus galloprovincialis were evaluated at the cellular and whole organism level utilizing both immune cells (hemocytes) and developing embryos. The effects were compared with those of ionic Ag+(AgNO3). In vitro short-term exposure (30 min) of hemocytes to AgNPs induced small lysosomal membrane destabilization (LMS EC50 = 273.1 μg/mL) and did not affect other immune parameters (phagocytosis and ROS production). Responses were little affected by hemolymph serum (HS) as exposure medium in comparison to ASW. However, AgNPs significantly affected mitochondrial membrane potential and actin cytoskeleton at lower concentrations. AgNO3 showed much higher toxicity, with an EC50 = 1.23 μg/mL for LMS, decreased phagocytosis and induced mitochondrial and cytoskeletal damage at similar concentrations.Both AgNPs and AgNO3 significantly affected Mytilus embryo development, with EC50 = 23.7 and 1 µg/L, respectively. AgNPs caused malformations and developmental delay, but no mortality, whereas AgNO3 mainly induced shell malformations followed by developmental arrest or death.Overall, the results indicate little toxicity of AgNPs compared with AgNO3; moreover, the mechanisms of action of AgNP appeared to be distinct from those of Ag+. The results indicate little contribution of released Ag+ in our experimental conditions. These data provide a further insight into potential impact of AgNPs in marine invertebrates.
  • [omim][BF4]-mediated toxicity in mussel hemocytes includes its interaction
           with cellular membrane proteins
    • Abstract: Publication date: Available online 6 August 2018Source: Aquatic ToxicologyAuthor(s): Vasiliki Tsarpali, Stefanos DailianisAbstractThe current study is based on the increasing demand for the assessment of ionic liquid (IL)-mediated aquatic toxicity. Specifically, although a lot of studies have been performed so far, investigating IL-mediated adverse effects on numerous aquatic organisms, little is known about their mode of action. Given that the use of in vitro models is considered as a reliable tool for determining the mediated biological effects, the modulation of specific biochemical pathways and the onset of various forms of damage with great precision and reproducibility, mixed primary cultures of mussel Mytilus galloprovincialis hemocytes were used for investigating whether 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF4]) mediated toxicity is related to its interaction with cellular membrane proteins. Specifically, [omim][BF4]-mediated cytotoxic, oxidative and genotoxic effects were investigated in mussel hemocytes before and after pre-treatment of cells with non-toxic concentration of guanidine hydrochloride (1 mM GndHCl). The results showed that [omim][BF4] at concentrations ranging from 0.7 to 1.75 μM can induce cytotoxic (almost
  • Developmental neurotoxicity of triphenyl phosphate in zebrafish larvae
    • Abstract: Publication date: Available online 3 August 2018Source: Aquatic ToxicologyAuthor(s): Qipeng Shi, Min Wang, Fengqiong Shi, Lihua Yang, Yongyong Guo, Chenglian Feng, Jingfu Liu, Bingsheng ZhouAbstractTriphenyl phosphate (TPhP), a typical organophosphate ester, is frequently detected in the environment and biota samples. It has been implicated as a neurotoxin as its structure is similar to neurotoxic organophosphate pesticides. The purpose of the present study was to investigate its potential developmental neurotoxicity in fish by using zebrafish larvae as a model. Zebrafish (Danio rerio) embryos were exposed to 0.8, 4, 20 and 100 μg/L of TPhP from 2 until 144 h post-fertilization. TPhP was found to have high bioconcentrations in zebrafish larvae after exposure. Further, it significantly reduced locomotor activity as well as the heart rate at the 100 μg/L concentration. TPhP exposure significantly altered the content of the neurotransmitters γ-aminobutyric and histamine. Downregulation of the genes related to central nervous system development (e.g., α1-tubulin, mbp, syn2a, shha, and elavl3) as well as the corresponding proteins (e.g., α1-tubulin, mbp, and syn2a) was observed, but the gap-43 protein was found to upregulated. Finally, marked inhibition of total acetylcholinesterase activity, which is considered as a biomarker of neurotoxicant exposure, was also observed in the larvae. Our results indicate that exposure to environmentally relevant concentrations of TPhP can affect different parameters related to center nervous system development, and thus contribute to developmental neurotoxicity in early developing zebrafish larvae.
  • Effects of copper on hemocyte parameters in the estuarine oyster
           Crassostrea rivularis under low pH conditions
    • Abstract: Publication date: Available online 2 August 2018Source: Aquatic ToxicologyAuthor(s): Xizhi Huang, Xiaoyu Jiang, Meng Sun, Sam Dupont, Wei Huang, Menghong Hu, Qiongzhen Li, Youji WangABSTRACtWith the development of industry and agriculture, the metal pollutants (e.g., Cu) are inevitably released into the aquatic environment. In addition, ocean acidification (OA) as a major environmental stress is affecting marine organisms. In this study, we investigated the hemocyte responses of the estuarine oyster Crassostrea rivularis exposed to six combinations of two pH levels (8.1 and 7.7) and three Cu concentrations (0, 10 and 50 μg/L) using flow cytometry in vitro and in vivo. In both experiments, Cu and low pH jointly affected the hemocyte parameters of oyster. High Cu exposure resulted in decreased total hemocyte count (THC), esterase activity (EA) and lysosomal content (LC) and increased hemocyte mortality (HM), phagocytosis activity (PA) and reactive oxygen species (ROS) production, especially under low pH conditions. The immune suppression of metal-exposure was more significant than low pH exposure with a 28-d experimental period in oysters. A slight recovery of the immune parameters was observed in THC, HM, PA, ROS and LC. During the depuration period, the modulatory effects of pH were still obvious. In addition, carry-over effects of high Cu and low pH were still observed. Overall, our results showed that copper and low pH weaken immune functions of hemocyte in oysters, with synergistic effects. This work provides new evidence of sublethal negative effects of metals on marine animals under global change scenarios, and copper likely leads to reduced fitness of oysters under low pH conditions.Graphical abstractGraphical abstract for this article
  • CREB element is essential for unfolded protein response (UPR) mediating
           the Cu-induced changes of hepatic lipogenic metabolism in Chinese yellow
           catfish (Pelteobagrus fulvidraco)
    • Abstract: Publication date: Available online 1 August 2018Source: Aquatic ToxicologyAuthor(s): Yu-Feng Song, Yi-Huan Xu, Mei-Qin Zhuo, Kun Wu, Zhi LuoAbstractThe present study was conducted to explore the underlying mechanism of unfolded protein response (UPR) mediating the Cu-induced changes of hepatic lipogenic metabolism in a low vertebrate, freshwater teleost yellow catfish Pelteobagrus fulvidraco. To this end, three experiments were conducted. In Exp. 1, we cloned the regions of grp78, perk, ire-1α and atf-6α promoters, and found that multiple cAMP-response element binding protein (CREB) binding sites were identified in their promoter regions. Furthermore, these CREB binding sites played crucial role in transcriptional regulation of UPR. In Exp. 2, the involvement of perk, ire-1α and atf-6α in Cu-induced changes of hepatic lipid metabolism was confirmed by specific miRNA. In Exp. 3, the regulatory mechanism of CREB underlying UPR mediating Cu-induced hepatic lipogenic metabolism were investigated. Cu induced UPR via the activation of CREB binding sites in the promoter regions of grp78, perk, ire-1α and atf-6α. In addition, the inhibition of CREB markedly attenuated the Cu-induced up-regulation of hepatic lipogenic metabolism in hepatocytes. This conclusion was further supported by the results from the trial of CREB over-expression. Taken together, the present study indicated that CREB was essential for UPR mediating Cu-induced lipogenic metabolism, supporting a mechanistic link among CREB, UPR and Cu-induced changes of lipid metabolism.
  • Sex-specific immunomodulatory action of the environmental estrogen
           17α-ethynylestradiol alongside with reproductive impairment in fish
    • Abstract: Publication date: Available online 31 July 2018Source: Aquatic ToxicologyAuthor(s): Roy R. Ye, Drew R. Peterson, Shin-Ichi Kitamura, Helmut Segner, Frauke Seemann, Doris W.T. AuAbstractEstrogenic endocrine disrupting chemicals (EEDCs) are present ubiquitously in sediments and aquatic ecosystems worldwide. The detrimental impact of EEDCs on the reproduction of wildlife is widely recognized. Increasing evidence shows the immunosuppressive effects of EEDCs in vertebrates. Yet, no studies have considered concomitantly EEDC-induced impacts on reproductive impairment and immune suppression in vivo, which are deemed essential for risk assessment and environmental monitoring. In this study, EE2 was used as a representative EEDC, for parallel evaluation of EEDC-induced immune suppression (immune marker gene expression, leukocyte numbers, host resistance assay, and immune competence index) and reproductive impairment (estrogen responsive gene expression, fecundity, fertilization success, hatching success, and reproductive competence index) in an established fish model (marine medaka Oryzias melastigma), considering sex-specific induction and adaptation and recovery responses under different EE2 exposure scenarios. The findings in marine medaka reveal distinct sex differences in the EE2-mediated biological responses. For female fish, low concentration of exogenous EE2 (33 ng/L) could induce hormesis (immune enhancement), enable adaptation (restored reproduction) and even boost fish resistance to bacterial challenge after abatement of EE2. However, a prolonged exposure to high levels of EE2 (113 ng/L) not only impaired F0 immune function, but also perturbed females recovering from reproductive impairment, resulting in a persistent impact on the F1 generation output. Thus, for female fish, the exposure concentration of EE2 is more critical than the dose of EE2 in determining the impacts of EE2 on immune function and reproduction. Conversely, male fish are far more sensitive than females to the presence of low levels of exogenous EE2 in water and the EE2-mediated biological impacts are clearly dose-dependent. It is also evident in male fish that direct contact of EE2 is essential to sustain impairments of immune competence and reproductive output as well as deregulation of immune function genes in vivo. The immunomodulatory pathways altered by EE2 were deciphered for male and female fish, separately. Downregulation of hepatic tlr3 and c3 (in female) and tlr3, tlr5 and c3 (in male) may be indicative of impaired fish immune competence. Taken together, impaired immune competence in the EE2-exposed fish poses an immediate thread on the survival of F0 population. Impaired reproduction in the EE2-exposed fish can directly affect F1 output. Parallel evaluation of immune competence and reproduction are important considerations when assessing the risk of sublethal levels of EE2/EEDCs in aquatic environments.
  • Copper and ocean acidification interact to lower maternal investment, but
           have little effect on adult physiology of the Sydney rock oyster
           Saccostrea glomerata
    • Abstract: Publication date: Available online 30 July 2018Source: Aquatic ToxicologyAuthor(s): Elliot Scanes, Laura M. Parker, Wayne A. O’Connor, Mitchell Gibbs, Pauline M. RossAbstractIt remains unknown how molluscs will respond to oceans which are increasingly predicted to be warmer, more acidic, and heavily polluted. Ocean acidification and trace metals will likely interact to increase the energy demands of marine organisms, especially oysters. This study tested the interactive effect of exposure to elevated pCO2 and copper on the energetic demands of the Sydney rock oyster (Saccostrea glomerata) during reproductive conditioning and determined whether there were any positive or negative effects on their offspring. Oysters were exposed to elevated pCO2 (1000 µatm) and elevated copper (Cu 50 µg L-1 [0.787 µM]) in an orthogonal design for eight weeks during reproductive conditioning. After eight weeks, energetic demands on oysters were measured including standard metabolic rate (SMR), nitrogen excretion, molar oxygen to nitrogen (O:N) ratio, and pHe of adult oysters as well as the size and total lipid content of their eggs. To determine egg viability, the gametes were collected and fertilised from adult oysters, the percentage of embryos that had reached the trochophore stage after 24 hours was recorded. Elevated pCO2 caused a lower extracellular pH and there was a greater O:N ratio in adult oysters exposed to copper. While the two stressors did not interact to cause significant effects on adult physiology, they did interact to reduce the size and lipid content of eggs indicating that energy demand on adult oysters was greater when both elevated pCO2 and copper were combined. Despite the lower energy, there were no negative effects on early embryonic development. In conclusion, elevated pCO2 can interact with metals and cause greater energetic demands on oysters; in response oysters may lower maternal investment to offspring.
  • Impacts of the combined exposure to seawater acidification and arsenic on
           the proteome of Crassostrea angulata and Crassostrea gigas
    • Abstract: Publication date: Available online 30 July 2018Source: Aquatic ToxicologyAuthor(s): Anthony Moreira, Etelvina Figueira, Nélia C. Mestre, Denise Schrama, Amadeu Soares, Rosa Freitas, Maria João BebiannoAbstractProteomic analysis was performed to compare the effects of Arsenic (As), seawater acidification (Low pH) and the combination of both stressors (Low pH + As) on Crassostrea angulata and Crassostrea gigas juveniles in the context of global environmental change. This study aimed to elucidate if two closely related Crassostrea species respond similarly to these environmental stressors, considering both single and combined exposures, to infer if the simultaneous exposure to both stressors induced a differentiated response. Identification of the most important differentially expressed proteins between conditions revealed marked differences in the response of each species towards single and combined exposures, evidencing species-related differences towards each experimental condition. Moreover, protein alterations observed in the combined exposure (Low pH + As) were substantially different from those observed in single exposures. Identified proteins and their putative biological functions revealed an array of modes of action in each condition. Among the most important, those involved in cellular structure (Actin, Atlastin, Severin, Gelsolin, Coronin) and extracellular matrix modulation (Ependymin, Tight junction ZO-1, Neprilysin) were strongly regulated, although in different exposure conditions and species. Data also revealed differences regarding metabolic modulation capacity (ATP β, Enolase, Aconitate hydratase) and oxidative stress response (Aldehyde dehydrogenase, Lactoylglutathione, Retinal dehydrogenase) of the species, which also depended on single or combined exposures, illustrating a different response capacity of both oyster species to the presence of multiple stressors. Interestingly, alterations of piRNA abundance in C. angulata suggested genome reconfiguration in response to multiple stressors, likely an important mode of action related to adaptive evolution mechanisms previously unknown to oyster species, which requires further investigation. Our findings provide a deeper insight into the complexity of C. angulata and C. gigas responses to environmental stress at the proteome level, evidencing different capacities to endure abiotic changes, with relevance regarding the ecophysiological fitness of the species and competitive advantages in a changing environment.
  • In vivo effects of 17α-ethinylestradiol, 17β-estradiol and 4-nonylphenol
           on insulin-like growth-factor binding proteins (igfbps) in Atlantic salmon
    • Abstract: Publication date: Available online 25 July 2018Source: Aquatic ToxicologyAuthor(s): Jason P. Breves, Tara A. Duffy, Ingibjörg E. Einarsdottir, Björn Thrandur Björnsson, Stephen D. McCormickAbstractFeminizing endocrine disrupting compounds (EDCs) affect the growth and development of teleost fishes. The major regulator of growth performance, the growth hormone (Gh)/insulin-like growth-factor (Igf) system, is sensitive to estrogenic compounds and mediates certain physiological and potentially behavioral consequences of EDC exposure. Igf binding proteins (Igfbps) are key modulators of Igf activity, but their alteration by EDCs has not been examined. We investigated two life-stages (fry and smolts) of Atlantic salmon (Salmo salar), and characterized how the Gh/Igf/Igfbp system responded to waterborne 17α-ethinylestradiol (EE2), 17β-estradiol (E2) and 4-nonylphenol (NP). Fry exposed to EE2 and NP for 21 days had increased hepatic vitellogenin (vtg) mRNA levels while hepatic estrogen receptor α (erα), gh receptor (ghr), igf1 and igf2 mRNA levels were decreased. NP-exposed fry had reduced body mass and total length compared to controls. EE2 and NP reduced hepatic igfbp1b1, -2a, -2b1, -4, -5b2 and -6b1, and stimulated igfbp5a. In smolts, hepatic vtg mRNA levels were induced following 4-day exposures to all three EDCs, while erα only responded to EE2 and E2. EDC exposures did not affect body mass or fork length; however, EE2 diminished plasma Gh and Igf1 levels in parallel with reductions in hepatic ghr and igf1. In smolts, EE2 and E2 diminished hepatic igfbp1b1, -4 and -6b1, and stimulated igfbp5a. There were no signs of compromised ionoregulation in smolts, as indicated by unchanged branchial ion pump/transporter mRNA levels. We conclude that hepatic igfbps respond (directly and/or indirectly) to environmental estrogens during two key life-stages of Atlantic salmon, and thus may modulate the growth and development of exposed individuals.
  • Establishment of Pantropic Spotted Dolphin (Stenella attenuata) Fibroblast
           Cell Line and Potential Influence of Polybrominated Diphenyl Ethers
           (PBDEs) on Cytokines Response
    • Abstract: Publication date: Available online 25 July 2018Source: Aquatic ToxicologyAuthor(s): Imran Rashid Rajput, Ziyang Xiao, Sun Yajing, Summra Yaqoob, Edmond Sanganyado, Huang Ying, Yu Fei, Wenhua LiuAbstractThe presence of polybrominated diphenyl ethers (PBDEs) in the aquatic environment is an issue of major concern which may be a cause of increasing prevalence and severity of diseases in marine mammals. Although, cell culture model development and in vitro investigation approach is a prime need of time to progress immunotoxic research on aquatic mammals. In this study, we stablished fibroblast cell line (pantropic spotted dolphin) to assess the potential effects of PBDEs on cytokines response. Cells were grown in 6 well cell culture plate and complete media (DMEM and Ham's F12 nutrient mixture, fetal bovine serum, antibiotic and essential amino acids) was provided. The primary culture of (PSP-LWH) cells identification was achieved by vimentin (gene and protein) expressions. Karyotyping revealed pantropic spotted dolphin chromosomes 20 pairs with XX. Transfection was achieved by SV40 LT antigen and transfected cells were expended for passages. Stability of cell line was confirmed at various passages intervals using RT-PCR, western blotting and immunofluorescence methods. After confirmation, cell line was exposed to BDE-47 (250 ng/ml), BDE-100 (250 ng/ml) and BDE-209 (1000 ng/ml), with control group (PBS), positive control DMSO (0.1%) and negative control LPS (500 ng/ml) for 24 hr. The ELISA results showed significant increase in IL-6 in BDE- 100 and BDE-209 while IL-1β and IL-8 were found higher in BDE-47 and BDE-100. TNFα and IL-10 secretion was noted higher in control and positive control groups. Altogether, these results emphasize importance of transfected (PSP-LWHT) cell line in aquatic research and potential effects of PBDEs on fibroblast provides evident to understand immune modulating effects of PBDEs in marine mammals. The impact of PBDEs on dolphin’s fibroblast cells immune response and altered cytokine response have been presented for the first time.
  • Triclosan toxicity alters behavioral and hematological parameters and
           vital antioxidant and neurological enzymes in Pangasianodon hypophthalmus
           (Sauvage, 1878)
    • Abstract: Publication date: September 2018Source: Aquatic Toxicology, Volume 202Author(s): Vikas Kumar Sahu, Sutanu Karmakar, Saurav Kumar, S.P. Shukla, Kundan KumarAbstractTriclosan and its metabolites are detected in a diverse aquatic environment and are major concerns for various aquatic organisms. The present study investigated the impact of acute and sub-lethal exposure of triclosan on behaviour, activities of acetylcholinesterase and selected antioxidant enzymes, haematological and serum gas-electrolyte parameters of Pangasianodon hypophthalmus. The 96 h LC50 of triclosan for P. hypophthalmus was estimated as 1458 μg L−1. Further, sub-lethal triclosan exposure to 1/15th (97 μg L-1), 1/10th (145 μg L-1) and 1/5th (291 μg L-1) of 96 h LC50 concentration for a period of 45 days lead to decrease in total erythrocyte count, haemoglobin content and packed cell volume of blood while total leukocyte count increased significantly (p 
    • Abstract: Publication date: Available online 20 July 2018Source: Aquatic ToxicologyAuthor(s): Lindsay Jasperse, Milton Levin, Katherine Tsantiris, Roxanna Smolowitz, Christopher Perkins, J. Evan Ward, Sylvain De GuiseAbstractGiven their particle feeding behavior, sessile behavior, and abundance in coastal zones, bivalves are at significant risk for exposure to oil and oil dispersant following environmental disasters like the Deepwater Horizon oil spill. However, the effects of oil combined with oil dispersants on the health of oysters are not well studied. Therefore, eastern oysters (Crassostrea virginica) were exposed in vivo to Corexit® 9500, crude oil (high-energy water accommodated fraction; HEWAF), and a Corexit/oil mixture (chemically-enhanced water accommodated fraction; CEWAF) to evaluate potential toxic effects on immunological (phagocytosis and respiratory burst), physiological (feeding rate), and histological endpoints. Phagocytosis was significantly increased following CEWAF exposure only. Respiratory burst was significantly decreased following Corexit® exposure, but significantly increased following exposure to the highest concentration of CEWAF. Oyster feeding rates were significantly decreased following exposure to Corexit®, HEWAF, and CEWAF, and were most sensitive to CEWAF exposure. These modulations of important immunological and physiological functions could result in serious health outcomes for oysters, such as increased parasitism and decreased growth. Our experiments showed that subtle, sub-lethal effects occurred following acute in vivo exposure to Corexit®, HEWAF, and CEWAF, though oysters were not equally sensitive to the three components. Data from this study can be used for more accurate risk assessment concerning the impact of oil and Corexit® on the health of oysters.
  • Gonadal differentiation and its sensitivity to androgens during
           development of Pelophylax nigromaculatus
    • Abstract: Publication date: Available online 20 July 2018Source: Aquatic ToxicologyAuthor(s): Yuan-Yuan Li, Tan Meng, Kun Gao, Zhan-Fen QinAbstractOur previous observations proposed Pelophylax nigromaculatus as a model species for studying the masculinizing effects of androgenic EDCs in amphibians. To better develop this model species, we studied the process of the gonadal differentiation/development and the sensitive stage to androgens. We found that the earliest sexual dimorphism in gonads at morphological and histological levels occurred at stages 38-40 and stage 36 respectively. Further examination of molecular markers for testicular and ovarian differentiation during development revealed that the cyp17 and cyp19 expressions were sexually dimorphic from stage 32 and stage 36 respectively. Further, we investigated the sex-reversal induced by 100 ng/L 5α-dihydrotestosterone (DHT) when exposures were initiated at stages 24, 26 and 28. We found that when exposed from stage 24, DHT resulted masculinization of all tadpoles with no typical ovaries, whereas exposures from stage 26 or 28 dramatically reduced the effect of DHT. Our findings show that gonads of P. nigromaculatus are bipotential at stage 24, in the process of differentiation at stage 26 and determined to become either testis or ovary at stage 28. Altogether, exposure of P. nigromaculatus should begin at stage 24 in order to sensitively detect masculinizing effects of EDCs. Present study provides useful information about the gonadal differentiation and development in P. nigromaculatus for effectively evaluating masculinizing effects of EDCs on gonads.
  • Adverse effects of the insecticides chlordecone and fipronil on population
           growth and expression of the entire cytochrome P450 (CYP) genes in the
           freshwater rotifer Brachionus calyciflorus and the marine rotifer
           Brachionus plicatilis
    • Abstract: Publication date: Available online 19 July 2018Source: Aquatic ToxicologyAuthor(s): Young Hwan Lee, Jun Chul Park, Un-Ki Hwang, Jae-Seong Lee, Jeonghoon HanAbstractChlordecone and fipronil are used as an insecticide and have been widely detected in the aquatic environments. However, their toxicity is still poorly investigated in aquatic invertebrates. In this study, we examined effects of chlordecone and fipronil on population growth and transcriptional regulation of the entire cytochrome P450 (CYP) genes in the freshwater rotifer Brachionus calyciflorus and the marine rotifer B. plicatilis. In B. calyciflorus, a 24 h-no observed effect concentration (NOEC-24 h) and a 24 h-median lethal concentration (LC50-24 h) of chlordecone were determined as 100 μg/L and 193.8 μg/L, respectively, while NOEC-24 h and LC50-24 h of fipronil were determined as 1000 μg/L and 2033.0 μg/L, respectively. In B. plicatilis, NOEC-24 h and LC50-24 h of chlordecone were 100 μg/L and 291.0 μg/L, respectively, while NOEC-24 h and LC50-24 h of fipronil were determined as 1000 μg/L and 5735.0 μg/L, respectively. Moreover, retardation in the population growth were observed in response to chlordecone and fipronil in both rotifer species, suggesting that chlordecone and fipronil have a potential adverse effects on life cycle parameters of two rotifer species. Additionally, modulation in the expressions of the entire CYP genes were demonstrated in response to chlordecone and fipronil at 24 h period. These results provide the better understanding on how chlordecone and fipronil can affect in population growth of two rotifers and CYP gene expressions in chlordecone- and fipronil-exposed rotifers.
  • Species-specific behaviours in amphipods highlight the need for
           understanding baseline behaviours in ecotoxicology
    • Abstract: Publication date: Available online 19 July 2018Source: Aquatic ToxicologyAuthor(s): Shanelle A. Kohler, Matthew O. Parker, Alex T. FordAbstractBehavioural studies in ecotoxicology are increasing with techniques and endpoints used in pharmacology being translated to other vertebrate and invertebrate species. Despite this, data on the baseline behaviours of model organisms, and inter-species variability in behaviour are currently under-studied. This study assessed a range of behaviours associated with anxiety including swimming speed, phototaxis and thigmotaxis in a marine and freshwater amphipod (Echinogammarus marinus and Gammarus pulex). Differences in sensitivity to these assays were observed between species with E. marinus showing a greater sensitivity to the phototaxis assay than G. pulex, while in thigmotaxis assays G. pulex appeared better suited than E. marinus for measuring differences in the use of central zones. Significant inter-species differences were also observed in swimming patterns when breaking the data into ten second time bins but not when data was broken into two-minute time bins. The results of this study provide evidence of phototactic and thigmotactic behaviours in two model crustacean species with potential for use in behavioural ecotoxicology. Inter-species variability in sensitivity to behavioural assays highlights the importance of systematic assessment of baseline responses for all model species used in behavioural studies. Careful analysis of data is also required when performing behavioural studies so as not to lose sensitivity in your data.
  • Toxicogenomic responses of low level anticancer drug exposures in
           Daphnia magna
    • Abstract: Publication date: Available online 19 July 2018Source: Aquatic ToxicologyAuthor(s): Chiara Russo, Marina Isidori, Jessica A. Deaver, Helen C. PoyntonThe use of anticancer drugs in chemotherapy is increasing, leading to growing environmental concentrations of imatinib mesylate (IMA), cisplatinum (CDDP), and etoposide (ETP) in aquatic systems. Previous studies have shown that these anticancer drugs cause DNA damage in the crustacean Daphnia magna at low, environmentally relevant concentrations. To explore the mechanism of action of these compounds and the downstream effects of DNA damage on D. magna growth and development at a sensitive life stage, we exposed neonates to low level concentrations equivalent to those that elicit DNA damage (IMA: 2000 ng/L, ETP: 300 ng/L, CDDP: 10 ng/L) and performed transcriptomic analysis using an RNA-seq approach. RNA sequencing generated 14 million reads per sample, which were aligned to the D. magna genome and assembled, producing approximately 23,000 transcripts per sample. Over 90% of the transcripts showed homology to proteins in GenBank, revealing a high quality transcriptome assembly, although functional annotation was much lower. RT-qPCR was used to identify robust biomarkers and confirmed the downregulation of an angiotensin converting enzyme-like gene (ance) involved in neuropeptide regulation across all three anticancer drugs and the down-regulation of DNA topoisomerase II by ETP. RNA-seq analysis also allowed for an in depth exploration of the differential splicing of transcripts revealing that regulation of different gene isoforms predicts potential impacts on translation and protein expression, providing a more meaningful assessment of transcriptomic data. Enrichment analysis and investigation of affected biological processes suggested that the DNA damage caused by ETP and IMA influences cell cycle regulation and GPCR signaling. This dysregulation is likely responsible for effects to neurological system processes and development, and overall growth and development. Our transcriptomic approach provided insight into the mechanisms that respond to DNA damage caused by anticancer drug exposure and generated novel hypotheses on how these chemicals may impact the growth and survival of this ecologically important zooplankton species.Graphical Graphical abstract for this article
  • Silicon limitation reduced the adsorption of cadmium in marine diatoms
    • Abstract: Publication date: Available online 17 July 2018Source: Aquatic ToxicologyAuthor(s): Jie Ma, Beibei Zhou, Dandan Duan, Yang Wei, Ke PanAbstractThe nitrogen (N) and phosphorus (P) loadings in coastal waters have greatly increased due to anthropogenic input. However, the silicate levels have remained stable in the past decades, leading to nutrient status alternating from N limitation to Si limitation. Few studies have examined the effects of such nutrient imbalance on Cd accumulation in marine diatoms. In the present study, we provide multiple lines of evidence that Si limitation reduced the Cd binding capability in the marine diatom Nitzschia closterium. Diatom cells adapted to lower Si exposure had weaker mechanical strength and less negatively charged surfaces. Close examination of the cell surface revealed that Si shortage changed the biochemical composition of the cell surface and decreased the diatom’s silicification ability. The lower density of the silanol groups in the cell wall is the most likely reason for the weaker Cd adsorption ability observed in the Si limited diatom cells. This study demonstrates the significance of Si in controlling the metal accumulation in marine diatoms.
  • Waterborne exposure to low concentrations of BDE-47 impedes early vascular
           development in zebrafish embryos/larvae
    • Abstract: Publication date: Available online 17 July 2018Source: Aquatic ToxicologyAuthor(s): Xiumei Xing, Jianmeng Kang, Jiahuang Qiu, Xiali Zhong, Xiongjie Shi, Bingsheng Zhou, Yanhong WeiAbstractPolybrominated diphenyl ethers (PBDEs) are persistent flame retardants ubiquitously existing in various environment matrices. In spite of a recent reduction in use according to the phase-out policy, high levels of PBDEs are still found in both environmental and biological samples due to their persistent property and large-scale production over a long history. Developmental toxicity is a major health concern of PBDEs. However, the impact of PBDE exposure on vascular development remains poorly understood. In this study, we investigated the effect of low concentrations of 2,2’,4,4’-Tetrabromodiphenyl ether (BDE-47), a predominant PBDE congener, in environmental matrices and biota, on early vascular development using zebrafish. Zebrafish embryos were continuously exposed to waterborne BDE-47 at 0.06, 0.2, 0.6 μM starting from 2 hours post-fertilization (hpf). Fluorescent images of vasculatures in Tg(kdrl:eGFP) zebrafish were acquired using a confocal microscope. The results indicated that BDE-47 exposure had no effect on hatching rate, survival, body weight, body length or heart rate in the early stage within 72 hpf, whereas zebrafish exposed to BDE-47 exhibited impairments in the growth of multiple types of blood vessels. The percentage of completed intersegmental vessels (ISV) at 30 hpf decreased in embryos treated with BDE-47 in a dose-dependent fashion. BDE-47 exposure led to a slight decrease in the growth of common cardinal vein (CCV), while dramatically hindered CCV remodeling process reflected by the larger CCV area and wider ventral diameter. BDE-47 exposure significantly reduced sub-intestinal vessels (SIV) area as well as the vascularized yolk area in zebrafish larvae at 72 hpf. In addition, the expression of genes related to vascular growth and remodeling was markedly suppressed in BDE-47-exposed zebrafish. These findings demonstrate the adverse effects of BDE-47 on early vascular development, and confirm the vascular toxicity of PBDEs in vivo. The results indicate that developing vasculature in zebrafish is sensitive to BDE-47 exposure, and may serve as a powerful tool for the assessment of early exposure to PBDEs.
  • Transcriptional effects of androstenedione and
           17α-hydroxyprogesterone in zebrafish embryos
    • Abstract: Publication date: September 2018Source: Aquatic Toxicology, Volume 202Author(s): Karl Fent, Patricia Franziska Siegenthaler, Andreas Alexandre SchmidAbstractSteroid hormones in the aquatic environment may pose a risk to fish health. Here we evaluated effects of two different class steroids that frequently occur in the aquatic environment, the androgen androstenedione (A4) and the progestin 17α-hydroxyprogesterone (17-OHP4). Zebrafish embryos were exposed to four concentrations of A4 and the positive control testosterone and to 17-OHP4, and transcriptional changes were determined at 96 h post fertilization (hpf) and 120 hpf. Transcriptional changes of 18 selected genes were assessed upon exposure to measured concentrations of 0.004, 0.046, 0.62 and 6.56 μg/L A4. Significant induction of the genes encoding sulfotransferase (sult2st3) and aromatase (cyp19b) occurred in 120 hpf embryos at 6.56 μg/L A4 and 1 μg/L testosterone. Additionally, cyp2k7 was significantly induced in two of three independent experiments. 17-OHP4 did not induce physiological effects (muscle contraction, heart rate, hatching success, swimming activity) at concentrations between 0.01 and 10 μg/L. Of the analyzed 15 genes, slight transcriptional alterations occurred for the genes encoding progesterone receptor, aromatases (cyp19a) and (cyp19b) and cyp2k7 at 10 μg/L. Our study highlights sult2st3, cyp19b and cyp2k7 as potential markers of androgen exposure in fish and indicates that 17-OHP4 is not likely to pose a risk for fish at environmental concentrations.
  • Impacts of exposure to the toxic dinoflagellate Karenia brevis on
           reproduction of the northern quahog, Mercenaria mercenaria
    • Abstract: Publication date: Available online 11 July 2018Source: Aquatic ToxicologyAuthor(s): Anne Rolton, Julien Vignier, Aswani Volety, Sandra Shumway, V. Monica Bricelj, Philippe SoudantAbstractThe Gulf of Mexico, including the southwest Florida coast, USA, experience recurrent blooms of the brevetoxin (PbTx)-producing dinoflagellate, Karenia brevis. Northern quahogs (hard clams) Mercenaria mercenaria, are an important commercial species in this region. This study examined the effects of field and laboratory exposure of adult clams to K. brevis during their reproductive period, and effects on their subsequently produced offspring. Ripe adult clams were collected from a site which had been exposed to an eight-month natural bloom of K. brevis and an unaffected reference site. Ripe adult clams were also exposed to bloom concentrations of K. brevis for 10 days in the laboratory. Clams exposed to K. brevis accumulated PbTx at concentrations of 1508 (field exposure), 1444 (1000 cells mL-1 laboratory treatment) and 5229 ng g-1 PbTx-3 eq (5000 cells mL-1 laboratory treatment). Field-exposed clams showed histopathological effects: a significantly higher prevalence of mucus in the stomach/ intestine (23.3%), edema in gill tissues (30%) and presence of the cestode parasite, Tylocephalum spp. in whole tissue (40%), compared to non-exposed clams (0, 3.3 and 6.7% respectively). These clams also showed reduced gonadal allocation (23% gonadal area) and a higher prevalence of clams of undetermined sex (20%) compared to those sampled from the non-exposed site (43% and 0%, respectively). It is hypothesized that less energy may be channeled into reproduction as more is allocated for homeostasis or tissue repair. The fertilization success of gametes obtained from both field and laboratory-exposed adults was significantly lower in clams that had been exposed to K. brevis and development of these offspring was negatively affected at Days 1 and 4 post-fertilization (in field- and laboratory-exposed clams at the higher K. brevis concentration and in laboratory-exposed clams at the higher K. brevis concentration, respectively). Negative effects may be due to toxin accumulation in the gametes of field-exposed clams (244 ± 50 ng PbTx g-1 and 470 ± 82 ng g-1 wet weight in oocytes and sperm, respectively). Adverse effects in M. mercenaria are compared to those previously reported in oysters, Crassostrea virginica, under similar conditions of exposure. This study provides further evidence of the impacts of K. brevis and its associated toxins on the adults and offspring of exposed shellfish. Site-selection for the collection of broodstock and aquaculture grow-out efforts should therefore consider the local occurrence of K. brevis blooms.
  • Fate and effects of sediment-associated triclosan in subtropical
           freshwater microcosms
    • Abstract: Publication date: Available online 11 July 2018Source: Aquatic ToxicologyAuthor(s): Feng-Jiao Peng, Noël J. Diepens, Chang-Gui Pan, Sally A Bracewell, Guang-Guo Ying, Daniel Salvito, Henriette Selck, Paul J. Van den BrinkAbstractTriclosan (TCS) is an antibacterial agent that is commonly used in personal care products. Because of its sediment-binding properties, TCS exposure presents a potential threat to sediment-dwelling aquatic organisms. Currently our knowledge of the fate and effects of sediment-associated TCS in aquatic systems is limited. To understand the impact of sediment-associated TCS, we used microcosms to assess effects of TCS exposure on a diverse range of organisms selected to mimic a subtropical community, with an exposure period of 28 days. We included the oligochaete freshwater worm Limnodrilus hoffmeisteri to evaluate the interaction between sediment-associated TCS and sediment-dwelling organisms, including potential loss of TCS from the sediment due to biological activity and bioaccumulation. Benthic macroinvertebrate presence significantly increased the TCS levels from 0.013 ± 0.007 µg/L to 0.613 ± 0.030 µg/L in the overlying water through biological activity, posing a potential additional risk to pelagic species, but it did not result in a significant reduction of the sediment concentration. Furthermore, worms accumulated TCS with estimated Biota-Sediment-Accumulation-Factors (BSAFs) ranging between 0.38-3.55. Other than for algae, TCS at environmental concentrations did not affect the survival of the introduced organisms, including the L. hoffmeisteri. Our results demonstrate that, although TCS at currently detected maximum concentration may not have observable toxic effects on the benthic macroinvertebrates in the short term, it can lead to bioaccumulation in worms.
  • Transchem+project+–+Part+I:+Impact+of+long-term+exposure+to+pendimethalin+on+the+health+status+of+rainbow+trout+(Oncorhynchus+mykiss+L.)+genitors&rft.title=Aquatic+Toxicology&rft.issn=0166-445X&">Transchem project – Part I: Impact of long-term exposure to
           pendimethalin on the health status of rainbow trout (Oncorhynchus mykiss
           L.) genitors
    • Abstract: Publication date: Available online 10 July 2018Source: Aquatic ToxicologyAuthor(s): Morgane Danion, Stéphane Le Floch, Pauline Pannetier, Kim Van Arkel, Thierry MorinAbstractPendimethalin is a herbicide active substance commonly used in terrestrial agricultural systems and is thus detected at high concentrations in the surface water of several European countries. Previous studies reported several histopathological changes, enzymatic antioxidant modulation and immunity disturbance in fish exposed to this pesticide. The objective of this work was to investigate the direct effects of long-term exposure to environmental concentrations of pendimethalin over a period of 18 months in rainbow trout (Oncorhynchus mykiss) genitors. To do so, an experimental system consisting of eight similar 400 L tanks with a flow-through of fresh river water was used to perform daily chemical contamination. Fish were exposed to 850 ng/L for one hour and the pendimethalin concentration was then gradually diluted during the day to maintain optimal conditions for the fish throughout the experiment and to achieve a mean theoretical exposure level of around 100 ng L−1 per day. Every November, males and females were stripped to collect eggs and sperm and two new first generations of offspring were obtained. Kinetic sampling revealed differences in immune system parameters and antioxidative defences in the contaminated trout compared to the controls, due to pesticide exposure combined with seasonal changes related to gamete maturation. Moreover, reproductive capacity was significantly affected by exposure to the herbicide; a time lag of more than five weeks was observed for egg maturation in contaminated females and high bioconcentrations of pendimethalin were measured in eggs and sperm. Chemical transfer from genitors to offspring via gametes may affect embryo development and negatively impact the early stages of development.
  • Are the impacts of carbon nanotubes enhanced in Mytilus galloprovincialis
           submitted to air exposure'
    • Abstract: Publication date: Available online 10 July 2018Source: Aquatic ToxicologyAuthor(s): Madalena Andrade, Lucia De Marchi, Carlo Pretti, Federica Chiellini, Andrea Morelli, Amadeu M.V.M. Soares, Rui Rocha, Etelvina Figueira, Rosa FreitasABSTRACTIntertidal species are frequently exposed to environmental changes associated with multiple stressors, which they must either avoid or tolerate by developing physiological and biochemical strategies. Some of the natural environmental changes are related with the tidal cycle which forces organisms to tolerate the differences between an aquatic and an aerial environment. Furthermore, in these environments, organisms are also subjected to pollutants from anthropogenic sources. The present study evaluated the impacts in Mytilus galloprovincialis exposed to multi-walled carbon nanotubes (0.01 mg/L MWCNT) when continuously submersed or exposed to tides (5 h of low tide, 7 h of high tide) for 14 days. Our results demonstrated that mussels were physiologically and biochemically affected by MWCNTs, especially when exposed to tides. In fact, when only exposed to MWCNTs or only exposed to tides, the stress induced was not enough to activate mussels’ antioxidant defenses which resulted in oxidative damage. However, when mussels were exposed to the combination of tides and MWCNTs increased metabolism was observed, associated with higher production of reactive oxygen species (ROS), leading to a significant increase in the activities of antioxidant enzymes (superoxide dismutase, SOD and glutathione peroxide, GPx) and oxidized glutathione content (GSSG), preventing the occurrence of cellular damage, with organisms showing no lipid peroxidation (LPO) or protein carbonylation (PC). Therefore, organisms seemed to be able to tolerate MWCNTS and air exposure during tidal regime; however, the combination of both stressors induced higher oxidative stress. These findings indicate that the increasing presence of carbon nanoparticles in marine ecosystems can induce higher toxic impacts in intertidal organisms compared to organisms continuously submerged. Also, our results may indicate that air exposure can act as a cofounding factor on the assessment of different stressors in organisms living in coastal systems.
  • Stoichiometric responses to nano ZnO under warming are modified by thermal
           evolution in Daphnia magna
    • Abstract: Publication date: Available online 7 July 2018Source: Aquatic ToxicologyAuthor(s): Chao Zhang, Mieke Jansen, Erik Smolders, Luc De Meester, Robby StoksAbstractEffects of stressors on body stoichiometry are important as these may cascade through food webs. Contamination and global warming are two key anthropogenic stressors, yet their effects on body stoichiometry have been rarely tested. Further, while thermal evolution may increase the ability to deal with warming, it is unknown how thermal evolution modifies the effect of contaminants under warming. Using resurrection ecology, we studied two Daphnia magna subpopulations (old/recent) of which the recent subpopulation evolved a higher heat tolerance. We exposed both subpopulations to a sublethal concentration of nano zinc oxide (nZnO) and 4 °C warming and quantified their effects on body stoichiometry: carbon (C), nitrogen (N), phosphorus (P) contents and their ratios (C:N, C:P, N:P). In the old subpopulation, nZnO only marginally decreased the C content and had no effect on N and P contents and their ratios. In contrast, in the recent subpopulation nZnO strongly increased the body P content (+51%) and reduced the C:P (-34%) and N:P (-34%) ratios at 24 °C but not at 20 °C. Moreover, these stoichiometric changes were not explained by changes of corresponding macromolecules as assumed by theory. Our results indicate that the stoichiometric responses to nZnO in Daphnia are temperature-dependent and modified by rapid evolution. The observed changes in body stoichiometry may affect the food quality of this important prey and have the potential to cascade through food webs and shape nutrients cycling.
  • Gold Octahedra nanoparticles (Au_0.03 and Au_0.045): Synthesis and impact
           on marine clams Ruditapes decussatus
    • Abstract: Publication date: Available online 5 July 2018Source: Aquatic ToxicologyAuthor(s): Anis Fkiri, Badreddine Sellami, Aymen Selmi, Abdelhafidh Khazri, Wiem Saidani, Bouzidi Imen, David Sheehan, Beyrem Hamouda, Leila Samia SmiriAbstractThe increased use of gold nanoparticles (AuNPs) in several applications has led to a rise in concerns about their potential toxicity to aquatic organisms. In addition, toxicity of nanoparticles to aquatic organisms is related to their physical and chemical properties. In the present study, we synthesize two forms of gold octahedra nanoparticles (Au_0.03 and Au_0.045) in 1.3-propandiol with polyvinyl-pyrrolidone K30 (PVPK30) as capping agent using polyol process. Shape, size and optical properties of the particles could be tuned by changing the molar ratio of PVP K30 to metal salts. The anisotropy in nanoparticles shape shows strong localized surface plasmon resonance (SPR) in the near infrared region of the electromagnetic spectrum.Environmental impact of Oct-AuNPs was determined in the marine bivalve, Ruditapes decussatus exposed to different concentrations of Au_0.03 and Au_0.045. The dynamic light scattering showed the stability and resistance of Au_0.03 and Au_0.045 in the natural seawater. No significant modification in vg-like proteins, MDA level and enzymatic activities were observed in treated clams with Au_0.03 even at high concentration. In contrast, Au_0.045 induced superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST) activities, in a concentration dependent manner indicating defense against oxidative stress. Enhanced lipid peroxidation represented by malondialdehyde content confirmed oxidative stress of Au_0.045 at high concentration.These results highlight the importance of the physical form of nanomaterials on their interactions with marine organisms and provide a useful guideline for future use of Oct-AuNPs. In addition, Vitellogenin is shown not to be an appropriate biomarker for Oct-AuNPs contamination even at high concentration. We further show that Oct-AuNPs exhibit an important antioxidant response without inducing estrogenic disruption.
  • Atrazine promotes immunomodulation by melanomacrophage centre alterations
           in spleen and vascular disorders in gills from Oreochromis niloticus
    • Abstract: Publication date: Available online 2 July 2018Source: Aquatic ToxicologyAuthor(s): Sabrina Elisa de Oliveira, Pauliane de Melo Costa, Sara Batista do Nascimento, Whocely Victor de Castro, Rosy Iara Maciel de Azambuja Ribeiro, Hélio Batista dos Santos, Ralph Gruppi ThoméAbstractAtrazine is a herbicide that is banned in Europe but remains widely used on different types of crops in several countries in the American continent. Atrazine is known to be an endocrine disruptor and its effects on gonads have been extensively reported, but the toxic action on other organs is poorly documented. In this paper, we investigated the toxicity of atrazine on the gills and spleens of Nile tilapia (Oreochromis niloticus). The median lethal concentration (LC50), capable of killing one-half of the test animals was calculated, and sublethal concentrations of atrazine were used in a semistatic and subchronic assay. The following four experimental groups were formed: control not exposed to atrazine, a group exposed to 1 ppm atrazine for 15 days, a group exposed to 2 ppm for 7 days, and a group exposed to 2 ppm for 15 days. The concentrations were verified during the study by high performance liquid chromatography. The gills and spleens were stained with hematoxylin and eosin and histopathological findings were made. The Perls technique was used on the spleens to identify hemosiderin, lipofuscin, and melanin pigments in the cells from melanomacrophage centres (MMCs). The spleens were submitted to proliferating cell nuclear antigen (PCNA) and inducible nitric oxide synthase (iNOS) immunohistochemistry, and morphometry was used to assess splenocyte proliferation and melanomacrophage iNOS expression. Finally, a colorimetric assay for caspase-3 was performed on the spleens to identify apoptosis. Vascular and structural alterations, such as venous sinus congestion, aneurysm, hemorrhage, pillar cell hypertrophy, disarrangement of secondary lamellae, and epithelial lifting were observed in the gills. The frequency of individuals with aneurysms was higher in the groups treated with 2 ppm than in other groups. Atrazine had an immunomodulatory effect on the spleen, observed by the alteration in the percentage of red and white pulp, alteration of the MMC area, changes in the melanomacrophage pigment content, slight iNOS suppression, decrease in splenocyte proliferation under 1 ppm atrazine, and increased caspase 3 activity under 2 ppm atrazine after 7 and 15 d. Such effects could compromise oxygenation and the immune response and, ultimately, the survival and fitness of the fish.
  • Subcellular partitioning of metals and metalloids (As, Cd, Cu, Se and Zn)
           in liver and gonads of wild white suckers (Catostomus commersonii)
           collected downstream from a mining operation
    • Abstract: Publication date: Available online 2 July 2018Source: Aquatic ToxicologyAuthor(s): Nastassia Urien, Sophie Cooper, Antoine Caron, Helga Sonnenberg, Lisa Rozon-Ramilo, Peter G.C. Campbell, Patrice CoutureAbstractIn the present study, we examined the subcellular distribution of metals and metalloids (As, Cd, Cu, Se and Zn) in the liver and gonads of wild white suckers (Catostomus commersonii) collected downstream from a metal mining operation (exposure area) and in a reference area. Metal partitioning among potentially metal-sensitive fractions (heat-denatured proteins (HDP), mitochondria and microsomes) and potentially biologically detoxified fractions (heat-stable proteins (HSP) and metal-rich granules) within cells was determined after differential centrifugation, NaOH digestion and heat-denaturation steps. Metal-handling strategies between liver and gonads, and between sexes, were examined. Hepatic metal concentrations were significantly higher in exposed compared to reference fish, especially for Se (14x), Cd (5x) and Cu (3x), and did not vary between sexes. In contrast, gonadal Cd, Cu, Se and Zn concentrations were consistently lower in testes than in ovaries; marked differences in Cd and Se concentrations between exposed and reference fish were observed for both sexes. Overall, metal-handling strategies were similar in both liver (male and female pooled) and female gonads, but differed from those in male gonads, likely due to the different functions assigned to ovaries and testes. Subcellular partitioning of As, Cd and Cu showed that the HSP fraction was most responsive to increased metal exposure, presumably reflecting Cu regulation, and possibly Cd and As detoxification. Zinc concentrations were tightly controlled and mainly found in the HDP fraction. Interestingly, changes in Cd-handling strategy in female gonads were particularly evident, with Cd shifting dramatically from the metal-sensitive HDP fraction in reference fish to the metal-detoxified HSP fraction in exposed fish. It seems that Cd detoxification in female gonads was not fully induced in the less contaminated fish, but became more effective above a threshold Cd concentration of 0.05 nmol/g dry weight. Partitioning of Se was different, with the largest contributor to the total liver and gonad Se burdens being the putative metal-sensitive HDP fraction, suggesting that excess Se in this fraction in exposed fish may lead to Se-related stress. The present subcellular partitioning results demonstrate that metal handling strategies vary among metals, between organs and (in some cases) as a function of metal exposure. They also show promise in identifying metals of potential concern in a risk assessment context.
  • Integrated multi-biomarker responses of juvenile seabass to diclofenac,
           warming and acidification co-exposure
    • Abstract: Publication date: Available online 30 June 2018Source: Aquatic ToxicologyAuthor(s): Ana Luísa Maulvault, Vera Barbosa, Ricardo Alves, Patrícia Anacleto, Carolina Camacho, Sara Cunha, José O. Fernandes, Pedro Pousão Ferreira, Rui Rosa, António Marques, Mário DinizAbstractPharmaceutical drugs, such as diclofenac (DCF), are frequently detected in the marine environment, and recent evidence has pointed out their toxicity to non-target marine biota. Concomitantly, altered environmental conditions associated with climate change (e.g. warming and acidification) can also affect the physiology of marine organisms. Yet, the underlying interactions between these environmental stressors (pharmaceutical exposure and climate change-related stressors) still require a deeper understanding. Comprehending the influence of abiotic variables on chemical contaminants’ toxicological attributes provides a broader view of the ecological consequences of climate change. Hence, the aim of this study was to assess the ecotoxicological responses of juvenile seabass Dicenthrachus labrax under the co-exposure to DCF (from dietary sources, 500 ± 36 ng kg-1 dw), warming (ΔTºC = +5 °C) and acidification (ΔpCO2 ~1000 µatm, equivalent to ΔpH = -0.4 units), using an “Integrated Biomarker Response” (IBR) approach. Fish were exposed to these three stressors, acting alone or combined, for 28 days in a full cross-factorial design, and blood, brain, liver and muscle tissues were subsequently collected in order to evaluate: i) animal/organ fitness; ii) hematological parameters and iii) molecular biomarkers. Results not only confirmed the toxicological attributes of dietary exposure to DCF in marine fish species at the tissue (e.g. lower HSI), cellular (e.g. increased ENAs and lower erythrocytes viability) and molecular levels (e.g. increased oxidative stress, protein degradation, AChE activity and VTG synthesis), but also showed that such attributes are altered by warming and acidification. Hence, while acidification and/or warming enhanced some effects of DCF exposure (e.g. by further lowering erythrocyte viability, and increasing brain GST activity and Ub synthesis in muscle), the co-exposure to these abiotic stressors also resulted in a reversion/inhibition of some molecular responses (e.g. lower CAT and SOD inhibition and VTG synthesis). IBRs evidenced that an overall higher degree of stress (i.e. high IBR index) was associated with DCF and warming co-exposure, while the effects of acidification were less evident. The distinct responses observed when DCF acted alone or the animals were co-exposed to the drug together with warming and acidification not only highlighted the relevance of considering the interactions between multiple environmental stressors in ecotoxicological studies, but also suggested that the toxicity of pharmaceuticals can be aggravated by climate change-related stressors (particularly warming), thus, posing additional biological challenges to marine fish populations.
  • Transcriptomics investigation of thyroid hormone disruption in the
           olfactory system of the Rana [Lithobates] catesbeiana tadpole
    • Abstract: Publication date: Available online 30 June 2018Source: Aquatic ToxicologyAuthor(s): Kevin W. Jackman, Nik Veldhoen, Rachel C. Miliano, Bonnie J. Robert, Linda Li, Azadeh Khojasteh, Xiaoyu Zheng, Tristan S.M. Zaborniak, Graham van Aggelen, Mary Lesperance, Wayne J. Parker, Eric R. Hall, Gregory G. Pyle, Caren C. HelbingAbstractThyroid hormones (THs) regulate vertebrate growth, development, and metabolism. Despite their importance, there is a need for effective detection of TH-disruption by endocrine disrupting chemicals (EDCs). The frog olfactory system substantially remodels during TH-dependent metamorphosis and the objective of the present study is to examine olfactory system gene expression for TH biomarkers that can evaluate the biological effects of complex mixtures such as municipal wastewater. We first examine classic TH-response gene transcripts using reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) in the olfactory epithelium (OE) and olfactory bulb (OB) of premetamorphic Rana (Lithobates) catesbeiana tadpoles after 48 h exposure to biologically-relevant concentrations of the THs, 3,5,3’-triiodothyronine (T3) and L-thyroxine (T4), or 17-beta estradiol (E2); a hormone that can crosstalk with THs. As the OE was particularly sensitive to THs, further RNA-seq analysis found>30,000 TH-responsive contigs. In contrast, E2 affected 267 contigs of which only 57 overlapped with THs suggesting that E2 has limited effect on the OE at this developmental phase. Gene ontology enrichment analyses identified sensory perception and nucleoside diphosphate phosphorylation as the top affected terms for THs and E2, respectively. Using classic and additional RNA-seq-derived TH-response gene transcripts, we queried TH-disrupting activity in municipal wastewater effluent from two different treatment systems: anaerobic membrane bioreactor (AnMBR) and membrane enhanced biological phosphorous removal (MEBPR). While we observed physical EDC removal in both systems, some TH disruption activity was retained in the effluents. This work lays an important foundation for linking TH-dependent gene expression with olfactory system function in amphibians.
  • Biogeography of resistance to paralytic shellfish toxins in softshell
           clam, Mya arenaria (L.), populations along the Atlantic coast of North
    • Abstract: Publication date: Available online 30 June 2018Source: Aquatic ToxicologyAuthor(s): Jennifer M. Phillips, V. Monica Bricelj, Maren Mitch, Robert M. Cerrato, Scott MacQuarrie, Laurie B. ConnellABSTRACTBlooms of Alexandrium spp., the causative agent of paralytic shellfish poisoning (PSP), recur with varying frequency and intensity on the Northwest Atlantic coast of North America, from New York, USA, to northern Canadian waters. Along this latitudinal range blooms co-occur with abundant, intertidal populations of softshell clams, Mya arenaria. Prior work identified a naturally-occurring genetic mutation in Domain II α-subunit of the clams’ voltage-gated sodium channels (NaV), which significantly reduces the binding affinity of the paralytic shellfish toxin, saxitoxin (STX). This mutation provides clams with resistance to the deleterious effects of STX, allowing them to continue feeding during Alexandrium spp. blooms and attain very high tissue toxicities. This study used genetic sequencing of the NaV mutation locus in clams from four coastal regions of the Bay of Fundy-Gulf of Maine and the mid-Atlantic to determine the percentage of clams in each region that possess the resistant NaV mutation. The genotype composition was related to the occurrence and magnitude of PSP outbreaks based on shellfish toxicity, primarily that of mussels, Mytilus edulis, used as a proxy for the prevalence and severity of Alexandrium blooms in each region. As hypothesized, the proportion of clams bearing the resistant mutation generally matched up well with the historical incidence and intensity of Alexandrium spp. blooms. The highest percentage of homozygote resistant clams (RR = 70.0%), and the lowest percentage of sensitive clams (SS = 4.5%) were found in eastern Gulf of Maine populations. Exceptions at a few sites where anomalously high numbers of M. arenaria with the resistant mutation were found despite the absence of blooms, may be attributable to larval gene flow. There was no evidence that Alexandrium blooms occurring in Northport Harbor, Long Island, have resulted in a shift in genotypic composition of the local clam population, presumably due to their low cell toxicity. Seasonal mismatch of highly vulnerable M. arenaria postset with toxic blooms at this latitude may also partly explain this result. This study provides strong supporting evidence that Alexandrium blooms can select for resistance to PSP-toxins in M. arenaria populations and proposes a mechanism for the persistence of the sensitive allele throughout the region. Implications for clam aquaculture (seeding) efforts, as well as for shellfish toxicity monitoring are discussed.
  • Developmental and latent effects of diluted bitumen exposure on early life
           stages of sockeye salmon (Oncorhynchus nerka)
    • Abstract: Publication date: Available online 26 June 2018Source: Aquatic ToxicologyAuthor(s): Sarah L. Alderman, Feng Lin, Todd E. Gillis, Anthony P. Farrell, Christopher J. KennedyAbstractThe early life stages of Pacific salmon are at risk of environmental exposure to diluted bitumen (dilbit) as Canada’s oil sands industry continues to expand. The toxicity and latent effects of dilbit exposure were assessed in sockeye salmon (Oncorhynchus nerka) exposed to water-soluble fractions of dilbit (WSFd) from fertilization to the swim-up stage, and then reared in clean water for 8 months. Mortality was significantly higher in WSFd-exposed embryos, with cumulative mortality up to 4.6-fold higher in exposed relative to unexposed embryos. The sublethal effects of WSFd exposure included transcriptional up-regulation of cyp1a, a concentration-dependent delay in the onset and progression of hatching, as well as increased prevalence of developmental deformities at total polycyclic aromatic hydrocarbon (TPAH) concentrations ≥35 μg L-1. Growth and body composition were negatively affected by WSFd exposure, including a concentration-specific decrease in soluble protein concentration and increases in total body lipid and triglyceride concentrations. Mortality continued during the first 2 months after transferring fish to clean water, reaching 53% in fish exposed to 100 μg L-1 TPAH; but there was no latent impact on swimming performance, heart mass, or heart morphology in surviving fish after 8 months. A latent effect of WSFd exposure on brain morphology was observed, with fish exposed to 4 μg L-1 TPAH having significantly larger brains compared to other treatment groups after 8 months in clean water. This study provides comprehensive data on the acute, sub-chronic, and latent impacts of dilbit exposure in early life stage sockeye, information that is critical for a proper risk analysis of the impact of a dilbit spill on this socioeconomically important fish species.
  • Chlorine toxicity to Navicula pelliculosa and Achnanthes spp. in a
           flow-through system: the use of immobilised microalgae and variable
           chlorophyll fluorescence
    • Abstract: Publication date: Available online 25 June 2018Source: Aquatic ToxicologyAuthor(s): Marta Vannoni, Veronique Creach, Jon Barry, Dave SheahanAbstractChlorination is a widely used antifouling method for freshwater and marine applications. Chlorine added to seawater reacts to form oxidants that are toxic to biofouling organisms. Further, the oxidants that result are short-lived, but may nevertheless affect non-target species in waterbodies receiving the antifouling effluent. This study evaluated the toxicity of chlorinated seawater (e.g. following sodium hypochlorite addition) on two different species of marine benthic diatoms (Achnanthes spp., and Navicula pelliculosa), which are representative of microphytobenthos communities - an important component in coastal habitats that may be exposed to chlorinated seawater. To evaluate the growth inhibition over a 72 hour period, algae were immobilised in alginate beads and exposed to different levels of chlorination in a flow through system. Growth rates and physiological condition of the microalgae were evaluated using a Fast Repetition Rate fluorometer (FRRf). To determine whether alginate influenced the sensitivity of algal response, studies were also conducted in a static test system (without renewal of test solutions) using both free cells and immobilised cells with initial chlorine added to achieve a similar range of concentrations as those used in the flow-through study. Within the first hour of the exposure period there was an indication that, for both species, the free algal cells in the static system were more sensitive to exposure to chlorinated seawater than were alginate-immobilised cells in the flow through system. Immobilised cells in a static system with a single addition of chlorine were also less sensitive to chlorination than free algal cells. However, for periods of 24 hours or more due to decay of TRO in the static system the exposure of immobilised algae in the flow through system had a greater impact and hence lower effect concentrations. For the flow-through studies Achnanthes spp. was the most sensitive after 72 hours exposure with a potential no effect concentration EC10 value of 0.02 mg l-1 as Cl2 equivalents expressed as total residual oxidants (TRO) compared 0.04 mg l-1 TRO for N. pelliculosa. Immobilisation of algal cells in alginate was found to be an effective means of determining the impact of chlorination and is likely to be effective for other non-persistent substances. Based on the data produced, the extent and significance of ecological effects of chlorination upon algal species typical of microphytobenthos are likely to be limited providing discharges comply with a maximum allowable concentration of 0.01 mg l-1 TRO at the edge of an agreed mixing zone.
  • Life history traits and genotoxic effects on Daphnia magna exposed to
           waterborne uranium and to a uranium mine effluent - a transgenerational
    • Abstract: Publication date: Available online 19 June 2018Source: Aquatic ToxicologyAuthor(s): Paulo Reis, Ruth Pereira, F.P. Carvalho, J. Oliveira, M. Malta, Sónia Mendo, Joana LourençoAssessing the impact of uranium mining industry on aquatic ecosystems near mining areas is critical to ensure the long-term health and sustainability of ecosystem services. As so, a transgenerational study with Daphnia magna has been conducted to perceive to what extent intermittent discharges of uranium mine effluents into watercourses may impact the DNA integrity and life history traits of cladocerans. Organisms were exposed for 48 h to a 2% dilution of an uranium mine effluent (UME) and to a corresponding dose of waterborne uranium (WU) that, according to our preliminary studies, induces significant DNA damage in daphnids. After exposure, organisms were transferred to clean medium, where three successive generations were monitored for genotoxicity and other effects at the individual and population level. Despite some differences between WU and UME data, our results revealed that the negative impacts of the short-term exposure gradually disappeared after placing the organisms in clean medium. These results suggest that, under intermittent stress, daphnids are able to recover, since after the 3rd brood release, DNA damage (measured as DNA strand breaks) is no longer observed and has no significant impact on the detectable life traits of offspring. Although our results indicate that populations of D. magna are not affected by intermittent and highly diluted discharges from uranium mining, aquatic systems under this kind of pressure should not be seen as hazardous-free. Future studies in this field are recommended and these should consider radionuclides in the water column, their accumulation in the sediments and also multiple life stages.Graphical abstractGraphical abstract for this article
  • Cadmium-mediated morphological, biochemical and physiological tuning in
           three different Anabaena species
    • Abstract: Publication date: Available online 19 June 2018Source: Aquatic ToxicologyAuthor(s): Prashant Kumar Singh, Wenjing Wang, Alok Kumar ShrivastavaAbstractCyanobacteria are a natural inhabitant of paddy field and enhance the crop productivity in an eco-friendly manner. Cadmium (Cd) is a perilous trace metal element which not only limits the crop productivity but also inhibits the growth and nitrogen-fixing ability of these diazotrophs as well as the biodiversity of rice field semiaquatic agroecosystems. However, the impact of Cd toxicity in diazotrophic cyanobacteria is yet not adequately addressed. Therefore, in the present study, three diazotrophic cyanobacterial species, i.e., Anabaena sp. PCC7120, Anabaena L31, and Anabaena doliolum were subjected to their LC50 doses of Cd, and their physiological (PSII, PSI, respiration, energy status and nitrogen fixation rate), biochemical variables (such as antioxidant contents and antioxidant enzymes) together with morphological parameters were evaluated. The results of physiological variables suggested that the Cd exposure adversely affects the photosynthesis, respiration, and biological nitrogen fixation ability across three Anabaena species. The results of biochemical variables in terms of accumulation of antioxidants (glutathione, thiol, phytochelatin and proline) content as well as antioxidant enzymes such as glutathione S-transferase (GST), glutathione reductase (GR), catalase-peroxidase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) revealed that their inter-species stress tolerance behavior may be attributed to the differential accumulation of antioxidants as well as differential antioxidant enzyme activity in three species. Furthermore, the enhanced antioxidant enzymes activity such as GST, GR, CAT, and SOD in Anabaena L31 advocated significantly higher as compared to Anabaena PCC7120 and Anabaena doliolum. In conclusion, Cd-toxicity assessment regarding physiological, biochemical and morphological aspects across three species identified Anabaena L31 as Cd-resistant species than the other two tested species, i.e., Anabaena PCC7120 and Anabaena doliolum.
  • Temporal variations in kidney metal concentrations and their implications
           for retinoid metabolism and oxidative stress response in wild yellow perch
           (Perca flavescens)
    • Abstract: Publication date: Available online 9 June 2018Source: Aquatic ToxicologyAuthor(s): Michel A. Defo, Louis Bernatchez, Peter G.C. Campbell, Patrice CoutureAbstractThe objective of this study was to determine if temporal variations in tissue metal concentrations are related to biomarkers of retinoid metabolism and oxidative stress responses in juvenile yellow perch (Perca flavescens). To this end, kidney metal (Cd, Cu and Zn) concentrations were measured in fish sampled in spring and fall 2012 in four lakes representing a wide range of water and sediment metal contamination in the Rouyn-Noranda (Quebec) region. Lakes Opasatica and Hélène were considered as reference lakes while lakes Dufault and Marlon were metal-contaminated. Kidney concentrations of Cd, Cu and Zn varied widely between spring and fall in fish from both clean and metal-contaminated lakes. An inter-lake difference in renal metal concentrations was only observed for Cd, with fish from Lake Marlon consistently displaying higher concentrations. In the spring, the concentrations of liver dehydroretinol, dehydroretinyl palmitate and total vitamin A esters were higher in fish sampled in the most contaminated lake.Strong temporal variations in the concentrations of these metabolites, as well as in the percentage of liver free dehydroretinol and the epidermal retinol dehydrogenase 2 transcription levels, were observed in fish living in the most metal-impacted lake, with generally higher values in the spring. In contrast to liver, in muscle, no clear seasonal variations in the concentrations of dehydroretinol, dehydroretinyl stearate or in the percentage of free dehydroretinol were observed in fish captured in the most contaminated lake. Temporal variations of traditional biomarkers of oxidative stress response were also observed in the most metal-impacted lake. For example, the transcription level of the gene encoding Cu/Zn superoxide dismutase-1 in liver and muscle catalase activity of perch sampled in the most contaminated lake were higher in spring than in fall. Positive relationships were found between kidney Cd concentrations and the transcription level of the gene encoding glucose 6-phosphate dehydrogenase, and all forms of retinoid concentrations in liver in spring, except with the percentage of free dehydroretinol where the correlation was negative. Our results translate to a state of stress caused by Cd and illustrate that temporal variations in tissue metal concentrations affect retinoid metabolism and antioxidant capacities in juvenile wild yellow perch. Overall this study contributes to evidence the importance of considering temporal variations when investigating the consequences of metal contamination on the physiology of wild fish.
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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