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Showing 1 - 200 of 1720 Journals sorted alphabetically
AAPS Journal     Hybrid Journal   (Followers: 20)
Achievements in the Life Sciences     Open Access   (Followers: 4)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 20)
Acta Biologica Colombiana     Open Access   (Followers: 6)
Acta Biologica Hungarica     Full-text available via subscription   (Followers: 4)
Acta Biologica Sibirica     Open Access  
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Acta Biotheoretica     Hybrid Journal   (Followers: 5)
Acta Chiropterologica     Full-text available via subscription   (Followers: 6)
acta ethologica     Hybrid Journal   (Followers: 4)
Acta Limnologica Brasiliensia     Open Access   (Followers: 3)
Acta Médica Costarricense     Open Access   (Followers: 2)
Acta Musei Silesiae, Scientiae Naturales : The Journal of Silesian Museum in Opava     Open Access  
Acta Parasitologica     Hybrid Journal   (Followers: 9)
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Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
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Advances in Virus Research     Full-text available via subscription   (Followers: 5)
African Journal of Range & Forage Science     Hybrid Journal   (Followers: 6)
AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 1)
Ageing Research Reviews     Hybrid Journal   (Followers: 7)
Aging Cell     Open Access   (Followers: 9)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Agrokreatif Jurnal Ilmiah Pengabdian kepada Masyarakat     Open Access  
AJP Cell Physiology     Full-text available via subscription   (Followers: 13)
AJP Endocrinology and Metabolism     Full-text available via subscription   (Followers: 23)
AJP Lung Cellular and Molecular Physiology     Full-text available via subscription   (Followers: 3)
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Alasbimn Journal     Open Access   (Followers: 1)
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American Biology Teacher     Full-text available via subscription   (Followers: 12)
American Fern Journal     Full-text available via subscription   (Followers: 1)
American Journal of Agricultural and Biological Sciences     Open Access   (Followers: 10)
American Journal of Bioethics     Hybrid Journal   (Followers: 10)
American Journal of Biostatistics     Open Access   (Followers: 9)
American Journal of Human Biology     Hybrid Journal   (Followers: 12)
American Journal of Medical and Biological Research     Open Access   (Followers: 5)
American Journal of Plant Sciences     Open Access   (Followers: 19)
American Journal of Primatology     Hybrid Journal   (Followers: 15)
American Malacological Bulletin     Full-text available via subscription   (Followers: 3)
American Naturalist     Full-text available via subscription   (Followers: 64)
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Animal Cells and Systems     Hybrid Journal   (Followers: 4)
Annales de Limnologie - International Journal of Limnology     Hybrid Journal   (Followers: 1)
Annales françaises d'Oto-rhino-laryngologie et de Pathologie Cervico-faciale     Full-text available via subscription   (Followers: 3)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Biologia     Open Access   (Followers: 1)
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Annals of Biomedical Engineering     Hybrid Journal   (Followers: 18)
Annals of Human Biology     Hybrid Journal   (Followers: 4)
Annual Review of Biomedical Engineering     Full-text available via subscription   (Followers: 17)
Annual Review of Biophysics     Full-text available via subscription   (Followers: 25)
Annual Review of Cell and Developmental Biology     Full-text available via subscription   (Followers: 37)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Annual Review of Genomics and Human Genetics     Full-text available via subscription   (Followers: 18)
Annual Review of Phytopathology     Full-text available via subscription   (Followers: 10)
Anthropological Review     Open Access   (Followers: 23)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
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Antioxidants     Open Access   (Followers: 4)
Antioxidants & Redox Signaling     Hybrid Journal   (Followers: 8)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apidologie     Hybrid Journal   (Followers: 4)
Apmis     Hybrid Journal   (Followers: 1)
APOPTOSIS     Hybrid Journal   (Followers: 8)
Applied Bionics and Biomechanics     Open Access   (Followers: 8)
Applied Vegetation Science     Full-text available via subscription   (Followers: 9)
Aquaculture Environment Interactions     Open Access   (Followers: 2)
Aquaculture International     Hybrid Journal   (Followers: 22)
Aquaculture Reports     Open Access   (Followers: 3)
Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society     Open Access   (Followers: 6)
Aquatic Biology     Open Access   (Followers: 4)
Aquatic Ecology     Hybrid Journal   (Followers: 30)
Aquatic Ecosystem Health & Management     Hybrid Journal   (Followers: 13)
Aquatic Science and Technology     Open Access   (Followers: 3)
Aquatic Toxicology     Hybrid Journal   (Followers: 19)
Archaea     Open Access   (Followers: 3)
Archiv für Molluskenkunde: International Journal of Malacology     Full-text available via subscription   (Followers: 3)
Archives of Biomedical Sciences     Open Access   (Followers: 7)
Archives of Microbiology     Hybrid Journal   (Followers: 8)
Archives of Natural History     Hybrid Journal   (Followers: 7)
Archives of Oral Biology     Hybrid Journal   (Followers: 2)
Archives of Virology     Hybrid Journal   (Followers: 5)
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2)
Arid Ecosystems     Hybrid Journal   (Followers: 3)
Arquivos do Instituto Biológico     Open Access   (Followers: 1)
Arquivos do Museu Dinâmico Interdisciplinar     Open Access  
Arthropod Structure & Development     Hybrid Journal   (Followers: 2)
Arthropods     Open Access   (Followers: 1)
Artificial DNA: PNA & XNA     Hybrid Journal   (Followers: 2)
Artificial Photosynthesis     Open Access   (Followers: 1)
Asian Bioethics Review     Full-text available via subscription   (Followers: 1)
Asian Journal of Biodiversity     Open Access   (Followers: 5)
Asian Journal of Biological Sciences     Open Access   (Followers: 3)
Asian Journal of Cell Biology     Open Access   (Followers: 5)
Asian Journal of Developmental Biology     Open Access   (Followers: 2)
Asian Journal of Medical and Biological Research     Open Access   (Followers: 2)
Asian Journal of Nematology     Open Access   (Followers: 3)
Asian Journal of Poultry Science     Open Access   (Followers: 4)
Australian Life Scientist     Full-text available via subscription   (Followers: 2)
Australian Mammalogy     Hybrid Journal   (Followers: 5)
Autophagy     Hybrid Journal   (Followers: 2)
Avian Biology Research     Full-text available via subscription   (Followers: 3)
Avian Conservation and Ecology     Open Access   (Followers: 7)
Bacteriology Journal     Open Access   (Followers: 2)
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)
Berita Biologi     Open Access   (Followers: 1)
Between the Species     Open Access   (Followers: 1)
Bio Tribune Magazine     Hybrid Journal  
BIO Web of Conferences     Open Access  
BIO-Complexity     Open Access  
Bio-Grafía. Escritos sobre la Biología y su enseñanza     Open Access  
Bioanalytical Reviews     Hybrid Journal   (Followers: 2)
Biocatalysis and Biotransformation     Hybrid Journal   (Followers: 6)
Biochemistry and Cell Biology     Hybrid Journal   (Followers: 14)
Biochimie     Hybrid Journal   (Followers: 7)
BioControl     Hybrid Journal   (Followers: 5)
Biocontrol Science and Technology     Hybrid Journal   (Followers: 5)
Biodemography and Social Biology     Hybrid Journal   (Followers: 1)
Biodiversidad Colombia     Open Access  
Biodiversity : Research and Conservation     Open Access   (Followers: 26)
Biodiversity and Natural History     Open Access   (Followers: 5)
Biodiversity Data Journal     Open Access   (Followers: 3)
Biodiversity Informatics     Open Access  
Bioedukasi : Jurnal Pendidikan Biologi FKIP UM Metro     Open Access  
Bioeksperimen : Jurnal Penelitian Biologi     Open Access  
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Bioelectromagnetics     Hybrid Journal   (Followers: 1)
Bioenergy Research     Hybrid Journal   (Followers: 2)
Bioengineering and Bioscience     Open Access   (Followers: 1)
BioEssays     Hybrid Journal   (Followers: 10)
Bioethics     Hybrid Journal   (Followers: 14)
BioéthiqueOnline     Open Access  
Biofabrication     Hybrid Journal   (Followers: 3)
Biogeosciences (BG)     Open Access   (Followers: 10)
Biogeosciences Discussions (BGD)     Open Access   (Followers: 1)
Bioinformatics     Hybrid Journal   (Followers: 236)
Bioinformatics and Biology Insights     Open Access   (Followers: 14)
Bioinspiration & Biomimetics     Hybrid Journal   (Followers: 6)
Biointerphases     Open Access   (Followers: 1)
Biojournal of Science and Technology     Open Access  
Biologia     Hybrid Journal  
Biologia on-line : Revista de divulgació de la Facultat de Biologia     Open Access  
Biological Bulletin     Partially Free   (Followers: 4)
Biological Control     Hybrid Journal   (Followers: 5)
Biological Invasions     Hybrid Journal   (Followers: 16)
Biological Journal of the Linnean Society     Hybrid Journal   (Followers: 14)
Biological Letters     Open Access   (Followers: 4)
Biological Procedures Online     Open Access  
Biological Psychiatry     Hybrid Journal   (Followers: 41)
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Biological Theory     Hybrid Journal   (Followers: 1)
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Biologics: Targets & Therapy     Open Access   (Followers: 1)
Biologie Aujourd'hui     Full-text available via subscription  
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 42)
Biologija     Open Access  
Biology     Open Access   (Followers: 5)
Biology and Philosophy     Hybrid Journal   (Followers: 16)
Biology Bulletin     Hybrid Journal   (Followers: 1)
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Biology Direct     Open Access   (Followers: 7)
Biology Letters     Full-text available via subscription   (Followers: 35)
Biology Methods and Protocols     Hybrid Journal  

        1 2 3 4 5 6 7 8 | Last

Journal Cover Aquatic Toxicology
  [SJR: 1.671]   [H-I: 105]   [19 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0166-445X - ISSN (Online) 1879-1514
   Published by Elsevier Homepage  [3034 journals]
  • Selenium accumulation and metabolism in algae
    • Authors: Michela Schiavon; Andrea Ertani; Sofia Parrasia; Francesca Dalla Vecchia
      Pages: 1 - 8
      Abstract: Publication date: August 2017
      Source:Aquatic Toxicology, Volume 189
      Author(s): Michela Schiavon, Andrea Ertani, Sofia Parrasia, Francesca Dalla Vecchia
      Selenium (Se) is an intriguing element because it is metabolically required by a variety of organisms, but it may induce toxicity at high doses. Algae primarily absorb selenium in the form of selenate or selenite using mechanisms similar to those reported in plants. However, while Se is needed by several species of microalgae, the essentiality of this element for plants has not been established yet. The study of Se uptake and accumulation strategies in micro- and macro-algae is of pivotal importance, as they represent potential vectors for Se movement in aquatic environments and Se at high levels may affect their growth causing a reduction in primary production. Some microalgae exhibit the capacity of efficiently converting Se to less harmful volatile compounds as a strategy to cope with Se toxicity. Therefore, they play a crucial role in Se-cycling through the ecosystem. On the other side, micro- or macro-algae enriched in Se may be used in Se biofortification programs aimed to improve Se content in human diet via supplementation of valuable food. Indeed, some organic forms of selenium (selenomethionine and methylselenocysteine) are known to act as anticarcinogenic compounds and exert a broad spectrum of beneficial effects in humans and other mammals. Here, we want to give an overview of the developments in the current understanding of Se uptake, accumulation and metabolism in algae, discussing potential ecotoxicological implications and nutritional aspects.

      PubDate: 2017-05-29T21:27:43Z
      DOI: 10.1016/j.aquatox.2017.05.011
      Issue No: Vol. 189 (2017)
  • Effects of road salt on larval amphibian susceptibility to parasitism
           through behavior and immunocompetence
    • Authors: Dino Milotic; Marin Milotic; Janet Koprivnikar
      Pages: 42 - 49
      Abstract: Publication date: August 2017
      Source:Aquatic Toxicology, Volume 189
      Author(s): Dino Milotic, Marin Milotic, Janet Koprivnikar
      Large quantities of road salts are used for de-icing in temperate climates but often leach into aquatic ecosystems where they can cause harm to inhabitants, including reduced growth and survival. However, the implications of road salt exposure for aquatic animal susceptibility to pathogens and parasites have not yet been examined even though infectious diseases can significantly contribute to wildlife population declines. Through a field survey, we found a range of NaCl concentrations (50–560mg/L) in ponds known to contain larval amphibians, with lower levels found in sites close to gravel- rather than hard-surfaced roads. We then investigated how chronic exposure to environmentally-realistic levels of road salt (up to 1140mg/L) affected susceptibility to infection by trematode parasites (helminths) in larval stages of two amphibian species (Lithobates sylvaticus − wood frogs, and L. pipiens − northern leopard frogs) by considering effects on host anti-parasite behavior and white blood cell profiles. Wood frogs exposed to road salt had higher parasite loads, and also exhibited reduced anti-parasite behavior in these conditions. In contrast, infection intensity in northern leopard frogs had a non-monotonic response to road salts even though lymphocytes were only elevated at the highest concentration. Our results indicate the potential for chronic road salt exposure to affect larval amphibian susceptibility to pathogenic parasites through alterations of behavior and immunocompetence, with further studies needed at higher concentrations, as well as that of road salts on free-living parasite infectious stages.

      PubDate: 2017-06-04T12:55:45Z
      DOI: 10.1016/j.aquatox.2017.05.015
      Issue No: Vol. 189 (2017)
  • Developing transcriptional profiles in Orbicella franksi exposed to
           copper: Characterizing responses associated with a spectrum of
           laboratory-controlled environmental conditions
    • Authors: Michael B. Morgan; Sara E. Edge; Alexander A. Venn; Ross J. Jones
      Pages: 60 - 76
      Abstract: Publication date: August 2017
      Source:Aquatic Toxicology, Volume 189
      Author(s): Michael B. Morgan, Sara E. Edge, Alexander A. Venn, Ross J. Jones

      PubDate: 2017-06-08T15:26:01Z
      DOI: 10.1016/j.aquatox.2017.05.005
      Issue No: Vol. 189 (2017)
  • Physiological determinants of individual variation in sensitivity to an
           organophosphate pesticide in Nile tilapia Oreochromis niloticus
    • Authors: David J. McKenzie; Felipe R. Blasco; Thiago C. Belão; Shaun S. Killen; Nathan D. Martins; Edwin W. Taylor; F. Tadeu Rantin
      Pages: 108 - 114
      Abstract: Publication date: August 2017
      Source:Aquatic Toxicology, Volume 189
      Author(s): David J. McKenzie, Felipe R. Blasco, Thiago C. Belão, Shaun S. Killen, Nathan D. Martins, Edwin W. Taylor, F. Tadeu Rantin
      Individual variation in sub-lethal sensitivity to the organophosphate pesticide trichlorfon was investigated in Nile tilapia, using critical swimming speed (Ucrit) as an indicator. Tilapia exposed for 96h to 500μgl−1 trichlorfon at 26°C (Tcfn group, n=27) showed a significant decline in mean Ucrit, compared to their own control (pre-exposure) performance in clean water (−14.5±2.3%, mean±SEM), but also compared to a Sham group (n=10) maintained for 96h in clean water. Individuals varied in their relative sensitivity to the pesticide, with the decline in Ucrit after exposure varying from 1 to 41%. The Ucrit of the Tcfn group did not recover completely after 96h in clean water, remaining 9.4±3.2% below their own control performance. The decline in performance was associated with a significant increase in net cost of aerobic swimming, of +28.4±6.5% at a sustained speed of 2bodylengthss−1, which translated into a significant decline in swimming efficiency (Eswim) of −17.6±4.0% at that speed. Within the Tcfn group, individual Eswim was a strong positive determinant of individual Ucrit across all trials, and a strong negative determinant of individual% decline in Ucrit after pesticide exposure (P<0.001, linear mixed effect models). Trichlorfon had no effects on standard metabolic rate or active metabolic rate (AMR) but, nonetheless, individual Ucrit in all trials, and% decline in Ucrit after exposure, were strongly associated with individual AMR (positively and negatively, respectively, P<0.001). Individual Ucrit under control conditions was also a strong positive determinant of Ucrit after trichlorfon exposure (P<0.001), but not of the% decline in Ucrit performance. In conclusion, the OP pesticide impaired Ucrit performance by reducing Eswim but individual tilapia varied widely in their relative sensitivity. Intrinsic individual physiology determined effects of the pesticide on performance and, in particular, good swimmers remained better swimmers after exposure.

      PubDate: 2017-06-13T15:28:39Z
      DOI: 10.1016/j.aquatox.2017.06.001
      Issue No: Vol. 189 (2017)
  • Growth and physiological responses of a marine diatom (Phaeodactylum
           tricornutum) against two imidazolium-based ionic liquids ([C4mim]BF4 and
    • Authors: Xiang-Yuan Deng; Biao Chen; Da Li; Xiao-Li Hu; Jie Cheng; Kun Gao; Chang-Hai Wang
      Pages: 115 - 122
      Abstract: Publication date: August 2017
      Source:Aquatic Toxicology, Volume 189
      Author(s): Xiang-Yuan Deng, Biao Chen, Da Li, Xiao-Li Hu, Jie Cheng, Kun Gao, Chang-Hai Wang
      Ionic liquids (ILs) have been considered as “green” substitutes for traditional organic solvents in many existing biological and chemical areas. However, they have high solubility and poor biodegradability in water, suggesting that they could become persistent chemical pollutants in aquatic environment. The ability of two widely used imidazolium-based ILs to affect the growth and physiological characteristics of a marine diatom (Phaeodactylum tricornutum) was investigated in this study. The diatom was exposed to different concentrations of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim]BF4) and 1-octyl-3-methylimidazolium tetrafluoroborate ([C8mim]BF4) for 96h within a batch-culture system. Results showed that [C4mim]BF4 and [C8mim]BF4 were very stable in seawater during 96h of exposure, and the compounds significantly inhibited the growth of P. tricornutum with 24, 48, 72 and 96h EC50 values of 30.81, 28.53, 39.92, 45.88mgL−1 and 30.17, 23.36, 28.62, 31.37mgL−1, respectively. In addition, the photosynthetic activity and chlorophyll a synthesis of P. tricornutum were inhibited by [C4mim]BF4 and [C8mim]BF4, indicating that the structural integrity of chloroplasts of the diatom may be disrupted or damaged by the two ILs. Compared with that of the controls, reactive oxygen species (ROS) level was increased by 0.65, 1.17, 1.85, 3.13, 2.94 times and 0.55, 1.77, 2.42, 3.45, 3.47 times in 5, 10, 20, 40 and 60mgL−1 [C4mim]BF4 and [C8mim]BF4 treatments, respectively. The excessive ROS may cause lipid peroxidation, shortage of metabolic energy and decline of photosynthetic efficiency, which may be the main reason for toxicity of the two ILs to marine diatoms. To withstand the damaging effects of excessive ROS, remarkable physiological and biochemical responses occurred in treatments with the two ILs to protect the cells of P. tricornutum. Parameters such as soluble protein content, soluble sugar content, and superoxide dismutase (SOD) and peroxidase (POD) activities of the diatom increased significantly with increasing concentrations of the two ILs at 96h of exposure relative to the controls. These findings not only provide strong background for evaluating the ecological risks and toxicity of ILs in marine environment, but also help to unravel the toxic mechanism of the two ILs to marine diatoms.

      PubDate: 2017-06-13T15:28:39Z
      DOI: 10.1016/j.aquatox.2017.05.016
      Issue No: Vol. 189 (2017)
  • Stage specific effects of soluble copper and copper oxide nanoparticles
           during sea urchin embryo development and their relation to intracellular
           copper uptake
    • Authors: Cristina Torres-Duarte; Karla M. Ramos-Torres; René Rahimoff; Gary N. Cherr
      Pages: 134 - 141
      Abstract: Publication date: August 2017
      Source:Aquatic Toxicology, Volume 189
      Author(s): Cristina Torres-Duarte, Karla M. Ramos-Torres, René Rahimoff, Gary N. Cherr
      The effects of exposure to either soluble copper (copper sulfate) or copper oxide nanoparticles (nano-CuO) during specific early developmental stages of sea urchin embryos were analyzed. Soluble copper caused significant malformations in embryos (skeletal malformations, delayed development or gut malformations) when present at any given stage, while cleavage stage was the most sensitive to nano-CuO exposure causing skeletal malformations and decreased total antioxidant capacity. The stage specificity was linked to higher endocytic activity during the first hours of development that leads to higher accumulation of copper in specific cells critical for development. Results indicate that nano-CuO results in higher accumulation of copper inside of embryos and this intracellular copper is more persistent as compared to soluble copper. The possible implications later in development are discussed.

      PubDate: 2017-06-18T15:31:19Z
      DOI: 10.1016/j.aquatox.2017.05.008
      Issue No: Vol. 189 (2017)
  • Phylogenetic signals in detoxification pathways in Cyprinid and
           Centrarchid species in relation to sensitivity to environmental pollutants
    • Authors: Peter van den Hurk; Lindsay E. Gerzel; Peter Calomiris; Dennis C. Haney
      Pages: 20 - 25
      Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188
      Author(s): Peter van den Hurk, Lindsay E. Gerzel, Peter Calomiris, Dennis C. Haney
      Observations in a previous study on biomarker responses in fish collected from urban creeks in Greenville, SC, indicated that there might be considerable differences in the expression of biotransformation enzymes in chub and sunfish species. To further investigate these species differences a dosing experiment was performed in which bluehead and creek chub (Nocomis leptocephalus and Semotilus atromaculatus), and redbreast sunfish, pumpkinseed, and bluegill (Lepomis auritus, L. gibbosus, and L. macrochirus) were injected with benzo[a]pyrene (BaP) as a model compound for common pollutants in urban creeks. Fish were injected with BaP doses of 0, 25 and 50mg/kg, and after 3days BaP metabolites in bile, and enzymatic activities of cytochrome P450-1A (CYP1A), UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST) were measured. CYP1A activity was significantly increased after BaP dosing in both species groups, but chubs had significantly lower levels than were observed in the dosed sunfish. The UGT activity in unexposed animals was comparable in both species groups, and significantly increased in both groups as a result of BaP dosage. Finally, GST activity was significantly higher in chubs, but did not change in either species group as a result of BaP exposure. There were no significant differences between species within each species group, and the results confirmed that unexposed chubs have much lower CYP1A activity, but a much higher GST activity than unexposed sunfish. The metabolized BaP was excreted in both species groups, but at the time of sampling there were no differences in the amount of BaP metabolites in the bile of dosed animals. The differences in baseline enzyme activity and induction capacity between both species groups are an example of phylogenetically determined differences between fish families, and may explain why chubs are in general more sensitive to exposure to environmental pollutants than sunfish. This conclusion was corroborated by the observation that the highest BaP dose of 50mg/kg was close to the apparent LC50 for chub, while no mortality was observed in the sunfish at this dose.

      PubDate: 2017-04-29T08:14:24Z
      DOI: 10.1016/j.aquatox.2017.04.004
      Issue No: Vol. 188 (2017)
  • Immunosuppressive effects and associated compensatory responses in
           zebrafish after full life-cycle exposure to environmentally relevant
           concentrations of cadmium
    • Authors: Sai-Nan Guo; Jia-Lang Zheng; Shuang-Shuang Yuan; Qing-Ling Zhu; Chang-Wen Wu
      Pages: 64 - 71
      Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188
      Author(s): Sai-Nan Guo, Jia-Lang Zheng, Shuang-Shuang Yuan, Qing-Ling Zhu, Chang-Wen Wu
      In natural environments, fish survive in polluted water by cadmium (Cd) throughout their whole life cycle. However, little information is available on Cd toxicity considering a life cycle assessment. The present study investigated effects of environmental levels of cadmium (0, 2.5, and 5μg/L) on immune responses in liver and spleen of zebrafish for 15 weeks, from embryos to sexually maturity. Nitric oxide (NO) levels and iNOS activity declined in liver and spleen of zebrafish exposed to 5μg/L Cd, suggesting an immunosuppressive effect. The result was further supported by the decreased transcriptional levels of proinflammatory cytokines by Cd, such as interleukin-6 (IL-6), interleukin-10 (IL-10), interleukin-1β (IL-1β), and tumour necrosis factor-α (TNF-α) in liver. However, a sharp increase in the mRNA levels of these cytokines was observed in spleen of zebrafish exposed to Cd. The increased mRNA expression of these proinflammatory cytokines may be the secondary effect following immunosuppression and just reflect a compensatory mechanism for coping with the decreased immunity, which may explain an increase in mRNA levels and a decrease in iNOS activity in spleen of zebrafish exposed to Cd. In liver, the down-regulated mRNA levels of iNOS paralleled with the decreased iNOS activity, suggesting a synchronous response from a molecular level to a biochemical level. Positive correlations between mRNA expression levels of nuclear transcription factor κB (NF-κB) and proinflammatory cytokines were also observed, suggesting that NF-κB might be required for the protracted induction of inflammatory genes. The corresponding changes in the mRNA levels of the inhibitor of κBα (IκBαa and IκBαb) may form a feedback loop to restore transcriptional activity of NF-κB. Furthermore, splenic ROS levels were increased by 5μg/L Cd, possibly activating NF-κB pathway. Taken together, immunosuppressive effects and tissue-dependent compensatory responses were demonstrated in zebrafish after full life-cycle exposure to environmental levels of Cd, indicating a compromise between survival and immunity.

      PubDate: 2017-04-29T08:14:24Z
      DOI: 10.1016/j.aquatox.2017.04.014
      Issue No: Vol. 188 (2017)
  • Acute toxicity and esterase response to carbaryl exposure in two different
           populations of amphipods Hyalella curvispina
    • Authors: Olga Liliana Anguiano; Melina Vacca; María Emilia Rodriguez Araujo; Mónica Montagna; Andrés Venturino; Ana Ferrari
      Pages: 72 - 79
      Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188
      Author(s): Olga Liliana Anguiano, Melina Vacca, María Emilia Rodriguez Araujo, Mónica Montagna, Andrés Venturino, Ana Ferrari
      During the last years, a carbaryl insecticide was extensively applied in the valley of Río Negro and Neuquén, North Patagonia Argentina, to manage codling moths (Cydia pomonella), the main pest of pear and apple trees. In this study carbaryl susceptibility and B-esterase activity from both insecticide-exposed and non-exposed field populations of amphipods Hyalella curvispina were studied. Two subpopulations, one susceptible to carbaryl (LC50 =213±7.5μg/L carbaryl) and one resistant to it (LC50 =14,663±2379μg/L carbaryl), were found in the agricultural area selected in this study. Both populations were, in turn, more resistant to carbaryl than the population from a pristine area (LC50 =11.31±2.27μg/L carbaryl). The in vivo 48h-IC50 values for cholinesterase (ChE) were close to the corresponding 48h-LC50 values as determined for the non-exposed population (IC50 =7.16±0.86μg/L carbaryl) and for the susceptible subpopulation from the insecticide-exposed site (IC50 =193±99μg/L carbaryl). Carbaryl exposure of the amphipods from the agricultural area mentioned above produced a significant decrease of carboxylesterase (CabE) activity, at a sublethal concentration (10μg/L) that was not able to significantly inhibit ChE, thereby showing a protective role of CabE and its usefulness as early biomarker. However, at lethal concentrations the inhibition of ChE activity was higher than that of CabE. On the other hand, CabE of amphipods from the pristine site was less sensitive to carbaryl than ChE, suggesting a different participation of CabE in ChE protection in the susceptible population of H. curvispina. Pulse exposure to carbaryl for 2h caused a significant inhibition of ChE in amphipods from both populations, with a fast recovery as expected for a carbamate insecticide. In conclusion, we proved that amphipods from the said agricultural area have developed resistance to carbaryl and showed the presence of two subpopulations with a different response to the insecticide. Moreover, these results reinforce the use of ChE together with CabE inhibition as indicators of carbamate exposure in H. curvispina.

      PubDate: 2017-05-05T07:13:28Z
      DOI: 10.1016/j.aquatox.2017.04.013
      Issue No: Vol. 188 (2017)
  • Modifications of the soluble proteome of a mediterranean strain of the
           invasive neurotoxic dinoflagellate Alexandrium catenella under metal
           stress conditions
    • Authors: Natacha Jean; Estelle Dumont; Faouzi Herzi; Thierry Balliau; Mohamed Laabir; Estelle Masseret; Stéphane Mounier
      Pages: 80 - 91
      Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188
      Author(s): Natacha Jean, Estelle Dumont, Faouzi Herzi, Thierry Balliau, Mohamed Laabir, Estelle Masseret, Stéphane Mounier
      The soluble proteome of the mediterranean strain ACT03 of the invasive neurotoxic dinoflagellate Alexandrium catenella exposed to lead or zinc at 6, 12 or 18μM (total concentrations), or under control conditions, was characterized by two-dimensional gel electrophoresis (2-DE). Zinc reduced (P<0.05) the total number of protein spots (−41%, −52% and −60%, at 6, 12 or 18μM, respectively). Besides, most of the proteins constituting the soluble proteome were down-regulated in response to lead or zinc stresses. These proteins were involved mainly in photosynthesis (20–37% for lead; 36–50% for zinc) (ribulose-1,5-bisphosphate carboxylase/oxygenase: RUBISCO; ferredoxin-NADP+ reductase: FNR; peridinin-chlorophyll a-protein: PCP), and in the oxidative stress response (29–34% for lead; 17–36% for zinc) (superoxide dismutase: SOD; proteasome α/β subunits). These negative effects could be partly compensated by the up-regulation of specific proteins such as ATP-synthase β subunit (+16.3 fold after exposure to lead at 12μM). Indeed, an increase in the abundance of ATP-synthase could enrich the ATP pool and provide more energy available for the cells to survive under metal stress, and make the ATP-synthase transport of metal cations out of the cells more efficient. Finally, this study shows that exposure to lead or zinc have a harmful effect on the soluble proteome of A. catenella ACT03, but also suggests the existence of an adaptative proteomic response to metal stresses, which could contribute to maintaining the development of this dinoflagellate in trace metal-contaminated ecosystems.

      PubDate: 2017-05-05T07:13:28Z
      DOI: 10.1016/j.aquatox.2017.04.011
      Issue No: Vol. 188 (2017)
  • Characterization of cadmium transport in hepatopancreatic cells of a
           mangrove crab Ucides cordatus: The role of calcium
    • Authors: Priscila Ortega; Marcio R. Custódio; Flavia P. Zanotto
      Pages: 92 - 99
      Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188
      Author(s): Priscila Ortega, Marcio R. Custódio, Flavia P. Zanotto
      Cadmium is a toxic metal, present in batteries and discarded in estuaries and mangrove habitats. Apart from that, it is a non-essential metal that causes toxic effects in many organisms. Cadmium accumulates in gills and hepatopancreas of crustaceans and its route into the cell is unknown. It is possible that occurs by calcium channels or calcium transporters. The objective of this study was to characterize the transport of cadmium and the role of calcium in different cell types from hepatopancreas of the mangrove crab Ucides cordatus. For this, the hepatopancreas was dissociated by magnetic stirring and after that separated by a sucrose gradient. Then, the cells were labeled with FluoZin-3 AM and different CdCl2 concentrations were added together with a variety of inhibitors. The results showed that Cd2+ transport occurs differently in each cell type from hepatopancreas and is partially explained by the function the cells perform in this organ. Embryonic (E) and Resorptive (R) cells transported more Cd2+ compared to Fibrillar (F) and Blister (B) cells. R cells responded to Ca2+ channel inhibitors and intracellular Ca2+ manipulations positively, as the other cell types and in a stronger way. B cells were the least responsive to Ca2+ channel inhibitors and, unlike the other cells, showed a competition of Cd2+ with intracellular Ca2+ manipulations. The results indicate that Ca2+ affects the transport of Cd2+ in hepatopancreatic cells of Ucides cordatus and uses Ca2+ channels to enter these cells. In addition, information about Ca concentration could be used as a mitigating factor for Cd accumulation in crabs’ hepatopancreas.

      PubDate: 2017-05-05T07:13:28Z
      DOI: 10.1016/j.aquatox.2017.04.012
      Issue No: Vol. 188 (2017)
  • Green-synthesized CdS nano-pesticides: Toxicity on young instars of
           malaria vectors and impact on enzymatic activities of the non-target mud
           crab Scylla serrata
    • Authors: Vasu Sujitha; Kadarkarai Murugan; Devakumar Dinesh; Amuthvalli Pandiyan; Rajasekar Aruliah; Jiang-Shiou Hwang; Kandasamy Kalimuthu; Chellasamy Panneerselvam; Akon Higuchi; Al Thabiani Aziz; Suresh Kumar; Abdullah A. Alarfaj; Baskaralingam Vaseeharan; Angelo Canale; Giovanni Benelli
      Pages: 100 - 108
      Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188
      Author(s): Vasu Sujitha, Kadarkarai Murugan, Devakumar Dinesh, Amuthvalli Pandiyan, Rajasekar Aruliah, Jiang-Shiou Hwang, Kandasamy Kalimuthu, Chellasamy Panneerselvam, Akon Higuchi, Al Thabiani Aziz, Suresh Kumar, Abdullah A. Alarfaj, Baskaralingam Vaseeharan, Angelo Canale, Giovanni Benelli
      Currently, nano-formulated mosquito larvicides have been widely proposed to control young instars of malaria vector populations. However, the fate of nanoparticles in the aquatic environment is scarcely known, with special reference to the impact of nanoparticles on enzymatic activity of non-target aquatic invertebrates. In this study, we synthesized CdS nanoparticles using a green protocol relying on the cheap extract of Valoniopsis pachynema algae. CdS nanoparticles showed high toxicity on young instars of the malaria vectors Anopheles stephensi and A. sundaicus. The antimalarial activity of the nano-synthesized product against chloroquine-resistant (CQ-r) Plasmodium falciparum parasites was investigated. From a non-target perspective, we focused on the impact of this novel nano-pesticide on antioxidant enzymes acetylcholinesterase (AChE) and glutathione S-transferase (GST) activities of the mud crab Scylla serrata. The characterization of nanomaterials was carried out by UV–vis and FTIR spectroscopy, as well as SEM and XRD analyses. In mosquitocidal assays, LC50 of V. pachynema-synthesized CdS nanoparticles on A. stephensi ranged from 16.856 (larva I), to 30.301μg/ml (pupa), while for An. sundaicus they ranged from 13.584 to 22.496μg/ml. The antiplasmodial activity of V. pachynema extract and CdS nanoparticles was evaluated against CQ-r and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. IC50 of V. pachynema extract was 58.1μg/ml (CQ-s) and 71.46μg/ml (CQ-r), while nano-CdS IC50 was 76.14μg/ml (CQ-s) and 89.21μg/ml (CQ-r). In enzymatic assays, S. serrata crabs were exposed to sub-lethal concentrations, i.e. 4, 6 and 8μg/ml of CdS nanoparticles, assessing changes in GST and AChE activity after 16days. We observed significantly higher activity of GST, if compared to the control, during the whole experiment period. In addition, a single treatment with CdS nanoparticles led to a significant decrease in AChE activity over time. The toxicity of CdS nanoparticles and Cd ions in aqueous solution was also assessed in mud crabs, showing higher toxicity of aqueous Cd ions if compared to nano-CdS. Overall, our results underlined the efficacy of green-synthesized CdS nanoparticles in malaria vector control, outlining also significant impacts on the enzymatic activity of non-target aquatic organisms, with special reference to mud crabs.

      PubDate: 2017-05-10T07:18:26Z
      DOI: 10.1016/j.aquatox.2017.04.015
      Issue No: Vol. 188 (2017)
  • RNA-sequencing and pathway analysis reveal alteration of hepatic steroid
           biosynthesis and retinol metabolism by tributyltin exposure in male rare
           minnow (Gobiocypris rarus)
    • Authors: Jiliang Zhang; Chunnuan Zhang; Ping Sun; Maoxian Huang; Mingzhen Fan; Min Liu
      Pages: 109 - 118
      Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188
      Author(s): Jiliang Zhang, Chunnuan Zhang, Ping Sun, Maoxian Huang, Mingzhen Fan, Min Liu
      Tributyltin (TBT) is widely spread in aquatic ecosystems. Although adverse effects of TBT on reproduction and lipogenesis are observed in fishes, the underlying mechanisms, especially in livers, are still scarce and inconclusive. Thus, RNA-sequencing runs were performed on the hepatic libraries of adult male rare minnow (Gobiocypris rarus) after TBT exposure for 60d. After differentially expressed genes were identified, enrichment analysis and validation by quantitative real-time PCR were conducted. The results showed that TBT up-regulated the profile of hepatic genes in the steroid biosynthesis pathway and down-regulated the profile of hepatic genes in the retinol metabolism pathway. In the hepatic steroid biosynthesis pathway, TBT might induce biosynthesis of cholesterol, which could affect the bioavailability of steroid hormones. More important, 3beta-hydroxysteroid 3-dehydrogenase, a key enzyme in the biosynthesis of all active steroid hormones, was up-regulated by TBT exposure. In the hepatic retinol metabolism pathway, TBT impaired retinoic acid homeostasis which plays essential roles in both reproduction and lipogenesis. The results of two pathways offered new mechanisms underlying the toxicology of TBT and represented a starting point from which detailed mechanistic links should be explored.

      PubDate: 2017-05-14T21:19:45Z
      DOI: 10.1016/j.aquatox.2017.03.015
      Issue No: Vol. 188 (2017)
  • Intracellular localization and toxicity of graphene oxide and reduced
           graphene oxide nanoplatelets to mussel hemocytes in vitro
    • Authors: Alberto Katsumiti; Radmila Tomovska; Miren P. Cajaraville
      Pages: 138 - 147
      Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188
      Author(s): Alberto Katsumiti, Radmila Tomovska, Miren P. Cajaraville
      Recently, graphene materials have attracted tremendous research interest due to their unique physicochemical properties that hold great promise in electronics, energy, materials and biomedical areas. Graphene oxide (GO) is one of the most extensively studied graphene derivatives. In order to improve GO electrical properties, nanoplatelets are chemically reduced, thus increasing nanoplatelet conductivity. This reduced GO (rGO) shows different properties and behavior compared to GO. Graphene-based wastes are expected to end up in the marine environment. Here we aimed to assess the potential toxic effects of GO and rGO to marine organisms by using in vitro assays with mussel (Mytilus galloprovincialis) hemocytes. Cells were exposed to a wide range of concentrations (up to 100mg/L) of GO (with and without polyvinylpyrrolidone-PVP as stabilizing agent: GO and GO-PVP) and rGO with PVP (rGO-PVP) to assess cytotoxicity and cell membrane integrity. Then, cells were exposed to sublethal concentrations of GO and rGO-PVP to assess their subcellular distribution through transmission electron microscopy (TEM) and to evaluate their effects on ROS production. GO, GO-PVP and rGO-PVP showed low and concentration-dependent cytotoxicity. rGO-PVP (LC50=29.902 and 33.94mg/L depending on the origin) was more toxic than GO (LC50=49.84 and 54.51mg/L depending on the origin) and GO-PVP (LC50=43.72mg/L). PVP was not toxic to hemocytes but increased bioavailability and toxicity of nanoplatelets. At TEM, GO and rGO-PVP nanoplatelets caused invaginations and perforations of the plasma membrane, which agrees with the observed decrease in cell membrane integrity. Nanoplatelets were internalized, at a higher extent for rGO-PVP than for GO, and found in the cytosol and in endolysosomal vesicles of hemocytes. Both GO and rGO-PVP increased ROS production at the highest sublethal concentration tested. In conclusion, GO, GO-PVP and rGO-PVP are not highly toxic to mussel cells but they cause membrane damage and their toxicity is ROS-mediated. Finally, in vitro assays with mussel hemocytes are sensitive tools to detect toxic effects of graphene-based nanomaterials.
      Graphical abstract image

      PubDate: 2017-05-19T21:21:24Z
      DOI: 10.1016/j.aquatox.2017.04.016
      Issue No: Vol. 188 (2017)
  • Tissue uptake, distribution and excretion of brevetoxin-3 after oral and
           intratracheal exposure in the freshwater turtle Trachemys scripta and the
           diamondback terrapin Malaclemys terrapin
    • Authors: Courtney C. Cocilova; Leanne J. Flewelling; Gregory D. Bossart; April A. Granholm; Sarah L. Milton
      Pages: 29 - 37
      Abstract: Publication date: June 2017
      Source:Aquatic Toxicology, Volume 187
      Author(s): Courtney C. Cocilova, Leanne J. Flewelling, Gregory D. Bossart, April A. Granholm, Sarah L. Milton
      Harmful algal blooms (HABs) occur nearly annually off the west coast of Florida and can impact both humans and wildlife, resulting in morbidity and increased mortality of marine animals including sea turtles. The key organism in Florida red tides is the dinoflagellate Karenia brevis that produces a suite of potent neurotoxins referred to as the brevetoxins (PbTx). Despite recent mortality events and rehabilitation efforts, still little is known about how the toxin directly impacts sea turtles, as they are not amenable to experimentation and what is known about toxin levels and distribution comes primarily from post-mortem data. In this study, we utilized the freshwater turtle Trachemys scripta and the diamondback terrapin, Malaclemys terrapin as model organisms to determine the distribution, clearance, and routes of excretion of the most common form of the toxin, brevetoxin-3, in turtles. Turtles were administered toxin via esophageal tube to mimic ingestion (33.48μg/kg PbTx-3, 3×/week for two weeks for a total of 7 doses) or by intratracheal instillation (10.53μg/kg, 3×/week for four weeks for a total of 12 doses) to mimic inhalation. Both oral and intratracheal administration of the toxin produced a suite of behavioral responses symptomatic of brevetoxicosis. The toxin distributed to all organ systems within 1h of administration but was rapidly cleared out over 24–48h, corresponding to a decline in clinical symptoms. Excretion appears to be primarily through conjugation to bile salts. Histopathological study revealed that the frequency of lesions varied within experimental groups with some turtles having no significant lesions at all, while similar lesions were found in a low number of control turtles suggesting another common factor(s) could be responsible. The overall goal of this research is better understand the impacts of brevetoxin on turtles in order to develop better treatment protocols for sea turtles exposed to HABs.

      PubDate: 2017-04-02T11:58:17Z
      DOI: 10.1016/j.aquatox.2017.03.003
      Issue No: Vol. 187 (2017)
  • Age-dependent changes in sensitivity to a pesticide in tadpoles of the
           common toad (Bufo bufo)
    • Authors: Zsanett Mikó; János Ujszegi; Attila Hettyey
      Pages: 48 - 54
      Abstract: Publication date: June 2017
      Source:Aquatic Toxicology, Volume 187
      Author(s): Zsanett Mikó, János Ujszegi, Attila Hettyey
      The worldwide en masse application of pesticides and the frequently reported malign effects on several non-target organisms underpin the importance of ecotoxicological research on these anthropogenic pollutants. Previous studies showed that sensitivity to herbicides can vary widely depending on additional stress factors, on the species and even on the population investigated. However, there is little information about how sensitivity changes during ontogeny, and how the duration of exposure is linked to the magnitude of malign effects, even though this knowledge would be important for the interpretation of toxicity test results and for formulating recommendations regarding the timing of pesticide application. We exposed tadpoles of the common toad (Bufo bufo) to three concentrations (0, 2 and 4mg a.e./L) of a glyphosate-based herbicide during the 1st, 2nd, 3rd, 4th, or 5th period of larval development or during the entire experiment, and measured survival, time until metamorphosis and body mass at metamorphosis to estimate fitness-consequences. Younger tadpoles were more sensitive to the herbicide in all measured traits than older ones, and this age-dependence was especially pronounced at the high herbicide concentration. Furthermore, tadpoles exposed to the herbicide during the entire experiment developed slower than tadpoles exposed only early on, but we did not observe a similar effect either on body mass or survival. The observed age-dependence of sensitivity to herbicides draws attention to the fact that results of toxicity tests obtained for one age-class are not necessarily generalizable across ontogeny. Also, the age of test animals has to be considered when planning ecotoxicological studies and interpreting their results. Finally, taking into account the temporal breeding habits of local amphibians when planning pesticide application would be highly favourable: if tadpoles would not get exposed to the herbicide during their most sensitive early development, they would sustain less anthropogenic damage from our efforts of controlling weeds.

      PubDate: 2017-04-08T12:07:03Z
      DOI: 10.1016/j.aquatox.2017.03.016
      Issue No: Vol. 187 (2017)
  • The ROS-mediated pathway coupled with the MAPK-p38 signalling pathway and
           antioxidant system plays roles in the responses of Mytilus edulis
           haemocytes induced by BDE-47
    • Authors: Yongshun Jiang; Xuexi Tang; Bin Zhou; Tianli Sun; Hongmei Chen; Xinyu Zhao; You Wang
      Pages: 55 - 63
      Abstract: Publication date: June 2017
      Source:Aquatic Toxicology, Volume 187
      Author(s): Yongshun Jiang, Xuexi Tang, Bin Zhou, Tianli Sun, Hongmei Chen, Xinyu Zhao, You Wang
      Our previous study found that BDE-47 could change the immune function of haemocytes in Mytilus edulis, and reactive oxygen species (ROS) might be involved in the process of physiological alteration. Here, we aimed to better understand this relationship. To accomplish this, we analysed changes in different ROS as well as various antioxidant system components. Additionally, the expression of MAPK-p38, a signalling protein regulated by ROS that helps to regulate numerous cellular processes, was also analysed. BDE-47 was given at low, medium, and high amounts. The results showed that (1) BDE-47 significantly affected ROS component levels in haemocytes. O 2 − content was increased under all conditions. H2O2 content was also increased under all conditions, except in the middle concentration group. In contrast, OH content was increased in the low and middle concentration groups and decreased in the high concentration group. (2) Estimations of the antioxidant systems revealed concentration-dependent changes. Catalase activity was increased throughout the experiment, while superoxide dismutase (SOD) exhibited a decreasing trend in the tested groups with an increase of exposure time. On day 21, only the high concentration group showed a slight increase in SOD activity compared to the control. Furthermore, glutathione peroxidase and glutathione reductase activity increased in the low and middle concentration groups but decreased in the high concentration group. The GSH/GSSG ratio increased for all treatments over time, indicating that changes in redox status occurred. (3) MAPK-p38 was activated following BDE-47 exposure. Based on our previous study, we speculate that BDE-47 exposure induces ROS production and affects the ROS-mediated pathway, which may explain the resultant functional damage observed in haemocytes. Furthermore, BDE-47 also affected the antioxidant system and altered redox status, although these changes did not ameliorate the damage caused by ROS.

      PubDate: 2017-04-08T12:07:03Z
      DOI: 10.1016/j.aquatox.2017.03.011
      Issue No: Vol. 187 (2017)
  • A shell-formation related carbonic anhydrase in Crassostrea gigas
           modulates intracellular calcium against CO2 exposure: implication for
           impacts of ocean acidification on mollusk calcification
    • Authors: Xiudan Wang; Mengqiang Wang; Zhihao Jia; Xiaorui Song; Lingling Wang; Linsheng Song
      Abstract: Publication date: Available online 16 June 2017
      Source:Aquatic Toxicology
      Author(s): Xiudan Wang, Mengqiang Wang, Zhihao Jia, Xiaorui Song, Lingling Wang, Linsheng Song
      Ocean acidification (OA) could decrease the shells and skeletons formation of mollusk by reducing the availability of carbonate ions at calcification sites. Carbonic anhydrases (CAs) convert CO2 to HCO3 − and play important roles in biomineralization process from invertebrate to vertebrate. In the present study, a CA (designated as CgCA) was identified and characterized in Pacific oyster C. gigas. The cDNA of CgCA was of 927bp encoding a predicted polypeptide of 308 amino acids with a signal peptide and a CA catalytic function domain. The mRNA transcripts of CgCA were constitutively expressed in all tested tissues with the highest levels in mantle and hemocytes. During the early development period, the mRNA transcripts of CgCA could be detected in all the stages with the highest level in D-veliger larvae. Elevated CO2 increased the mRNA transcripts of CgCA in muscle, mantle, hepatopancreas, gill and hemocytes significantly (p <0.05) and induced the translocation of CgCA in hemocytes and mantle. Moreover, elevated CO2 also caused the decrease of intracellular Ca2+ in hemocytes (p <0.05). The inhibition of CA by acetazolamide and suppression of CgCA gene via RNA interference could increase the intracellular Ca2+ in hemocytes (p <0.05). Besides, the decrease of intracellular Ca2+ content caused by Ca2+ reagent ionomycin could affect localization of CgCA in mantle tissue. The results indicated CgCA played essential roles in calcification and elevated CO2 accelerated the mutual modulation between calcium and CgCA, implying reduced calcification rate and dissolved shells under OA.

      PubDate: 2017-06-18T15:31:19Z
      DOI: 10.1016/j.aquatox.2017.06.009
  • Antifouling biocides: Impairment of bivalve immune system by
    • Authors: Amanda da Silveira Guerreiro; Regina Coimbra Rola; Monique Tomazele Rovani; Simone Rutz da Costa; Juliana Zomer Sandrini
      Abstract: Publication date: Available online 16 June 2017
      Source:Aquatic Toxicology
      Author(s): Amanda da Silveira Guerreiro, Regina Coimbra Rola, Monique Tomazele Rovani, Simone Rutz da Costa, Juliana Zomer Sandrini
      Marine ecosystems are subjected to a variety of contaminants. Antifouling paints, for example, have been extensively used to protect ship surfaces from marine biofouling, but their toxicity has generated great concern. Thus, we evaluated the effect of the biocide chlorothalonil on the immune system of Perna perna mussels. The mussels were exposed to 0 (control), 0.1μg/L and 10μg/L of chlorothalonil for up to 96hours. After 24h and 96h of exposure, the following immune-related parameters were analyzed in the hemolymph of mussels: total hemocyte count, cell adhesion, phagocytic activity, level of reactive oxygen species, cell viability and comet assay. After 24h and 96h of chlorothalonil exposure, cellular adhesion increased and the hemocyte viability reduced. Moreover, an increased in phagocytic activity was also observed after 96h of exposure to cholorothalonil. The exposure to 10μg/L of chlorothalonil for 96h reduced the air survival capacity of mussels. Total hemocyte count, ROS generation and DNA damage were not affected by the contaminant exposure. Our results indicate that chlorothalonil affected important immune responses of the bivalves, demonstrating that this biocide has effects on non-target species. This modulation of immune system reduced the health status of mussels, which could compromise their ability to survive in the environment.

      PubDate: 2017-06-18T15:31:19Z
      DOI: 10.1016/j.aquatox.2017.06.012
  • Surface coating-modulated toxic responses to silver nanoparticles in
           Wolffia globosa
    • Authors: Xiaoyan Zou; Penghui Li; Jie Lou; Hongwu Zhang
      Abstract: Publication date: Available online 15 June 2017
      Source:Aquatic Toxicology
      Author(s): Xiaoyan Zou, Penghui Li, Jie Lou, Hongwu Zhang
      With the omnipresence of silver nanoparticles (AgNPs) in our daily consumer products, their release has raised serious concerns. However, the biochemical mechanisms by which plants counteract the toxicity of nanoparticles are largely unknown. This study investigated the exposure of aquatic Wolffia globosa to ATP-nAg (AgNPs coated with adenosine triphosphate), cit-nAg (AgNPs coated with citrate), and Ag+. Hill reaction activity was basically lost in W. globosa treated with 10mg/L ATP-nAg and Ag+, while the activity was still maintained at 38.7%-38.9% of the respective controls at 10mg/L cit-nAg. The reduction of amounts of chlorophyll and soluble protein were shown in response to the Ag stresses. This was accompanied by the accumulation of sugar in W. globosa treated with cit-nAg. By contrast, the depletion of sugar was recorded after 10mg/L ATP-nAg and Ag+ treatments. The superoxide dismutase and peroxidase activities were significantly increased after exposure to 10mg/L ATP-nAg and Ag+, which did not occurred in W. globosa treated with cit-nAg. The ratio between NADPH/NADP+ was higher after cit-nAg and Ag+ stresses than the respective controls. The accumulation of Ag was found to increase in a concentration-dependent manner. Ag+ and ATP-nAg inhibited the uptake of P and K, and promoted the uptake of Fe and Cu. In contrast, cit-nAg only promoted the uptake of Cu. Our results implied that surface coating induced different physiological responses of W. globosa to AgNPs. Based on above results, we speculated that after exposure to cit-nAg, citrate possibly could serve as the substrate for the tricarboxylic acid cycle and accumulated sugar may promote pentose phosphate pathways. For ATP-nAg treatments, ATP would act as an exogenous energy source of plant metabolisms. Our findings demonstrate that surface coating regulates the physiological responses of plants to AgNPs through distinct mechanisms.

      PubDate: 2017-06-18T15:31:19Z
      DOI: 10.1016/j.aquatox.2017.06.010
  • Long-term toxicity of surface-charged polystyrene nanoplastics to marine
           planktonic species Dunaliella tertiolecta and Artemia franciscana
    • Authors: E. Bergami; S. Pugnalini; M.L. Vannuccini; L. Manfra; C. Faleri; F. Savorelli; K.A. Dawson; I. Corsi
      Abstract: Publication date: Available online 15 June 2017
      Source:Aquatic Toxicology
      Author(s): E. Bergami, S. Pugnalini, M.L. Vannuccini, L. Manfra, C. Faleri, F. Savorelli, K.A. Dawson, I. Corsi
      Plastic pollution has been globally recognized as a critical issue for marine ecosystems and nanoplastics constitute one of the last unexplored areas to understand the magnitude of this threat. However, current difficulties in sampling and identifying nano-sized debris make hard to assess their occurrence in marine environment. Polystyrene nanoparticles (PS NPs) are largely used as nanoplastics in ecotoxicological studies and although acute exposures have been already investigated, long-term toxicity on marine organisms is unknown. Our study aims at evaluating the effects of 40nm PS anionic carboxylated (PS-COOH) and 50nm cationic amino-modified (PS-NH2) NPs in two planktonic species, the green microalga Dunaliella tertiolecta and the brine shrimp Artemia franciscana, respectively prey and predator. PS NP behaviour in exposure media was determined through DLS, while their toxicity to microalgae and brine shrimps evaluated through 72h growth inhibition test and 14 d long-term toxicity test respectively. Moreover, the expression of target genes (i.e. clap and cstb), having a role in brine shrimp larval growth and molting, was measured in 48h brine shrimp larvae. A different behaviour of the two PS NPs in exposure media as well as diverse toxicity to the two planktonic species was observed. PS-COOH formed micro-scale aggregates (Z-Average>1μm) and did not affect the growth of microalgae up to 50μg/ml or that of brine shrimps up to 10μg/ml. However, these negatively charged NPs were adsorbed on microalgae and accumulated (and excreted) in brine shrimps, suggesting a potential trophic transfer from prey to predator. On the opposite, PS-NH2-formed nano-scale aggregates (Z-Average<200nm), caused inhibition of algal growth (EC50 =12.97μg/ml) and mortality in brine shrimps at 14 d (LC50 =0.83μg/ml). Moreover, 1μg/ml PS-NH2 significantly induced clap and cstb genes, explaining the physiological alterations (e.g. increase in molting) previously observed in 48h larvae, but also suggesting an apoptotic pathway triggered by cathepsin L-like protease in brine shrimps upon PS-NH2 exposure. These findings provide a first insight into long-term toxicity of nanoplastics to marine plankton, underlining the role of the surface chemistry in determining the behaviour and effects of PS NPs, in terms of adsorption, growth inhibition, accumulation, gene modulation and mortality. The use of long-term end-point has been identified as valuable tool for assessing the impact of nanoplastics on marine planktonic species, being more predictable of real exposure scenarios for risk assessment purposes.

      PubDate: 2017-06-18T15:31:19Z
      DOI: 10.1016/j.aquatox.2017.06.008
  • Zinc and calcium alter the relationship between mitochondrial respiration,
           ROS and membrane potential in rainbow trout (Oncorhynchus mykiss) liver
    • Authors: Mahmoud S. Sharaf; Don Stevens; Collins Kamunde
      Abstract: Publication date: Available online 12 June 2017
      Source:Aquatic Toxicology
      Author(s): Mahmoud S. Sharaf, Don Stevens, Collins Kamunde
      At excess levels, zinc (Zn) disrupts mitochondrial functional integrity and induces oxidative stress in aquatic organisms. Although much is known about the modulation of Zn toxicity by calcium (Ca) in fish, their interactions at the mitochondrial level have scarcely been investigated. Here we assessed the individual and combined effects of Zn and Ca on the relationship between mitochondrial respiration, ROS and membrane potential (ΔΨmt) in rainbow trout liver mitochondria. We tested if cation uptake through the mitochondrial calcium uniporter (MCU) is a prerequisite for Zn- and/or Ca-induced alteration of mitochondrial function. Furthermore, using our recently developed real-time multi-parametric method, we investigated the changes in respiration, ΔΨmt, and reactive oxygen species (ROS, as hydrogen peroxide (H2O2)) release associated with Ca-induced mitochondrial depolarization imposed by transient and permanent openings of the mitochondrial permeability transition pore (mPTP). We found that independent of the MCU, Zn precipitated an immediate depolarization of the ΔΨmt that was associated with relatively slow enhancement of H2O2 release, inhibition of respiration and reversal of the positive correlation between ROS and ΔΨmt. In contrast, an equitoxic dose of Ca caused transient depolarization, and stimulation of both respiration and H2O2 release, effects that were completely abolished when the MCU was blocked. Contrary to our expectation that mitochondrial transition ROS Spike (mTRS) would be sensitive to both Zn and Ca, only Ca suppressed it. Moreover, Zn and Ca in combination immediately depolarized the ΔΨmt, and caused transient and sustained stimulation of respiration and H2O2 release, respectively. Lastly, we uncovered and characterized an mPTP-independent Ca-induced depolarization spike that was associated with exposure to moderately elevated levels of Ca. Moreover, we showed the stimulation of ROS release associated with highly elevated but not unrealistic Ca loads was not the cause but a result of mPTP opening in the high conductance mode.

      PubDate: 2017-06-13T15:28:39Z
      DOI: 10.1016/j.aquatox.2017.06.005
  • Oxidative stress mediated toxicity of TiO2 nanoparticles after a
           concentration and time dependent exposure of the aquatic macrophyte
           Hydrilla verticillata
    • Authors: Annette Spengler; Lena Wanninger; Stephan Pflugmacher
      Abstract: Publication date: Available online 12 June 2017
      Source:Aquatic Toxicology
      Author(s): Annette Spengler, Lena Wanninger, Stephan Pflugmacher
      The present study focused on oxidative stress effects in the aquatic macrophyte Hydrilla verticillata after exposure to titanium dioxide nanoparticles (TiO2-NPs). Experiments were conducted with different TiO2-NPs and concentrations (0.1 mg/L and 10 mg/L) in a time-dependent manner (0 h, 24 h, 48 h, 96 h, 168 h). To assess various levels of the oxidative stress response in H. verticillata, the level of hydrogen peroxide (H2O2), the ratio of reduced to oxidized glutathione (GSH/GSSG), and activities of the antioxidative enzymes catalase (CAT) and glutathione reductase (GR) were evaluated. Study results imply oxidative stress effects after TiO2-NP exposure as adaptations in plant metabolism became apparent to counteract increased ROS formation. All TiO2-NPs caused elevated activities of the enzymes CAT and GR. Moreover, decreased ratios of GSH/GSSG indicated an activation of GSH-dependent pathways counteracting ROS formation. Plants exposed to a bulk-sized control revealed a size-dependent influence on the antioxidative stress response. As H2O2 level increases were solely detected after exposure to 10 mg/L TiO2-NPs and nano-exposed plants showed normalization in its antioxidative stress response after 168h of exposure, it can be suggested that macrophytes are able to cope with currently predicted low-level exposures to TiO2-NPs.

      PubDate: 2017-06-13T15:28:39Z
      DOI: 10.1016/j.aquatox.2017.06.006
  • Candidate cytochrome P450 genes for ethoxyresorufin O-deethylase activity
           in oyster Crassostrea gigas
    • Authors: Marília Nardelli Siebert; Jacó Joaquim Mattos; Guilherme Toledo-Silva; Guilherme Razzera; Afonso Celso Dias Bainy
      Abstract: Publication date: Available online 9 June 2017
      Source:Aquatic Toxicology
      Author(s): Marília Nardelli Siebert, Jacó Joaquim Mattos, Guilherme Toledo-Silva, Guilherme Razzera, Afonso Celso Dias Bainy
      Vertebrate cytochrome P450 1 (CYP1) enzymes metabolize endogenous and xenobiotic compounds and usually demonstrate a substrate-inducible response. Ethoxyresorufin O-deethylase activity (EROD) is a common method to quantify CYP1 enzymes activity in these organisms. Despite the absence of this gene family in protostomes, CYP1-like genes were identified in several species, even though no evolutionary relationship has been established with the vertebrate CYP1 family. In the present study, EROD activity was evaluated in microsomal fraction of gills, digestive gland and mantle of Crassostrea gigas. Enzyme activity was quantified in gills, although no activity was detected in digestive gland and mantle. EROD kinetic characterization in gills using typical Michaelis-Menten equation demonstrated an apparent Km of 1.15μM and Vmax of 229.2 fmol.min−1 mg.protein −1. EROD activity was analyzed in the presence of CYP1 inhibitors, ellipticine (ELP), furafylline (FRF), clotrimazole (CTZ), α-naphthoflavone (ANF), and the non-ionic surfactant Triton X-100. CTZ inhibited EROD activity in all tested concentrations while Triton X-100 (0.5mM) caused 16% inhibition. Transcript levels of four CYP1-like genes were determined in gills, digestive gland and mantle. In general, CYP1-like genes showed higher transcript levels in gills compared to other tissues. The transcript levels of CYP1-like 1 and 2, analyzed together, positively correlated with EROD activity observed in gills, suggesting the possible involvement of these two gene products to EROD activity in this tissue. Homology models of translated CYP1-like 1 and 2 were generated based on human CYP1A1 structure and were similar to the general canonical cytochrome P450 fold. Molecular docking analysis showed that the two putative oyster CYP1-like structures have the potential to metabolize 7-ethoxyresorufin (7-ER), although the contribution of other CYP1-like genes needs to be investigated. Proteins encoded by CYP1-like 1 and 2 genes are plausible candidates for EROD activity observed in gills of C. gigas.

      PubDate: 2017-06-13T15:28:39Z
      DOI: 10.1016/j.aquatox.2017.06.004
  • Exposure to sublethal concentrations of Co3O4 and Mn2O3 nanoparticles
           induced elevated metal body burden in Daphnia magna
    • Authors: Margit Heinlaan; Marge Muna; Katre Juganson; Olena Oriekhova; Serge Stoll; Anne Kahru; Vera I. Slaveykova
      Abstract: Publication date: Available online 6 June 2017
      Source:Aquatic Toxicology
      Author(s): Margit Heinlaan, Marge Muna, Katre Juganson, Olena Oriekhova, Serge Stoll, Anne Kahru, Vera I. Slaveykova
      Despite the significant progress made in ecotoxicological research on nanoparticles (NPs), there is still very limited information available regarding the biological effects of certain types of NPs such as Co3O4 and Mn2O3. Only a couple of studies provide data on their impact on aquatic organisms whereas, alarmingly, these NPs have been proposed to have high toxicity potential. In addition, more data are needed to determine whether the adverse effects the metal NPs induce on aquatic organisms are rather due to their chemical or particulate nature. To address these open questions, the (sub)lethal effects of Co and Mn NPs in parallel with the respective soluble metal salts on Daphnia magna were studied. The aims of the current study were to i) assess the acute toxicity of Co3O4 and Mn2O3 NPs (primary size 10–30nm) to D. magna, ii) evaluate whether the acute NP exposure at sublethal concentrations influences D. magna post-exposure feeding behaviour and iii) quantify D. magna metal body burden after exposure and after the post-exposure feeding to estimate the potential of trophic transfer of metals. Flow cytometry and total reflection X-ray fluorescence spectroscopy were applied for feeding and metal body burden evaluations, respectively. CuO NPs (primary size 22–25nm) that are very toxic to D. magna were included in the study as a positive control. Since the release of metal ions is an important possibility for toxicity of metal NPs, soluble Co-, Mn- and Cu-salts were analysed in parallel. The solubilisation of Co3O4 NPs in the OECD202 assay conditions was 0.1% and Mn2O3 NPs 35%. Mn2O3 NPs also produced reactive oxygen species in abiotic conditions. However Co3O4 and Mn2O3 NPs were not acutely toxic to D. magna (48h EC50 >100mg metal/L) at OECD202 assay conditions. The 48h EC50 values of soluble Co- and Mn-salts were 3.2mgCo/L and 41mgMn/L, respectively. Post-exposure feeding behaviour after 48h exposure to sublethal concentrations (≤10mg/L) of Co3O4 and Mn2O3 NPs differed from that of the unexposed (control) D. magna only at the highest exposure concentrations but was comparable to the feeding behaviour of the respective metal salt-exposed organisms. Upon 48h exposure, dose-dependent increase of D. magna total metal body burden in case of both the NPs and the soluble salts was observed. After 48h post-exposure feeding with algae C. reinhardtii (depuration): D. magna body burden remained elevated (up to 760-fold compared to the control organism) only in case of the NPs. This may indicate potential for trophic transfer of NPs/heavy metals and thus hazard for freshwater ecosystem.
      Graphical abstract image

      PubDate: 2017-06-08T15:26:01Z
      DOI: 10.1016/j.aquatox.2017.06.002
  • Impacts of triclosan exposure on zebrafish early-life stage: toxicity and
           acclimation mechanisms
    • Authors: Falisse Elodie; Voisin Anne-Sophie; Silvestre Frédéric
      Abstract: Publication date: Available online 6 June 2017
      Source:Aquatic Toxicology
      Author(s): Falisse Elodie, Voisin Anne-Sophie, Silvestre Frédéric
      Triclosan (TCS) is a broad spectrum antibacterial agent widely used in personal care products and present in most aquatic ecosystems. This study investigated the occurrence of triclosan acclimation and the biological mechanisms underlying the stress response triggered in early-life stage of zebrafish. Zebrafish eggs were first exposed to four different sublethal concentrations of TCS (2, 20, 50 and 100μg/L) for 7days following fertilization and subsequently exposed to a lethal concentration of TCS (1000μg/L). During the time-to-death exposure (TTD), mortality was continuously recorded to evaluate if increased resistance occurred. Overall, larvae exposed to 50μg/L of TCS demonstrated higher sensitivity, with delayed hatching and increased mortality during the sub-lethal exposure and significant lower mean time-to-death (TTD) value compared to the other groups. Interestingly, fish exposed to the highest concentration of TCS (100μg/L) presented a similar mean TTD value as controls and a significantly better survival in comparison with embryos exposed to 50μg/L, suggesting that acclimation process has been triggered at this concentration. Proteomic and enzymatic analyses were conducted on 7days post fertilization (dpf) larvae exposed to 50μg/L and 100μg/L of TCS giving insights into the functional changes triggered at those specific concentrations. TCS seemed to affect proteins involved in cytoskeleton, stress response, eyes and neuronal development. This was endorsed by the enzymatic results, which suggest impairment in glutathione metabolism and acute neurotoxicity. A significant 2.5-fold and 3-fold increase of AChE activity was observed following TCS exposure. Moreover, GPx activity was significantly increased whereas a significant inhibition of GR activity was observed, suggesting that de novo synthesis of reduced GSH might occur in order to maintain the ratio between reduced and oxidized GSH. Proteomic results revealed possible candidate protein involved in the acclimation process of larvae exposed to 100μg/L of TCS. Our integrative analysis revealed complex non-monotonic concentration-related effects on zebrafish early-life stages with increased resistance between 50 and 100μg/L exposures. This research highlighted oxidative stress and neurotoxicity as major toxicity mechanisms of TCS during development.

      PubDate: 2017-06-08T15:26:01Z
      DOI: 10.1016/j.aquatox.2017.06.003
  • Developmental Toxicity Of Hydroxylated Chrysene Metabolites in Zebrafish
    • Authors: Graciel Diamante; Gabrielle do Amaral e Silva Müller; Norma Menjivar-Cervantes; Elvis Genbo Xu; David C. Volz; Afonso Celso Dias Bainy; Daniel Schlenk
      Abstract: Publication date: Available online 3 June 2017
      Source:Aquatic Toxicology
      Author(s): Graciel Diamante, Gabrielle do Amaral e Silva Müller, Norma Menjivar-Cervantes, Elvis Genbo Xu, David C. Volz, Afonso Celso Dias Bainy, Daniel Schlenk
      One of the primary sources of polycyclic aromatic hydrocarbons (PAHs) in marine environments is oil. Photochemical oxidation and microbial transformation of PAH-containing oils can result in the formation of oxygenated products. Among the PAHs in crude oil, chrysene is one of the most persistent within the water column and may be transformed to 2- and 6-hydroxychrysene (OHCHR). Both of these compounds have been shown to activate (2-OHCHR) and antagonize (6-OHCHR) the estrogen receptor (ER). Previous studies in our lab have shown that estrogen can significantly alter zebrafish development. However, little is known about the developmental toxicity of hydroxylated PAHs. Zebrafish embryos were exposed to 0.5–10μM of 2- or 6-OHCHR from 2hours post-fertilization (hpf) until 76 hpf. A significant decrease in survival was observed following exposure to 6-OHCHR − but not 2-OHCHR. Both OHCHRs significantly increased the percentage of overall deformities after treatment. In addition to cardiac malformations, ocular and circulatory defects were also observed in embryos exposed to both compounds, while 2-OHCHR generally resulted in a higher prevalence of effect. Moreover, treatment with 2-OHCHR resulted in a significant decrease in hemoglobin levels. ER nor G-Protein coupled estrogen receptor (GPER) antagonists and agonists did not rescue the observed defects. We also analyzed the expression of cardiac-, eye- and circulation-related genes previously shown to be affected by oil. Rhodopsin mRNA expresssion was significantly decreased by both compounds equally. However, exposure to 2-OHCHR significantly increased the expression of the hematopoietic regulator, runx1 (runt related transcription factor 1). These results indicate the toxicity of oxygenated photoproducts of PAHs and suggest that other targets and signaling pathways may contribute to developmental toxicity of weathered oil. Our findings also demonstrate the regio-selective toxicity of hydroxy-PAHs in the effects on eye and circulatory development and raise the need to identify mechanisms and ecological risks of oxy-PAHs to fish populations.

      PubDate: 2017-06-04T12:55:45Z
      DOI: 10.1016/j.aquatox.2017.05.013
  • Diclofenac affects kidney histopathology in the three-spined stickleback
           (Gasterosteus aculeatus) at low μg/L concentrations
    • Authors: Johanna Näslund; Jerker Fick; Noomi Asker; Elisabet Ekman; D.G. Joakim Larsson; Leif Norrgren
      Abstract: Publication date: Available online 31 May 2017
      Source:Aquatic Toxicology
      Author(s): Johanna Näslund, Jerker Fick, Noomi Asker, Elisabet Ekman, D.G. Joakim Larsson, Leif Norrgren
      Diclofenac, a commonly used non-steroidal anti-inflammatory drug, is considered for regulation under the European water framework directive due to reported effects on fish at concentrations around those regularly found in treated sewage (∼1μg/L). However, a recent publication reports no effects on fish at 320μg/L. In this study, three-spined sticklebacks (Gasterosteus aculeatus) were exposed to 4.6, 22, 82 and 271μg/L diclofenac in flow-through systems for 28days using triplicate aquaria per concentration. At the highest concentration, significant mortalities were observed already after 21days (no mortalities found up to 22μg/L). Histological analysis revealed a significant increase in the proportion of renal hematopoietic tissue (renal hematopoietic hyperplasia) after 28days at the lowest concentration and at all higher concentrations, following a clear dose-response pattern. Skin ulcerations of the jaw were noted by macroscopic observations, primarily at the two highest concentrations. No histological changes were observed in the liver. There was an increase in the relative hepatic mRNA levels of c7 (complement component 7), a gene involved in the innate immune system, at 22μg/L and at all higher concentrations again following a clear dose-response. The bioconcentration factor was stable across concentrations, but lower than reported for rainbow trout, suggesting lower internal exposure to the drug in the stickleback. In conclusion, this study demonstrates that diclofenac causes histological changes in the three-spined stickleback at low μg/L concentrations, which cause concern for fish populations exposed to treated sewage effluent.

      PubDate: 2017-06-04T12:55:45Z
      DOI: 10.1016/j.aquatox.2017.05.017
  • Inside Front Cover - Editorial Board Page/Cover image legend if applicable
    • Abstract: Publication date: July 2017
      Source:Aquatic Toxicology, Volume 188

      PubDate: 2017-05-29T21:27:43Z
  • Biomarker responses to environmental contamination in estuaries: a
           comparative multi-taxa approach
    • Authors: Irina A. Duarte; Patrick Reis-Santos; Susana França; Henrique Cabral; Vanessa F. Fonseca
      Abstract: Publication date: Available online 26 May 2017
      Source:Aquatic Toxicology
      Author(s): Irina A. Duarte, Patrick Reis-Santos, Susana França, Henrique Cabral, Vanessa F. Fonseca
      Estuaries are highly productive ecosystems subjected to numerous anthropogenic pressures with consequent environmental quality degradation. In this study, multiple biomarker responses [superoxide dismutase (SOD), catalase (CAT), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities, as well as lipid peroxidation (LPO) and DNA damage (DNAd)] were determined in two fish (Dicentrarchus labrax and Pomatoschistus microps) and four macroinvertebrate species (Carcinus maenas, Crangon crangon, Hediste diversicolor and Scrobicularia plana) from the Ria de Aveiro and Tejo estuaries over distinct months. Two sites per estuarine system were selected based on anthropogenic pressures and magnitude of environmental contamination. Antioxidant enzyme activities in fish species suggested a ubiquitous response to oxidative stress, while biotransformation and effect biomarkers exhibited higher spatial and temporal variation. In invertebrate species, biotransformation enzyme activity was clearly less variable than in fish evidencing lower xenobiotic transformation capability. Overall, largest biomarker responses were found in the most contaminated sites (Tejo), yet species-specific patterns were evident. These should be factored in multi taxa approaches, considering that the differential functional traits of species, such as habitat use, life-stage, feeding or physiology can influence exposure routes and biomarker responses. The Integrated Biomarker Response index highlighted patterns in biomarker responses which were not immediately evident when analyzing biomarkers individually. Overall, results provided insights into the complexity of species responses to contamination in naturally varying estuarine environments. Ultimately, multi-taxa and multi-biomarker approaches provide a comprehensive and complementary view of ecosystem health, encompassing diverse forms of biological integration and exposure routes, and allow the validation of results among markers and species.

      PubDate: 2017-05-29T21:27:43Z
      DOI: 10.1016/j.aquatox.2017.05.010
  • Effects of triclosan (TCS) on fecundity, the antioxidant system, and
           oxidative stress-mediated gene expression in the copepod Tigriopus
    • Authors: Jun Chul Park; Jeonghoon Han; Min-Chul Lee; Jung Soo Seo; Jae-Seong Lee
      Abstract: Publication date: Available online 26 May 2017
      Source:Aquatic Toxicology
      Author(s): Jun Chul Park, Jeonghoon Han, Min-Chul Lee, Jung Soo Seo, Jae-Seong Lee
      Triclosan (TCS) is an antimicrobial agent that has been widely dispersed and detected in the marine environment. However, the effects of TCS in marine invertebrates are poorly understood. In this study, the effects of TCS on life cycle history (e.g. mortality and fecundity) along with cellular reactive oxygen species (ROS) levels, GSH content, antioxidant enzymatic activities, and mRNA expression levels of oxidative stress-mediated genes were measured in the copepod Tigriopus japonicus. The no observed effect concentration (NOEC) and median lethal concentration (LC50) of TCS in the adult stage were determined to be 300μg/L and 437.476μg/L, respectively, while in the nauplius stages the corresponding values were 20μg/L, and 51.76μg/L, respectively. Fecundity was significantly reduced (P < 0.05) in response to TCS at 100μg/L. Concentration- and time-dependent analysis of ROS, GSH content (%), and antioxidant enzymatic activities (e.g. GST, GPx, and SOD) were significantly increased (P < 0.05) in response to TCS exposure. Additionally, mRNA expression of detoxification (e.g., CYPs) and antioxidant (e.g., glutathione S-transferase-sigma isoforms, Cu/Zn superoxide dismutase, catalase) genes was modulated in response to TCS exposure at different concentrations over a 24h period. Our results revealed that TCS can induce reduced fecundity and oxidative stress with transcriptional regulation of oxidative stress-mediated genes with activation of the antioxidant system in the copepod T. japonicus.

      PubDate: 2017-05-29T21:27:43Z
      DOI: 10.1016/j.aquatox.2017.05.012
  • Copper alters hypoxia sensitivity and the behavioural emersion response in
           the amphibious fish (Kryptolebias marmoratus)
    • Authors: Tamzin A. Blewett; Robyn A. Simon; Andy J. Turko; Patricia A. Wright
      Abstract: Publication date: Available online 23 May 2017
      Source:Aquatic Toxicology
      Author(s): Tamzin A. Blewett, Robyn A. Simon, Andy J. Turko, Patricia A. Wright
      Elevated levels of metals have been reported in mangrove ecosystems worldwide. Mangrove fishes also routinely experience severe environmental stressors, such as hypoxia. In the amphibious fish Kryptolebias marmoratus (mangrove rivulus), a key behavioural response to avoid aquatic stress is to leave water (emersion). We hypothesized that copper (Cu) exposure would increase the sensitivity of this behavioural hypoxia avoidance response due to histopathological effects of Cu on gill structure and function. K. marmoratus were exposed to either control (no added Cu) or Cu (300μg/L) for 96hours. Following this period, fish were exposed to an acute hypoxic challenge (decline in dissolved oxygen to ∼0% over 15minutes), and the emersion response was recorded. Gills were examined for histological changes. Fish exposed to Cu emersed at a higher dissolved oxygen level (7.5±0.6%), relative to the control treatment group (5.8±0.4%). Histological analysis showed that the gill surface area increased and the interlamellar cell mass (ILCM) was reduced following Cu exposure, contrary to our prediction. Overall, these data indicate that Cu induces hypoxia-like changes to gill morphology and increases the sensitivity of the hypoxia emersion response.

      PubDate: 2017-05-24T21:23:41Z
      DOI: 10.1016/j.aquatox.2017.05.007
  • Toxicity of Triphenyltin on the Development of Retinal Axons in Zebrafish
           at Low Dose
    • Authors: Yue Xiao; Jieqiong Jiang; Wenxin Hu; Yanbin Zhao; Jianying Hu
      Abstract: Publication date: Available online 22 May 2017
      Source:Aquatic Toxicology
      Author(s): Yue Xiao, Jieqiong Jiang, Wenxin Hu, Yanbin Zhao, Jianying Hu
      The impacts of triphenyltin (TPT) on ecological health are of particular concern due to the unexpectedly high levels found in wild fish around the world. Here, zebrafish embryos were exposed to TPT via in ovo nano-injection to study its toxicity on the development of retinal axons in fish. Lipophilic dye labeling revealed obvious defects in retinal axon development in larvae with normally shaped eyes, with incidences of 0, 1.08%, 2.66%, 4.26%, and 6.85% observed in the control, 0.8, 4.0, 20.0, and 100ng TPT-Cl/g wet weight (ww) exposure groups, respectively, showing a dose-dependent increase. Since the lowest observable effective concentration of TPT to induce retinal axon development defects was 0.8ng TPT-Cl/g ww, which is lower than the concentrations in wild fish eggs, this defect would occur in wild fish larvae. Alterations in the expressions of pax6 and ephrinBs, which regulate the establishment of retinal polarity, were correlated with defect incidence. Expression levels of the CYP26A1 gene and protein were significantly up-regulated in all exposure groups compared with the control, which may lead to significant decreases in concentrations of all-trans retinoic acid (atRA). Such a disruption of RA metabolism would, at least partly, contribute to the incidence of developmental defects in retinal axons. This study is the first to report that TPT can interfere with development of retinal axons in fish at low dose.

      PubDate: 2017-05-24T21:23:41Z
      DOI: 10.1016/j.aquatox.2017.05.009
  • Microcystin-LR induces changes in the GABA neurotransmitter system of
    • Authors: Wei Yan; Li Li; Guangyu Li; Sujuan Zhao
      Abstract: Publication date: Available online 15 May 2017
      Source:Aquatic Toxicology
      Author(s): Wei Yan, Li Li, Guangyu Li, Sujuan Zhao
      It has been reported that exposure to microcystins altered adult zebrafish swimming performance parameters, but the possible mechanisms of action remain unknown. Neuronal activity depends on the balance between the number of excitatory and inhibitory processes which are associated with neurotransmitters. In the present study, zebrafish embryos (5 d post-fertilization) were exposed to 0, 0.3, 3 and 30μg/L (microcystin-LR) MCLR for 90day until reaching sexual maturity. To investigate the effects of MCLR on the neurotransmitter system, mRNA levels involved in amino acid g-aminobutyric acid (GABA) and glutamate metabolic pathways were tested using quantitative real-time PCR. Significant increase of GABAA receptor, alpha 1 (gabra1), glutamate decarboxylase (gad1b), glutaminase (glsa) and reduction of mRNA expression of GABA transporter (gat1) at transcriptional level were observed in the brain. Meanwhile, western blotting showed that the protein levels of gabra1, gad1b were induced by MCLR, whereas the expression of gat1 was decreased. In addition, MCLR induced severe damage to cerebrum ultrastructure, showing edematous and collapsed myelinated nerve fibers, distention of endoplasmic reticulum and swelling mitochondria. Our results suggested that MCLR showed neurotoxicity in zebrafish which might attribute to the disorder of GABA neurotransmitter pathway.

      PubDate: 2017-05-19T21:21:24Z
      DOI: 10.1016/j.aquatox.2017.05.006
  • Metabolic Profiling of Goldfish (Carassius auratis) After Long-term
           Glyphosate-based Herbicide Exposure
    • Authors: Ming-Hui Li; Ling-Yu Ruan; Jin-Wei Zhou; Yong-Hong Fu; Lei Jiang; He Zhao; Jun-Song Wang
      Abstract: Publication date: Available online 13 May 2017
      Source:Aquatic Toxicology
      Author(s): Ming-Hui Li, Ling-Yu Ruan, Jin-Wei Zhou, Yong-Hong Fu, Lei Jiang, He Zhao, Jun-Song Wang
      Glyphosate is an efficient herbicide widely used worldwide. However, its toxicity to non-targeted organisms has not been fully elucidated. In this study, the toxicity of glyphosate-based herbicide was evaluated on goldfish (Carassius auratus) after long-term exposure. Tissues of brains, kidneys and livers were collected and submitted to NMR-based metabolomics analysis and histopathological inspection. Plasma was collected and the blood biochemical indexes of AST, ALT, BUN, CRE, LDH, SOD, GSH-Px, GR and MDA were measured. Long-term glyphosate exposure caused disorders of blood biochemical indexes and renal tissue injury in goldfish. Metabolomics analysis combined with correlation network analysis uncovered significant perturbations in oxidative stress, energy metabolism, amino acids metabolism and nucleosides metabolism in glyphosate dosed fish, which provide new clues to the toxicity of glyphosate. This integrated metabolomics approach showed its applicability in discovering the toxic mechanisms of pesticides, which provided new strategy for the assessment of the environmental risk of herbicides to non-target organisms.

      PubDate: 2017-05-14T21:19:45Z
      DOI: 10.1016/j.aquatox.2017.05.004
  • Inside Front Cover - Editorial Board Page/Cover image legend if applicable
    • Abstract: Publication date: June 2017
      Source:Aquatic Toxicology, Volume 187

      PubDate: 2017-05-10T07:18:26Z
  • Microcystin-LR bioconcentration induces antioxidant responses in the
           digestive gland of two marine bivalves Crassostrea gigas and Mytilus
    • Authors: Young Dae Kim; Won Jin Kim; Yun Kyung Shin; Do-Hee Lee; Youn-Jung Kim; Jang Kyun Kim; Jae-Sung Rhee
      Abstract: Publication date: Available online 8 May 2017
      Source:Aquatic Toxicology
      Author(s): Young Dae Kim, Won Jin Kim, Yun Kyung Shin, Do-Hee Lee, Youn-Jung Kim, Jang Kyun Kim, Jae-Sung Rhee
      Microcystins (MCs) are a major group of potent cyanobacterial toxins found in freshwater and even brackish waterbodies. To understand the putative correlation between bioconcentration of MCs and antioxidant responses of the digestive gland of bivalves, Pacific oyster Crassostrea gigas and blue mussel Mytilus edulis were exposed to different concentrations (0.1, 1, 10 and 20μgL−1) of MC-Leucine-Arginine (LR) for seven days. MC-LR bioconcentrated in the digestive glands of both bivalves during exposure period. The levels were slightly reduced when the bivalves were exposed to seawater during depuration (7 days), while approximately 0.1μgL−1 of MC-LR was observed in the 10 and 20μgL−1 exposed bivalves at the end of depuration. Intracellular malondialdehyde (MDA) and glutathione (GSH) levels were significantly elevated in the 10 and 20μgL−1 exposed bivalves at 7day, and the levels were maintained during depuration in both bivalves. Overall, significant higher levels of enzymatic activities of antioxidant defense systems such as glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) were observed in the 10 and 20μgL−1 exposed bivalves. Interestingly, most of higher levels of Pacific oyster were detected at exposure period, while blue mussel showed higher levels at depuration phase, suggesting a species-specific sensitivity upon MC-LR. These patterns were correlated with the bioconcentration patterns of MC-LR as Pacific oyster was highly accumulated by MC-LR during exposure period, but blue mussel showed prolonged high levels of MC-LR for depuration phase. Our results will be useful to understand species-specific bioconcentration of MC-LR in bivalves and their effects on intracellular oxidative status via accumulation.

      PubDate: 2017-05-10T07:18:26Z
      DOI: 10.1016/j.aquatox.2017.05.003
    • Authors: Esmail Lutfi; Natàlia Riera-Heredia; Marlon Córdoba; Cinta Porte; Joaquim Gutiérrez; Encarnación Capilla; Isabel Navarro
      Abstract: Publication date: Available online 8 May 2017
      Source:Aquatic Toxicology
      Author(s): Esmail Lutfi, Natàlia Riera-Heredia, Marlon Córdoba, Cinta Porte, Joaquim Gutiérrez, Encarnación Capilla, Isabel Navarro
      Numerous environmental pollutants have been identified as potential obesogenic compounds affecting endocrine signaling and lipid homeostasis. Among them, organotins such as tributyltin (TBT) and triphenyltin (TPT), can be found in significant concentrations in aquatic environments. The aim of the present study was to investigate in vitro the effects of TBT and TPT on the development and lipid metabolism of rainbow trout (Onchorynchus mykiss) primary cultured adipocytes. Results showed that TBT and TPT induced lipid accumulation and slightly enhanced peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT enhancer binding protein alpha (C/EBPα) protein expression when compared to a control, both in the presence or absence of lipid mixture. Notwithstanding, the effects were higher when combined with lipid, and in the absence of it, the organotins did not cause complete mature adipocyte morphology. Regarding gene expression analyses, exposure to TBT and TPT caused an increase in fatty acid synthase (fasn) mRNA levels confirming the pro-adipogenic properties of these compounds. In addition, when added together with lipid, TBT and TPT significantly increased cebpa, tumor necrosis factor alpha (tnfa) and ATP-binding cassette transporter 1 (abca1) mRNA levels suggesting a synergistic effect. Overall, our data highlighted that TBT and TPT activate adipocyte differentiation in rainbow trout supporting an obesogenic role for these compounds, although by themselves they are not able to induce complete adipocyte development and maturation suggesting that these adipocytes might not be properly functional.

      PubDate: 2017-05-10T07:18:26Z
      DOI: 10.1016/j.aquatox.2017.05.001
  • The Effects of Copper Oxide Nanoparticles on Dorsoventral Patterning,
           Convergent Extension, and Neural and Cardiac Development of Zebrafish
    • Authors: Jia Xu; Qiuping Zhang; Xu Li; Sihui Zhan; Lifeng Wang; Dongyan Chen
      Abstract: Publication date: Available online 4 May 2017
      Source:Aquatic Toxicology
      Author(s): Jia Xu, Qiuping Zhang, Xu Li, Sihui Zhan, Lifeng Wang, Dongyan Chen
      Currently, nanoparticles are widely used in biomedicine and industry. CuO nanoparticles (CuO-NPs) are versatile materials in our daily life and their toxicity has drawn extensive attention. In this study, we concentrate on the effect of CuO-NPs on early zebrafish development. The results reveal that CuO-NPs can induce abnormal phenotypes of a smaller head and eyes and delayed epiboly. The gene expression pattern shows that CuO-NPs spatially narrow the expression of dorsal genes chordin and goosecoid and alter the expression of dlx3, ntl and hgg which are related to the cell migration of gastrulation. The decreased expression of pax2 and pax6 involved in neural differentiation was accordant with the decreased sizes of neural structures. Cmlc2 expression suggests that CuO-NPs prevented looping of the heart tube during cardiogenesis. Furthermore, quantitative RT-PCR results suggest that the CuO-NPs could increase the canonical Wnt signaling pathway to narrow the expression of chordin and goosecoid in dorsoventral patterning as well as decrease the transcription of Wnt5 and Wnt11 to result in slower, less directed movements and an abnormal cell shape. These findings indicated the CuO-NPs exert developmental toxicity. The present study evaluates the ecological and developmental toxicity, providing warnings about the application of CuO-NPs.

      PubDate: 2017-05-05T07:13:28Z
      DOI: 10.1016/j.aquatox.2017.05.002
  • Effects of diclofenac on the expression of Nrf2 and its downstream target
           genes in mosquito fish (Gambusia affinis)
    • Authors: Shuang Bao; Xiangping Nie; Ruikang Ou; Chao Wang; Peijia Ku; Kaibing Li
      Abstract: Publication date: Available online 20 April 2017
      Source:Aquatic Toxicology
      Author(s): Shuang Bao, Xiangping Nie, Ruikang Ou, Chao Wang, Peijia Ku, Kaibing Li
      Diclofenac (DCF) is one of widely used non-steroidal anti-inflammatory drugs. Recently, this drug has been universally detected in aquatic environment. However, its potential adverse effects and oxidative stress toxic mechanisms on fish remain unclear. In the present study, we first cloned the crucial partial sequences of some key oxidative stress related genes, which include NF-E2-related factor 2 (Nrf2), NAD(P)H: quinoneoxidoreductase (NQO1), glutamate-cysteine ligase catalytic subunit (GCLC), Cu-Zn superoxide dismutase (SOD2), catalase (CAT), alpha-glutathione S-transferase (GSTA), and UDP-glucuronosyltransferases (UGT) in mosquito fish (Gambusia affinis). We also deduced amino acids of Nrf2 and then constructed the phylogenetic trees of Nrf2, NQO1 and GCLC, respectively. Results showed that a high identity percentage was founded between G. affinis and other bony fish species, such as Xiphophorus maculates and Poecilia reticulate. The transcriptional expression of these genes and partly related enzymes activities were then investigated under the included environmental relevant concentration DCF exposure (0μmolL−1, 1.572×10-3 μmolL−1, 1.572×10-2 μmolL−1, 0.1572μmolL−1 and 1.572μmolL−1) for 24h and 168h. The expression of Nrf2 was inhibited at 24h but induced at 168h, exhibiting a significant time and/or dose-effect relationship under DCF exposure. Similar observation was found in its downstream target genes. However, Nrf2-mediated antioxidant enzymes activities displayed differently under the same concentration of DCF exposure for the same time. Under DCF exposure for 168h, the genes exhibited dramatic induction trend, but there were no significant changes in enzyme activities and MDA content. Overall, mRNA responses were more sensitive than enzyme changes in mosquito fish under DCF exposure.

      PubDate: 2017-04-22T08:07:40Z
      DOI: 10.1016/j.aquatox.2017.04.008
  • Toxicity of clomazone and its formulations to zebrafish embryos (Danio
    • Authors: Marija Stevanovic; Slavica Gasic; Marek Pipal; Lucie Blahova; Dragica Brkic; Nesko Neskovic; Klara Hilscherova
      Abstract: Publication date: Available online 19 April 2017
      Source:Aquatic Toxicology
      Author(s): Marija Stevanovic, Slavica Gasic, Marek Pipal, Lucie Blahova, Dragica Brkic, Nesko Neskovic, Klara Hilscherova
      Herbicides are the most widely used group of pesticides but after reaching water bodies they are able to cause adverse effects on non-target organisms. Different formulations using the same active ingredient are frequently available, which raises the issue of potential influence of different formulation types on herbicide toxicity. The present study evaluated the toxicity and teratogenic effects of the active ingredient clomazone and its two formulations (Rampa® EC and GAT Cenit 36 CS, both containing 360g a.i./l of clomazone) on zebrafish embryos. The crucial difference between the two formulation types is the way of active substance release. This investigation is the first report on zebrafish embryotoxicity of both clomazone and its formulations. The technical active ingredient and formulations caused mortality and diverse teratogenic effects, showing different levels of toxicity. The LC50 values for the technical ingredient, Rampa® EC and GAT Cenit 36 CS were 61.4, 9.6 and 92.5mg a.i./l, respectively. Spontaneous movements in 22 hpf embryos decreased under exposure to both the technical ingredient and formulations. A significant number of underdeveloped embryos was detected after exposure to clomazone and Rampa® EC, while no underdevelopment was noted in embryos exposed to GAT Cenit 36 CS. Exposure to the technical ingredient and formulations led also to a series of morphological changes and interfered with the growth of zebrafish embryos. The EC50 based on detection of edemas, spine and tail tip deformations and gas bladder absence (120hpf) was 12.1, 10.1 and 24.1mg/l for technical clomazone, Rampa® EC and GAT Cenit 36 CS, while teratogenicity index (TI) based on LC50/EC50 ratio was 5.1, 1 and 3.8, respectively. The data in this study showed that the emulsifiable concentrate formulation (Rampa® EC) caused statistically significantly higher toxicity, and the aqueous capsule suspension (GAT Cenit 36 CS) lower toxicity than technical clomazone. It indicates that different formulations with the same active ingredient may have different environmental impacts, which is why risk assessment based only on active ingredient toxicity might not be sufficient in terms of preventing formulation effects on the environment.

      PubDate: 2017-04-22T08:07:40Z
      DOI: 10.1016/j.aquatox.2017.04.007
  • Toxicity and Bioaccumulation of Three Hexabromocyclododecane
           Diastereoisomers in the Marine Copepod Tigriopus japonicas
    • Authors: Haizheng Hong; Dongmei Lv; Wanxin Liu; Lingming Huang; Leyun Chen; Rong Shen; Dalin Shi
      Abstract: Publication date: Available online 18 April 2017
      Source:Aquatic Toxicology
      Author(s): Haizheng Hong, Dongmei Lv, Wanxin Liu, Lingming Huang, Leyun Chen, Rong Shen, Dalin Shi
      The three major hexabromocyclododecane (HBCD) diastereoisomers, i.e. α-, β- and γ-HBCD, have distinct physical and chemical properties that may potentially result in different levels of bioaccumulation and toxicity in aquatic organisms. To assess the impact of diastereomeric variation in HBCDs, the marine copepod Tigriopus japonicus was exposed to α-, β- and γ-HBCD in isolation. Results showed that all the three diastereoisomers had a similar potency to cause growth delay in T. japonicas. Variation was observed in the overall survival rate with exposure to α- and β-HBCD, and this resulted in significantly higher lethal toxicity in T. japonicas than that with exposure to γ-HBCD. Exposure to α-, β- and γ-HBCD led to the generation of ROS in T. japonicas, a possibly toxic mechanism. Both α- and β-HBCD showed a higher potential to induce oxidative stress, which may be a factor in the higher lethal toxicity observed with α- and β-HBCD exposure. It is of note that T. japonicus was found to be more sensitive to all three diastereoisomers in the F1 generation than in the F0 generation. The bioconcentration potential of HBCD diastereoisomers can be ranked in the order α-HBCD >γ-HBCD >β-HBCD and was found to be higher in T. japonicus than has been reported for fish species.

      PubDate: 2017-04-22T08:07:40Z
      DOI: 10.1016/j.aquatox.2017.04.010
  • Dechlorane Plus induces oxidative stress and decreases cyclooxygenase
           activity in the blue mussel
    • Authors: Pierre-Luc Gagné; Marlène Fortier; Marc Fraser; Lise Parent; Cathy Vaillancourt; Jonathan Verreault
      Abstract: Publication date: Available online 17 April 2017
      Source:Aquatic Toxicology
      Author(s): Pierre-Luc Gagné, Marlène Fortier, Marc Fraser, Lise Parent, Cathy Vaillancourt, Jonathan Verreault
      Dechlorane Plus (DP) is a chlorinated flame retardant used mainly in electrical wire and cable coating, computer connectors, and plastic roofing materials. Concentrations of DP (syn and anti isomers) are increasingly being reported in aquatic ecosystems worldwide. However, there is exceedingly little information on the exposure-related toxicity of DP in aquatic organisms, especially in bivalves. The objective of this study was to investigate the in vivo and in vitro effects of DP exposure on histopathology, lipid peroxidation (LPO) levels, cyclooxygenase (COX) activity, phagocytosis capacity and efficiency, and DNA strand breakage in the blue mussel (Mytilus edulis) following a 29days exposure (0.001, 0.01, 0.1 and 1.0μg DP/L). Blue mussels accumulated DP in muscle and digestive gland in a dose-dependent manner. LPO levels in gills were found to increase by 82% and 67% at the 0.01 and 1.0μg DP/L doses, respectively, while COX activity in gills decreased by 44% at the 1μg/L dose. No histopathological lesion was found in gonads following DP exposure. Moreover, no change in hemocyte DNA strand breakage, phagocytosis rate, and viability was observed following DP exposure. Present study showed that toxicity of DP may occur primarily via oxidative stress in the blue mussel and potentially other bivalves, and that gills represent the most responsive tissue to this exposure.

      PubDate: 2017-04-22T08:07:40Z
      DOI: 10.1016/j.aquatox.2017.04.009
  • Toxicity assessment of ZnO-decorated Au nanoparticles in the Mediterranean
           clam Ruditapes decussatus
    • Authors: Badreddine Sellami; Amine Mezni Abdelhafidh Khazri Imen Bouzidi Wiem Saidani
      Abstract: Publication date: Available online 15 April 2017
      Source:Aquatic Toxicology
      Author(s): Badreddine Sellami, Amine Mezni, Abdelhafidh Khazri, Imen Bouzidi, Wiem Saidani, David Sheehan, Hamouda Beyrem
      The synthesis of hybrid nanomaterials has greatly increased in recent years due to their special physical and chemical properties. However, information regarding the environmental toxicity associated with these chemicals is limited, in particular in the aquatic environment. In the present study, an experiment was performed in which the marine bivalve (Ruditapes decussatus) was exposed for 14days to 2 concentrations of zinc oxide-decorated Au nanoparticles (Au-ZnONPs: Au-ZnONP50=50μg/l; Au-ZnONP100=100μg/l). The stability and resistance of Au-ZnONPs in the natural seawater were assessed by combining transmission electron microscopy and dynamic light scattering. Inductively coupled plasma-atomic emission spectroscopy revealed uptake of these nanoparticles within clams and their ability to induce metallic deregulation. The results obtained indicate that Au-ZnONPs induce biochemical and histological alterations within either the digestive gland or gill tissues at high concentration. This was deduced from the significant increase in H2O2 level, superoxide dismutase and catalase activities and malondialdehyde content. Furthermore, the toxicity of Au-ZnO nanoparticles was linked with the increase of intracellular iron and calcium levels in both tissues. Histological alterations in gill and digestive gland were more pronounced with Au-ZnONP100 and this is likely related to oxidative mechanisms. Gill and digestive gland are differentially sensitive to Au-ZnONPs if the exposure concentration is higher than 50μg/L. In conclusion, the parameters considered here could constitute reliable biomarkers for evaluation of hybrid nanoparticles toxicity in environmental model organisms. In addition, based on the results obtained, gill and digestive gland of R. decussatus could be proposed as models to detect harmful effects of hybrid nanoparticles.

      PubDate: 2017-04-15T08:03:32Z
  • Characterisation of Pb-induced changes and prediction of Pb exposure in
           microalgae using infrared spectroscopy
    • Authors: Dao John; Beardall Philip Heraud
      Abstract: Publication date: Available online 14 April 2017
      Source:Aquatic Toxicology
      Author(s): Ly Dao, John Beardall, Philip Heraud
      Macromolecular changes in Chlorella sp. FleB1 and Scenedesmus acutus YaA6 exposed to Pb were characterised by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. Spectra were collected in the mid-infrared spectral region and a chemometric approach was used to analyse the spectra. Principal Component Analysis showed that under Pb treatment, carbohydrates and lipids increased while proteins and phosphorylated molecules decreased in both the isolates. These conclusions were corroborated by conventional measurements of photosynthesis and neutral lipids. In the two strains, Pb inhibited photosynthesis, which directly affects the synthesis of polysaccharides and other macromolecules. Neutral lipids as measured by Nile Red were increased in lead-treated samples. Modelling of spectral data against Pb exposure levels allowed Pb-exposed samples to be readily discriminated from unexposed controls and the level of Pb exposure could be predicted with good accuracy in independent validation testing. This study demonstrates the utility of the spectroscopic approach as a rapid, inexpensive, non-destructive method to understand changes in cellular composition induced by Pb and allowing detection and quantification of Pb levels in metal-contaminated cells in a “snapshot”.

      PubDate: 2017-04-15T08:03:32Z
  • Extreme nitrite tolerance in the clown knifefish Chitala ornata is linked
           to up-regulation of methaemoglobin reductase activity
    • Authors: Le Thi Hong Gam; Frank Bo Jensen; Christian Damsgaard; Do Thi Thanh Huong; Nguyen Thanh Phuong; Mark Bayley
      Abstract: Publication date: Available online 19 March 2017
      Source:Aquatic Toxicology
      Author(s): Le Thi Hong Gam, Frank Bo Jensen, Christian Damsgaard, Do Thi Thanh Huong, Nguyen Thanh Phuong, Mark Bayley
      The clown knifefish is a facultative air breather, which is widely farmed in freshwater ponds in Vietnam. Here we report a very high nitrite tolerance (96h LC50 of 7.82mM) in this species and examine the effects of 1mM (LC5) and 2.5mM (LC10) ambient nitrite on haemoglobin (Hb) derivatives, electrolyte levels, acid-base status, and total body water content during 7days of exposure. Furthermore, we tested the hypothesis that erythrocyte methaemoglobin (metHb) reductase activity is upregulated by nitrite exposure. Plasma nitrite levels increased for 2–3days but stayed below environmental levels and fell towards control values during the last half of the exposure period. Plasma nitrate, in contrast, rose continuously, reflecting detoxification of nitrite to nitrate. MetHb generated from the reaction between nitrite and erythrocyte Hb reached 38% at day 2, but then decreased to 17% by the end of experiment. The first order rate constant for metHb reduction by erythrocyte metHb reductase increased from 0.01 in controls to 0.046min−1 after 6days of nitrite exposure, showing up-regulation of this enzyme. While such upregulation has been suggested in nitrite-exposed fish species, this study provides the first experimental evidence.

      PubDate: 2017-03-20T05:19:36Z
      DOI: 10.1016/j.aquatox.2017.03.013
  • Interaction between the zebrafish (Danio rerio) organic cation transporter
           1 (Oct1) and endo- and xenobiotics
    • Authors: Mihaljević Ivan; Popović Marta; Žaja Roko; Maraković Nikola; Šinko Goran; Smital Tvrtko
      Abstract: Publication date: Available online 18 March 2017
      Source:Aquatic Toxicology
      Author(s): Mihaljević Ivan, Popović Marta, Žaja Roko, Maraković Nikola, Šinko Goran, Smital Tvrtko
      Organic cation transporters (OCTs) serve as uptake transporters of numerous endo- and xenobiotics. They have been in the focus of medical toxicological research for more than a decade due to their key role in absorption, distribution, metabolism and excretion due to their expression on basolateral membranes of various barrier tissues. OCTs belong to the SLC22A family within the SLC (Solute carrier) protein superfamily, with three co-orthologs identified in humans (OCT1, 2 and 3), and two Oct orthologs in zebrafish (Oct1 and Oct2). The structural and functional properties of zebrafish Octs, along with their toxicological relevance, have still not been explored. In this study, we performed a functional characterization of zebrafish Oct1 using transient and stable heterologous expression systems and model fluorescent substrates as the basis for interaction studies with a wide range of endo- and xenobiotics. We also conducted a basic topology analysis and homology modeling to determine the structure and membrane localization of Oct1. Finally, we performed an MTT assay to evaluate the toxic effects of the seven interactors identified – oxaliplatin, cisplatin, berberine, MPP+, prazosin, paraquat and mitoxantrone – in human embryonic kidney cells (HEK293T) stably expressing zebrafish Oct1 (HEK293T-drOct1 cells). Our results show that the zebrafish Oct1 structure consists of 12 transmembrane alpha helices, which form the active region with more than one active site. Five new fluorescent substrates of Oct1 were identified: ASP+ (Km =26μM), rhodamine 123 (Km =103.7nM), berberine (Km =3.96μM), DAPI (Km =780nM), and ethidium bromide (Km =97nM). Interaction studies revealed numerous interactors that inhibited the Oct1-dependent uptake of fluorescent substrates. The identified interactors ranged from physiological compounds (mainly steroid hormones) to different classes of xenobiotics, with IC50 values in nanomolar (e.g., pyrimethamine and prazosin) to millimolar range (e.g., cimetidine). Cytotoxicity experiments with HEK293T-drOct1 cells enabled us to identify berberine, oxaliplatin and MPP+ as substrates of Oct1. The data presented in this study provide the first insights into the functional properties of zebrafish Oct1 and offer an important basis for more detailed molecular and ecotoxicological characterizations of this transporter.

      PubDate: 2017-03-20T05:19:36Z
      DOI: 10.1016/j.aquatox.2017.03.012
  • The impacts of emergent pollutants on Ruditapes philippinarum: biochemical
           responses to carbon nanoparticles exposure
    • Authors: Lucia De Marchi; Victor Neto; Carlo Pretti; Etelvina Figueira; Federica Chiellini; Amadeu M.V.M. Soares; Rosa Freitas
      Abstract: Publication date: Available online 18 March 2017
      Source:Aquatic Toxicology
      Author(s): Lucia De Marchi, Victor Neto, Carlo Pretti, Etelvina Figueira, Federica Chiellini, Amadeu M.V.M. Soares, Rosa Freitas
      Multi-walled carbon nanotubes (MWCNTs) are one of the most important carbon Nanoparticles (NPs). The production and use of these NPs is increasing rapidly and, therefore, the need to assess their presence in the environment and associated risks has become of prime importance. Recent studies demonstrated the impacts of different NPs on bivalves, a taxonomic group where species tolerance to anthropogenic stressors, such as pollutants, is widely variable. The Manila clam Ruditapes philippinarum is one of the most commonly used bivalve species in environmental monitoring studies and ecotoxicology tests, however, to our knowledge, no information is available on biochemical alterations on this species due to MWCNTs exposure. Thus, the present study aimed to assess the toxic effects of different MWCNT concentrations (0.01; 0.10 and 1.00mg/L) in R. philippinarum biochemical (energy reserves, metabolic capacity, oxidative status and neurotoxicity) performance, after 28days of exposure. The results obtained revealed that exposure to MWCNTs altered energy-related responses, with higher metabolic capacity and lower glycogen and protein concentrations in clams exposed to these carbon NPs. Moreover, R. philippinarum exposed to MWCNTs showed oxidative stress expressed in higher lipid peroxidation and lower ratio between reduced and oxidized glutathione, despite the activation of defense mechanisms in exposed clams. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to MWCNTs. The present study provides valuable information regarding how these emerging pollutans could become a potential risk for the environment and living organisms.

      PubDate: 2017-03-20T05:19:36Z
      DOI: 10.1016/j.aquatox.2017.03.010
  • Selenium speciation influences bioaccumulation in Limnodynastes peronii
    • Authors: C.M. Lanctôt; S.D. Melvin; T. Cresswell
      Abstract: Publication date: Available online 12 March 2017
      Source:Aquatic Toxicology
      Author(s): C.M. Lanctôt, S.D. Melvin, T. Cresswell
      Despite being essential for animal health and fitness, Se has a relatively narrow range between deficiency and toxicity, and excess Se can cause a variety of adverse effects in aquatic organisms. Amphibians are particularly vulnerable to contaminants during larval aquatic life stage, because they can accumulate toxic ions through various routes including skin, gills, lungs and digestive tract. Few attempts have been made to understand the tissue-specific accumulation of trace elements, including the impacts of chemical speciation in developing amphibian larvae. We used radiolabelled 75Se to explore the biokinetics and tissue distributions of the two dominant forms occurring in surface waters, selenite (SeIV) and selenate (SeVI). Tadpoles of the native Australian frog Limnodynastes peronii were exposed to Se in both forms, and live-animal gamma spectroscopy was used to track accumulation and retention over time. Tissue biodistributions were also quantified at the end of the uptake and depuration phases. Results showed the bioconcentration of SeIV to be 3 times greater compared to SeVI, but rates of elimination were similar for both forms. This suggests a change of Se speciation within the organism prior to excretion. Depuration kinetics were best described by a one-phase exponential decay model, and tadpoles retained approximately 19% of the accumulated Se after 12 days of depuration in clean water. Selenium bioaccumulation was greatest in digestive and excretory organs, as well as the eye, which may directly relate to previously reported Se-induced impairments. Results demonstrate how the use of radiotracing techniques can significantly improve our understanding of trace element toxicokinetics and tissue distributions in developing amphibians. From an environmental monitoring perspective, the findings highlight the importance of considering chemical speciation as this could influence the accuracy of risk assessment.

      PubDate: 2017-03-15T05:17:10Z
      DOI: 10.1016/j.aquatox.2017.03.009
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