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BIOLOGY (1424 journals)                  1 2 3 4 5 6 7 8 | Last

Showing 1 - 200 of 1720 Journals sorted alphabetically
AAPS Journal     Hybrid Journal   (Followers: 20)
Achievements in the Life Sciences     Open Access   (Followers: 4)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 21)
Acta Biologica Colombiana     Open Access   (Followers: 7)
Acta Biologica Hungarica     Full-text available via subscription   (Followers: 4)
Acta Biologica Sibirica     Open Access  
Acta Biomaterialia     Hybrid Journal   (Followers: 25)
Acta Biotheoretica     Hybrid Journal   (Followers: 5)
Acta Chiropterologica     Full-text available via subscription   (Followers: 6)
acta ethologica     Hybrid Journal   (Followers: 4)
Acta Limnologica Brasiliensia     Open Access   (Followers: 3)
Acta Médica Costarricense     Open Access   (Followers: 2)
Acta Musei Silesiae, Scientiae Naturales : The Journal of Silesian Museum in Opava     Open Access  
Acta Neurobiologiae Experimentalis     Open Access  
Acta Parasitologica     Hybrid Journal   (Followers: 9)
Acta Scientiarum. Biological Sciences     Open Access   (Followers: 2)
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Advanced Health Care Technologies     Open Access   (Followers: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
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Advances in Environmental Sciences - International Journal of the Bioflux Society     Open Access   (Followers: 20)
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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: 8)
Aging Cell     Open Access   (Followers: 10)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Agrokreatif Jurnal Ilmiah Pengabdian kepada Masyarakat     Open Access  
AJP Cell Physiology     Full-text available via subscription   (Followers: 13)
AJP Endocrinology and Metabolism     Full-text available via subscription   (Followers: 22)
AJP Lung Cellular and Molecular Physiology     Full-text available via subscription   (Followers: 3)
Al-Kauniyah : Jurnal Biologi     Open Access  
Alasbimn Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Biology Teacher     Full-text available via subscription   (Followers: 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: 65)
Amphibia-Reptilia     Hybrid Journal   (Followers: 6)
Anaerobe     Hybrid Journal   (Followers: 4)
Analytical Methods     Full-text available via subscription   (Followers: 7)
Anatomical Science International     Hybrid Journal   (Followers: 2)
Animal Cells and Systems     Hybrid Journal   (Followers: 4)
Annales de Limnologie - International Journal of Limnology     Hybrid Journal   (Followers: 1)
Annales françaises d'Oto-rhino-laryngologie et de Pathologie Cervico-faciale     Full-text available via subscription   (Followers: 3)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3)
Annales UMCS, Biologia     Open Access   (Followers: 1)
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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 Cancer Biology     Full-text available via subscription   (Followers: 1)
Annual Review of Cell and Developmental Biology     Full-text available via subscription   (Followers: 39)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Annual Review of Genomics and Human Genetics     Full-text available via subscription   (Followers: 19)
Annual Review of Phytopathology     Full-text available via subscription   (Followers: 10)
Anthropological Review     Open Access   (Followers: 25)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antibiotics     Open Access   (Followers: 9)
Antioxidants     Open Access   (Followers: 4)
Antioxidants & Redox Signaling     Hybrid Journal   (Followers: 8)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apidologie     Hybrid Journal   (Followers: 4)
Apmis     Hybrid Journal   (Followers: 1)
APOPTOSIS     Hybrid Journal   (Followers: 8)
Applied Bionics and Biomechanics     Open Access   (Followers: 8)
Applied Vegetation Science     Full-text available via subscription   (Followers: 9)
Aquaculture Environment Interactions     Open Access   (Followers: 2)
Aquaculture International     Hybrid Journal   (Followers: 22)
Aquaculture Reports     Open Access   (Followers: 3)
Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society     Open Access   (Followers: 6)
Aquatic Biology     Open Access   (Followers: 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: 4)
Avian Conservation and Ecology     Open Access   (Followers: 11)
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: 246)
Bioinformatics and Biology Insights     Open Access   (Followers: 15)
Bioinspiration & Biomimetics     Hybrid Journal   (Followers: 6)
Biointerphases     Open Access   (Followers: 1)
Biojournal of Science and Technology     Open Access  
Biologia     Hybrid Journal  
Biologia on-line : Revista de divulgació de la Facultat de Biologia     Open Access  
Biological Bulletin     Partially Free   (Followers: 4)
Biological Control     Hybrid Journal   (Followers: 5)
Biological Invasions     Hybrid Journal   (Followers: 16)
Biological Journal of the Linnean Society     Hybrid Journal   (Followers: 15)
Biological Letters     Open Access   (Followers: 4)
Biological Procedures Online     Open Access  
Biological Psychiatry     Hybrid Journal   (Followers: 42)
Biological Psychology     Hybrid Journal   (Followers: 6)
Biological Research     Open Access  
Biological Rhythm Research     Hybrid Journal   (Followers: 2)
Biological Theory     Hybrid Journal   (Followers: 1)
Biological Trace Element Research     Hybrid Journal  
Biologicals     Full-text available via subscription   (Followers: 9)
Biologics: Targets & Therapy     Open Access   (Followers: 1)
Biologie Aujourd'hui     Full-text available via subscription  
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 42)
Biologija     Open Access  
Biology     Open Access   (Followers: 5)
Biology and Philosophy     Hybrid Journal   (Followers: 16)
Biology Bulletin     Hybrid Journal   (Followers: 1)
Biology Bulletin Reviews     Hybrid Journal  
Biology Direct     Open Access   (Followers: 7)
Biology Letters     Full-text available via subscription   (Followers: 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  [3043 journals]
  • Acute exposure to tris (2-butoxyethyl) phosphate (TBOEP) affects growth
           and development of embryo-larval zebrafish
    • Authors: Yiran Liu; Ding Wu; Qinglong Xu; Liqin Yu; Chunsheng Liu; Jianghua Wang
      Pages: 17 - 24
      Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Yiran Liu, Ding Wu, Qinglong Xu, Liqin Yu, Chunsheng Liu, Jianghua Wang
      Tris (2-butoxyethyl) phosphate (TBOEP), is used as a flame retardant worldwide. It is an additive in materials and can be easily discharged into the surrounding environment. There is evidence linking TBOEP exposure to abnormal development and growth in zebrafish embryos/larvae. Here, using zebrafish embryo as a model, we investigated toxicological effects on developing zebrafish (Danio rerio) caused by TBOEP at concentrations of 0, 20, 200, 1000, 2000μg/L starting from 2h post-fertilization (hpf). Our findings revealed that TBOEP exposure caused developmental toxicity, such as malformation, growth delay and decreased heart rate in zebrafish larvae. Correlation analysis indicated that inhibition of growth was possibly due to down-regulation of expression of genes related to the growth hormone/insulin-like growth factor (GH/IGF) axis. Furthermore, exposure to TBOEP significantly increased thyroxine (T4) and 3,5,3′-triiodothyronine (T3) in whole larvae. In addition, changed expression of genes involved in the hypothalamic-pituitary-thyroid (HPT) axis was observed, indicating that perturbation of HPT axis might be responsible for the developmental damage and growth delay induced by TBOEP. The present study provides a new set of evidence that exposure of embryo-larval zebrafish to TBOEP can cause perturbation of GH/IGF axis and HPT axis, which could result in developmental impairment and growth inhibition.

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

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

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

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.07.018
      Issue No: Vol. 191 (2017)
  • The paralytic shellfish toxin, saxitoxin, enters the cytoplasm and induces
           apoptosis of oyster immune cells through a caspase-dependent pathway
    • Authors: Celina Abi-Khalil; Darren S. Finkelstein; Genevieve Conejero; Justin Du Bois; Delphine Destoumieux-Garzon; Jean Luc Rolland
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Celina Abi-Khalil, Darren S. Finkelstein, Genevieve Conejero, Justin Du Bois, Delphine Destoumieux-Garzon, Jean Luc Rolland
      Exposure of the toxin-producing dinoflagellate Alexandrium catenella (A. catenella) was previously demonstrated to cause apoptosis of hemocytes in the oyster species Crassostrea gigas. In this work, a coumarin-labeled saxitoxin appeared to spread throughout the cytoplasm of the hemocytes. PSTs, including saxitoxin, were also shown to be directly responsible for inducing apoptosis in hemocytes, a process dependent on caspase activation and independent of reactive oxygen species (ROS) production. A series of in vitro labelling and microscopy experiments revealed that STX and analogs there of induced nuclear condensation, phosphatidylserine exposure, membrane permeability, and DNA fragmentation of hemocytes. Unlike in vertebrates, gonyautoxin-5 (GTX5), which is present in high concentrations in A. catenella, was found to be more toxic than saxitoxin (STX) to oyster immune cells. Altogether, results show that PSTs produced by toxic dinoflagellates enter the cytoplasm and induce apoptosis of oyster immune cells through a caspase-dependent pathway. Because of the central role of hemocytes in mollusc immune defense, PST-induced death of hemocytes could negatively affect resistance of bivalve molluscs to microbial infection.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.07.001
      Issue No: Vol. 190 (2017)
  • A multi-tiered, in vivo, quantitative assay suite for environmental
           disruptors of thyroid hormone signaling
    • Authors: Brenda J. Mengeling; Yuzhu Wei; Lucia N. Dobrawa; Mischa Streekstra; Jochem Louisse; Vikrant Singh; Latika Singh; Pamela J. Lein; Heike Wulff; Albertinka J. Murk; J. David Furlow
      Pages: 1 - 10
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Brenda J. Mengeling, Yuzhu Wei, Lucia N. Dobrawa, Mischa Streekstra, Jochem Louisse, Vikrant Singh, Latika Singh, Pamela J. Lein, Heike Wulff, Albertinka J. Murk, J. David Furlow
      The essential role of thyroid hormone (TH) signaling in mammalian development warrants the examination of man-made chemicals for its disruption. Among vertebrate species, the molecular components of TH signaling are highly conserved, including the thyroid hormone receptors (TRs), their heterodimer binding partners the retinoid-X receptors (RXRs), and their DNA recognition sequences (TREs). This molecular conservation allows examination of potential TH disruption in the tractable, in vivo model system of amphibian metamorphosis. Metamorphosis requires TH signaling for both instigation and progression, and it provides dramatic and well-characterized phenotypes involving different cell fates. Here we describe a quantitative, precocious-metamorphosis assay suite we developed using one-week post-fertilization (PF) Xenopus laevis tadpoles in order to assess disruption of TH signaling. Tadpoles at this developmental stage (Nieuwkoop-Faber (NF)-48) are competent to respond to TH hormone, although not yet producing TH, along many metamorphic pathways, and they are uniform in size. This allowed us to quantify changes in morphology associated with natural metamorphosis (e.g. gill and tail resorption, brain expansion, and craniofacial remodeling) after five days of treatment. Using the same tadpoles from morphological measurements, we quantified a 20-fold increase in TH-induced cellular proliferation in the rostral head region by whole-mount immunocytochemistry. At the molecular level, we used F3-generation tadpoles from a transgenic X. laevis line, which expresses luciferase under the control of a native TRE, to assess the ability of compounds to disrupt TR function. The luciferase reporter showed over 10-fold activation by physiologic concentrations of TH. We used the synthetic TR antagonist NH-3 to demonstrate the feasibility of our assay suite to measure inhibition of TH activity at the level of the receptor. Finally, we assessed the capabilities of suspected TH-disrupting chemicals tetrabrominated diphenyl ether 47 (BDE-47) and tetrabromobisphenol A (TBBPA). We found that BDE-47 displays general toxicity rather than TH disruption, as it did not increase brain width nor affect the TRE-luciferase reporter. However, TBBPA, a suspected TR antagonist, although not effective in antagonizing cell proliferation, significantly inhibited the TRE-luciferase reporter, suggesting that it bears closer scrutiny as a TH disruptor. Overall the assay suite has important advantages over the classical tadpole metamorphosis assays with respect to the uniformity of animal size, small test volume, reproducibility, and short test period. The assays are performed before endogenous TH production and free feeding start, which further reduces complexity and variability.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.06.019
      Issue No: Vol. 190 (2017)
  • Effect of contaminants of emerging concern on liver mitochondrial function
           in Chinook salmon
    • Authors: Andrew Yeh; David J. Marcinek; James P. Meador; Evan P. Gallagher
      Pages: 21 - 31
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Andrew Yeh, David J. Marcinek, James P. Meador, Evan P. Gallagher
      We previously reported the bioaccumulation of contaminants of emerging concern (CECs), including pharmaceuticals and personal care products (PPCPs) and perfluorinated compounds, in field-collected juvenile Chinook salmon from urban estuaries of Puget Sound, WA (Meador et al., 2016). Although the toxicological impacts of CECs on salmon are poorly understood, several of the detected contaminants disrupt mitochondrial function in other species. Here, we sought to determine whether environmental exposures to CECs are associated with hepatic mitochondrial dysfunction in juvenile Chinook. Fish were exposed in the laboratory to a dietary mixture of 16 analytes representative of the predominant CECs detected in our field study. Liver mitochondrial content was reduced in fish exposed to CECs, which occurred concomitantly with a 24–32% reduction in expression of peroxisome proliferator-activated receptor (PPAR) Y coactivator-1a (pgc-1α), a positive transcriptional regulator of mitochondrial biogenesis. The laboratory exposures also caused a 40–70% elevation of state 4 respiration per unit mitochondria, which drove a 29–38% reduction of efficiency of oxidative phosphorylation relative to controls. The mixture-induced elevation of respiration was associated with increased oxidative injury as evidenced by increased mitochondrial protein carbonyls, elevated expression of glutathione (GSH) peroxidase 4 (gpx4), a mitochondrial-associated GSH peroxidase that protects against lipid peroxidation, and reduction of mitochondrial GSH. Juvenile Chinook sampled in a WWTP effluent-impacted estuary with demonstrated releases of CECs showed similar trends toward reduced liver mitochondrial content and elevated respiratory activity per mitochondria (including state 3 and uncoupled respiration). However, respiratory control ratios were greater in fish from the contaminated site relative to fish from a minimally-polluted reference site, which may have been due to differences in the timing of exposure to CECs under laboratory and field conditions. Our results indicate that exposure to CECs can affect both mitochondrial quality and content, and support the analysis of mitochondrial function as an indicator of the sublethal effects of CECs in wild fish.

      PubDate: 2017-07-04T02:12:04Z
      DOI: 10.1016/j.aquatox.2017.06.011
      Issue No: Vol. 190 (2017)
  • Exploring uptake and biodistribution of polystyrene (nano)particles in
           zebrafish embryos at different developmental stages
    • Authors: M. van Pomeren; N.R. Brun; W.J.G.M. Peijnenburg; M.G. Vijver
      Pages: 40 - 45
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): M. van Pomeren, N.R. Brun, W.J.G.M. Peijnenburg, M.G. Vijver
      In ecotoxicology, it is continuously questioned whether (nano)particle exposure results in particle uptake and subsequent biodistribution or if particles adsorb to the epithelial layer only. To contribute to answering this question, we investigated different uptake routes in zebrafish embryos and how they affect particle uptake into organs and within whole organisms. This is addressed by exposing three different life stages of the zebrafish embryo in order to cover the following exposure routes: via chorion and dermal exposure; dermal exposure; oral and dermal exposure. How different nanoparticle sizes affect uptake routes was assessed by using polystyrene particles of 25, 50, 250 and 700nm. In our experimental study, we showed that particle uptake in biota is restricted to oral exposure, whereas the dermal route resulted in adsorption to the epidermis and gills only. Ingestion followed by biodistribution was observed for the tested particles of 25 and 50nm. The particles spread through the body and eventually accumulated in specific organs and tissues such as the eyes. Particles larger than 50nm were predominantly adsorbed onto the intestinal tract and outer epidermis of zebrafish embryos. Embryos exposed to particles via both epidermis and intestine showed highest uptake and eventually accumulated particles in the eye, whereas uptake of particles via the chorion and epidermis resulted in marginal uptake. Organ uptake and internal distribution should be monitored more closely to provide more in depth information of the toxicity of particles.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.06.017
      Issue No: Vol. 190 (2017)
  • Prenatal transfer of decabromodiphenyl ether (BDE-209) results in
           disruption of the thyroid system and developmental toxicity in zebrafish
    • Authors: Zhihua Han; Yufei Li; Shenghu Zhang; Ninghui Song; Huaizhou Xu; Yao Dang; Chunsheng Liu; John P. Giesy; Hongxia Yu
      Pages: 46 - 52
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Zhihua Han, Yufei Li, Shenghu Zhang, Ninghui Song, Huaizhou Xu, Yao Dang, Chunsheng Liu, John P. Giesy, Hongxia Yu
      Decabromodiphenyl ether (BDE-209) was one of most widely-used polybrominated diphenyl ether (PBDE) flame retardants and is frequently detected in both abiotic and biotic samples from environment. However, knowledge of its transgenerational risks is limited. Here, 4-month-old zebrafish were exposed to various concentrations of BDE-209 (0, 3, 30 or 300μg/L) for 28days and spawned in clean water without BDE-209. Concentrations of triiodothyronine (T3) and thyroxine (T4) as well as expressions of genes involved in the hypothalamic–pituitary–thyroid (HPT) axis were measured in offspring after exposure of adult zebrafish to BDE-209. BDE-209 was accumulated in adult fish and F1 eggs, which suggests transfer of this compound from adult fish to their offspring. Exposure of BDE-209 to parents resulted in developmental abnormalities in offspring and a significant decrease in T4 concentrations in F1 larvae 120h post-fertilization (hpf). Furthermore, expressions of several genes involved in the HPT axis were also altered. Expressions of thyroid hormone receptor α (tr-α), thyrotropin releasing hormone (trh), thyroid stimulating hormone β (tsh-β) and deiodinase 1 (dio 1) were significantly down-regulated in F1 individuals, while expressions of thyroid stimulating hormone receptor (tshr) and transthyretin (ttr) were significantly up-regulated. These results suggest that exposure of parent zebrafish to BDE-209 can cause developmental toxicity in offspring and disruption of the thyroid endocrine system of offspring.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.06.020
      Issue No: Vol. 190 (2017)
  • 6:2 fluorotelomer carboxylic acid (6:2 FTCA) exposure induces
           developmental toxicity and inhibits the formation of erythrocytes during
           zebrafish embryogenesis
    • Authors: Guohui Shi; Qianqian Cui; Yitao Pan; Nan Sheng; Yong Guo; Jiayin Dai
      Pages: 53 - 61
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Guohui Shi, Qianqian Cui, Yitao Pan, Nan Sheng, Yong Guo, Jiayin Dai
      Saturated fluorotelomer carboxylic acids (FTCAs) are intermediates in the degradation of fluorotelomer alcohols (FTOHs) to perfluorinated carboxylic acids (PFCAs). Recent studies have detected FTCAs in precipitation, surface waters, and wildlife, but few studies have focused on their toxicity. In this study, zebrafish embryos were exposed to different concentrations of 6:2 FTCA (0, 4, 8, and 12mg/L) from 6 to 120h post-fertilization (hpf) to investigate its developmental toxicity. Results showed that 6:2 FTCA exposure decreased the hatching and survival percentages, reduced the heart rate, and increased the malformation of zebrafish embryos. The median lethal concentration of 6:2 FTCA was 7.33mg/L at 120 hpf, which was lower than that of perfluorooctanoic acid (PFOA), thus indicating higher toxicity for zebrafish. The most common developmental malformation was pericardial edema, which appeared in the 8 and 12mg/L 6:2 FTCA-exposed embryos from 60 hpf. Using o-dianisidine staining, we found that the hemoglobin content in embryos was reduced in a concentration-dependent manner after 6:2 FTCA exposure at 72 hpf. Based on quantitative real-time polymerase chain reaction (q-RT-PCR) and whole-mount in situ hybridization, the transcriptional levels of hemoglobin markers (hbae1, hbbe1, and hbae3) were down-regulated at 48 and 72 hpf, even though no observed malformation appeared in zebrafish at 48 hpf. Moreover, 6:2 FTCA exposure decreased the protein level of gata1, a principal early erythrocytic marker, in Tg (gata1:DsRed) transgenic zebrafish at 72 hpf. We analyzed the transcriptional level of other erythrocyte-related genes using q-RT-PCR assay. For heme formation, the transcription of alas2, which encodes the key enzyme for heme biosynthesis, was down-regulated after 6:2 FTCA exposure, whereas the transcription of ho-1, which is related to heme degradation, was up-regulated at 48 and 72 hpf. The transcriptional patterns of gata1 and gata2, which are related to erythroid differentiation, differed. At 48 hpf, the mRNA level of gata2 was significantly increased, whereas that of gata1 exhibited no significant changes in any treatment group. At 72 hpf, the expressions of both were down-regulated in a concentration-dependent manner. Taken together, 6:2 FTCA exposure decreased the erythrocyte number and disrupted erythroid differentiation during zebrafish embryonic development. Our results suggest that 6:2 FTCA can cause developmental toxicity in zebrafish embryos, and that FTCAs exhibit greater toxicity than that of PFCAs.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.06.023
      Issue No: Vol. 190 (2017)
  • Single and mixture impacts of two pyrethroids on damselfly predatory
           behavior and physiological biomarkers
    • Authors: Warren Kunce; Robby Stoks; Frank Johansson
      Pages: 70 - 77
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Warren Kunce, Robby Stoks, Frank Johansson
      Direct mortality due to toxicity of single pesticide exposure along a concentration gradient, while the most common, is only one important parameter for assessing the effects of pesticide contamination on aquatic ecosystems. Sub-lethal toxicity can induce changes in an organism’s behavior and physiology that may have population-level ramifications and consequences for ecosystem health. Additionally, the simultaneous detection of multiple contaminants in monitored watersheds stresses the importance of gaining a greater understanding of the toxicities of combined exposures, particularly at low, environmentally relevant concentrations. Using larvae of the Azure Damselfly (Coenagrion puella), we conducted a combined exposure investigation of two widely-used pyrethroid insecticides presumed to share the same neurotoxic mechanism of action, and estimated their effect on predatory ability, mobility and three physiological biomarkers (Glutathione S-transferase; GST, respiratory electron transport system; ETS, and malondialdehyde; MDA). Deltamethrin exposure (0.065μg/L and 0.13μg/L) was found to reduce the predatory ability, but it did not affect the larvae’s mobility. Esfenvalerate exposure (0.069μg/L and 0.13μg/L), on the other hand, induced no significant changes in predatory ability or mobility. The decrease in predatory ability after the combination exposure (0.067μg/L deltamethrin and 0.12μg/L esfenvalerate) did not significantly differ from the impact of the single deltamethrin exposures. Glutathione-S-transferase was induced after single esfenvalerate exposure and the lower deltamethrin concentration exposure, but seemingly inhibited after exposure to the higher concentration of deltamethrin as well as the combination of both pyrethroids. Our data indicate that sub-lethal exposure to deltamethrin reduces predatory ability and suggest that sub-lethal combined exposure to deltamethrin and esfenvalerate inhibits the GST detoxification pathway. These effects can eventually result in a lower emergence of adults from contaminated ponds.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.06.025
      Issue No: Vol. 190 (2017)
  • Uptake and toxicity of CuO nanoparticles to Daphnia magna varies between
           indirect dietary and direct waterborne exposures
    • Authors: Fan Wu; Amy Bortvedt; Bryan J. Harper; Lauren E. Crandon; Stacey L. Harper
      Pages: 78 - 86
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Fan Wu, Amy Bortvedt, Bryan J. Harper, Lauren E. Crandon, Stacey L. Harper
      Research examining the direct and indirect ecological effects of nanomaterials in aquatic ecosystems is important for developing a more realistic understanding of the environmental implications of nanotechnology. Copper oxide nanoparticles (CuO NPs) are being used extensively in many industries but are considered highly toxic to aquatic species residing in surface waters. Few studies have addressed whether CuO NPs can be transferred through the aquatic food chain, and if such indirect exposure to nanomaterials impacts their toxicity. We investigated the uptake and trophic transfer of CuO NPs from the algae Chlorella vulgaris to the crustacean Daphnia magna and assessed bio-partitioning and resulting toxicity. We hypothesized that CuO NPs can be associated with algal cells and be transported to predators through feeding, and that the chronic toxicity can be altered in comparison to direct CuO NP exposure. For the indirect feeding exposure, algae pre-incubated with CuO NPs (Cu-algae) were washed to remove loose NPs and fed to D. magna while Cu uptake and toxicity were evaluated. For the direct waterborne exposures, a parallel group of D. magna were exposed to equivalent concentrations of CuO NPs while being fed unexposed algae. Using hyperspectral imaging we observed strong surface associations between pre-incubated CuO NPs and algae used in the feeding exposure, and quantified the average Cu content (0.15mg Cu/L) with ICP-OES. Cu accumulated in daphnid bodies to a greater extent in direct exposures, whereas molted carapaces and neonate offspring had more copper following the indirect feeding exposure, implying that D. magna may regulate internal Cu differently depending on the method of CuO NP delivery. Significantly higher D. magna mortality was observed following direct exposure relative to feeding exposure, and neonate production from adult daphnids exposed indirectly to CuO NPs was significantly reduced. Thus, nanoparticle interaction with biota at one trophic level may alter the biological response at the next trophic level in a way that is dependent on the delivery scenario. This study highlights the importance of evaluating potential ecological impacts of nanomaterials in more relevant, complex exposure scenarios.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.06.021
      Issue No: Vol. 190 (2017)
  • Responses of Landoltia punctata to cobalt and nickel: Removal, growth,
           photosynthesis, antioxidant system and starch metabolism
    • Authors: Ling Guo; Yanqiang Ding; Yaliang Xu; Zhidan Li; Yanling Jin; Kaize He; Yang Fang; Hai Zhao
      Pages: 87 - 93
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Ling Guo, Yanqiang Ding, Yaliang Xu, Zhidan Li, Yanling Jin, Kaize He, Yang Fang, Hai Zhao
      Landoltia punctata has been considered as a potential bioenergy crop due to its high biomass and starch yields in different cultivations. Cobalt and nickel are known to induce starch accumulation in duckweed. We monitored the growth rate, net photosynthesis rate, total chlorophyll content, Rubisco activity, Co2+ and Ni2+ contents, activity of antioxidant enzymes, starch content and activity of related enzymes under various concentrations of cobalt and nickel. The results indicate that Co2+ and Ni2+ (≤0.5mgL−1) can facilitate growth in the beginning. Although the growth rate, net photosynthesis rate, chlorophyll content and Rubisco activity were significantly inhibited at higher concentrations (5mgL−1), the starch content increased sharply up to 53.3% dry weight (DW) in L. punctata. These results were attributed to the increase in adenosine diphosphate-glucose pyrophosphorylase (AGPase) and soluble starch synthase (SSS) activities and the decrease in α-amylase activity upon exposure to excess Co2+ and Ni2+. In addition, a substantial increase in the antioxidant enzyme activities and high flavonoid contents in L. punctata may have largely resulted in the metal tolerance. Furthermore, the high Co2+ and Ni2+ contents (2012.9±18.8 and 1997.7±29.2mgkg−1 DW) in the tissue indicate that L. punctata is a hyperaccumulator. Thus, L. punctata can be considered as a potential candidate for the simultaneous bioremediation of Co2+- and Ni2+-polluted water and high-quality biomass production.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.06.024
      Issue No: Vol. 190 (2017)
  • Preheating mitigates cadmium toxicity in zebrafish livers: Evidence from
           promoter demethylation, gene transcription to biochemical levels
    • Authors: Jia-Lang Zheng; Sai-Nan Guo; Shuang-Shuang Yuan; Hu Xia; Qing-Ling Zhu; Zhen-Ming Lv
      Pages: 104 - 111
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Jia-Lang Zheng, Sai-Nan Guo, Shuang-Shuang Yuan, Hu Xia, Qing-Ling Zhu, Zhen-Ming Lv
      The working hypothesis for this study was that moderate heat stress would alleviate the deleterious effects of subsequent cadmium (Cd) exposure on fish. Thus, zebrafish (Danio rerio) were subjected to water maintained at 26°C and 34°C for 4days, and then exposed to 0 or 200μg/L Cd for 1 week at 26°C. Multiple indicators were measured from livers of zebrafish at different levels, including DNA, RNA, protein and enzymatic activity associated with oxidative stress, inflammation and metal transport. The ameliorative effect of preheatinging on Cd toxicity was demonstrated. In the Cd-exposed groups, preheating decreased mortality and lipid peroxidation, increased activity levels of catalase (CAT) and copper/zinc-superoxide dismutase (Cu/Zn-SOD), and up-regulated mRNA levels of heat shock protein 70 (HSP70) and heat shock factor 2 (HSF2). Preheating also mitigated Cd-induced increases in protein and mRNA levels of metallothioneins (MTs), and mRNA levels of several inflammation-related genes. Furthermore, preheating alone dramatically up-regulated mRNA levels of genes related to antioxidant and immune defenses, zinc and copper transporters, protein folding, and reduced methylation levels in the HSF binding motif of the HSP70 promoter. Overall, preheating-induced accumulation of transcripts via demethylation might support the rapid defense responses at post-transcriptional levels caused by subsequent Cd exposure, indicating an adaptive mechanism for organisms exposed to one mild stressor followed by another.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.06.022
      Issue No: Vol. 190 (2017)
  • Pathway analysis of systemic transcriptome responses to injected
           polystyrene particles in zebrafish larvae
    • Authors: Wouter J. Veneman; Herman P. Spaink; Nadja R. Brun; Thijs Bosker; Martina G. Vijver
      Pages: 112 - 120
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Wouter J. Veneman, Herman P. Spaink, Nadja R. Brun, Thijs Bosker, Martina G. Vijver
      Microplastics are a contaminant of emergent concern in the environment, however, to date there is a limited understanding on their movement within organisms and the response of organisms. In the current study zebrafish embryos at different development stages were exposed to 700nm fluorescent polystyrene (PS) particles and the response pathway after exposure was investigated using imaging and transcriptomics. Our results show limited spreading of particles within the larvae after injection during the blastula stage. This is in contrast to injection of PS particles in the yolk of 2-day old embryos, which resulted in redistribution of the PS particles throughout the bloodstream, and accumulation in the heart region. Although injection was local, the transcriptome profiling showed strong responses of zebrafish embryos exposed to PS particle, indicating a systemic response. We found several biological pathways activated which are related to an immune response in the PS exposed zebrafish larvae. Most notably the complement system was enriched as indicated by upregulation of genes in the alternative complement pathway (e.g. cfhl3, cfhl4, cfb and c9). The fact that complement pathway is activated indicates that plastic microparticles are integrated in immunological recognition processes. This was supported by fluorescence microscopy results, in which we observed co-localisation of neutrophils and macrophages around the PS particles. Identifying these key events can be a first building block to the development of an adverse outcome pathway (AOP). These data subsequently can be used within ecological and human risk assessment.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.06.014
      Issue No: Vol. 190 (2017)
  • Effects of increasing temperature alone and combined with copper exposure
           on biochemical and physiological parameters in the zooxanthellate
           scleractinian coral Mussismilia harttii
    • Authors: Juliana da Silva Fonseca; Laura Fernandes de Barros Marangoni; Joseane Aparecida Marques; Adalto Bianchini
      Pages: 121 - 132
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Juliana da Silva Fonseca, Laura Fernandes de Barros Marangoni, Joseane Aparecida Marques, Adalto Bianchini
      Effects of increasing temperature alone and in combination with exposure to dissolved copper (Cu) were evaluated in the zooxanthellate scleractinian coral Mussismilia harttii using a marine mesocosm system. Endpoints analyzed included parameters involved in metabolism [maximum photosynthetic capacity of zooxanthellae (Fv/Fm), chlorophyll a and ATP concentrations], calcification [carbonic anhydrase (CA) and Ca2+-Mg2+-ATPase activity], and oxidative status [antioxidant capacity against peroxyl radicals (ACAP) and lipid peroxidation (LPO)]. Coral polyps were collected, acclimated and exposed to three increasing temperature conditions [25.0±0.1°C (control; average temperature of local seawater), 26.6±0.1°C and 27.3±0.1°C] using a marine mesocosm system. They were tested alone and in combination with four environmentally relevant concentrations of dissolved Cu in seawater [2.9±0.7 (control; average concentration in local seawater), 3.8±0.8, 5.4±0.9 and 8.6±0.3μg/L] for 4, 8 and 12days. Fv/Fm reduced over the experimental period with increasing temperature. Combination of increasing temperature with Cu exposure enhanced this effect. CA and Ca2+-Mg2+-ATPase activities increased up to 8days of exposure, but recovered back after 12days of experiment. Short-term exposure to increasing temperature or long-term exposure to the combination of stressors reduced LPO, suggesting the occurrence of a remodeling process in the lipid composition of biological membranes. ACAP, ATP and chlorophyll a were not significantly affected by the stressors. These findings indicate that increasing temperature combined with exposure to dissolved Cu increase susceptibility to bleaching and reduce growth in the zooxanthellate scleractinian coral M. harttii.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.07.002
      Issue No: Vol. 190 (2017)
  • Toxicity of organic compounds from unresolved complex mixtures (UCMs) to
           primary fish hepatocytes
    • Authors: Karina Petersen; Maria T. Hultman; Steven J. Rowland; Knut Erik Tollefsen
      Pages: 150 - 161
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Karina Petersen, Maria T. Hultman, Steven J. Rowland, Knut Erik Tollefsen
      Many environmental matrices contaminated with organic pollutants derived from crude oil or degraded petroleum contain mixtures so complex that they are typically unresolved by conventional analytical techniques such as gas chromatography. The resulting chromatographic features have become known as ‘humps’ or unresolved complex mixtures (UCMs). These UCMs often dominate the organic contaminants of polluted environmental samples: for example, in oil sands produced water up to 150mgL−1 of ‘naphthenic acids’ appear as UCMs when examined by gas chromatography as the esters. In oil-contaminated mussels, aromatic hydrocarbon UCMs may comprise almost all of the total toxic hydrocarbons, with over 7000μgg−1 dry weight reported in some samples. Over the last 25 years, efforts to resolve and thus identify, or at least to produce average structures, for some UCM components, have proved fruitful. Numerous non-polar UCM hydrocarbons and more polar UCM acids have been identified, then synthesised or purchased from commercial suppliers. As UCMs have been proposed to represent a risk to aquatic organisms, the need for assessment of the ecotoxicological effects and characterisation of the mode of action (MoA) of these environmental pollutants has arisen. In the present study, several chemicals with structures typical of those found in some UCMs, were assessed for their potential to disrupt membrane integrity, inhibit metabolic activity, activate the aryl hydrocarbon receptor (AhR), and activate the estrogen receptor (ER) in primary rainbow trout hepatocytes (Oncorhynchus mykiss). These endpoints were determined in order to screen for common toxic modes of action (MoA) in this diverse group of chemicals. The results from the in vitro screening indicated that of the endpoints tested, the predominant toxic MoA was cytotoxicity. EC50 values for cytotoxicity were obtained for 16 compounds and ranged from 77μM–24mM, whereof aliphatic monocyclic acids, monoaromatic acids, polycyclic monoaromatic acids and alkylnaphthalenes were the most toxic. The observed cytotoxicity of the chemicals correlated well with the hydrophobicity (LogKOW) suggesting that the toxicity was predominantly due to a non-specific MoA. Interestingly, two compounds induced the ER-mediated production of vitellogenin (Vtg) and six compounds induced the AhR-mediated Ethoxyresorufin-O-deethylase (EROD) enzymatic activity to >20% of the positive control; by doing so suggesting that they may act as ER or AhR agonists in fish. The heterogeneous group of ‘UCM compounds’ tested exhibited multiple MoA that may potentially cause adverse effects in fish. Additional studies to determine if these compounds may cause adverse effects in vivo at environmentally relevant concentrations, are warranted to identify if such compounds are indeed of potential environmental concern.

      PubDate: 2017-07-23T12:38:04Z
      DOI: 10.1016/j.aquatox.2017.06.007
      Issue No: Vol. 190 (2017)
  • Early life co-exposures to a real-world PAH mixture and hypoxia result in
           later life and next generation consequences in medaka (Oryzias latipes)
    • Authors: Jingli Mu; Melissa Chernick; Wu Dong; Richard T. Di Giulio; David E. Hinton
      Pages: 162 - 173
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Jingli Mu, Melissa Chernick, Wu Dong, Richard T. Di Giulio, David E. Hinton
      Acute effects of individual and complex mixtures of polycyclic aromatic hydrocarbons (PAHs) are well documented in vertebrate species. Hypoxia in fish reduces metabolic rate and reproduction. However, less is known about the later life consequences stemming from early-life exposure to PAHs or hypoxia, particularly their co-exposure. To address this, medaka (Oryzias latipes) embryos were exposed to a complex PAH mixture sediment extract from the Elizabeth River, VA (ERSE) at concentrations of 0.1, 0.5, or 1.0% or to one of three different hypoxia scenarios: continuous, nocturnal, or late stage embryogenesis hypoxia. Co-exposures with 0.1% ERSE and each of the hypoxia scenarios were conducted. Results included decreased survival with ERSE, hatching delays with hypoxia, and higher occurrences of deformities with each. The continuous hypoxia scenario caused the most significant changes in all endpoints. These early-life exposures altered later-life growth, impaired reproductive capacity, and reduced the quality of their offspring. ERSE alone resulted in a female-biased sex ratio while continuous or nocturnal hypoxia produced significantly greater numbers of males; and co-exposure produced an equal sex ratio. Exposure to a PAH mixture and hypoxia during early life stages has meaningful later-life and next generational consequences.

      PubDate: 2017-07-23T12:38:04Z
      DOI: 10.1016/j.aquatox.2017.06.026
      Issue No: Vol. 190 (2017)
  • Cell damage and apoptosis in the hepatopancreas of Eriocheir sinensis
           induced by cadmium
    • Authors: Yong Lin; Jia-jia Huang; Hans-Uwe Dahms; Jing-jing Zhen; Xue-ping Ying
      Pages: 190 - 198
      Abstract: Publication date: Available online 18 July 2017
      Source:Aquatic Toxicology
      Author(s): Yong Lin, Jia-jia Huang, Hans-Uwe Dahms, Jing-jing Zhen, Xue-ping Ying
      Cadmium (Cd) is one of the most common pollutants in the environment and it is known to cause a range of tissue damages and apoptosis in invertebrates. In this study, we investigated the effect of Cd on the hepatopancreas of the crab Eriocheir sinensis, a commercially and ecologically important species of crustacean. The crabs were first exposed to water containing different concentrations of Cd2+ (0, 0.63, 1.26, 2.52, 5.04 and 10.07mg/L) for 6 days. Typical morphological characteristics and physiological changes of apoptosis were then observed using various methods, including AO/EB double fluorescence staining, transmission electron microscopy and DNA fragmentation analysis. The results showed that Cd2+ induced cell damage and apoptosis in a concentration-dependent manner. Transmission electron microscopy revealed the presence of cellular swelling and necrosis with reduced number of microvilli on the cell surface and damages to individual organelles. The mitochondria became swollen and vacuolated. The rough endoplasmic reticulum (Rer) was expanded, with membrane rupture and many different sizes of vesicles, suggesting the destruction of protein-synthesizing structures in the hepatopancreatic cells. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidases (GPx) initially increased and subsequently decreased with increasing Cd2+ concentrations. This was accompanied by increases in malondialdehyde (MDA) and H2O2 contents, which led to membrane lipid peroxidation. Crabs exposed to Cd2+ also displayed significant increases in caspase-3, −8, and −9 activities compared to control crabs. Cadmium induced the production and accumulation of ROS in the hepatopancreas, which resulted in oxidative damage and abnormal metabolism. Taken together, the results indicated that Cd2+ could induce oxidative damage as well caspase-dependent apoptosis in E. sinensis hepatopancreas.

      PubDate: 2017-07-23T12:38:04Z
      DOI: 10.1016/j.aquatox.2017.07.008
      Issue No: Vol. 190 (2017)
  • Expression stability and selection of optimal reference genes for gene
           expression normalization in early life stage rainbow trout exposed to
           cadmium and copper
    • Authors: Kamran Shekh; Song Tang; Som Niyogi; Markus Hecker
      Pages: 217 - 227
      Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190
      Author(s): Kamran Shekh, Song Tang, Som Niyogi, Markus Hecker
      Gene expression analysis represents a powerful approach to characterize the specific mechanisms by which contaminants interact with organisms. One of the key considerations when conducting gene expression analyses using quantitative real-time reverse transcription-polymerase chain reaction (qPCR) is the selection of appropriate reference genes, which is often overlooked. Specifically, to reach meaningful conclusions when using relative quantification approaches, expression levels of reference genes must be highly stable and cannot vary as a function of experimental conditions. However, to date, information on the stability of commonly used reference genes across developmental stages, tissues and after exposure to contaminants such as metals is lacking for many vertebrate species including teleost fish. Therefore, in this study, we assessed the stability of expression of 8 reference gene candidates in the gills and skin of three different early life-stages of rainbow trout after acute exposure (24h) to two metals, cadmium (Cd) and copper (Cu) using qPCR. Candidate housekeeping genes were: beta actin (b-actin), DNA directed RNA polymerase II subunit I (DRP2), elongation factor-1 alpha (EF1a), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), glucose-6-phosphate dehydrogenase (G6PD), hypoxanthine phosphoribosyltransferase (HPRT), ribosomal protein L8 (RPL8), and 18S ribosomal RNA (18S). Four algorithms, geNorm, NormFinder, BestKeeper, and the comparative ΔCt method were employed to systematically evaluate the expression stability of these candidate genes under control and exposed conditions as well as across three different life-stages. Finally, stability of genes was ranked by taking geometric means of the ranks established by the different methods. Stability of reference genes was ranked in the following order (from lower to higher stability): HPRT<GAPDH < EF1a < G6PD < RPL8 < DRP2 < b-actin in gills of fish exposed to Cd; b-actin < GAPDH < G6PD < DRP2 < RPL8 < HPRT < EF1a in gills of fish exposed to Cu; RPL8 <HPRT < GAPDH < G6PD < EF1a < DRP2 < b-actin in the skin of fish exposed to Cd; and EF1a < GAPDH < RPL8 < HPRT < G6PD < b-actin < DRP2 in the skin of fish exposed to Cu. The results demonstrated that the stability of reference genes depended on the metal, life-stage and/or organ in question. Thus, attention should be paid to these factors before selection of reference gene for relative quantification of the gene expressions.

      PubDate: 2017-07-30T12:56:42Z
      DOI: 10.1016/j.aquatox.2017.07.009
      Issue No: Vol. 190 (2017)
  • 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 phenanthrene on early development of the Pacific oyster
           Crassostrea gigas (Thunberg, 1789)
    • Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Diego J. Nogueira, Jacó J. Mattos, Patrick R. Dybas, Fabrıcio Flores-Nunes, Silvio Tarou Sasaki, Satie Taniguchi, Éder C. Schmidt, Zenilda L. Bouzon, Márcia C. Bícego, Claudio M.R. Melo, Guilherme Toledo-Silva, Afonso C.D. Bainy
      Phenanthnere (PHE) is a polycyclic aromatic hydrocarbon continuously discarded in the marine environment and bioavailable to many aquatic species. Although studies about PHE toxicity have been documented for adult oysters, the effects on early developmental stages are poorly characterized in bivalves. In this study, the effects of PHE (0.02 and 2.0μg.L−1) were evaluated on the embryogenesis and larval development of Crassostrea gigas. Toxicity bioassays, growth and deformities assessment, analysis of shell calcium abundance and transcript levels of genes related to xenobiotic biotransformation (CYP2AU2, CYP30C1), immune system (Cg-Tal) and tissue growth and shell formation (Ferritin, Insulin-like, Cg-Try, Calmodulin and Nacrein) were assayed in D-shape larvae after 24h of PHE exposure. At the highest concentration (2.0μg.L−1), PHE decreased the frequency of normal development (19.7±2.9%) and shell size (53.5±2.8mm). Developmental deformities were mostly related to abnormal mantle and shell formation. Lower calcium levels in oyster shells exposed to PHE 2.0μg.L−1 were observed, suggesting effects on shell structure. At this same PHE concentration, CYP30C1, Cg-Tal, Cg-Tyr, Calmodulin were upregulated and CYP2AU2, Ferritin, Nacrein, and Insulin-Like were downregulated compared to control larvae. At the lowest PHE concentration (0.02μg.L−1), it was observed a minor decrease in normal larval development (89,6±6%) and the remaining parameters were not affected. This is the first study to provide evidences that exposure to PHE can affect early oyster development at the molecular and morphological levels, possibly threatening this bivalve species.

      PubDate: 2017-08-18T13:16:24Z
  • Exposure of European sea bass (Dicentrarchus labrax) to chemically
           dispersed oil has a chronic residual effect on hypoxia tolerance but not
           aerobic scope
    • Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Yangfan Zhang, Florian Mauduit, Anthony P. Farrell, Denis Chabot, Hélène Ollivier, Adrien Rio-Cabello, Stéphane Le Floch, Guy Claireaux
      We tested the hypothesis that the chronic residual effects of an acute exposure of European sea bass (Dicentrarchus labrax) to chemically dispersed crude oil is manifest in indices of hypoxic performance rather than aerobic performance. Sea bass were pre-screened with a hypoxia challenge test to establish their incipient lethal oxygen saturation (ILOS), but on discovering a wide breadth for individual ILOS values (2.6–11.0% O2 saturation), fish were subsequently subdivided into either hypoxia sensitive (HS) or hypoxia tolerant (HT) phenotypes, traits that were shown to be experimentally repeatable. The HT phenotype had a lower ILOS and critical oxygen saturation (O2crit) compared with the HS phenotype and switched to glycolytic metabolism at a lower dissolved oxygen, even though both phenotypes accumulated lactate and glucose to the same plasma concentrations at ILOS. As initially hypothesized, and regardless of the phenotype considered, we found no residual effect of oil on any of the indices of aerobic performance. Contrary to our hypothesis, however, oil exposure had no residual effect on any of the indices of hypoxic performance in the HS phenotype. In the HT phenotype, on the other hand, oil exposure had residual effects as illustrated by the impaired repeatability of hypoxia tolerance and also by the 24% increase in O2crit, the 40% increase in scope for oxygen deficit, the 17% increase in factorial scope for oxygen deficit and the 57% increase in accumulated oxygen deficit. Thus, sea bass with a HT phenotype remained chronically impaired for a minimum of 167days following an acute 24-h oil exposure while the HS phenotypes did not. We reasoned that impaired oxygen extraction at gill due to oil exposure activates glycolytic metabolism at a higher dissolved oxygen, conferring on the HT phenotype an inferior hypoxia resistance that might eventually compromise their ability to survive hypoxic episodes.

      PubDate: 2017-08-18T13:16:24Z
  • Time-gated luminescence imaging of singlet oxygen photoinduced by
           fluoroquinolones and functionalized graphenes in Daphnia magna
    • Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Tianlie Luo, Jingwen Chen, Bo Song, Hua Ma, Zhiqiang Fu, Willie J.G.M. Peijnenburg
      Singlet oxygen (1O2) can be photogenerated by photoactive xenobiotics and is capable of causing adverse effects due to its electrophilicity and its high reactivity with biological molecules. Detection of the production and distribution of 1O2 in living organisms is therefore of great importance. In this study, a luminescent probe ATTA-Eu3+ combined with time-gated luminescence imaging was adopted to detect the distribution and temporal variation of 1O2 photoinduced by fluoroquinolone antibiotics and carboxylated/aminated graphenes in Daphnia magna. Results show that the xenobiotics generate 1O2 in living daphnids under simulated sunlight irradiation (SSR). The photogeneration of 1O2 by carboxylated/aminated graphenes was also confirmed by electron paramagnetic resonance spectroscopy. The strongest luminescence signals of 1O2 were observed in the hindgut of daphnids, and the signals in different areas of the daphnids (gut, thoracic legs and post-abdominal claw) displayed a similar trend of enhancement over irradiation time. Mean 1O2 concentrations at different regions of daphnids within one hour of SSR irradiation were estimated to be in the range of 0.5∼4.8μM. This study presented an efficient method for visualizing and quantifying the temporal and spatial distribution of 1O2 photogenerated by xenobiotics in living organisms, which can be employed for phototoxicity evaluation of xenobiotics.
      Graphical abstract image

      PubDate: 2017-08-18T13:16:24Z
  • Comparative toxicity of the plasticizer dibutyl phthalate to two
           freshwater algae
    • Abstract: Publication date: October 2017
      Source:Aquatic Toxicology, Volume 191
      Author(s): Shurui Gu, Hao Zheng, Qingqing Xu, Cuizhu Sun, Mei Shi, Zhenyu Wang, Fengmin Li
      Phthalate esters (PAEs), a family of emerging environmental contaminants, have been frequently detected in soils and water. However, intensive studies on the toxicity of PAEs have focused on growth response of terrestrial and aquatic animals, while only limited attention has been paid to aquatic plants, especially phytoplankton, the primary producer in aquatic ecosystems. Therefore, the acute toxic effects and underlying mechanisms of dibutyl phthalate (DBP) at different concentrations (0–20mgL−1) on two typical freshwater algae (Scenedesmus obliquus and Chlorella pyrenoidosa) were investigated. The growth of S. obliquus and C. pyrenoidosa was conspicuously inhibited by DBP exposure at 2–20mgL−1. The 96-h median effective concentration values (96h-EC50) were 15.3mgL−1 and 3.14mgL−1 for S. obliquus and C. pyrenoidosa, respectively, implying that the spherical C. pyrenoidosa is more sensitive to DBP than the spindle-shaped S. obliquus. As expected from the damage done to cell organelles (i.e. cell membranes, chloroplasts, and protein rings), cell densities and chlorophyll content conspicuously decreased under DBP treatments. Moreover, the algal growth inhibition was closely linked to the increased production of intracellular reactive oxygen species and malondialdehyde content, indicating oxidative stress and lipid peroxidation in both algae. This was proved by the increased activity of antioxidant enzymes such as superoxide dismutase and catalase. Our findings will contribute to the understanding of toxic mechanisms in PAEs and the evaluation of environmental risks for primary producers in aquatic ecosystems.
      Graphical abstract image

      PubDate: 2017-08-18T13:16:24Z
  • Sub-lethal Effects of Waterborne Exposure to Copper Nanoparticles compared
           to Copper Sulphate on the Shore Crab (Carcinus maenas)
    • Abstract: Publication date: Available online 10 August 2017
      Source:Aquatic Toxicology
      Author(s): Lisa M. Rossbach, Benjamin J. Shaw, Dawid Piegza, William F. Vevers, Andrew J. Atfield, Richard D. Handy
      The toxicity of soluble copper (Cu) to marine organisms is reasonably well described. However, the hazard of Cu engineered nanomaterial (ENMs) is poorly understood. The aim of the present study was to compare the toxicity of Cu ENMs to Cu as CuSO4 in the shore crab, Carcinus maenas. The crabs were exposed via the water using a semi-static approach to 0.2 or 1mgL−1 of Cu ENMs or 1mgL−1 of Cu as CuSO4. Gills, hepatopancreas, chela muscle and haemolymph were collected at days 0, 4 and 7 for the body burden of Cu, histology and biochemical analysis [thiobarbituric acid reactive substances (TBARS) and total glutathione (GSH)]. Nominal exposure concentrations of both the ENMs and the metal salt were maintained at over 80% in each treatment throughout the experiment. By day 7, 54% mortality was recorded in the 1mgL−1 CuSO4 treatment, compared to just 21% in the 1mgL−1 Cu ENM-exposed crabs. The target organs for Cu accumulation were similar for both forms of Cu with highest concentrations in the gills, particularly the posterior gills; followed by the hepatopancreas, and with the lowest concentrations in the chela muscle. No changes were observed in the osmolarity of the haemolymph (ANOVA, P>0.05). TBARS were measured as an indicator of lipid peroxidation and showed the greatest change in the anterior and posterior gills and hepatopancreas of animals exposed to 1mgL−1 Cu ENMs (ANOVA or Kruskal-Wallis, P<0.05). No statistically significant changes in total GSH were observed (ANOVA, P>0.05; n =6 crabs per treatment). Histological analysis revealed organ injuries in all treatments. The types of pathologies observed in the Cu ENM treatments were broadly similar to those of the Cu as CuSO4 treatment. Overall, the target organs and Cu accumulation from Cu ENMs were comparable to that following exposure to Cu as CuSO4, and although there were some differences in the sub-lethal effects, the metal salt was more acutely toxic.

      PubDate: 2017-08-18T13:16:24Z
  • Zebrafish sex differentiation and gonad development: a review on the
           impact of environmental factors
    • Abstract: Publication date: Available online 10 August 2017
      Source:Aquatic Toxicology
      Author(s): Dércia Santos, Ana Luzio, Ana M. Coimbra
      Zebrafish (Danio rerio) is extensively used in research; however the mechanisms that control this species sex determination are still poorly understood. In the latest decades, it has been established that zebrafish sex is determined by genetic factors on a polygenic basis, as various candidate genes with sex dimorphic expression, as well sex-linked loci have been identified in different zebrafish strains. However, it has been evidenced that sex determination in this species is also influenced by environmental factors. For instance, temperature can have a crucial role in zebrafish sex determination. Likewise, the exposure to endocrine disrupting chemicals (EDCs), the most studied zebrafish sex changing factor, can strongly influence the course of sex differentiation and unbalance the sex ratio of zebrafish populations. Despite this, so far the influence of environmental factors is still less understood and only few studies have addressed this topic. Therefore, this review intends to gather current knowledge on the environmental factors involved in sex determination of zebrafish and identify important gaps in this research area. Briefly, the current understanding on zebrafish sex related genetics is also addressed.

      PubDate: 2017-08-18T13:16:24Z
  • Integrated assessment of toxic effects of maghemite (γ-Fe2O3)
           nanoparticles in zebrafish
    • Abstract: Publication date: Available online 8 August 2017
      Source:Aquatic Toxicology
      Author(s): Rolando A.R. Villacis, José S. Filho, Benjamin Piña, Ricardo B. Azevedo, Aline Pic-Taylor, Juliana F. Mazzeu, César K. Grisolia
      The increasing use of nanotechnology in the last decade has raised concerns about the impact of nanoparticles in the environment. In particular, the potential harmful effects of iron oxide nanoparticles (IONPs) in aquatic organisms have been poorly addressed. We analyze here the toxic effects induced by IONPs in zebrafish using a combination of classical (genotoxicity, oxidative stress) and molecular (transcriptomic) methodologies. Adult animals were exposed for 96h to five sub-lethal IONP concentrations, ranging from 4.7 to 74.4mg/L. Comet and micronucleus assays revealed a significant number of DNA lesions induced by IONPs at all concentrations tested. Conversely, the thiobarbituric acid reactive substances (TBARS) test detected only a mild oxidative damage in liver cells (∼1.5-fold increase of malondialdehyde concentrations) and only at the two higher IONP concentrations tested. Microarray analysis of liver samples identified 953 transcripts (927 unique genes) differentially expressed between controls and IONP-exposed samples. Subsequent functional analysis identified genes related to cation/metal ion binding, membrane formation, and morphogenesis among the transcripts overrepresented upon IONP treatments, whereas mRNAs encompassing genes associated with RNA biogenesis, translation, ribosomes, and several metabolic processes became underrepresented in treated samples. Taken together, these results indicate considerable genotoxic effects of IONPs combined with general negative effect on cell growth and on the ability of the cell produce new proteins. On the contrary, IONPs showed only a limited capacity to induce oxidative stress. To our knowledge, this is the first study on IONPs toxicity using such an integrative approach in an aquatic organism.

      PubDate: 2017-08-18T13:16:24Z
  • Inside Front Cover - Editorial Board Page
    • Abstract: Publication date: September 2017
      Source:Aquatic Toxicology, Volume 190

      PubDate: 2017-08-07T13:04:21Z
  • Combined Effects of Oil Exposure, Temperature and Ultraviolet Radiation on
           Buoyancy and Oxygen Consumption of Embryonic Mahi-mahi, Coryphaena
    • Authors: Christina Pasparakis; Lauren E. Sweet; John D. Stieglitz; Daniel Benetti; Conrad T. Casente; Aaron P. Roberts; Martin Grosell
      Abstract: Publication date: Available online 5 August 2017
      Source:Aquatic Toxicology
      Author(s): Christina Pasparakis, Lauren E. Sweet, John D. Stieglitz, Daniel Benetti, Conrad T. Casente, Aaron P. Roberts, Martin Grosell
      The Deepwater Horizon oil spill occurred in the summer of 2010 and coincided with the spawning window of the ecologically and economically important pelagic fish mahi-mahi (Coryphaena hippurus). During summer months, early life stage mahi-mahi were likely also exposed to other naturally occurring stressors such as increased temperature and ultraviolet radiation (UV). Previous research has shown that co-exposure to oil and additional natural stressors can affect the timing and duration of negative buoyancy in mahi-mahi embryos. The current study aimed to elucidate the factors affecting the onset of negative buoyancy and to also explore possible mechanisms behind buoyancy change. Embryos co-exposed to oil and/or increased temperature and UV radiation displayed early onset of negative buoyancy with concurrent increases in oxygen consumption and sinking rates, which are normally only seen during the period directly preceding hatch. Results also suggest a behavioral response in which embryos avoid UV radiation by sinking down the water column but reestablish positive buoyancy once the UV radiation is removed. These findings imply that embryos can dynamically change their position in the water column in response to external cues and thus may have much greater control over buoyancy than previously thought.

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

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.08.002
  • Environmental exposure to a major urban wastewater effluent: Effects on
           the energy metabolism of northern pike
    • Authors: Julie Reinling; Magali Houde; Jonathan Verreault
      Abstract: Publication date: Available online 4 August 2017
      Source:Aquatic Toxicology
      Author(s): Julie Reinling, Magali Houde, Jonathan Verreault
      Municipal wastewater effluents (MWWEs) consist of dynamic and complex mixtures of chemical and biological compounds that can alter the health of exposed aquatic organisms. Disturbance of energy metabolism has been reported in fish exposed to MWWEs. However, there is a scarcity of knowledge on the physiological events leading to perturbation of energy balance and thyroid regulation, and associated lipid metabolism. The objective of the present study was to use a set of biomarkers, from gene transcription to body condition, to investigate the effects of a chronic environmental exposure to a major primary MWWE on fatty acid metabolism and thyroid hormone levels in northern pike (Esox lucius) collected from the St. Lawrence River near Montreal (QC, Canada). The exposure of pike to MWWE was examined through determination of a suite of persistent and bioaccumulative halogenated flame retardants in liver as this effluent is a known regional source for these chemicals. Greater hepatic concentrations of polybrominated diphenyl ethers (PBDEs, range: 29.6–465ng/g w.w. and 88.8–823ng/g w.w. in females and males, respectively) and other halogenated flame retardants (e.g., dechlorane-related compounds) were determined in fish collected downstream of the MWWE’s point of discharge relative to the upstream site. This exposure in male pike was associated with decreased acyl-coA oxidase (acox1) and fatty acid synthase (fasn) mRNA levels as well as a decreased acyl-coA oxidase (ACOX) activity in liver. In female pike, MWWE exposure was associated with lower circulating free and total triiodothyronine (T3) levels and a tendency for greater total lipid percentages in liver. Present findings provide evidence that chronic exposure of a top predator fish to MWWE can be related to gender-specific effects on fatty acid metabolism and thyroid hormone homeostasis, and highlight the need for further investigation.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.08.003
  • The Longitudinal Effects of Early Developmental Cadmium Exposure on
           Conditioned Place Preference and Cardiovascular Physiology in Zebrafish
    • Authors: Marissa Wold; Myranda Beckmann; Shelby Poitra; Ana Espinoza; Robert Longie; Erik Mersereau; Diane C. Darland; Tristan Darland
      Abstract: Publication date: Available online 3 August 2017
      Source:Aquatic Toxicology
      Author(s): Marissa Wold, Myranda Beckmann, Shelby Poitra, Ana Espinoza, Robert Longie, Erik Mersereau, Diane C. Darland, Tristan Darland
      Cadmium (Cd) is a naturally occurring trace metal that is widely considered to be highly toxic to aquatic organisms and a significant health hazard to humans (Amzal et al., 2009; Bernhoft 2013; Burger, 2008; Satarug et al., 2009). The zebrafish (Danio rerio) has been used as a model organism for toxicological studies with Cd (Banni et al., 2011; Blechinger et al., 2007; Chow et al., 2009; Chow et al., 2008; Favorito et al., 2011; Kusch et al., 2007; Matz et al., 2007; Wang and Gallagher, 2013). We asked what the lasting longitudinal effects would be from short early developmental Cd exposure (between 24–96hours post-fertilization) in a range that larvae might experience living atop typical Cd-containing surface sediments (0, 0.01, 0.1, 1.0 and 10μM CdCl2: 1.124, 11.24, 112.4 and 1124μg Cd/L). The goal of this exposure window was to specifically target secondary neurogenesis, monoaminergic differentiation and cardiovascular development, without affecting earlier patterning processes. Developmental abnormalities in body size and CNS morphology increased with concentration, but were statistically significant only at the highest concentration used (10μM). Heart rate for Cd-treated larvae increased with concentration, and was significant even at the lowest concentration used (0.01μM). Longitudinal survival was significantly lower for fish developmentally exposed to the highest concentration. Except for brain weight, overall morphology was not affected by developmental Cd exposure. However, developmental exposure to lower concentrations of Cd (0.01, 0.1, and 1.0μM) progressively lowered cocaine-induced conditioned place preference (CPP), used to measure function of the reward pathways in the brain. Baseline heart rate was significantly lower in longitudinal fish developmentally exposed to 1.0μM Cd. Cardiovascular response to isoproterenol, a potent ß-adrenergic agonist, in longitudinal adults was also significantly affected by developmental exposure to Cd at low doses (0.01, 0.1 and 1.0μM). Surviving longitudinal adult fish exposed to the highest concentration of Cd showed normal CPP and cardiovascular physiology. The data imply that even lower exposure concentrations can potentially result in fitness-affecting parameters without affecting survival in a laboratory setting.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.07.017
  • Cytotoxic effects of the proton pump inhibitor omeprazole on the
           non-target marine microalga Tetraselmis suecica
    • Authors: Marta Seoane; Marta Esperanza; Ángeles Cid
      Abstract: Publication date: Available online 2 August 2017
      Source:Aquatic Toxicology
      Author(s): Marta Seoane, Marta Esperanza, Ángeles Cid
      Omeprazole (OMP) is one of the most commonly used drugs for the treatment of gastro-intestinal disorders. Although it is daily consumed in high quantities and commonly detected in waters worldwide, relatively little is known about its ecotoxicity. The aim of this study was to evaluate the potential acute toxicity of increasing concentrations of OMP on the marine microalga Tetraselmis suecica analysing several cytotoxicity biomarkers by flow cytometry after 24h of exposure. Results showed that OMP caused a decrease in growth and autofluorescence, an increase in cellular volume and intracellular complexity, hyperpolarization of cytoplasmic and mitochondrial membranes and intracellular acidification. In addition, large amounts of reactive oxygen species (ROS) were generated which resulted in a decrease in the percentage of the viable population. However, the viable population showed an increase in their metabolic activity as an early response to overcome the stress. In conclusion, OMP may affect proton pumps in non-target organisms such as microalgae; it disturbed pH homeostasis and provoked an early accumulation of ROS that resulted in a rapid cell death in cells exposed to the highest concentration assayed.

      PubDate: 2017-08-07T13:04:21Z
      DOI: 10.1016/j.aquatox.2017.08.001
  • Embryotoxic effects of dissolved okadaic acid on the development of
           Longfin yellowtail Seriola rivoliana
    • Authors: E.J.
      Abstract: Publication date: Available online 21 July 2017
      Source:Aquatic Toxicology
      Author(s): J. Le Du, D. Tovar-Ramírez, E.J. Núñez-Vázquez
      In the context of global climate change where harmful algal blooms (HABs) might become more frequent and more severe, several studies have been conducted on the perturbation of embryonic development of marine animals by microalgal toxins. Okadaic acid (OA) and analogs (DSP toxins) produced by dinoflagellates of the genera Dynophysis and Prorocentrum are known to disturb embryogenesis. This study investigated the impact of dissolved DSP toxin (OA and Dinophysistoxin 1, DTX-1) exposure on embryo development of Longfin yellowtail Seriola rivoliana. Eggs were exposed to different concentrations of dissolved DSP toxins (low treatment: at 120μgl−1 OA eq; high treatment 175μgl−1 OA eq.). The first objective was to study the global toxic effect of DSP toxins with hatching percentages. Secondly, the effect of these toxins was investigated at molecular and functional level by measuring expression of responsible genes for bone morphogenetic protein (BMP) and proliferating cell nuclear antigen (PCNA) measuring phosphatase enzyme (serine/threonine and alkaline phosphatases) activities. Our results showed drastic mortalities induced by DSP toxins in both low and high concentration treatments. Activities of both protein and alkaline phosphatases were significantly inhibited by DSP toxin treatments, whose effects on gene expression were less evident, but levels of BMP expression in eggs treated with the lowest toxin concentration were significantly different from that in the control treatment. This work revealed an embryotoxic effect of DSP toxins resulting in high mortality of eggs. Phosphatase inhibition could have participated in part in these global effects by perturbing the regulation of pathways related to embryogenesis and resulting in a perturbation of gene expression.

      PubDate: 2017-07-23T12:38:04Z
  • The Increased Toxicity of UV-Degraded Nitroguanidine and IMX-101 to
           Zebrafish Larvae: Evidence Implicating Oxidative Stress
    • Authors: Kurt A. Gust; Jacob K. Stanley; Mitchell S. Wilbanks; Michael L. Mayo; Pornsawan Chappell; Shinita M. Jordan; Lee C. Moores; Alan J. Kennedy; Natalie D. Barker
      Abstract: Publication date: Available online 21 July 2017
      Source:Aquatic Toxicology
      Author(s): Kurt A. Gust, Jacob K. Stanley, Mitchell S. Wilbanks, Michael L. Mayo, Pornsawan Chappell, Shinita M. Jordan, Lee C. Moores, Alan J. Kennedy, Natalie D. Barker
      Insensitive munitions (IMs) improve soldier safety by decreasing sympathetic detonation during training and use in theatre. IMs are being increasingly deployed, although the environmental effects of IM constituents such as nitroguanidine (NQ) and IM mixture formulations such as IMX-101 remain largely unknown. In the present study, we investigated the acute (96h) toxicity of NQ and IMX-101 to zebrafish larvae (21d post-fertilization), both in the parent materials and after the materials had been irradiated with environmentally-relevant levels of ultraviolet (UV) light. The UV-treatment increased the toxicity of NQ by 17-fold (LC50 decreased from 1323mg/L to 77.2mg/L). Similarly, UV-treatment increased the toxicity of IMX-101 by nearly two fold (LC50 decreased from 131.3 to 67.6mg/L). To gain insight into the cause(s) of the observed UV-enhanced toxicity of the IMs, comparative molecular responses to parent and UV-treated IMs were assessed using microarray-based global transcript expression assays. Both gene set enrichment analysis (GSEA) and differential transcript expression analysis coupled with pathway and annotation cluster enrichment were conducted to provide functional interpretations of expression results and hypothetical modes of toxicity. The parent NQ exposure caused significant enrichment of functions related to immune responses and proteasome-mediated protein metabolism occurring primarily at low, sublethal exposure levels (5.5 and 45.6mg/L). Enriched functions in the IMX-101 exposure were indicative of increased xenobiotic metabolism, oxidative stress mitigation, protein degradation, and anti-inflammatory responses, each of which displayed predominantly positive concentration-response relationships. UV-treated NQ had a fundamentally different transcriptomic expression profile relative to parent NQ causing positive concentration-response relationships for genes involved in oxidative-stress mitigation pathways and inhibited expression of multiple cadherins that facilitate zebrafish neurological and retinal development. Transcriptomic profiles were similar between UV-treated versus parent IMX-101 exposures. However, more significant and diverse enrichment as well as greater magnitudes of differential expression for oxidative stress responses were observed in UV-treated IMX-101 exposures. Further, transcriptomics indicated potential for cytokine signaling suppression providing potential connections between oxidative stress and anti-inflammatory responses. Given the overall results, we hypothesize that the increased toxicity of UV-irradiated NQ and the IMX-101 mixture result from breakdown products with elevated potential to elicit oxidative stress.

      PubDate: 2017-07-23T12:38:04Z
      DOI: 10.1016/j.aquatox.2017.07.004
  • Heat indicators of oxidative stress, inflammation and metal transport show
           dependence of cadmium pollution history in the liver of female zebrafish
    • Authors: Qing-Ling Zhu; Sai-Nan Guo; Shuang-Shuang Yuan; Zhen-Ming Lv; Jia-Lang Zheng; Hu Xia
      Abstract: Publication date: Available online 20 July 2017
      Source:Aquatic Toxicology
      Author(s): Qing-Ling Zhu, Sai-Nan Guo, Shuang-Shuang Yuan, Zhen-Ming Lv, Jia-Lang Zheng, Hu Xia
      Environmental stressors such as high temperature and metal exposure may occur sequentially, simultaneously, previously in aquatic ecosystems. However, information about whether responses to high temperature depend on Cd exposure history is still unknown in fish. Zebrafish were exposed to 0 (group 1), 2.5 (group 2) and 5μg/L (group 3) cadmium (Cd) for 10 weeks, and then each group was subjected to Cd-free water maintained at 26°C and 32°C for 7days respectively. 26 indicators were used to compare differences between 26°C and 32°C in the liver of female zebrafish, including 5 biochemical indicators (activity of Cu/Zn-SOD, CAT and iNOS; LPO; MT protein), 8 molecular indicators of oxidative stress (mRNA levels of Nrf2, Cu/Zn-SOD, CAT, HSF1, HSF2, HSP70, MTF-1 and MT), 5 molecular indicators of inflammation (mRNA levels of IL-6, IL-1β, TNF-α, iNOS and NF-κB), 8 molecular indicators of metal transport (mRNA levels of, ZnT1, ZnT5, ZIP8, ZIP10, ATP7A, ATP7B and CTR1). All biochemical indicators were unchanged in group 1 and changed in group 2 and 3. Contrarily, differences were observed in almost all of molecular indicators of inflammation and metal transport in group 1, about half in group 2, and few in group 3. We also found that all molecular indicators of oxidative stress in group 2 and fewer in group 1 and 3 were significantly affected by heat. Our data indicated that heat indicators of oxidative stress, inflammation and metal transport showed dependence of previous cadmium exposure in the liver of zebrafish, emphasizing metal pollution history should be carefully considered when evaluating heat stress in fish.

      PubDate: 2017-07-23T12:38:04Z
      DOI: 10.1016/j.aquatox.2017.07.010
  • Assessing the relevance of a multiplexed methodology for proteomic
           biomarker measurement in the invertebrate species Gammarus fossarum: a
           physiological and ecotoxicological study
    • Authors: D. Gouveia; A. Chaumot; A. Charnot; H. Quéau; J. Armengaud; C. Almunia; A. Salvador; O. Geffard
      Abstract: Publication date: Available online 17 July 2017
      Source:Aquatic Toxicology
      Author(s): D. Gouveia, A. Chaumot, A. Charnot, H. Quéau, J. Armengaud, C. Almunia, A. Salvador, O. Geffard
      Recently, a protein sequence database was built specifically for the sentinel non-model species Gammarus fossarum using a proteogenomics approach. A quantitative multiplexed targeted proteomics assay (using Selected Reaction Monitoring mass spectrometry) was then developed for a fast and simultaneous quantification of dozens of biomarker peptides specific of this freshwater sentinel crustacean species. In order to assess the relevance of this breakthrough methodology in ecotoxicology, the response patterns of a panel of 26 peptides reporting for 20 proteins from the Gammarus fossarum proteome with putative key functional roles (homeostasis, osmoregulation, nutrition, reproduction, molting,…) were recorded through male and female reproductive cycles and after exposure to environmental concentrations of cadmium and lead in laboratory-controlled conditions. Based on these results, we validated the implication of annotated vtg-like peptides in the oogenesis process, and the implication of Na+/K+ ATPase proteins in the molt cycle of organisms. Upon metal (cadmium and lead) contamination, peptides belonging to proteins annotated as involved in antioxidant and detoxification functions, immunity and molting were significantly down-regulated. Overall, this multiplex assay allowed gaining relevant insights upon disruption of different main functions in the sentinel species Gammarus fossarum. This breakthrough methodology in ecotoxicology offers a valid and high throughput alternative to currently used protocols, paving the way for future practical applications of proteogenomics-derived protein biomarkers in chemical risk assessment and environmental monitoring.

      PubDate: 2017-07-23T12:38:04Z
      DOI: 10.1016/j.aquatox.2017.07.007
  • Adverse effects of methylmercury (MeHg) on life parameters, antioxidant
           systems, and MAPK signaling pathways in the rotifer Brachionus koreanus
           and the copepod Paracyclopina nana
    • Authors: Young Hwan Lee; Duck-Hyun Kim; Hye-Min Kang; Minghua Wang; Chang-Bum Jeong; Jae-Seong Lee
      Abstract: Publication date: Available online 12 July 2017
      Source:Aquatic Toxicology
      Author(s): Young Hwan Lee, Duck-Hyun Kim, Hye-Min Kang, Minghua Wang, Chang-Bum Jeong, Jae-Seong Lee
      To evaluate the adverse effects of MeHg on the rotifer Brachionus koreanus and the copepod Paracyclopina nana, we assessed the effects of MeHg toxicity on life parameters (e.g. growth retardation and fecundity), antioxidant systems, and mitogen-activated protein kinase (MAPK) signaling pathways at various concentrations (1ng/L, 10ng/L, 100ng/L, 500ng/L, and 1000ng/L). MeHg exposure resulted in the growth retardation with the increased ROS levels but decreased glutathione (GSH) levels in a dose-dependent manner in both B. koreanus and P. nana. Antioxidant enzymatic activities (e.g. glutathione S-transferase [GST], glutathione reductase [GR], and glutathione peroxidase [GPx]) in B. koreanus showed more positive responses compared the control but in P. nana, those antioxidant enzymatic activities showed subtle changes due to different no observed effect concentration (NOEC) values among the two species. Expression of antioxidant genes (e.g. superoxide dismutase [SOD], GSTs, glutathione peroxidase [GPx], and catalase [CAT]) also demonstrated similar effects as shown in antioxidant enzymatic activities. In B. koreanus, the level of p-ERK was decreased in the presence of 1000ng/L MeHg, while the levels of p-ERK and p-p38 in P. nana were reduced in the presence of 10ng/L MeHg. However, p-JNK levels were not altered by MeHg in B. koreanus and P. nana, compared to the corresponding controls. In summary, life parameters (e.g. reduced fecundity and survival rate) were closely associated with effects on the antioxidant system in response to MeHg. These observations provide a better understanding on the adverse effects of MeHg on in vivo life parameters and molecular defense mechanisms in B. koreanus and P. nana.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.07.006
  • Accumulation and detoxification dynamics of Chromium and antioxidant
           responses in juvenile rare minnow, Gobiocypris rarus
    • Authors: Cong Yuan; Meng Li; Yao Zheng; Ying Zhou; Feili Wu; Zaizhao Wang
      Abstract: Publication date: Available online 11 July 2017
      Source:Aquatic Toxicology
      Author(s): Cong Yuan, Meng Li, Yao Zheng, Ying Zhou, Feili Wu, Zaizhao Wang
      Hexavalent chromium (Cr6+) compounds are hazardous via all exposure routes. To explore the dynamics of Cr accumulation and elimination and to reveal the mechanisms underlying detoxification and antioxidation in juvenile Gobiocypris rarus, one-month old G. rarus larvae were exposed to 0.1mgL−1 Cr6+ for four weeks for accumulation and subsequently placed to clean water for another week for depuration. The contents of Cr were measured weekly in the whole body of G. rarus juveniles. The activities of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST) and glutathione reductase (GR), and contents of glutathione (GSH) and malonaldehyde (MDA), and transcripts of cat, Cu/Zn-sod, Mn-sod, gpx1, gstpi, gr, mt1, nrf2 and uba52 were determined. The results indicated that G. rarus juveniles had a strong ability to resist the Cr accumulation by Cr6+ exposure and to remove Cr from the body in clean water. In addition, GST and MT proteins may be involved in the detoxification of Cr6+. Moreover, Cr6+-induced GST detoxification in G. rarus juveniles might be accomplished through the Nrf2-mediated regulation of gene expressions. The antioxidant enzyme systems exhibited a response mechanism of the protective enzymes in organisms when they are subjected to external environmental stress. Two weeks of Cr6+ treatments could have led to the damage and consecutive degradation of antioxidant enzymes via ubiquitination, and MT proteins could be involved in protecting the activity of these enzymes. The capability of antioxidant enzyme systems to recover from the Cr6+-induced damage was strong in G. rarus juveniles after Cr6+ was removed from the water.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.07.005
  • Multigenerational effects evaluation of the flame retardant
           tris(2-butoxyethyl) phosphate (TBOEP) using Daphnia magna
    • Authors: Maeva Giraudo; Maxime Dubé; Mélanie Lépine; Pierre Gagnon; Mélanie Douville; Magali Houde
      Abstract: Publication date: Available online 8 July 2017
      Source:Aquatic Toxicology
      Author(s): Maeva Giraudo, Maxime Dubé, Mélanie Lépine, Pierre Gagnon, Mélanie Douville, Magali Houde
      Tris(2-butoxyethyl) phosphate (TBOEP) is an organophosphate ester used as substitute following the phase-out of brominated flamed retardants. Because of its high production volume and its use in a broad range of applications, this chemical is now frequently detected in the environment and biota. However, limited information is available on the long-term effects of TBOEP in aquatic organisms. In this study, Daphnia magna were exposed over three 21d generations to an environmentally relevant concentration of TBOEP (10μg/L) and effects were evaluated at the gene transcription, protein, and life-history (i.e., survival, reproduction and growth) levels. Chronic exposure to TBEOP did not impact survival or reproduction of D. magna but affected the growth output. The mean number of molts was also found to be lower in daphnids exposed to the chemical compared to control for a given generation, however there were no significant differences over the three generations. Molecular responses indicated significant differences in the transcription of genes related to growth, molting, ecdysteroid and juvenile hormone signaling, proteolysis, oxidative stress, and oxygen transport within generations. Levels of mRNA were also found to be significantly different for genes known to be involved in endocrine-mediated mechanisms such as reproduction and growth between generations F0, F1, and F2, indicating effects of parental exposure on offspring. Transcription results were supported by protein analyses with the significant decreased activity of catalase (CAT) activity in F1 generation, following the decreased transcription of cat in the parental generation. Taken together, these multi-biological level results suggest long-term potential endocrine disruption effects of TBOEP in D. magna exposed to an environmentally relevant concentration. This study highlights the importance of using chronic and multigenerational biological evaluation to assess risks of emerging chemicals.

      PubDate: 2017-07-13T02:25:22Z
      DOI: 10.1016/j.aquatox.2017.07.003
  • Inside Front Cover - Editorial Board Page
    • Abstract: Publication date: August 2017
      Source:Aquatic Toxicology, Volume 189

      PubDate: 2017-07-04T02:12:04Z
  • Sulfate transport kinetics and toxicity are modulated by sodium in aquatic
    • Authors: Shane Scheibener; Justin M. Conley; David Buchwalter
      Abstract: Publication date: Available online 1 July 2017
      Source:Aquatic Toxicology
      Author(s): Shane Scheibener, Justin M. Conley, David Buchwalter
      The salinization of freshwater ecosystems is emerging as a major ecological issue. Several anthropogenic causes of salinization (e.g. surface coal mining, hydro-fracking, road de-icing, irrigation of arid lands, etc.) are associated with biodiversity losses in freshwater ecosystems. Because insects tend to dominate freshwater ecology, it is important that we develop a better understanding of how and why different species respond to salinity matrices dominated by different major ions. This study builds upon previous work demonstrating that major ion toxicity to the mayfly Neocloeon triangulifer was apparently due to the ionic composition of water rather than specific conductance. Synthetic waters with low Ca:Mg ratios and high SO4:Na ratios produced toxicity, whereas waters with higher Ca:Mg ratios and lower SO4:Na ratios were not toxic to mayflies at comparable conductivities. Here we used a radiotracer approach to show that Mg did not competitively exclude Ca uptake at environmentally realistic ratios in 4 aquatic insect species. We characterized SO4 uptake kinetics in 5 mayflies and assessed the influence of different ions on SO4 uptake. Dual label experiments show an inverse relationship between SO4 and Na transport rates as SO4 was held constant and Na was increased, suggesting that Na (and not Cl or HCO3) is antagonistic to SO4 transport. Based on this observation, we tested the hypothesis that increasing Na would protect against SO4 induced toxicity in a Na-dependent manner. Increasing Na from 0.7 to 10.9mM improved 96-h survivorship associated with 20.8mM SO4 from 44% to 73% in a concentration dependent manner. However, when Na reached 21.8mM, survivorship decreased to 16%, suggesting that other interactive effects of major ions caused toxicity under those conditions. Thus, the combination of elevated sulfate and low sodium commonly observed in streams affected by mountaintop coal mining has the potential to cause toxicity in sensitive aquatic insects. Overall, it is important that we develop a better understanding of major ion toxicity to effectively mitigate and protect freshwater biodiversity from salinization.

      PubDate: 2017-07-04T02:12:04Z
      DOI: 10.1016/j.aquatox.2017.06.027
  • Effect of progesterone and its synthetic analogs on reproduction and
           embryonic development of a freshwater invertebrate model
    • Authors: Zita Zrinyi; Gabor Maasz; Linwen Zhang; Akos Vertes; Sandor Lovas; Tibor Kiss; Karoly Elekes; Zsolt Pirger
      Abstract: Publication date: Available online 29 June 2017
      Source:Aquatic Toxicology
      Author(s): Zita Zrinyi, Gabor Maasz, Linwen Zhang, Akos Vertes, Sandor Lovas, Tibor Kiss, Karoly Elekes, Zsolt Pirger
      The presence of a mixture of progestogens at ng/L concentration levels in surface waters is a worldwide problem. Only a few studies explore the effect of progestogen treatment in a mixture as opposed to individual chemicals to shed light on how non-target species respond to these contaminants. In the present study, we used an invertebrate model species, Lymnaea stagnalis, exposed to a mixture of four progestogens (progesterone, levonorgestrel, drospirenone, and gestodene) in 10ng/L concentration for 3 weeks. Data at both physiological and cellular/molecular level were analyzed using the ELISA technique, stereomicroscopy combined with time lapse software, and capillary microsampling combined with mass spectrometry. The treatment of adult Lymnaeas caused reduced egg production, and low quality egg mass on the first week, compared to the control. Starting from the second week, the egg production, and the quality of egg mass were similar in both groups. At the end of the third week, the egg production and the vitellogenin-like protein content of the hepatopancreas were significantly elevated in the treated group. At the cellular level, accelerated cell proliferation was observed during early embryogenesis in the treated group. The investigation of metabolomic changes resulted significantly elevated hexose utilization in the single-cell zygote cytoplasm, and elevated adenylate energy charge in the egg albumen. These changes suggested that treated snails provided more hexose in the eggs in order to improve offspring viability. Our study contributes to the knowledge of physiological effect of equi-concentration progestogens mixture at environmentally relevant dose on non-target aquatic species.

      PubDate: 2017-07-04T02:12:04Z
      DOI: 10.1016/j.aquatox.2017.06.029
  • Mortality and histopathological effects in harbour-transplanted snails
           with different exposure histories
    • Authors: Maria Alexandra Bighiu; Burkard Watermann; Xueli Guo; Bethanie Carney Almroth; Ann-Kristin Eriksson-Wiklund
      Abstract: Publication date: Available online 21 June 2017
      Source:Aquatic Toxicology
      Author(s): Maria Alexandra Bighiu, Burkard Watermann, Xueli Guo, Bethanie Carney Almroth, Ann-Kristin Eriksson-Wiklund
      Contaminants are important stressors in the aquatic environment and may exert selective pressures on organisms. We hypothesized that snails originating from a metal-contaminated habitat (B) would have increased tolerance to harbour contaminants (e.g. metals from antifouling paints), compared to snails originating from a relatively clean habitat (A). We assessed tolerance to metals in terms of survival and histopathological alterations after 2, 4 and 8 weeks of in situ exposure in three Baltic Sea boat harbours and three reference sites. We also hypothesized that any potential tolerance to contaminants would be associated with differences in genetic diversity between the two snail populations (evaluated as mitochondrial cytochrome c oxidase subunit I, COI). The results show that snails from population A survived to a higher extent compared to population B, possibly indicating either a lack of adaptation to metals in snails B or impaired health condition due to contaminant pre-exposure or a higher resilience of snails A. Moreover, the genetic diversity of COI was low within each population and did not differ between populations. In general, 83% of all the types of histopathological alterations (e.g. lysis and necrosis of gonads and digestive gland or granulocytoma and phagocytosis in the storage tissue, among others) had a higher probability of occurrence among harbour-exposed snails compared to reference-exposed snails, regardless of snail population origin. The only significant difference in histological effects between the two populations was in the frequency of parasite infestations and shell fouling, both being larger for population A than B. Interestingly, the rate of parasite infestations was higher for males than females from population A, whereas no sexual dichotomy was observed for population B. Our results show that exposure to harbour contaminants causes both lethal and sublethal toxicity to snails, and the association between many of the toxic responses and metals substantiates that antifouling substances contribute to the observed effects, although there is a large proportion of variation in our data that remains unexplained.

      PubDate: 2017-06-23T15:34:01Z
      DOI: 10.1016/j.aquatox.2017.06.018
  • 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
  • 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
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