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Perfluorooctanoic acid (PFOA) is a persistent, toxic, anthropogenic chemical recalcitrant to biodegradation. Based on previous studies in lower and higher vertebrates, it was hypothesized that chronic, sub-lethal, embryonic exposu...
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Perfluorooctanoic acid (PFOA) is a persistent, toxic, anthropogenic chemical recalcitrant to biodegradation. Based on previous studies in lower and higher vertebrates, it was hypothesized that chronic, sub-lethal, embryonic exposure to PFOA in zebrafish (Danio rerio) would adversely impact fish development, survival, and fecundity. Zebrafish embryo/sac-fry were water exposed to 2.0 or 0 nM PFOA from 3 to 120 hpf, and juvenile to adult cohorts were fed spiked food (8 pM) until 6 months. After chronic exposure, PFOA exposed fish were significantly smaller in total weight and length. Gene expression analysis found a significant decrease of transporters slco2b1, slco4a1, slco3a1 and tgib1a, and a significant increase of slcoldl expression. PFOA exposed fish produced significantly fewer eggs with reduced viability and developmental stage delay in F1. Chronic, low-dose exposure of zebrafish to PFOA significantly altered normal development, survival and fecundity and would likely impact wild fish population fitness in watersheds chronically exposed to PFOA. (C) 2017 Elsevier Inc. All rights reserved.
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Fish birnaviruses and rhabdoviruses are major causes of diseases that pose a threat to the fish farming industry. In this work we investigated the interaction between IPNV (birnavirus) and SVCV (rhabdovirus) in a zebrafish model w...
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Fish birnaviruses and rhabdoviruses are major causes of diseases that pose a threat to the fish farming industry. In this work we investigated the interaction between IPNV (birnavirus) and SVCV (rhabdovirus) in a zebrafish model where SVCV is lethal while IPNV causes asymptomatic infection. Two situations were analyzed: 1) A primary IPNV infection followed by a second challenge with SVCV; 2) SVCV as the first infection and a second challenge with IPNV. Irrespective of the order of infections, IPNV increased survival of SVCV-infected fish, reflecting viral interference that correlated with the inhibition of SVCV RNA synthesis. In contrast, in some instances a synergistic effect occurred between SVCV and IPNV: IPNV replication was enhanced in mixed infections with SVCV compared to the single IPNV infection. Expression of host immune response genes il1b, mx and gig2 was modulated differently depending on the order of virus infections: while higher levels of expression of il1b, mx and gig2 were found in fish infected first with IPNV, those three genes were down-regulated in fish infected with SVCV and then challenged with IPNV.
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To understand the development of serotonergic neurons in vertebrates, we used zebrafish as a model system. In this study we cloned two cDNAs (complementary DNAs) coding for serotonin transporter (SERT) from the zebrafish, named se...
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To understand the development of serotonergic neurons in vertebrates, we used zebrafish as a model system. In this study we cloned two cDNAs (complementary DNAs) coding for serotonin transporter (SERT) from the zebrafish, named serta and sertb. The serta cDNA encodes a protein of 693 amino acids and showed high level of sequence identity with rat and human SERTs. In situ hybridization showed serta to be expressed in raphe nuclei, ventral posterior tuberculum and pineal organ. The expression of serta in raphe and ventral posterior tuberculum overlapped with the location of serotonin and expression of tryptophan hydroxylase, which is a key enzyme for serotonin synthesis. In the pineal organ serta is expressed in the cells in the vicinity of tryptophan hydroxylase-positive cells. We also cloned another zebrafish serotonin transporter, sertb, and found to be expressed in the medulla oblongata and in the inner nuclear layer of retina. The existence of two sert genes in the zebrafish genome indicates the gene was duplicated in the process of evolution as can be seen in other genes in the teleosts including zebrafish. The expression of the serta cDNA in cultured cells conferred a serotonin transport activity, thus indicating the validity of the cloned cDNA. We have established the expression system of zebrafish serotonin transporter in the cell culture in the present study, which is useful for the pharmacological analysis to determine the important residues for the interaction with serotonin and inhibitors. The expression system in the cell culture can be used to determine the effective concentration of inhibitors and addictive drugs. These information might be useful to evaluate the effect of those chemicals on serotonin neuron development and behavior of the animal.
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The Zebrafish Embryo Genotyper (ZEG) device provides a promising tool for genotyping live embryos. Although the gross morphology and survival of embryos after the use of ZEG are unaffected, the cellular and molecular effects of th...
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The Zebrafish Embryo Genotyper (ZEG) device provides a promising tool for genotyping live embryos. Although the gross morphology and survival of embryos after the use of ZEG are unaffected, the cellular and molecular effects of the ZEG protocol remain unknown. To address this, we have examined the integrity of specific tissues, and evaluated the expression of stress-responsive genes to determine the impact of the ZEG protocol. Our analyses reveal that although ZEG results in a low-level acute stress response, no long-lasting effects are evident, supporting its utilization for a variety of downstream assays.
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Caveolins are integral membrane proteins that localize predominantly to lipid rafts, where they oligomerize to form flask-shaped organelles termed caveolae and play important roles in membrane trafficking, signal transduction, and...
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Caveolins are integral membrane proteins that localize predominantly to lipid rafts, where they oligomerize to form flask-shaped organelles termed caveolae and play important roles in membrane trafficking, signal transduction, and other cellular processes. To investigate potential roles for caveolin-1 (cav-1) in development, cav-1alpha and -1beta cDNAs were functionally characterized in the zebrafish. Cav-1alpha and -1beta mRNAs exhibited overlapping but distinct expression patterns throughout embryogenesis. Targeted depletion of either Cav-1 isoform, using antisense morpholino oligomers, resulted in a substantial loss of caveolae and dramatic neural, eye, and somite defects by 12 hours after fertilization, the time at which mRNA levels of both isoforms substantially increased in wild-type animals. Morphant phenotypes were rescued by injection of homotypic (cav-1alpha/cav-1alpha) but not heterotypic (cav-1alpha/cav-1beta) zebrafish and human cav-1 cRNAs, revealing nonredundant and evolutionarily conserved functions for the individual Cav-1 isoforms. Mutation of a known Cav-1 phosphorylation site unique to Cav-1alpha (Y14-->F) resulted in a failure to rescue the cav-1alpha morphant phenotype, verifying an essential role for Cav-1alpha specifically and implicating this residue in early developmental functions. Cav-1alpha and -1beta morphants also exhibited disruption in the actin cytoskeleton. These results support important and previously unanticipated roles for the Caveolin-1 isoforms in vertebrate organogenesis.
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The embryonic vertebrate heart begins pumping blood long before the development of discernable chambers and valves. At these early stages, the heart tube has been described as a peristaltic pump. Recent advances in confocal laser ...
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The embryonic vertebrate heart begins pumping blood long before the development of discernable chambers and valves. At these early stages, the heart tube has been described as a peristaltic pump. Recent advances in confocal laser scanning microscopy and four-dimensional visualization have warranted another look at early cardiac structure and function. We examined the movement of cells in the embryonic zebrafish heart tube and the flow of blood through the heart and obtained results that contradict peristalsis as a pumping mechanism in the embryonic heart. We propose a more likely explanation of early cardiac dynamics in which the pumping action results from suction due to elastic wave propagation in the heart tube.
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Improved methods for discovering small-molecule mechanisms of action are needed. In this issue of Chemistry & Biology, Zhang et al. [1] make clever use of the zebrafish to study the mechanism of the angiogenesis inhibitor fumagillin and reveal that it targets the noncanonical Wnt pathway....
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Improved methods for discovering small-molecule mechanisms of action are needed. In this issue of Chemistry & Biology, Zhang et al. [1] make clever use of the zebrafish to study the mechanism of the angiogenesis inhibitor fumagillin and reveal that it targets the noncanonical Wnt pathway.
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Naphthalene has been used worldwide as a commercial insecticide for decades, which when detected in the environment can have various negative effects on non-target organism, such as hepatotoxicity. However, the molecular mechanism...
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Naphthalene has been used worldwide as a commercial insecticide for decades, which when detected in the environment can have various negative effects on non-target organism, such as hepatotoxicity. However, the molecular mechanisms of how naphthalene acts to affect the liver in zebrafish (Danio rerio) remains unknown. In this study, we evaluated the potential toxic effects of naphthalene on livers in female adult zebrafish over a 21-day subacute exposure. Global hepatic gene expression was examined by microarrays and the results indicated the regulated genes were associated significantly with vital hepatic injury pathways and GO categories upon naphthalene exposure, such as disruptions in lipid metabolism, inflammatory response, and the carcinogenic processes. According to our observations of liver histology, nuclear enlargement as a potential indicator of cancers and hepatic lipometabolic disorder precisely were supported. The 96 h acute naphthalene tests on Tg(lysC:DsRed) and LiPan lines larvae revealed recruitment of neutrophils by the liver, as well as decreased liver size, which further confirmed hepatic inflammation response to naphthalene exposure. Thus, these findings advance the field of ecotoxicology by unveiling a new role of naphthalene as a leading cause of liver damage and provide potential biomarker-genes for environmental naphthalene monitoring.
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The pharyngeal cartilages of zebrafish endothelin 1 (sucker or ednl) mutants are severely defective (Miller et al., 2000). Similar but milder defects are present in mutants for any of three other still molecularly unknown "anterio...
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The pharyngeal cartilages of zebrafish endothelin 1 (sucker or ednl) mutants are severely defective (Miller et al., 2000). Similar but milder defects are present in mutants for any of three other still molecularly unknown "anterior arch" class genes (Kimmel et al., 1998; Piotrowski et aL, 1996). These milder phenotypes might be the result of partial loss of Endothelin 1 signaling, as we now examine directly by injecting a concentration series of endothelin1-morpholino oligonucleotides (ednl-MO) to gradually reduce ednl fimction. We observe that high amounts (5-15 ng) phenocopy the facial and pharyngeal cartilage phenotypes of ednl mutants, and lower amounts (0.5-1.5 ng) phenocopy the milder phenotypes of the other anterior arch class mutants (Table 1, Fig. 1a-f), ednl-MO-injected and mutant phenotypes strikingly correspond; for example, joints are more sensitive to slight reduction of ednl function than ventral cartilage, as in the original mutant phenotypic series (Kimmel et al., 1998). We verified that the high level injections eliminated the same specific expression domains of the ednl target genes dHAND and goosecoid as eliminated in ednl mutants (Fig. 1g-1; see Miller et al., 2000). Hence our experiments show that ednl-MOs allow ednl function to be reduced in a graded fashion, and provide strong support for the hypothesis that all of the anterior arch loci function in the edn1 pathway.
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The i(4)/i(4) genotype of the medakafish, Oryzias latipes, exhibits a quasi albino phenotype due to insertion of a novel transposable element, Tol2, into the tyrosinase gene. Tol2 is 4681 bp in length, has short inverted terminal ...
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The i(4)/i(4) genotype of the medakafish, Oryzias latipes, exhibits a quasi albino phenotype due to insertion of a novel transposable element, Tol2, into the tyrosinase gene. Tol2 is 4681 bp in length, has short inverted terminal repeats, and contains four ORFs with the potential to encode a transposase protein. Excision activity of the element has been detected by PCR analysis. Genomic Southern of the Tol2 element revealed that about 20 copies are present in the diploid genome. Dot-matrix comparisons of amino acid sequences of ORFs show relatively high similarity with transposases from Ac of maize, hobo of Drosophila, and Tam3 of snapdragon. which are all active transposable elements. Tol2 is thus concluded to be an active Ac-like transposable element probably encoding a transposase protein. It should therefore find application as a unique material for establishing a gene tagging system in fish.
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