Transcriptome and physiological effects of toxaphene on the liver-gonad reproductive axis in male and female largemouth bass (Micropterus salmoides)
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ABSTRACT:
ORGANISM(S): Micropterus salmoides
PROVIDER: GSE142397 | GEO | 2019/12/20
REPOSITORIES: GEO
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Project description:Toxaphene is an organochlorine pesticide and environmental contaminant that is concerning due to its atmospheric transport and persistence in soil. In Florida, toxaphene and other organochlorine pesticides were used heavily in agriculture on the north shore of Lake Apopka and they are still detectable in soil. Wild largemouth bass that inhabit the lake and the marshes along the north shore have been exposed to a variety of organochlorine pesticides including dieldrin, methoxychlor, and p,p'-DDE, among others. While these other organochlorine pesticides have been studied for their endocrine disrupting effects in largemouth bass, there is little information for toxaphene. In this study, male and female largemouth bass were given food containing 50 mg/kg toxaphene for almost 3 months, to achieve tissue levels similar to those found in fish at Lake Apopka. Sex-specific toxicity was then evaluated by measuring various reproductive endpoints and transcriptomic changes. In females, gonadosomatic index showed a trend towards reduction (p = 0.051) and plasma vitellogenin was reduced by ~40% relative to controls. However plasma levels of 17β-estradiol and testosterone were not perturbed by toxaphene exposure. These data suggest that toxaphene does not act as a weak estrogen as many other organochlorine pesticides do, but rather appears to be acting as an antiestrogen in female fish. There were no obvious changes in the gonadosomatic index and plasma hormones in male bass. However, ex vivo explant experiments revealed that toxaphene prevented human chorionic gonadotropin-stimulated testosterone production in the testis. This suggested that toxaphene had anti-androgenic effects in males. Subsequent transcriptomic analyses of the testis revealed that androgen receptor/beta-2-microglobulin signaling was up-regulated while insulin-related pathways were suppressed with toxaphene, which could be interpreted as a compensatory response to androgen suppression. In the male liver, the transcriptome analysis revealed an overwhelming suppression in immune-related signaling cascades (e.g. lectin-like receptor and ITSM-Containing Receptor signaling, CD16/CD14 Proinflammatory Monocyte Activation, and CD38/CD3-JUN/FOS/NF-kB Signaling in T-cell Proliferation). Overall, this study showed that toxaphene induced sex-specific effects. The transcriptomic and physiological responses observed can contribute to the development of adverse outcome pathways for toxaphene exposure in fish.
| S-EPMC7687068 | biostudies-literature
Project description:Toxaphene (TOX) is an organochlorine pesticide (OCPs) that remains abundant in the environment due to its heavy use in agriculture, its persistence, and its atmospheric transport. In Florida, the north shore of Lake Apopka was heavily used for agriculture decades ago, and TOX remains present in the soil. Wild largemouth bass inhabit the lake, and are potentially exposed to a variety of OCPs. While other OCPs (dieldrin, methoxychlor, p,p’DDE) have been studied for their endocrine disrupting effects in largemouth bass, there are little data available for TOX. Here we performed a 2-month feeding study of male and female largemouth bass with TOX-laced food to mimic the levels found in fish at Lake Apopka. Subsamples of the gonad and liver were collected and preserved in 10% buffered formalin for histopathology and reproductive staging. Plasma levels of vitellogenin (Vtg) testosterone (T) and 17β-estradiol (E2) were quantified and snippets of testis and ovaries were placed into culture to determine ex vivo production of hormones. Lastly, transcriptomics was conducted in both the male testis and liver, as most studies investigating OCPs have analyzed female ovary/liver and data are scarce for OCPs and male bass. Female GSI did not change with TOX but was trending towards a decrease while male GSI did not change with exposure. Female vitellogenin decreased with toxaphene by ~40% but male vitellogenin was not induced. Female and male E2 and T were not different following dietary exposure compared to control bass and this corresponded to ex vivo culture experiments, which revealed no change in E2 and T production from the gonads. Taken together, TOX did not alter the production of E2 and T directly in the gonad tissue. In the testis, transcriptomics revealed that androgen receptor/beta-2-microglobulin signaling was up-regulated while insulin-related pathways were suppressed with TOX. In the liver, the transcriptome analysis revealed an overwhelming suppression in immune-related signaling cascades (e.g. lectin-like receptor and ITSM-Containing Receptor signaling, CD16/CD14 Proinflammatory Monocyte Activation, and CD38/CD3 -> JUN/FOS/NF-kB Signaling in T-cell Proliferation). Ninety percent of the pathways were reduced between 10 to 40% in median network expression. Reduced immune pathways are consistent with other studies investigating OCPs in fish. In the current study, TOX, at the concentrations tested in the diet, did not act as a weak estrogen as many other OCPs do, but rather appeared to be acting as an antiestrogen (or androgen) based upon reduced female Vtg and activation of androgen-receptor mediated pathways in the testis. These data contribute to a comprehensive transcriptomic-physiological framework for TOX and suggests that endocrine disruption may not be the result of direct effects on steroidogenesis in the gonad, but may rather occur at higher levels of the reproductive axis.
2019-12-20 | GSE142396 | GEO
Project description:Toxaphene (TOX) is an organochlorine pesticide (OCPs) that remains abundant in the environment due to its heavy use in agriculture, its persistence, and its atmospheric transport. In Florida, the north shore of Lake Apopka was heavily used for agriculture decades ago, and TOX remains present in the soil. Wild largemouth bass inhabit the lake, and are potentially exposed to a variety of OCPs. While other OCPs (dieldrin, methoxychlor, p,p’DDE) have been studied for their endocrine disrupting effects in largemouth bass, there are little data available for TOX. Here we performed a 2-month feeding study of male and female largemouth bass with TOX-laced food to mimic the levels found in fish at Lake Apopka. Subsamples of the gonad and liver were collected and preserved in 10% buffered formalin for histopathology and reproductive staging. Plasma levels of vitellogenin (Vtg) testosterone (T) and 17β-estradiol (E2) were quantified and snippets of testis and ovaries were placed into culture to determine ex vivo production of hormones. Lastly, transcriptomics was conducted in both the male testis and liver, as most studies investigating OCPs have analyzed female ovary/liver and data are scarce for OCPs and male bass. Female GSI did not change with TOX but was trending towards a decrease while male GSI did not change with exposure. Female vitellogenin decreased with toxaphene by ~40% but male vitellogenin was not induced. Female and male E2 and T were not different following dietary exposure compared to control bass and this corresponded to ex vivo culture experiments, which revealed no change in E2 and T production from the gonads. Taken together, TOX did not alter the production of E2 and T directly in the gonad tissue. In the testis, transcriptomics revealed that androgen receptor/beta-2-microglobulin signaling was up-regulated while insulin-related pathways were suppressed with TOX. In the liver, the transcriptome analysis revealed an overwhelming suppression in immune-related signaling cascades (e.g. lectin-like receptor and ITSM-Containing Receptor signaling, CD16/CD14 Proinflammatory Monocyte Activation, and CD38/CD3 -> JUN/FOS/NF-kB Signaling in T-cell Proliferation). Ninety percent of the pathways were reduced between 10 to 40% in median network expression. Reduced immune pathways are consistent with other studies investigating OCPs in fish. In the current study, TOX, at the concentrations tested in the diet, did not act as a weak estrogen as many other OCPs do, but rather appeared to be acting as an antiestrogen (or androgen) based upon reduced female Vtg and activation of androgen-receptor mediated pathways in the testis. These data contribute to a comprehensive transcriptomic-physiological framework for TOX and suggests that endocrine disruption may not be the result of direct effects on steroidogenesis in the gonad, but may rather occur at higher levels of the reproductive axis.
2019-12-20 | GSE142395 | GEO
Project description:17Alpha-ethinylestradiol (EE2), used for birth control in humans, is a potent estrogen that is found in wastewater at low concentrations (ng/l). EE2 has the ability to interfere with the endocrine system of fish, affecting reproduction which can result in population level effects. The objective of this study was to determine if dietary exposure to EE2 would alter gene expression patterns and key pathways in the liver and ovary and whether these could be associated with reproductive endpoints in female largemouth bass during egg development. Female LMB received 70ng EE2/g feed (administered at 1% of body weight) for 60 days. EE2 dietary exposure significantly reduced plasma vitellogenin concentrations by 70%. Hepatosomatic and gonadosomatic indices were also decreased with EE2 feeding by 38.5% and 40%, respectively. Transcriptomic profiling revealed that there were more changes in steady state mRNA levels in the liver compared to the ovary. Genes associated with reproduction were differentially expressed, such as vitellogenin in the liver and aromatase in the gonad. In addition, a set of genes related with oxidative stress (e.g. glutathione reductase and glutathione peroxidase) were identified as altered in the liver and genes associated with the immune system (e.g. complement component 1, and macrophage-inducible C-type lectin) were altered in the gonad. In a follow-up study with 0.2ng EE2/g feed for 60 days, similar phenotypic and gene expression changes were observed that support these findings with the higher concentrations. This study provides new insights into how dietary exposure to EE2 interferes with endocrine signaling pathways in female LMB during a critical period of reproductive oogenesis.
| S-EPMC4252624 | biostudies-literature
Project description:Reproductive abnormalities, that could lead to possible effects at the population level, have been observed in wild fish throughout the United States, with high prevalence in largemouth bass (LMB; Micropterus salmoides) and smallmouth bass (Micropterus dolomieu). Estrone (E1) and atrazine (ATR) are common environmental contaminants often associated with agricultural land use. 17alpha-ethinylestradiol (EE2) is a contaminant associated with wastewater treatment effluent, and a representative, well-studied estrogen commonly used for fish toxicity testing. Our objective was to assess whether early gonad recrudescence in adult fish was a period of sensitivity for alterations in reproductive condition and function. Adult male LMB were exposed from post-spawning to early gonad recrudescence to either a mixture of E1 (47.9 ng/L) + ATR (5.4 µg/L), or EE2 (2.4 ng/L) in outdoor experimental ponds. Gonad samples were collected from fish just prior to the start of exposure (July), at the end of the exposure period (December), the following spring just prior to spawning (April), and post spawning (May). Gonadosomatic index (GSI) was significantly reduced in E1 + ATR-exposed and EE2-exposed males compared to control at every post-exposure time point. Reduced sperm count and sperm motility were observed in the mixture treatment (E1 + ATR) compared to the control. Sperm motility was also reduced in the EE2 treatment. These data together indicate that estrogenic endocrine-disrupting compounds can lessen the reproductive condition of adult male LMB, and that effects of exposure during early gonad recrudescence can persist at least through the subsequent spawning cycle.
| S-EPMC9785829 | biostudies-literature
Project description:Largemouth bass is an important commercially farmed fish in China, but the rapid expansion of its breeding has resulted in increased incidence of diseases caused by bacteria, viruses and parasites. In this study, moribund largemouth bass containing ulcer foci on body surfaces indicated the most likely pathogens were iridovirus and rhabdovirus members and this was confirmed using a combination of immunohistochemistry, cell culture, electron microscopy and conserved gene sequence analysis. We identified that these fish had been co-infected with these viruses. We observed bullet-shaped virions (100−140 nm long and 50−100 nm in diameter) along with hexagonal virions with 140 nm diameters in cell culture inoculated with tissue homogenates. The viruses were plaque purified and a comparison of the highly conserved regions of the genome of these viruses indicated that they are most similar to largemouth bass virus (LMBV) and hybrid snakehead rhabdovirus (HSHRV), respectively. Regression infection experiments indicated fish mortalities for LMBV-FS2021 and HSHRV-MS2021 were 86.7 and 11.1%, respectively. While co-infection resulted in 93.3% mortality that was significantly (p < 0.05) higher than the single infections even though the viral loads differed by >100-fold. Overall, we simultaneously isolated and identified LMBV and a HSHRV-like virus from diseased largemouth bass, and our results can provide novel ideas for the prevention and treatment of combined virus infection especially in largemouth bass.
| S-EPMC9415833 | biostudies-literature
Project description:BackgroundOocyte maturation in fish involves numerous cell signaling cascades that are activated or inhibited during specific stages of oocyte development. The objectives of this study were to characterize molecular pathways and temporal gene expression patterns throughout a complete breeding cycle in wild female largemouth bass to improve understanding of the molecular sequence of events underlying oocyte maturation.MethodsTranscriptomic analysis was performed on eight morphologically diverse stages of the ovary, including primary and secondary stages of oocyte growth, ovulation, and atresia. Ovary histology, plasma vitellogenin, 17β-estradiol, and testosterone were also measured to correlate with gene networks.ResultsGlobal expression patterns revealed dramatic differences across ovarian development, with 552 and 2070 genes being differentially expressed during both ovulation and atresia respectively. Gene set enrichment analysis (GSEA) revealed that early primary stages of oocyte growth involved increases in expression of genes involved in pathways of B-cell and T-cell receptor-mediated signaling cascades and fibronectin regulation. These pathways as well as pathways that included adrenergic receptor signaling, sphingolipid metabolism and natural killer cell activation were down-regulated at ovulation. At atresia, down-regulated pathways included gap junction and actin cytoskeleton regulation, gonadotrope and mast cell activation, and vasopressin receptor signaling and up-regulated pathways included oxidative phosphorylation and reactive oxygen species metabolism. Expression targets for luteinizing hormone signaling were low during vitellogenesis but increased 150% at ovulation. Other networks found to play a significant role in oocyte maturation included those with genes regulated by members of the TGF-beta superfamily (activins, inhibins, bone morphogenic protein 7 and growth differentiation factor 9), neuregulin 1, retinoid X receptor, and nerve growth factor family.ConclusionsThis study offers novel insight into the gene networks underlying vitellogenesis, ovulation and atresia and generates new hypotheses about the cellular pathways regulating oocyte maturation.
| S-EPMC3604104 | biostudies-literature
Project description:The present study utilized digestives tracts from adult largemouth bass (LMB) to hydrolyze Bighead carp muscle and obtain an optimal profile of muscle protein hydrolysates that would be easily assimilated within the primitive digestive tract of larval LMB. Specifically, muscle protein source was digested for the larva using the fully developed digestive system of the same species. The objectives of this study were: 1) to develop an optimal in vitro methodology for carp muscle hydrolysis using LMB endogenous digestive enzymes, and 2) to evaluate the effect of dietary inclusion of the carp muscle protein hydrolysate on LMB growth, survival, occurrence of skeletal deformities, and whole-body free amino acid composition. The study found that the in vitro hydrolysis method using carp intact muscle and LMB digestive tracts incubated at both acid and alkaline pH (to mimic digestive process of LMB) yielded a wide range of low molecular weight fractions (peptides), as opposed to the non-hydrolyzed muscle protein or muscle treated only with acid pH or alkaline pH without enzymes from LMB digestive tracts, which were comprised of large molecular weight fractions (polypeptides above 150 kDa). Overall, the dietary inclusion of the carp muscle hydrolysate improved growth performance of larval LMB in terms of final average weight, weight gain, DGC, SGR, and body length after 21 days of feeding compared to fish that received the diet based on non-hydrolyzed carp muscle. The study also found that hydrolysate-based feed significantly reduced skeletal deformities. The positive growth performance presented by fish in the hydrolysate-fed group possibly resulted from matching the specific requirements of the larvae with respect to their digestive organ development, levels of digestive enzymes present in the gut, and nutritional requirements.
| S-EPMC8714084 | biostudies-literature
Project description:Methoxychlor (MXC) is an organochlorine pesticide that has been shown to have estrogenic activity by activating estrogen receptors and inducing vitellogenin production in male fish. Previous studies report that exposure to MXC induces changes in mRNA abundance of reproductive genes in the liver and testes of largemouth bass (Micropterus salmoides). The objective of the present study was to better characterize the mode of action of MXC by measuring the global transcriptomic response in the male largemouth liver using an oligonucleotide microarray. Microarray analysis identified highly significant changes in the expression of 37 transcripts (p<0.001) (20 induced and 17 decreased) in the liver after MXC injection and a total of 900 expression changes (p<0.05) in transcripts with high homology to known genes. Largemouth bass estrogen receptor alpha (esr1) and androgen receptor (ar) were among the transcripts that were increased in the liver after MXC treatment. Functional enrichment analysis identified the molecular functions of steroid binding and androgen receptor activity as well as steroid hormone receptor activity as being significantly over-represented gene ontology terms. Pathway analysis identified c-fos signaling as being putatively affected through both estrogen and androgen signaling. This study provides evidence that MXC elicits transcriptional effects through the estrogen receptor as well as androgen receptor-mediated pathways in the liver.
| S-EPMC3222593 | biostudies-literature
Project description:Transcriptome and physiological effects of toxaphene on the liver-gonad reproductive axis in male and female largemouth bass (Micropterus salmoides)
| PRJNA596811 | ENA