The effects of 17β-estradiol (E2) were evaluated using the medaka DNA microarray representing 36,398 genes. We first evaluated chronic effects on medaka exposed to E2 at different concentrations for 60 days posthatch. At ≥ 30 ng/L of E2 severe reproductive impairments such as sex reversal were observed. Larval medaka, Oryzias latipes, (within 24 hrs posthatch) were then exposed to E2 at various concentrations (3, 30, 100 ng/L) for up to 7 days. Microarray analyses of the E2-exposed larvae revealed that exposure to E2 up-regulated and down-regulated 339 and 105 genes, respectively. The up-regulated genes included ones involved in the p53 signaling pathway, apoptosis, and growth and development, in addition to well-known biomarkers such as vitellogenin and choriogenins. Down-regulated genes included heat shock proteins and estrogen receptors. Most of the up-regulated genes encoding the p53 signaling pathway, apoptosis, and growth and development exhibited a dose-dependent increase in gene expression, whereas the down-regulated genes in the heat shock protein category showed a dose-dependent decrease in gene expression. Time course experiments suggested that the E2 treatment attenuated the time-dependent changes in gene expressions of these genes. Among the genes related to oocyte maturation, estrogen-regulated genes such as choriogenins and vitellogenins were dramatically induced in response to E2 exposure, whereas other steroid-regulated genes such as zona pellucida-domain proteins did not change in gene expression by the E2 treatment. Results suggest that transcriptomic studies on larval medaka help elucidate the effects caused by endocrine disruptors on various biological pathways in vertebrate development.
Here, we used physiological and transcriptomic analyses to evaluate the effects of 17β-trenbolone (TB) on metabolism during the early life stage of medaka (Oryzias latipes). In the physiological experiments, sex reversal rates increased continuously in proportion to TB concentrations (2-100 ng/L), and were 100% (all males) in the 200 ng/L treatment group. TB caused a significant increase in the gonadosomatic index of females at concentrations of 60 and 100 ng/L. These females exhibited swollen abdomens and decreased egg production and fertility. Significant increases were observed in the body mass index of these females. TB caused decreased fertility in males at concentrations >20 ng/L, but no other effects were observed. In the transcriptomic (microarray) experiments, larvae were exposed to TB for up to 7 d. Analyses using the KEGG Orthology Database revealed that predominant categories of significantly upregulated genes included "lipid metabolism" and "metabolism of terpenoids and polyketides." Thirteen genes (including those for hydroxymethylglutaryl-CoA synthase, cytoplasmic synthase, and lanosterol synthase) related to cholesterol biosynthesis via the mevalonate pathway were highlighted in these categories. Reverse transcriptase-polymerase chain reaction analyses were consistent with the microarray results, in terms of the direction and magnitude of change to gene expression. Among the downregulated genes, angiopoietin-like 4 and mitochondrial uncoupling protein 1, which are inversely correlated with obesity, were detected in the TB treatments. In conclusion, the results suggest that the exposure of females to TB during the early life stage may cause metabolic dysfunctions, including obesity and disrupted cholesterol synthesis. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1539-1551, 2016.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.