RRC ID 20984
Author Lee W, Kang CW, Su CK, Okubo K, Nagahama Y.
Title Screening estrogenic activity of environmental contaminants and water samples using a transgenic medaka embryo bioassay.
Journal Chemosphere
Abstract Many natural or synthetic chemicals may act as exogenous estrogens and affect the reproductive health of humans and wildlife. Since these xenoestrogens are ubiquitous, it is essential to monitor their presence in the environment. Hence, we developed a bioassay using the transgenic medaka (Oryzias latipes) embryo, in which the green fluorescent protein (GFP) was placed under the control of the gnrh3 promoter, one of the three paralogous gonadotropin-releasing hormone (GnRH) genes that regulate reproductive function and behavior. As medaka embryos are transparent, the fluorescent expression of GFP can be easily observed in vivo during development. We exposed newly fertilized medaka embryos to varying solutions of bisphenol A (BPA), nonylphenol (NP), 17β-estradiol (E2), or a river water sample, and monitored their development. During embryonic development, the mRNA levels of GnRHs, GnRH receptors, and estrogen receptors (ERs) were measured with quantitative real-time reverse transcription-PCR. Our results showed that the chemicals and the river water significantly decreased the fluorescent intensity of the GnRH3 neurons, postponed the eye development, and retarded the growth of the embryos. The three xenoestrogens also lowered the heart rate, lengthened the time to hatch, suppressed the expression of the three GnRH genes, and up-regulated the ERα mRNA level. In addition, the GnRH3 mRNA level was significantly correlated with the fluorescence intensity of the GnRH neurons. We concluded that the transgenic medaka embryo is a rapid and sensitive bioassay for screening environmental water samples. We also found that xenoestrogens had significant effects on GnRH gene expression and embryonic development.
Volume 88(8)
Pages 945-52
Published 2012-8-1
DOI 10.1016/j.chemosphere.2012.03.024
PII S0045-6535(12)00352-9
PMID 22497783
MeSH Animals Animals, Genetically Modified Benzhydryl Compounds Biological Assay Embryo, Nonmammalian / drug effects Embryo, Nonmammalian / metabolism* Embryonic Development / drug effects Endocrine Disruptors / chemistry Endocrine Disruptors / toxicity* Estradiol / chemistry Estradiol / toxicity* Gonadotropin-Releasing Hormone / genetics Gonadotropin-Releasing Hormone / metabolism Green Fluorescent Proteins / genetics Green Fluorescent Proteins / metabolism Heart Rate / drug effects Oryzias / growth & development Phenols / chemistry Phenols / toxicity Pigment Epithelium of Eye / drug effects Receptors, Estrogen / genetics Receptors, Estrogen / metabolism Receptors, LHRH / genetics Receptors, LHRH / metabolism Up-Regulation Water Pollutants, Chemical / chemistry Water Pollutants, Chemical / toxicity*
IF 5.778
Times Cited 28
Medaka NA