title: GFP transgenic medaka (Oryzias latipes) under the inducible cyp1a promoter provide a sensitive and convenient biological indicator for the presence of TCDD and other persistent organic chemicals.
abstract: Persistent organic pollutants (POPs) are resistant to environmental degradation and can cause multitude of health problems. Cytochrome P450 1A (Cyp1a) is often up-regulated by POPs through the activation of aryl hydrocarbon receptor (AhR) pathway and is thus usually used as a biomarker for xenobiotics exposure. To develop a convenient in vivo tool to monitor xenobiotic contamination in the water, we have established GFP transgenic medaka using the inducible cyp1a promoter, Tg(cyp1a:gfp). Here we tested Tg(cyp1a:gfp) medaka at three different stages, prehatching embryos, newly hatched fry and adult with 2,3,7,8-tetrachlorodiebnzo-p-dioxin (TCDD), a dioxin. While GFP induction was observed in all three stages, newly hatched fry were the most sensitive with the lowest observed effective concentration of 0.005 nM or 16.1 ng/L. The highly sensitive organs included the kidney, liver and intestine. With high concentrations of TCDD, several other organs such as the olfactory pit, tail fin, gills, lateral line neuromast cells and blood vessels also showed GFP expression. In addition, Tg(cyp1a:gfp) medaka fry also responded to two other AhR agonists, 3-methylcholanthrene and benzo[a]pyrene, for GFP induction, but no significant GFP induction was observed towards several other chemicals tested, indicating the specificity of this transgenic line. The GFP inducibility of Tg(cyp1a:gfp) medaka at both fry and adult stages may be useful for development of high-throughput assays as well as online water monitoring system to detect xenobiotic toxicity.
authors.affiliation: Department of Biological Sciences, NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.
authors.forename: Grace Hwee Boon
authors.initials: GH
authors.lastname: Ng
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Gong
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000096:biosynthesis* / Q000235:genetics; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D009928:Organ Specificity; D009990:Oryzias / Q000235:genetics* / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000032:analysis* / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D015533:Transcriptional Activation / Q000187:drug effects; D015854:Up-Regulation; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000494:pharmacology
chemical_list: D000072317:Polychlorinated Dibenzodioxins; D014874:Water Pollutants, Chemical; D049452:Green Fluorescent Proteins; D001189:Aryl Hydrocarbon Hydroxylases