title: Toxic threshold of dietary microcystin (-LR) for quart medaka.
abstract: This study was designed to estimate the toxic threshold of male and female fish to microcystins based on different biomarkers. Japanese medaka (Oryzias latipes) were fed dietary Microcystin-LR (0, 0.46, 0.85, 2.01 and 3.93 microg MC-LR/g dry diet for 8 weeks at 25 degrees C. The results revealed that dietary MC-LR inhibited growth at the end of 8 weeks. The survival of embryos and the RNA/DNA ratio of whole fish decreased significantly (P < 0.05) in fish fed 3.93 microg MC-LR/g dry diet. Heat shock protein (Hsp60) expression was induced in the liver of female and male fish fed diets containing > or =0.85 and 0.46 microg MC-LR/g diet, respectively. The activity of liver caspase 3/7 was significantly higher in female fish fed 3.93 microg MC-LR/g diet and in males fed 2.01 MC-LR microg/g dry diet than fish fed the control diet. The threshold for inhibition of liver protein phosphatase expression was lower in female (2.01 microg/g diet) than that in male fish (3.93 microg/g diet). Histopathological examination showed significant single-cell necrosis in female and male medaka fed diets containing 0.85 and 3.93 microg MC-LR/g diet, respectively. Based on different biomarkers, this study demonstrated that dietary MC-LR is toxic to Medaka and the effects are gender dependent.
authors: Center for Health and the Environment and Aquatic Toxicology Program, School of Veterinary Medicine, University of California, 1321 Haring Hall, One Shield Ave, Davis, CA 95616, USA.
authors: Dong-Fang
authors: DF
authors: Deng
authors: Keke
authors: K
authors: Zheng
authors: Foo-Ching
authors: FC
authors: Teh
authors: Peggy W
authors: PW
authors: Lehman
authors: Swee J
authors: SJ
authors: Teh
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D018834:Chaperonin 60 / Q000378:metabolism; D004032:Diet; D005260:Female; D008297:Male; D008387:Marine Toxins; D052998:Microcystins / Q000008:administration & dosage / Q000633:toxicity*; D009990:Oryzias / Q000254:growth & development / Q000502:physiology; D012737:Sex Factors
chemical_list: D015415:Biomarkers; D018834:Chaperonin 60; D008387:Marine Toxins; D052998:Microcystins; C057862:cyanoginosin LR