title: Effects of microcystin-LR on development of medaka fish embryos (Oryzias latipes).
abstract: Chronic and subchronic toxicity from exposure to microcystins, cyclic hepatotoxic heptapeptides from cyanobacteria, receives increasing attention as a public human health biohazard. So far, the effects of microcystin on fish have been studied mainly in adults, rather than during early life stages. Limitations of direct ambient exposure experiments to fish egg have resulted from the difficult access of microcystin through the egg chorion. Using a microinjection technology, we have introduced microcystin-LR (MC-LR) directly into one-cell stage embryos or into the vitellus of late neurula embryos (stage 19) or into the vitellus of stage 25 embryos of medaka (Oryzias latipes) at the onset of the liver anlage. Microinjection (100 pl; stage 1 or 2 nl; stage 19 or 25) of MC-LR resulted in a dose dependent mortality of embryos. Survival rates were reduced up to 90% with microcystin concentrations of 10 or 1 microg/ml (corresponding to 1-20 pg or 0.1-2 pg of toxin injected), injected either at stages 1, 19 or 25. Also, a dose dependent advanced embryonic hatching processing was observed; hatching being brought forward from 2 or 3 days compared to controls in most of the microcystin injected groups. In agreement with the known hepatotoxic effects of microcystin, injected embryos consistently displayed hepatobiliary abnormalities such as liver hypertrophy and hepatic hemorrhage, also evidenced in post-hatching juveniles. Thus, the methodology presented in this paper should be valuable tool to analyze the effects of toxins on the development of aquatic vertebrate embryos.
authors.affiliation: USM 0505 Ecosystèmes et Interactions Toxiques, Muséum National d'Histoire Naturelle, 12 rue Buffon, F-75231, Paris cedex 05, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Jacquet
authors.forename: Violette
authors.initials: V
authors.lastname: Thermes
authors.forename: Amaury
authors.initials: A
authors.lastname: de Luze
authors.forename: Simone
authors.initials: S
authors.lastname: Puiseux-Dao
authors.forename: Cécile
authors.initials: C
authors.lastname: Bernard
authors.forename: Jean-Stéphane
authors.initials: JS
authors.lastname: Joly
authors.forename: Franck
authors.initials: F
authors.lastname: Bourrat
authors.forename: Marc
authors.initials: M
authors.lastname: Edery
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000633:toxicity*; D001659:Biliary Tract / Q000187:drug effects / Q000473:pathology; D000458:Cyanobacteria; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000473:pathology*; D008387:Marine Toxins; D052998:Microcystins; D008845:Microinjections; D009990:Oryzias / Q000196:embryology*; D010456:Peptides, Cyclic / Q000633:toxicity*; D013997:Time Factors; D023382:Toxicity Tests, Acute / Q000379:methods*
chemical_list: D001427:Bacterial Toxins; D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C057862:cyanoginosin LR