title: Microcystin-LR and embryo-larval development of medaka fish, Oryzias latipes. I. Effects on the digestive tract and associated systems.
abstract: The cyanobacterial hepatotoxin microcystin-LR (MC-LR) is a specific potent PP1 and PP2A protein phosphatase inhibitor. In view to obtain an integrated whole-body, understanding of the key target organs of MC-LR subsequent to embryonic exposure on the anatomy of medaka fish hatchlings, embryos at stage 19 were microinjected with a sublethal dose of MC-LR corresponding to 0.2 pg/vitellus. MC-LR-induced histo-pathological modifications of the alimentary system (i.e. digestive tract, pancreas, liver) were analysed in newly hatched embryos. Our data are indicative of an MC-LR-induced inhibition of both yolk sac resorption and gas concentrating swimbladder expansion. In contrast to control hatchlings, (i) no mucus-secreting cells in the oesophagus, (ii) a decreased folding of the stomach and intestine, (iii) a clear reduction in size of the exocrine pancreas associated with a destructuration of acinar units, and (iv) a strong decrease in the mass and size of the liver were observed in MC-LR treated embryos. Furthermore, as an indication of MC-LR-induced hepatic glycogen store depletion, unstained cytoplasmic areas present in control hatchling hepatocytes, were fully absent in all liver examined in treated embryos. Finally, as a general observation in MC-LR-treated embryos, our data clearly indicated terminal differentiation disorders in all organs associated with the digestive tract.
authors.affiliation: Laboratoire d'Anatomie Pathologique, Ecole Nationale Vétérinaire d'Alfort, 7 Avenue du Général de Gaulle, F-94704 Maisons-Alfort cedex, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Huynh-Delerme
authors.forename: Marc
authors.initials: M
authors.lastname: Edery
authors.forename: Hélène
authors.initials: H
authors.lastname: Huet
authors.forename: Simone
authors.initials: S
authors.lastname: Puiseux-Dao
authors.forename: Cécile
authors.initials: C
authors.lastname: Bernard
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Fontaine
authors.forename: François
authors.initials: F
authors.lastname: Crespeau
authors.forename: Amaury
authors.initials: A
authors.lastname: de Luze
mesh_terms: D000818:Animals; D004064:Digestive System / Q000187:drug effects* / Q000196:embryology / Q000254:growth & development; D004625:Embryo, Nonmammalian / Q000187:drug effects; D007814:Larva / Q000187:drug effects; D008387:Marine Toxins / Q000494:pharmacology*; D052998:Microcystins; D009990:Oryzias / Q000196:embryology* / Q000254:growth & development*; D010456:Peptides, Cyclic / Q000494:pharmacology*
chemical_list: D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C057862:cyanoginosin LR