Microcystin-LR and embryo-larval development of medaka fish, Oryzias latipes. I. Effects on the digestive tract and associated systems.
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.
Huynh-Delerme
Céline
C
Laboratoire d'Anatomie Pathologique, Ecole Nationale Vétérinaire d'Alfort, 7 Avenue du Général de Gaulle, F-94704 Maisons-Alfort cedex, France.
Edery
Marc
M
Huet
Hélène
H
Puiseux-Dao
Simone
S
Bernard
Cécile
C
Fontaine
Jean-Jacques
JJ
Crespeau
François
F
de Luze
Amaury
A
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*
D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C057862:cyanoginosin LR