title: Comparative teratogenicity of chlorpyrifos and malathion on Xenopus laevis development.
abstract: The embryotoxic potential of chlorpyrifos (CPF) and malathion (MTN), two organophosphorus insecticides (OPs), was evaluated by modified Frog Embryo Teratogenesis Assay-Xenopus (FETAX). CPF and MTN were not embryolethal even at the highest concentration tested (6000 microg/l), but both exhibited a powerful teratogenicity. The probit analysis of malformed larva percentages showed a TC(50) of 161.54mug/l for CPF, and a TC(50) of 2394.01 microg/l for MTN. Therefore, CPF teratogenicity was about 15 times higher than MTN. Larvae of both exposed groups were mainly affected by ventral and/or lateral tail flexure coupled with abnormal gut coiling. Histopathological diagnosis displayed abnormal myotomes and myocytes with marked hypertrophies localized at the cell extremity, probably due to a break away of myofibril extremities at the intersomitic junction level. We speculate that this muscular damage was related to inhibition of acetylcholinesterase that showed a clear concentration-response in CPF and MTN exposed larvae. The teratogenic effects of these anti-cholinesterase compounds on Xenopus laevis myogenesis suggest a possible role played by OPs on induction of congenital muscular dystrophy.
authors.affiliation: Dipartimento di Scienze dell'Ambiente e del Territorio, Università degli Studi di Milano Bicocca, Piazza delle Scienza 1, I-20126 Milano, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Bonfanti
authors.forename: Anita
authors.initials: A
authors.lastname: Colombo
authors.forename: Federica
authors.initials: F
authors.lastname: Orsi
authors.forename: Ilaria
authors.initials: I
authors.lastname: Nizzetto
authors.forename: Manuela
authors.initials: M
authors.lastname: Andrioletti
authors.forename: Renato
authors.initials: R
authors.lastname: Bacchetta
authors.forename: Paride
authors.initials: P
authors.lastname: Mantecca
authors.forename: Umberto
authors.initials: U
authors.lastname: Fascio
authors.forename: Giovanni
authors.initials: G
authors.lastname: Vailati
authors.forename: Claudio
authors.initials: C
authors.lastname: Vismara
mesh_terms: D000014:Abnormalities, Drug-Induced / Q000473:pathology*; D000818:Animals; D001681:Biological Assay; D004390:Chlorpyrifos / Q000633:toxicity*; D002800:Cholinesterase Inhibitors / Q000633:toxicity*; D006652:Histological Techniques; D008294:Malathion / Q000633:toxicity*; D009132:Muscles / Q000002:abnormalities; D013623:Tail / Q000002:abnormalities; D014982:Xenopus laevis / Q000002:abnormalities* / Q000196:embryology*
chemical_list: D002800:Cholinesterase Inhibitors; D004390:Chlorpyrifos; D008294:Malathion