Assessment of mutagenic damage by monofunctional alkylating agents and gamma radiation in haploid and diploid frogs, Xenopus iaevis

Abstract

Adult male South African clawed frogs, Xenopus laevis, were mutagenized by 3-day immersion in aqueous solutions of ethyl methanesulfonate (EMS), diethyl nitrosamine (DEN), or ethyl nitrosourea (ENU), or by acute exposure to gamma radiation. They were then spawned repeatedly at 2-week intervals with untreated females, and embryonic survival of the progeny was used to assess genetic damage. Recessive lethal effects were assessed from reduced survival of androgenetic haploid progeny. Neither recessive nor dominant lethal effects were obtained after exposure to 100 mg/liter EMS or 2 g/liter DEN. At 250 mg/liter EMS, peak dominant lethality occurred 3-5 wk after treatment. Most embryos hatched, but many were abnormal and died shortly after hatching. Haploid survival was significantly reduced over a broader period, from 1 to 13 wk after mutagenesis. Treatment with 75 mg/liter ENU produced effects similar to the 250-mg/liter EMS mutagenesis. At 400 mg/liter EMS, the frequency and severity of the effects on both diploid and haploid embryos were increased over the lower dose. Gamma irradiation at 1,500 R produced effects similar to the 400-mg/liter mutagenesis, except that peak dominant lethality extended from 1 to 7 wk.

Zebrafish and Xenopus tadpoles: Small animal models to study angiogenesis and lymphangiogenesis

“…Inbreeding of populations [84,85], gynogenesis (suppression of second meiotic division in eggs fertilized with irradiated sperm) [86,87] and chemical mutagenesis with ENU [88] are useful, but all share the difficulty of cloning the targeted genes. Insertional mutagenesis methods have provided a way of readily cloning the mutated gene, and successful studies, using either REMIbased transgenesis [89] or the Tol2 system [80], have been reported.…”