Analysis of Responses of a Radiation Sensitive Medaka Mutant to Gamma-irradiation at Early Developmental Stage

Abstract

Three radiation sensitive mutant strains of medaka which showed significant increase of malformation by irradiation at organogenesis stage were established. Here, we examined the responses of early embryonic cells in the radiation sensitive mutant. After irradiation with 1Gy at morula stage, although no significant increase of embryonic abnormality was observed in wild-type (CAB strain) embryos, lower hatchability (about 21%) and higher malformation rate (about 21%) were shown in the mutant. Similarly, when embryos of the mutant strain were irradiated with 5Gy at late blastula stage, increase of embryonic abnormalities was shown in comparison with CAB strain. These results suggest that the mutant show high radiation sensitivity at both early embryonic stages and organogenesis stage. In addition, we have performed the TUNEL assay in flattened whole mounts to detected radiation-induced apoptotic cells and comet assay to examine DNA repair at early embryonic stages. [J Radiat Res 44:404 (2003)]