Optimum Conditions of UV Ray Irradiation for Genetic Inactivation of Loach Eggs.

Abstract

Optimum conditions of ultraviolet (UV) ray irradiation for genetic inactivation of eggs were examined to develop simple and easy techniques to induce androgenesis in the loach , Misgurnus anguillicaudatus, since ionizing radiation such as gamma-or X-ray, which has been used generally for fish androgenesis, gives technical problems of safety and the need for special facilities . In the first and second experiments, unfertilized eggs were exposed to UV rays from two sources, germicidal lamps affixed to the ceiling and below, at dosages from 1875 to 15000 erg/mm2. While in the third experiment, eggs being shaken in a micro mixer were irradiated with UV rays from ceiling lamps at dosages between 4200 and 21000 erg/mm2. Most embryos developing after fertilization with normal spermatozoa showed abnormal morphology and a haploid number of chromosomes (n=25) in all the experiments, indicating successful induction of androgenesis. Occurrence of some aneuploids and diploids suggests the necessity of further improvement for homogeneity of treatment. Androgenetic