Effects of ultraviolet irradiation on genetical inactivation and morphological structure of sperm of the Japanese scallop, Patinopecten yessoensis

Effects of ultraviolet (UV) irradiation on genetic inactivation and morphol ogical structure of sperms were examined in the scallop, Patinopecten yesso ensis. Haploid gynogenesis of the scallop was successfully induced by 50-60 s UV irradiation of 720 mu W cm(-2) s(-1). The fertilization rate apparent ly decreased with increasing irradiation time, and the development of the e ggs fertilized with the genetically inactivated sperms terminated before re aching the D-shaped larvae stage. Scanning electron microscopy (SEM) showed clear destruction of the sperm acrosome and flagellum in the UV-irradiated sperms. As the duration of UV irradiation increased, the acrosome of sperm s tended to suffer greater damage, until the sperms eventually lost their f lagella. Abnormalities in these structures have appeared to account, at lea st in part, for the decline of the fertilization rate of eggs inseminated w ith UV-irradiated sperms. (C) 2000 Elsevier Science B.V. All rights reserve d.