Effects of ultraviolet irradiation on genetical inactivation and morphological features of sperm of the Pacific oyster Crassostrea gigas

Abstract

SUMMARY: Effects of ultraviolet (UV) irradiation on genetical inactivation and morphological features of sperm were examined in the Pacific oyster. Ultraviolet light (254 nm) was effective for inactivating sperm chromosomes. Irradiation for 60 s at a UV intensity of 72 erg/mm 2 per s was the optimum dose to achieve haploid gynogenesis. The rates of the fertilization and the development of D‐shaped larvae decreased with increasing irradiation time, and the development of the eggs fertilized with the genetically inactivated sperms terminated before reaching the D‐shaped stage. Electron microscopy showed clear destruction of the sperm acrosome and flagellum in the UV‐irradiated sperms. As the duration of irradiation increased, the acrosome of sperms tended to suffer greater damage until the sperms eventually lost their flagella. Abnormalities in these structures have appeared to account, at least in part, for the decline of the fertilization rate of eggs inseminated with UV‐irradiated sperms.

Cytological studies on artificially induced gynogenesis in the Pacific abalone

“…The dish was placed on a recipro shaker 15 cm below a 15 W UV germicidal light (254 nm; TOSHIBA GL15, Toshiba, Japan) that provided a UV intensity of 72 erg/mm 2 per s. The sperm was exposed to the UV light for 20 s. This irradiation duration proved to be the optimum dose for inducing haploid gynogenesis in the abalone. 23 Both the treated sperm and the untreated sperm (control) were mixed separately with 8 mL of egg suspension (5 × 10 3 egg/mL), and the eggs were then allowed to develop at 20.0°C.…”

Induction of gynogenesis and effects of ultraviolet irradiation on ultrastructure of sperm of the Zhikong scallop Chlamys farreri

“…For the ultraviolet irradiation of sperm, the apparatus and conditions of treatments were performed according to Li et al . 17 To determine optimal UV dosage, sperm was exposed to UV light for various durations. Before starting irradiation, the UV lamp was turned on and warmed up for stabilization for 10-15 min.…”

“…The ploidy of embryos was determined with chromosome preparations at 22 h post-insemination, following the procedures adopted by Li et al . 17 Samples of the larvae (trochophores) were collected from each group, placed in 0.1% colchicine for 2 h, subjected to a hypotonic treatment with 0.075 mol/L KCl solution for 30 min, and fixed by Carnoy's solution (methanol : acetic acid, 3 : 1, v/v). During fixation, the solution was changed several times and the samples were stored in Carnoy's solution at -20 ∞ C until used.…”

“…Li et al . first showed UV‐irradiated destruction on the sperm acrosome and flagellum using scanning electron microscopy, and pointed out that the damage might partly cause the decline in the fertilization rate 16,17 . However, effects of UV irradiation on the inner structure of the sperm have not been examined by transmission electron microscopy.…”

“…first showed UV-irradiated destruction on the sperm acrosome and flagellum using scanning electron microscopy, and pointed out that the damage might partly cause the decline in the fertilization rate. 16,17 However, effects of UV irradiation on the inner structure of the sperm have not been examined by transmission electron microscopy. The relationships between ultrastructural changes in sperm and irradiation conditions, as well as the mechanism of gynogenesis, are still completely unknown.…”