Genetic studies on the pacific abalone. XI. Gynogenesis with ultraviolet ray irradiated sperm in the pacific abalone.

Abstract

Probable usefulness of induced gynogenesis followed by diploidization has been discussed as a part of breeding technologies for genetic improvement of aquacultural organisms.The present study examined sets of conditions of treating spermatozoa by ultraviolet ray irradiation for effective induction of gynogenesis in the pacific abalone Haliotis discus hannai on the basis of observations on fertilization rate of the eggs, survival rate and chromosome constitutions of the zygotes.An aliquot of sperm suspension, placed in a plastic petri dish ion-sputtered in advance, was exposed to irradiation of ultraviolet ray of 42 erg per mm2 per s for varying durations.Immediate after the irradiation, the treated spermatozoa suspension was added to egg suspension at room temperature for fertilization. Irradiation of spermatozoa by ultraviolet ray of the above intensity for 30 to 60 s successfully induced gynogenesis, indicating the high frequency occurrence of the haploid zygotes consonant with the recovery in survival rate of zygotes, called Hertwig effect.

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

“…In the present study, the pattern of decreasing fertilization rate with increasing irradiation time was shown as reported in H. discus hannai , 17,19 C. gigas 14 and M. edulis . 15 This result suggests that the ability of sperm to activate eggs was reduced with increasing irradiation dose.…”

“…Aneuploids shown here have also been reported in previous studies. 14,15,17,19 Inactivation of sperm chromosomes is suggested to be a continuous process. 14 As the mode at the haploid chromosome number appeared, cells showing low chromosome counts of 6–9 were seen in this study.…”

Chromosome number and telomere sequence mapping of the Japanese sea cucumber Apostichopus japonicus

“…In the group treated with 0.1% colchicine (initiated at 3,5,7,9,11,13,15,17,19, and 21 h after insemination), including specimens that both surfaced and did not surface, metaphase plates did not exist in all these conditions. In the 8-, 10-, 13-, 16-, 18-, and 22-h insemination groups treated with 0.005% colchicine, metaphase plates were observed only in the case of specimens that did not surface.…”

“…Therefore, during chromosome preparation in the present study, we examined these two different colchicine concentrations in seawater for treatment of the fertilized eggs, embryos, or larvae: 0.1% for 2 h at 20°C and 0.005% for 2 h at 20°C. The 0.1% treatment was initiated at 3,5,7,9,11,13,15,17,19, and 21 h after insemination. The 0.005% treatment was initiated at 8, 10, 13, 16, 18, and 22 h after insemination.…”

“…In both the 0.1% and 0.005% groups some embryos began to swim and surface 13 h after insemination; therefore, the specimens that surfaced and those that had not yet surfaced were treated separately with the aforementioned concentrations of colchicine. After each treatment, all the specimens were treated with 0.075 M KCl for 1.5 h in 20°C and fixed with Carnoy's solution in a freezer at -20°C for 3 h or more (according to the method of Arai et al [9] with some modifications). The chromosome preparations used for chromosome counting and FISH analyses were prepared by the chopping method [10] with approximately 100 fixed specimens per slide.…”