Association between HSP70 Genotypes and Oocytes Development on In vitro Maturation/Fertilization in Pig

M S Wee,Z D Li,S H Choi,S H Yeon,C Y Cho,C K Park,S R Cho,B D Sang,H J Jin,C D Kim,D S Son,S S Lee

doi:10.5713/ajas.2008.70623

Abstract

This study was performed to clarify whether the variation of stress related heat shock protein 70 (HSP70) (GenBank X68213) gene was associated with the nuclear morphological change of in vitro maturation and in vitro capacitation in oocytes of pig ovaries obtained at the slaughterhouse. The nucleic acid substitution of C to G at the 483rd position was found out in HSP70 K1 (290- 512) from X68213. The ovaries were categorized into CC, CG, and GG genotypes using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) (BsiHKA I). After the second in vitro maturation of immature fresh oocytes, the relation of nuclear morphological change in oocytes with the genotype of HSP70 K1 gene was such that the MII ratios of the genotype GG and CG (46.93% and 42.20%, respectively) were significantly higher than that of the CC genotype (10.71%) (p<0.05). With respect to in vitro maturation of frozen-thawed oocytes by an open pulled straw (OPS) method, the percentage of oocytes matured to MII stage of the CG genotype showed a higher trend than CC and GG genotypes. After the in vitro maturation of immature fresh oocytes and frozen-thawed oocytes by the OPS method, the relation of the pronuclei change in oocytes matured in vitro with HSP70 genotype was assessed, and the result showed that the enlarged sperm heads (ESH) of matured fresh oocytes and frozen-thawed oocytes were 80.0% and 60.0% in the CC genotype, respectively. The CC genotype group had a significantly higher rate of ESH than the CG and the GG genotype group (p<0.05). The ratios of polyspermic invasion were not different among HSP70 of the three genotypes. It was considered that the rate of in vitro maturation of fertilized oocytes was expected to differ according to genotype of the stress related gene. (Key Words : Fertilization, Maturation, Porcine Oocytes, HSP70 Genotypes)

Highlights

Porcine HSP reacts on cell growth substantially under stressful conditions caused by the change of temperature, in response to sudden elevation of the external temperature, HSP is very important for the maintenance of the cell viability of fetus or neonates (Dezeure et al, 1993; Lindquist, 1986)
Oocytes with the C allelic gene was the pattern of bands with 194 bp and 29 bp only, and the heterozygote of C and G allelic gene showed the pattern with 223 bp, 194 bp and 29 bp bands, and the G allelic gene homozygote showed the pattern of 223 bp band
Fukui et al (1991) have reported that the maturation condition of the nucleus and cytoplasm of follicular oocytes plays a decisive role in the growth of in vitro fertilized oocytes after fertilization, and cumulus cells mediate an important effect on acrosomal reaction of sperms, in vitro fertilization and the growth of fertilized oocytes in pigs

Summary

Introduction

Porcine HSP reacts on cell growth substantially under stressful conditions caused by the change of temperature, in response to sudden elevation of the external temperature, HSP is very important for the maintenance of the cell viability of fetus or neonates (Dezeure et al, 1993; Lindquist, 1986). During the in vitro maturation of porcine follicular oocytes, the heat reaction of HSP70 gene functioned as an important factor of the in vitro fertilization and development (Fukui, 1991).

Results

Conclusion