猪胚胎附植期Eph A4的组织表达及其多态性对产仔数的影响

为研究Eph A4对猪繁殖性能的影响,在猪妊娠第13天(附植前期)、第18天(中期)和第24天(后期),用PCR-SSCP方法检测了7个品种的950头母猪群中Eph A4基因的多态性,检测了Eph A4基因在大白猪子宫内膜等组织中的mRNA和蛋白表达量,并与猪的产仔数进行了关联分析.结果表明:Eph A4基因在子宫内膜附着点的mRNA表达量要高于任何其他组织的,且妊娠第13、18和24天的表达量差异不显著,但妊娠猪极显著低于空怀猪的(P＜0.01)；Eph A4的蛋白表达量在附植前、中和后期的表达量两两间差异均显著(P＜0.05),且妊娠第18天最高,妊娠第24天最低.Eph A4基因第3外显子上检测到了2个突变位点EphA4_1和EphA4_2.EphA4_1是一个A→G的突变,使谷氨酸变成了赖氨酸,G为优势等位基因,且GG基因型关联的产仔数显著高于AG或GG基因型的(P＜0.05)；EphA4_2是一个T→C的突变,C为优势等位基因,且CC基因型关联的产仔数显著高于TC或TT基因型的(P＜0.05).上述结果表明,Eph A4的表达对猪的胚胎附植发挥着一定的调控作用,EphA4_1位点GG基因型和EphA4_2位点CC基因型可以作为产仔数性状的标记基因型.

Expression of Eph A4 in tissues during embryo implantation and its polymorphism influence on litter size in pigs

Erythropoietin-Producing Hepatocellular receptor A4(Eph A4) plays a role of regulating embryo implantation in some mammals.In order to investigate Eph A4 effect on swine reproduction performances,mRNA and protein expression of Eph A4 in endometrium of Yorkshire was detected on pregnancy day-13(pre-implantation),day-18(mid-implantation) and day-24(post-implantation).Association of Eph A4 polymorphism with the reproductive traits was assessed by SSCP in 950 sows of seven breeds.Results showed that,mRNA expression intensity on endomtrium attachment sites was higher than any other tissues.There were no significant differences in mRNA expression intensity on pregnancy day 13,18 and 24,however,the mRNA intensity in pregnant sows was significantly lower than in non-pregnant sows(P<0.01).There were significant differences in protein expression among pregnancy day 13,18 and 24 (P<0.05),and it expressed highest on 18 d and lowest on 24 d.Two single nucleotide polymorphism(SNP) loci,EphA4_1 and EphA4_2 in Exon 3 of Eph A4 gene were determined whether Eph A4 polymorphism influenced litter size.At EphA4_1 locus,there was a A/G transition,and the A/G mutation directly caused an amino acid change,from glutamic acid into lysine acid;G allele seemed to have advantageous effects on litter size,and litter size associated with GG was significantly higher than that of AG or AA(P<0.05).At EphA4_2 locus,C allele seemed C allele seemed to have advantageous effects on litter size,and litter size associated with CC was significantly higher than that of TC or TT(P<0.05).In conclusion,Eph A4 expression might play role in the regulation of embryo implantation in pigs,GG genotype at EphA4_1 and CC genotype at EphA4_2 were favorable marker genotypes for litter size.