Studies Of The Structure And Function Of FSH-β And ER In Guizhou Local Pig Breeds

The little size's heritance of pig is very low as well as restrictively expressed in sow. So the improvement of the litter size is limited by the conventional breeding technology. This urges the scientists to find the major gene that control the reproduction of pig and the genetic marker that related to it. But there are not the unified standard about the major gene controlling the reproduction of pig. The ER and FSH-βgene were proved to be the major gene that control the litter size in swine. The research of low prolificacy of the Guizhou local breeds is little.The menthods of gene engineering are used to colone the fragment of FSH-βin Nuogu pigs, Rongjiang xiang pigs and Congjiang xiang pigs. The length of FSH-βin Nuogu pigs are 1985bp, which contain two exons and one intron. There are 3704bp in Congjiang xiang pig including three exons and two introns. We got two kinds of FSH-βin Rongjiang xiang pigs,which are 3443bp and 1985bp.They all encode 129 animo acids, 18 signal peptide and 111 mature peptide. By comparing to the other animals, the identity between pigs and mammalian is highest, especially between the other pig breeds. Some substituted animo acids located at important domain, which may change the function of the protein and have some relation to the low prolificacy of the local pig breeds.We examined a polymorphism region of the first intron of follicle stimulating hormone beta Subunit gene in three Chinese breeds of pigs and two western meat pigs. AA, AB or BB genotypes were observed in those pig breeds. We found that the Homozygous AA genotypes were dominant in these three Chinese breeds of pigs, but the BB genotypes were mainly detected in landrace and Yorkshine breeds of pigs. Analysis of these regions of intron 1 sequence between the three genotypes revealed the presence of an about 280 bp insert sequence in a homozygous AA genotype and a heterozygous AB genotype but absent in BB genotype. The inserted sequence had a 3' poly (A) tract with variable uninterrupted adenines and resulted in the polymorphisms of the FSH-βgene in pigs. It was similar to the SINE and showed 95%～99% sequence identity with SINE. Therefore, this insertion sequence was belonged to short interspersed nucleotide elements (SINEs).Utilizing this sequence as a genetic marker, we could differentiate the Chinese breeds and western meat breeds of pigs.We investigated the expression pattern in the heterozygous AB genotype by RT-PCRand Northern blotting. The transcripts from B allele were detected in heterozygous breeds of pigs. In contrast, there was no transcript from the A allele was determined. This result suggests that heritable changes in expression levels could drive selection for the benefit allele. Therefore, we predict, in heterozygous breeds of pigs, the allele B of FSHB locus is the dominant character in pig genome.The length of ER-α,ER-βin Congjiang xiang pig are 1788bp, 1581bp,encoding 595, 526 animo acids,respectively. The homology of ER-αand ER-βgenes between the pig and mammala are high. The forecasted three-dimensional structure of ER-αand ER-βmatured peptides of xiang pig demonstrated that the substituted amino acids influencet the structure. The difference of the structure may result the low prolificacy.We analysis the polymorphism of the ERgene by PCR-SSCP, AA, AB or BB genotypes were observed in those pig breeds. B allele is advanced in the Xiang pigs, Kele pigs, and A allele is dominant in the York-shine and Landraces, this is contrary to the conclusion that B allele is close correlation to the prolificacy.