Pig Androgen Receptor Polymorphism Detection And Its Impact On Litter Size

The litter size's heritance of pig is very low(about 0.1) 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. Diverse physiological effects of the androgen receptor (AR), a nuclear transcription factor, and.its mapping position within a quantitative trait loci (QTL) region on chromosome X propose it as an interesting candidate gene for pig reproduction and performance. The androgen. receptor (AR) mediates hormonal responsiveness to androgens, which play important roles in sexual differentiation and development emphasising on male. AR functions as a nuclear transcription factor influencing diverse physiological developments, it is potentially a positional functional candidate gene for reproduction and production traits. Polymorphisms of the pocine AR gene was analyzed using single-strand conformation polymorphism(SSCP) between the two breeds,JM I and SLB. Based on comparative sequencing, two single nucleotide polymorphisms (SNPs), three SNPs in the 5'-untranslated region (UTR), and a CAG-INDEL in exon 1 were detected. The genetic effects of the AR genotypes influencing the total number born and number of live born for the first parity and later parities were determined by the least- square analysis. The results showed:1.The frequency of the allele A and B in AR gene is different in the two breeds.The frequency of genotypes of AR gene is also different. Between allele variety tested,the frequency of allele A is lower than B.The frequency of genotype BB is higher than the other genotypes.2 .AR is a candidate gene which controls the trait prolificacy is pigs. In this research the effect of AR on prolificacy is proved to be obvious.3. The effects of every genotype in AR gene is successively BB,AB,AA from high to low.For example, in this research, TNBs of genotype AA,AB,BB for AR in SLB are successively 9.4231,10.0719,11.4750, and mean NBAs are successively 8.3571, 8.8571, 96250; in JM I similar conclusion is obtained too. TNBs of genotype AA,AB,BB for AR in JM I are successively 9.4583,10.8000, 11.0000, and mean NBAs are successively 8.0000, 9.2000, 9.4166. It is one candidate gene controls the prolificacy in swine and its advantageous allele is allele B.4. Effect of breeds, and of combnation of breeds and genotype on born nuber was not obvious.There was no mutual effect between them.5. Age is one important factor influencing of prolificacy, the TNB of first parity is less than the still parity ,so does in NBA.6. The trait prolificacy is low in hertability and is sex-limitod.The progress achieved by normal seletion methods is not obvious.In this research .the effects of AR on prolificacy is proved to be obvious,and polymorphism,so we can use it as molecular marker in MAS to improve the level of prolificacy.