| The study was conducted to understand the molecular basis of the fecundity in Small Tailed Han sheep. Three populations including 101 Small Tailed Han sheep, 79 Poll Dorset and 81 hybrids (Poll Dorset X Small Tailed Han sheep) were used to detect the polymorphisms of sheep BMPRIB gene and BMP15 gene to analyze whether they could be candidate genes or molecular markers to improve the reproduction of sheep. The polymorphism was revealed from the analysis of three populations by the technique of PCR-SSCP, a mutation from A to G at 746 of the coding region in BMPRIB gene was confirmed by sequencing in several individual and the mutation induced the amino acid to change from the arginine of wild type to glutamic acid of the mutational type. But it was no found the polymorphism in the FecX1 and FecXH sites of the BMP15 in three populations. Analysis of variance showed that the polymorphism of BMPRIB gene was associated with positive effect on litter size traits. The means of genotype BB and AB were about 1.04 and 0.74 more than genotype AA for litter size (P<0.05). By analysis to BMPRIB genotype effects on litter size in three populations, it indicates the existence genotype BB or B allele is benefit to increase the litter size. It suggested that the polymorphism in exon 6 (at 746 in the coding region) of sheep BMPRIB gene may be used as a marker for early selection of prolificacy in sheep. The mRNA levels of the ovaries in 8 Small Tailed Han sheep with different BMPRIB genotype were analyzed by semi-quantitation and fluorescent quantitation PCR. The result showed the BMPRIB mRNA levels from the right ovary of BB and AB genotype ewes were up compared with AA genotype, but there were no significant difference (P>0.05). It suggested that the hypefecundity in Small Tailed Han sheep were no directly relative to the mRNA levels of BMPRIB gene. The relation between different BMPRIB genotype in Small Tailed Han sheep and FSH receptor or LH receptor mRNA levels during the oestrum was studied by semi-quantity PCR. The result showed FSH receptor mRNA levels from the right ovary of BB (1.14 ± 0.11) ewes were higher than those of AA (0.44 ± 0.11) and AB (0.36 ± 0.08) ewes (P<0.01); LH receptor mRNA levels from the right ovary of BB (0.42±0.02) ewes were significant higher than those of AA (0.23 ± 0.02) and AB (0.25±0.04) ewes (P<0.01), but there were no significant difference in the left ovary among the genotypes during the oestrum. It indicated the higher mRNA levels of FSH and LH receptor from the right ovary of BB ewes were related to the higher litter size of Small Tail Han sheep. The relation between different BMPRIB genotype in Small Tail Han sheep and ERa or PR mRNA levels during the oestrum was studied by semi-quantity PCR. The results showed PR mRNA levels from the right ovary of BB (0.81 ±0.10) genotype ewes were higher than AA (0.43 ±0.10) genotype (P<0.05), but left ovary were no significant difference among genetypes; ERa mRNA levels from the left or right ovary were no significant difference among genetypes (P>0.05). It suggested that the prolificancy in Small Tailed Han sheep was relative to the mRNA levels of PR gene, but no directly relative to ERa. It appeared that the polymorphism at 746 in the coding region of sheep BMPRIB gene may be used as a marker for early selection of prolificacy in sheep and the prolificacy of Small Tailed Han sheep was no directly relativeto the mRNA levels of BMPRIB and ERa, but was relative to the mRNA levels of FSHR , LHR and PR.
|
PDF Full Text Request