A single nucleotide polymorphism of 5' flanking region of the prolactin gene was investigated in both high prolificacy breeds (Small Tail Han and Hu sheep) and low prolificacy breeds (Dorset and Suffolk sheep) using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP). The results indicated that two genotypes (AA and AB) were detected in Small Tail Han sheep (n = 239), only one genotype (AA) was detected in Hu (n = 40), Dorset (n = 50) and Suffolk sheep (n = 39). The mutant homozygous genotype (BB) was not detected in four sheep breeds. In Small Tail Han sheep (n = 239), the frequency of genotypes AA and AB was 0.91 and 0.09, the frequency of the A and B alleles was 0.95 and 0.05, respectively. The fitness tests showed that the Small Tail Han sheep population was in Hardy-Weinberg equilibrium. Sequencing revealed a mutation (G-->T) at the position 63 bp of the 5' flanking region of prolactin gene in AB genotype compared with AA genotype in Small Tail Han sheep. The Small Tail Han ewes with AB genotype had 0.83 (p < 0.05) lambs more than those with AA genotype. These results preliminarily showed that the prolactin locus is either a major gene that influences the high prolificacy in Small Tail Han sheep or is in close linkage with such a gene.
Bone morphogenetic proteins (BMPs), belonging to the transforming growth factor-beta family, are crucial factors in follicular growth and development in the mammalian ovary. In this study, we examined the effects of BMP2, 4, 6 and 7 on goat granulosa cells by in vitro culture. The results showed that BMP2, 4 and 7 increased follicle-stimulating hormone receptor (FSHR) level in goat granulosa cells whereas they decreased luteinizing hormone receptor (LHR) level in both transcript and protein levels; however, BMP6 upregulated LHR transcript and protein level in goat granulosa cells, whereas it had no effect on FSHR level. FSHR knockdown increased granulosa cell apoptosis. Our data provided the first evidence that BMP2, 4, 6 and 7 may inhibit granulosa cell apoptosis through the regulation of FSHR and/or LHR level. These findings provided new insight into the biological functions of BMP2, 4, 6 and 7 for follicular development in goat ovary.
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