Study On Candidate Gene Related To Breeding Performance Of Goats

To detect single nucleotide polymorphisms (SNPs) of BMP2,GnRH1,CYP21,AA-NAT and HIOMT gene in year-round estrus and high prolificacy breed (Jining Grey goat) and year-round estrus and moderate prolificacy (Boer goat) and seasonal estrus and low prolificacy breeds (Angora goat, Liaoning Mongolia Cashmere goats and Inner Mongolia Cashmere goats) by PCR-SSCP, PCR-PAGE, CR-RFLP, sequence analysis and gene cloning. The relation between SNPs identified in the study and high prolificacy and year-round estrus in goats was also studied. The results were as follows.â… .There was no polymorphism in the amplification region of BMP2 gene in four goat breeds. The results indicated that the region of BMP2 gene may not be the functional domains that affect the high prolificacy in Jining Grey goats.â…¡. There was no polymorphism in the amplification region of GnRH1 gene in four goat breeds. The results indicated that the region of GnRH1 gene may not be the functional domains that affect the high prolificacy in Jining Grey goats.â…¢. Only the products amplified by primer P10 of CYP21 gene displayed polymorphisms. For primer P10, three genotypes (HH, HB and BB) were detected in Jining Grey, Boer and Inner Mongolia Cashmere goats, and two genotypes (HH and HB) were detected in Angora goats. Sequencing revealed six nucleotide mutations (A2789C, C2791A, G2818A, G2851C, G2852T, G2854A) and one deletion mutation(c.2821₂822delCG)at exon 10 of CYP21 gene in the BB genotype compared with the HH genotype. As a result, nineteen amino acids were changed from the 426th to the 448th. The Jining Grey goats with genotype BB and HB had 0.81 (P<0.05) and 0.47 (P<0.05) kids more than those with genotype HH, and the difference of the litter size between genotypes BB and HB was non-significant ( P>0.05 ) . These results preliminarily indicated that allele B of CYP21 gene is a potential DNA marker for improving litter size in goats.â…£. Only the products amplified by primers P2, P3 and P5 of AA-NAT gene displayed polymorphisms. For primer P2, three genotypes (KK, KL and LL) were detected and sequencing revealed one silent mutation (T588C) of AA-NAT gene in the genotype LL in comparison to the genotype KK, the differences of the litter size between three genotypes were not significant in Jining Grey goats (P>0.05). For primer P3, two genotypes (QQ and QR) were detected and sequencing revealed one mutation (C1012T) of AA-NAT gene in one chromosome of the genotype QR in comparison to that of the genotype QQ, and this mutation resulted in an amino acid change of Arg→Cys (R89C). The does with genotype QR had 0.56 kids more than those with genotype QQ in Jining Grey goats (P<0.05). For primer P5, three genotypes (EE, EF and FF) were detected and sequencing revealed one mutation (C1656T) of AA-NAT gene in the genotype FF in comparison to the genotype EE, and this mutation caused an amino acid change of Arg→Trp (R196W), the differences of the litter size between three genotypes were not significant in Jining Grey goats (P>0.05). These results preliminarily indicated that allele D of C1012T polymorphic site of AA-NAT gene is a potential DNA marker for improving litter size in goats.â…¤. The products amplified by both P2 and P3 of HIOMT gene displayed polymorphisms. For primer P2, three genotypes (TT, TC and CC) were detected by digesting PCR products with restriction endonuclease Afaâ… and sequencing revealed one mutation (T19225C) of HIOMT gene in the genotype CC in comparison to the genotype TT, and this mutation caused an amino acid change of Tyr→His (Y298H). The does with genotype TC or CC had 0.66 (P<0.05) or 0.75 (P<0.05) kids more than those with genotype TT in Jining Grey goats. For primer P3, three genotypes (GG, GA and AA) were detected by digesting PCR products with restriction endonuclease Mspâ… and sequencing revealed one mutation (G19804A) of HIOMT gene in the genotype AA in comparison to the genotype GG. The differences of the litter size between three genotypes were not significant in Jining Grey goats (P>0.05). These results preliminarily indicated that allele C of T/C polymorphic site of HIOMT gene is a potential DNA marker for improving litter size in goats.