Research Of Mutations Of CaSR Gene And Its Genetic Effects In Chinese Cattle

CaSR, the member of GPCRs, could modulate food digestion in response to the intracellular singal which was transformed from extracellular singal. In our research, PCR-SSCP and DNA sequencing methods were used to investigate the genetic variation of Ca SR gene in LX, QC and JX cattle. We analyzed the genetic structure and genetic diversity. Furthermore, we investigated the relationship between the mutations and the growth traits in order to discover the significant molecular marker of important economic traits. The method could offer us foundation of marker-assisted selection（MAS） and molecular marker library. Our results were shown under below.1. Research of the mutation of Ca SR gene in Chinese cattleFour novel mutations and one previously reported mutation were discovered（NC₀07299.5: g.67630865T>C（Exon 2）, 67638409G>C（Exon 4）, 67660395G>C（Exon 7）, 67661546C>G（Exon 7） and 67661892A>C（Exon 7）） and they were all in the exon. Four mutations were in coding region and the last were in 3′-UTR. The SNPs（Gen Bank accession number, NC₀07299.5） g.67630865T>C（exon 2）, g.67638409G>C（exon 4）, g.67660395G>C（exon 7） and g.67661546C>G（exon 7） resulted in missense mutations, to which corresponding p.Val47 Ala, p.Arg370 Pro, p.Arg608 Pro and p.Pro992 Ala amino acid variations, respectively.2. Analysis of genetic structure of Ca SR gene in cattleTwo genotypes（TT and TC genotype） were found in P2 mutation site of Exon 2 in LX, QC and JX cattle. TT genotype and T allele were dominant among them and the site had low polymorphism information. Genotype frequency and allele frequency in the SNP in JX, LX and QC cattle had no significant difference（P>0.05）.Three genotypes（GG, GC and CC genotype） were found in P4₂ site of Exon 4 in LX, QC and JX cattle. GC genotype and G allele were dominant among them and the site had intermediate polymorphism information. Genotype frequency and allele frequency in the SNP among the three kinds of bovine had no significant difference（P>0.05）.P7₁, P7₄ and P7₅ variants in Exon 7 in the three kinds of cattle were detected. Three genotypes（GG, GC and CC genotype） were discovered in P7₁. GC genotype and G allele were dominant among them in P7₁ SNP and the site had intermediate polymorphism information. Genotype frequency and allele frequency in the SNP between LX and QC cattle had significant difference（P<0.05） and so were the JX and QC cattle（P<0.01 or P<0.05）.Three genotypes（GG, GC and CC genotype） were discovered in P7₄. GC genotype and G allele were dominant in P7₄ site in LX cattle; GC genotype and C allele were dominant in P7₄ site in JX and QC cattle. The site had intermediate polymorphism information. Genotype frequency in the site between JX and QC cattle had significant difference（P<0.01）; allele frequency in the SNP between JX and LX cattle had significant difference（P<0.05）.Two genotypes（AC and CC genotype） were discovered in P7₅. CC genotype and C allele were dominant in P7₅ site among the three kinds of bovine. The site had low polymorphism information. Genotype frequency and allele frequency in the SNP had no significant difference（P>0.05）.3. The analyze of the relationship between the variants of Ca SR gene in Chinese cattle and its growth traits3.1 P2 SNP and its association with growth traitsTwo genotypes（TT and TC genotype） were detected in P2 SNP. The P2 SNP had no significant association with growth traits in LX and QC cattle（P>0.05）, but with chest circumference, sciatic wide, hip cross height and body weight in JX cattle（P<0.05 or P<0.01）. These growth indexes in JX cattle with TT genotype were higher than the cattle with TC genotype.3.2 P4₂ SNP and its association with growth traitsThree genotypes（GG, GC and CC genotype） were detected in P4₂ SNP. The SNP had no significant association with growth traits in LX cattle（P>0.05） but with body weight, body height, body length, chest circumference, sciatic wide and hip cross height and back height in QC cattle（P<0.05 or P<0.01）. Furthermore, the growth indexes in QC cattle with CC genotype were higher than the cattle with GC genotype. Furthermore, the SNP were significant associated with growth traits body weight and chest circumference in JX cattle（P<0.01）. Both body weight and chest circumference in JX cattle with GC genotype were higher than the cattle with CC genotype and GG genotype.3.3 P7₁ SNP and its association with growth traitsThree genotypes（GG, GC and CC genotype） were detected in P7₁ SNP. The SNP was significant associated with body weight, body length, chest circumference and abdominal circumference in LX cattle（P<0.01 or P<0.05）. These growth traits in LX cattle with GC genotype were higher than the cattle with GG genotype. The SNP was significant associated with body weight, body length（P<0.05）, chest circumference and back height in QC cattle（P<0.05）. These growth indexes in QC cattle with GG genotype were higher than the cattle with GC genotype and CC genotype. But the SNP were not significant associated with JX cattle（P>0.05）.3.4 P7₄ SNP and its association with growth traitsThree genotypes（GG, GC and CC genotype） were detected in P7₄ SNP. The SNP was not significant associated with LX cattle and QC cattle（P>0.05） but was significant associated with body weight and chest circumference in JX cattle（P<0.01）. The two growth indexes in JX cattle with GC genotype were higher than the cattle with CC genotype and GG genotype.3.5 P7₅ SNP and its association with growth traitsTwo genotypes（AC and CC genotype） were detected in P7₅ SNP. The relationship between the SNP and growth traits had no significant difference with LX cattle, JX cattle and QC cattle（P>0.05）.3.6 Haplotype of Ca SR gene in LX cattle and its association with growth traitsNine main haplotypes were found in LX cattle. Combined haplotypes were detected to be insignificant associated with growth traits in LX cattle.3.7 Haplotype of Ca SR gene in QC cattle and its association with growth traitsEight main haplotypes were found in QC cattle. Combined haplotypes（P4₂ and P7₁ sites） were detected to be significant associated with cannon circumference in QC cattle（P<0.05）. Furthermore, combined haplotype of CCGG was better than others.3.8 Haplotype of Ca SR gene in JX cattle and its association with growth traitsFive main haplotypes were found in JX cattle. Combined haplotypes（P2, P4₂ and P7₄ sites） were detected to be significant associated with cannon circumference and chest circumference in JX cattle（P<0.05）. Furthermore, combined haplotype of TTGCGC was better than others.From the above, we found that heritable variation of single site in Ca SR gene was significant associated with growth traits in Chinese cattle, and so as the combined haplotypes and growth traits in QC cattle and JX cattle. Our research could offer credible foundation to molecular breeding in Chinese cattle.