| The level of genetic differentiation and genetic structure in seven Chinese cattle populations (Luxi cattle, Bohai cattle, Minnan cattle, and Chinese Simmental cattle) were analyzed based on12microsatellite markers and mtDNA D-loop region; To explore the variations of blood indices resistant against heat shock of Chinese cattle in Chinese southern tropical and subtropical region (Leiqiong cattle, BMY cattle, Yunnan highpump cattle), six blood indexes (concentration of serum K+, red blood cell K+, ALT, AST, ALP), using Chinese Simmental cattle as controlled population; PCR-SSCP method was used to detect the SNPs of the HSP70-1Gene in three southern cattle breed of China, Leiqiong cattle, BMY cattle, Yunnan highpump cattle, using Chinese Simmental cattle as controlled populations, and we analyzed its relationship with blood indexes in four cattle populations (Leiqiong cattle, BMY cattle, Yunnan highpump cattle and Minnan catttle), as well in order to lay the foundation for Marker-assisted Selection (MAS) of heat resistance for Chinese cattle; PCR-SSCP method was used to detect the SNPs of the SCD1gene and DGAT1gene in Chinese Simmental cattle using three southern cattle breed of China (Leiqiong cattle, BMY cattle, Yunnan highpump cattle) as controlled populations, and we analyzed their relationships with fat related traits in Chinese Simmental cattle as well in order to lay the foundation for Marker-assisted Selection (MAS) for Chinese Simmental cattle; In order to find out the molecule mechanism that the mutation C3343T had significant effect heat resistance traits, FQ-PCR method was used to study the expression level in Leiqiong cattle blood among3genotypes which were formed by the mutation C3343T in the HSP70-1gene, and the expression level in blood tissue in Leiqiong cattle was also studied. The main results of our research were listed as follows:1. Based on12microsatellite markers, a total of209distinct alleles were observed across the7breeds (Leiqiong cattle, BMY cattle, Yunnan highpump cattle, Luxi cattle, Minnan cattle, Bohai Black cattle and Chinese Simmental), and20of these alleles were unique to only one breed. Yunnan highpump cattle carried the largest at180, and Leiqiong cattle had lowest number of alleles at85. The average heterozygosity was highest in Chinese Simmental cattle, and PIC value and Ne were highest in Yunnan highpump cattle, indicating Chinese Simmental cattle and Yunnan highpump cattle populations had higher genetic diversity. The result of coefficient of gene differentiation (GST), genetic diversity and cluster analysis achieve the unanimous basically, indicating these indexes are suitable for the researches on the genetic polarization. Cluster analysis based on DA and (σμ)2genetic distance showed that LQ, YN, MN and BMY cattle were close to each other, while farther away from other poputions, indicating unique phenogenetic status and genetic diversity of Chinese southern cattle.2. The complete mitochondrial D-loop sequence,910bp in length, evinces high polymorphism, and nucleotide mutations types are along with the following types, transition, transversion, insertion, deletion and coexistence of transition and transversion. The nucleotide transitions existed mainly in T←'C with the value of62.96%, and A←'G with the value of37.04%. In the all six populations, the average content of G+C%was amount to38.7%, and A+T%amount to61.3%. Sixty-two nucleotide mutations were found in all, and of all variable positions,58mutations were transitions, while4mutations were transversion. Yunnan high pump cattle and Bohai Blank cattle contain the most mutations in all populations, amounting to43, while Leiqiong cattle had the least mutations, amounting to32. And the other three populations had the medium mutation, BMY cattle and Minnan cattle own42mutations, and Chinese Simmental cattle own41mutations.3. Twenty haplotype had been found in total when sequence alignment had been made among31sequences of mtDNA D-loop regions, indicating the ratio of haplotype to the size of population was64.52%. Two groups of haplotype had been found in cluster analysis of NJ method, representing the two maternal origin system of Chinese cattle, Group I standing for Bos taurus origin, and Group Ⅱ for Bos indicus origin. Our study validated the Bos indicus blood origin of Southern Chinese cattle once more. Differences had been found in our study among different groups and within group, indicating abundant mitochondrial genetic diversity among interbreeds and individuals in Chinese cattle and some populations had special haplotype, which should be protected appropriately, validating Bos indicus blood of Chinese sourthern cattle. Differences exist in breeds and populations, indicating rich genetic resources in Chinese sourthern cattles. Some populations have special haplotype. which shoud be protected approprietly.4. Sourthern Chinese cattle had higher Concentration of RBC K+, GOT, GPT and ALP than controlling cattle, and concentration of glutamic-oxaloacetic transaminase was significant difference in different populations in different regions. RBC K+and ALP can be used as indices for heat resitance of cattle.5. Fourteen mutations had been detected in three southern populations and one controlled population, in which five mutations (A329G, T576C, C1199G,A1221C and C1334T) were in5’-flanking and nine mutations (A1501G、C1745T、A1926G、 C2540T、C2720T、A3035G、A3062G、A3108G) in coding region in HSP70-1gene. A329G, C1334T, C1745T, A3035G and C3343T were moderate polymorphism sites in Leiqiong cattle and Yunnan highpump cattle, other sites were lower polymorphism; A329G and C1334T in Chinese Simmental cattle were moderate polymorphism sites, other sites were lower polymorphism; while all sites in BMY cattle were lowe polymorphism.6. The effect of C1334T site of HSP70-1gene on Hemoglobin was significant in Leiqiong cattle, the effect of A329G site of HSP70-1gene on Hemoglobin was significant in BMY cattle, and other sites in all populations had no significant effect on the blood indexex. As to the nine mutations in codn rengion, C334T site had significant effect on red blood cell K+and ALP concentration in LQ, YN and BMY cattle (P<0.05).7. Using FQ-PCR method, it showed that the expression level differs in Leiqiong cattle blood among three genotypes (CC, CT and TT) which were formed by the mutation C3343T in the HSP70-1gene. The expression level of genotype TT individuals in HSP70-1gene was1.361times higher than that in genotype CC individuals in Leiqiong cattle and the expression level of genotype CT individuals were1.282times higher than that in genotype CC individuals, further verifying that HSP70-1gene was suitable to be used as candidate gene of heat resistant trait in Chinese southern cattle.8. C878T (C was favorable gene) and T762C (T was favorable gene) in SCD1and DGAT1(GC was favorable gene) gene had significant effect on meat traits in Chinese Simmental cattle (P<0.05). elevating MIF by5.1%,4.2%and13.1%. respectively. The haplotype of CTGC of site C878T and T762C in SCD1gene and duble nucleitide mutation AA/GC in DGAT1gene had evidence effect on intermuscle fat trait and shearing force trait in Chinese Simmental cattle (P<0.05). improved by5.7%and14.6%respectively. Therefore, SCD1gene and DGAT1gene were candidate genes for fat traits in Chinese Simmental, indicating wide applying prospects of two genes in combinded inbreeding of beef. At the same time, the cattle populations in Southern of China own higher frequencies of tow sites of SCD1gene than Chinese Simmental cattle indicating that these populations have great popential in beef performance. |
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