Study On DNA Molecular Markers And Its Related Research On Prolificacy In Sheep

Techniques such as candidate genes, microsatellite marker linkage analysis were used to study the frequency of prolific genes and the relationship among litter size, growth and development in seven sheep breeds or strains. A rapid and simple method for detection of FecB gene was established in this study. The purpose of the current study is to provide a method for molecular marker assistant breeding. The main contents presented as follows:1. Study of candidate genes on sheep prolificacyDNA samples were collected and amplified for bone morphogenetic protein receptor type IB gene (BMPR-IB), BMP 15 gene and GDF genes by PCR-RFLP method from 553 sheep from 7 breeds or strains such as Hu, Chinese Merino meat-Prolificacy strain, Suffolk, Dorset, Charolais, Chinese Merino and Romney Hills. Furthermore, relationship between the polymorphism of BMPR-IB gene and prolificacy as well as growth and development were analyzed. The results showed that the genotype frequency of BMPR-IB gene was significantly different in these breeds or strains. In Chinese Merino meat-prolificacy strain, the genotype frequency of BB, B+ and ++ is 51% 30% and 19% respectively. Except for Hu sheep with only BB genotype, other breeds had only ++ genotype. Analyzing the litter size, body weight and body size within Chinese Merino meat-Prolificacy strain, we found show that the mean litter size at 1st lambing of BB, B+ and ++ genotype populations is 2.0, 1.5 and 1.1 respectively, and there are significantly difference between groups (BB vs B+, P<0.05; BB vs ++, P<0.01). Sheep with genotype BB and B+ had a greater total litter size than those with genotype ++ (P<0.01), the number is 2.8, 2.3 and 1.2 respectively. At ages of 90 days, the body weight of lambs with genotype BB and B+ were (18.6±3.70)kg and ( 18.0 ± 3.31 ) kg, which were significantly greater than that of population with ++ (15.6 + 2.22 kg) genotype (p<0.05). Furthermore, at this age, the lambs with genotype BB and B+ were significantly greater than those with genotype ++ in chest circumstance and chest width, but at age of 120 days there was no significant difference between these two groups.These findings indicate that the BMPR-IB gene is a major gene that regulates litter size and affects growth and development during a certain period.2 . Study on polymorphisms of microsatellites in different sheeppopulationsSix microsatellite markers named LscvO43, BMS2508, GC101, 300U, Bulge5 and 471U which were closely linked to the FecB gene were analyzed in samples of Hu collected from Natural Source Conservative Region and Shanghai.for genetic diversity and relationship on litter size in Hu sheep as candidate markers. And Chinese Merino prolific meat strain as control. To evaluate the Hu breed by comparison with polymorphism information content (PIC), genetic heterozygosity (h), index of genetic diversity (H), and effective number of allele (E). The results showed that six markers were all polymorphic markers within Hu sheep, and total mean PIC, H, h and E within Hu come from Natural Source Conservative Region were higher than that of from Shanghai, but was lower than that of Chinese Merino prolific meat strain. The genetic distance (D) and index of similarity (I) of three different sheep population is in according with its breeding process. The mean litter size at 1st lambing for LscvO43 site HObp/llObp was the highest and total mean litter size for 300U site 148bp/148bp was the highest within Hu sheep population. Total mean litter size for LscvO43 site 107bp/123bp was significantly higher than that for LscvO43 site H0bp/123bp (PO.05). The 1st mean litter size for BMS2508 site 154bp/154bp, 154bp/170bp and 154bp/200bp was significantly higher than that for BMS2508 site 170bp/170bp (PO.05). There was difference between the mean litter size at 1st lambing and total mean litter size of microsatellite markers GC101, 300U, 471U and Bulge5 but no significantly difference was detected.3. Development of a method using tetra-primer ARMS PCR for detection of FecB gene mutation in sheepTetra-primer ARMS PCR is a rapid, simple and efficient method to detect single nucleotide polymorphism (SNP). Bone morphogenetic protein receptor IB (BMPR-IB) gene was a major effect gene that control prolific trait in Booroola Merino sheep. To establish a tetra-primer ARMS PCR method to genotype BMPR-IB gene. Specific primers around the mutation locus (A746G) were designed on the basis of tetra-primer...