Single nucleotide polymorphisms in chicken lmbr1 gene were associated with chicken growth and carcass traits.

Lmbr1 is the key candidate gene controlling vertebrate limb development, but its effects on animal growth and carcass traits have never been reported. In this experiment, lmbr1 was taken as the candidate gene affecting chicken growth and carcass traits. T/C and G/A mutations located in exon 16 and one A/C mutation located in intron 5 of chicken lmbr1 were detected from Silky, White Plymouth Rock broilers and their F2 crossing chickens by PCR-SSCP and sequencing methods. The analysis of variance (ANOVA) results suggests that T/C polymorphism of exon 16 had significant association with eviscerated yield rate (EYR), gizzard rate (GR), shank and claw rate (SCR) and shank girth (SG); A/C polymorphism of intron 5 was significantly associated with SCR, liver rate and head-neck weight (HNW), while both sites had no significant association with other growth and carcass traits. These results demonstrate that lmbr1 gene could be a genetic locus or linked to a major gene significantly affecting these growth and carcass traits in chicken.

Single nucleotide polymorphisms in the chicken Lmbr1 gene are associated with chicken polydactyly.

Polydactyly is a common malformation of vertebrate limbs. Preaxial polydactyly (PPD) has been mapped in human, mouse and chicken to the syntenic region of human 7q36. Lmbr1 was thought as the critical candidate gene for human and mouse PPD. To understand the molecular mechanism underlying chicken polydactyly, we have cloned the open reading frame (ORF) of chicken Lmbr1, which contains 1467 nucleotides. Within this ORF, we found one short and one long splice forms. The short splice form has a complete deletion of exon 4. Six cSNPs were found in the chicken ORF, and two of these cSNPs, G797A and G1255A, lead to amino acid substitutions. However, G797A substitution had no significant association with polydactyly and the G1255A substitution had very low frequency in the population. The T1254C polymorphism in exon 13 was found to be strongly associated with polydactyly. Radiation hybrid mapping of a DNA fragment containing intron 13 of the chicken Lmbr1 assigned the gene to chromosome 2 between MCW071 (a marker within the EN2 gene) and ADL0270, a syntenic region to human 7q36.

[Genetic differentiation of domestic goose breeds in China].

The 1 042 bp control region of mitochondrial DNA from 84 geese of 15 domestic goose breeds was sequenced and genetic differentiation was analysed. Results showed that the interpopulation nucleotide divergence was highest (3.805% -4.067%) between Yili and the other 14 breeds. The average nucleotide diversity variation within different domestic breeds was 0 - 0.116%. Excluding the Yili, the interpopulation nucleotide divergence between Huoyan and the remaining breeds, was 0.211% - 0.272%, which was significantly higher than that between any other two breeds (0 -0.094%). During the formation of domestic breeds in China,there is an association between the genetic differentiation of domestic geese and their geographic distribution. The divergence time of Huoyan breed was relatively earlier and genetic drift may have been the main factor to affect the genetic differentiation of the Huoyan breed (Nm = 0.02 -0.54). On the other hand, gene flow is the main reason for the lack of a clear differentiation among the remaining 13 Chinese domestic geese breeds (Nm = 12.0 - 65.33).

[The genetic diversity of the second exon about SLA-DQB in some Chinese native pigs].

Polymorphism of the second exon about SLA-DQB genes in some Chinese native pigs was investigated employing PCR-SSCP analysis and DNA cloning sequencing. Combined with the sequences in GenBank, 73 new alleles were gained, among them function alleles of SLA-DQB were sixty-eight, five alleles of pseudogene (SLA-DXB) were gained. There were disequilibrium distribution of the alleles in all breeds, the same allele was shared by most breeds. C08 allele existed in 11 breeds of six groups and in the wild pigs of Yunnan and Sichuan province, and its frequency reached 55.10%. More than five sequences were found in each individual, suggesting duplication in these loci examined, there were three copies about SLA-DQB genes. The variable sites based on nucleotide and amino acids reached to eighty-one and forty-nine, respectively. The values of allelic diversity (H=0.889) and the nucleotide diversity (Pi=0.047) were revealed very high, from both values of H and Pi were higher in the beta pleated sheet region than those in alpha helix region in Chinese native pigs. In general, values of H and Pi in Huanan pigs and Xinan pigs were higher, vice versa in Tibet pigs. The genetic distance within group were showed the same order as comparison Pi values, hence we concluded the different rate of nucleotide substitution were positive correlated with the degree of nucleotide diversity in Chinese domestic groups. The genetic distances about SLA-DQB gene between groups were detected as follow: the great genetic distance were existed between the Jianghai and Huabei groups, and the smallest genetic distance were existed between the Huazhong and Gaoyuan groups.

[Detection and typing for swine leukocyte antigen].

Traditionally the cluster of swine leukocyte antigen (SLA) was typed by serological, cytological and biochemical methods. Many special molecular typing methods have been developed with the progress of molecular biological technology, such as PCR-RFLP, PCR-SSCP , MS and DNA sequencing. Here we discussed the advantages and disadvantages of each method based on the polymorphic and conservative (from the functional aspect, such as supertype and supermotif) characteristics of SLA, and illustrated the development of typing for SLA in the future. In addition, we pointed out the editorial mistakes about the serological haplotype of SLA in reference book and emphasized that the accurate polymorphism of SLA-DQB gene must be based on the cloning sequencing.

[Progress on polydactyly character of vertebrate].

Polydactyly is a common abnormal limb phenotype in vertebrate and there is similar limb phenotype among different species. Research shows that polydactyly has a similar development mechanism, and this kind of polydactyly character seems to be controlled by homologous genes among species. The latest research results on human and mouse further shows that PPD should be caused by the disruption of a long range cis-acting regulator for Shh within Lmbr1 intron. Here the development mechanism and related genes controlling polydactyly character of vertebrate are reviewed.

[Study of molecular genetics of the size of reproductive organs and litter size in the sow].

The mutations of ESR, PRLR and FSHR genes were investigated by SNP; 103 F2 sows were slaughtered and their reproductive organs were determined; the litter size of sow was recorded. The linkage between mutations of genes and size of reproductive organ, litter size was analyzed. The results revealed: these sows that could provide more piglets with bigger reproductive organs usually carried genotype like as genotype BB on the sites of ESR, FSHRB and the genotype AA on the sites of ESRB and PRLR, that is, the genotype of BB on the sites of ESR or FSHRB in sow was not only helpful to promote growth of reproductive organs, but also benefit to improve litter size; The size of productive organs and litter size of the sow with genotype AA on the sites of ESRB or PRLR were significantly higher than those of sow with genotype AB or BB.