| Poultry resource is abundant in China, but it is reduced because of the introduced chicken breeds. Study on poultry resource help to understand the status and feature, provide the good base for protection of breed resources and reasonable exploition. Chicken MHC (major histocompatibility complex) is a cluster of genes located in 16 chromosome of chicken. The cluster of genes located in MHC B region includes B-F(â… ), B-L(â…¡) and B-G(â…£). Extensive studies showed that polymorphisms of MHC gene were significant correlated with the resistibility of many infectious diseases, and MHC gene is a good candidate of diseases resistance for poultry breeding.In this study, genetic structure and variations of 584 individuals including six native breeds (Zang, Wenchang, Guyuan, Lueyang, Shanbei, and Taibei breed) were detected using microsatellite and PCR-SSCP techniques. Following is results.1. Genetic structure and variations of six local breeds in 20 microsatellites.1.1 The average number of alleles of 20 microsatellites in six native breeds is 4.9802, and the average number of effective alleles is 3.5464. Of all the loci, the number of alleles of LEI0073 is 12, which is maximum; both the number of alleles of MCW0351 and MCW0287 are 4, which is minimum. Except for MCW0287, MCW0264, MCW0145 and MCW0104, the Chi-Square test for goodness of fit showed Hardy-Weinberg disequilibrium is statistically significant over all the other selected loci in these populations. (p<0.05).1.2 The average heterozygositie of populations was 0.6717. Of all the breeds, the He of Zang breed is maximum (0.7138), which indicated that both genetic variation and polymorphism are maximum. The selected pressure on this breed should be higher in later breeding practice to improve the genetic homogeneity of Zang breed.1.3 The PIC of breeds range from 0.6694 (Zang breed) to 0.5445 (Shanbei breed), all over 0.5. The microsatellites in these breeds show higher polymorphic, which indicated the 20 microsatellites used in this study could effectively analyze genetic variations of breeds.2. Genetic variations of exon 2 of MHC B-LBâ…¡gene in six native breeds.2.1 Three genotypes (AA, AB and BB genotype) were detected in six native breeds. Except for Zang breed, Genotypic frequecy of AA is higher than other two genotyes in other five native breeds, allelic frequency of A is higher than that of B, thus allele A was dominant allele. The Chi-Square test for goodness of fit showed Hardy-Weinberg disequilibrium was statistically significant in all these populations. (p<0.01).2.2 The sequencing results showed that there are 11 mutations in the 176 bp fragmnet, which is 6.25% in all nucleotides of this fragment. Among these mutations, 9 mutation were missense and two were synonymy. There are 5 amino acid changed in all 58 amino acid. The similarity of nucleotide sequence is lower than amino acid sequence.2.3 The He of MHC B-LBâ…¡gene in six native breeds is low, ranging from 0.4977 to 0.1420. The PIC range from 0.3738 to 0.1319. The He and PIC of Zang breed was maximum, which indicates genetic resource of Zang breed is abundant.This study could provide basic data for research on breeds characteristics of Chinese native chicken breeds and scientific basis for the protection and exploition of native chicken breeds.
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