Expression Analysis Of Polydactyly Candidate Gene Of Beijing Fatty Chicken

In chicken, the number of digits is four in normal, but polydactyly is a breed characteristic in some species as the Beijing Fatty chicken. Although previous hybridization tests proved that polydactyly trait belonged with an autosomal dominant inheritance but the penetrance is difference in offspring populations. Genetic mapping and comparative genomics analysis showed that the chromosome 2 short arm (close to 45cM on the chicken reference genetical linkage map especially) was key region for some candidate genes of chicken polydactyly, and this region is highly homologous with the gathering area of human and mouse PPD candidate genes (human 7q36 region and mouse chromosome 5 region).In order to understand the genetic basis of polydactyly character, we detected the expression of 11_candidate gene which be reference to date of human and mouse limb development using the method of real time quantitative PCR in the toe tissue in developping embryo (the first 6-10d of embryonic development) of Beijing Fatty Chicken and Shiqiza Chicken which the genotype have been identified with genetical hybridization test as Homozygote. The results showed that the expression of most candidate genes were significantly deifferent between Beijing Fatty chicken and Shiqiza chicken in different time of embryonic development. Interestingly, the expression of HB9 gene is extremely higher in the Beijing Fatty chicken than in the Shiqiza chicken in whole time 6 to 10 days of embryonic development (the 2-ΔΔCT value is up to 93-282 folds). In addition, further analysis showed that the position of HB9 gene on the genetical linage map is located the region 45cM of chromosome 2 short arm, near to microsatellite sites of ADL270. So we strongly inferred the HB9 gene may be an important major gene for controlling polydactyly character in Beijing Fatty chicken. It's suggesting the HB9 gene take on potential worthy in further research work.