Study On The Candidate Gene Of Chicken Autosomol Dwarfism

In order to detect the recessive mutation which causes autosomal dwarfism (adw) of chicken, our investigation was preformed on the following respects:1. A 2.7-Mb conservative syntenic region, containing 52 genes in chicken chromosome 1 was chosen to be the candidate region based on previous mapping result and comparative genomics method. By sequencing the exons and promoters of genes in this region between dwarfs and normals, including two dwarf pedigrees, Cornish dwarf cocks and White Leghorn dwarf cocks, 39 SNPs including 9 non-synonymous mutations in 4 different genes of the upstream 1.7-Mb region were validated and remained for further survey.2. The results of PCR-RFLP showed that one homozygous T allele that replaced normal C allele herein caused a proline to leucine substitution in ASCL4 gene exon1 only exist in autosomal dwarf chicken breed. Subsequently, chickens from 11 segregating dwarf families were typed individually by PCR-RFLP for this mutation. The result showed this homozygous T allele was absolutely linked with adw.3. Different chicken breeds in China, incluing 27 Chinese native chicken breeds, 1 sex-linked dwarf and 1 autosomal dwarf chicken breed were scanned by Pyrosequencing to detect this mutation. The results showed that only the homozygous C alleles exist in all these chicken breeds in China and no T allele was detected.4. The quantitative real-time PCR was used to explore gene expression differentia in different developmental stages and in different tissues in White Leghorn. The results showed that ASCL4 was mainly expressed in the brain, body and skin of normal chicken during the embryo stage, mainly and higher in the skin during the adult stage.ASCL4 gene, known as having the function of DNA binding and transcription regulatory activity according to GeneOntology description, has high possibility to be the causative gene for adw.