[Differential expression of CIDH gene between purebreds and hybrids in chicken and relationship with heterosis]

The technique of silver staining mRNA Differential Display was used to check the molecular genetic mechanism of heterosis in chicken. A differentially expressed fragment CE15A15, which was only expressed in two crossbreds, was found between purebreds and crossbreds. It is proved that the fragment intensively expresses in crossbreds through reverse Northern dot blot and RT-PCR. It shares 97% of sequence identity with a partial cDNA sequence of chicken that has been deposited in GenBank (AW198493) and believed to be identity with the cytosolic isocitrate dehydrogenase (CIDH) gene (ID:AF048831) of Microtus mexicanus. This suggests that the identified fragment may be a partial cDNA sequence of CIDH gene. The statistic analyses of phenotypes showed that the body weight and the carcass traits in crossbred of Silk Chicken (CC) x White Polymouth Rock (EE) and White Polymouth Rock (EE) x Silk Chicken (CC) had negative heterosis, while their fatty traits had positive heterosis. CIDH directly participates in the biosynthesis of fatty acids. This indicates that differential expression of the fragment between purebreds and crossbreds might be closely related to heterosis of crossbreds.