Anas platyrhynchos BLVRA Gene:Molecular Cloning and Correlation between Green Shell Character and mRNA Expression in the Shell Gland in the Duck

摘要

This study has examined the structure and function of the biliverdin reductase A (BLVRA) gene and its correlation with the green eggshell character in Jinyun ducks. The previously unknown sequences of 3' and 5' ends of duck BLVRA mRNA were cloned, using RT-PCR and 5' RACE methods with four pairs of primers designed from the known coding sequence (CDS) of the duck BLVRA gene. Gene expression levels of BLVRA in the shell gland were quantified by real-time PCR, and eggshell colors were determined objectively by the reflection coefficient. The cDNA sequence of BLVRA was comprised of 1071 nucleotides, encoding a protein of 303 amino acids with an isoelectric point of 7.15 and molecular weight of 34.3 kDa. The 5' and 3' ends of the duck BLVRA gene sequence published in the GenBank were extended by 238 and 199 bp, respectively. The deduced amino acid sequence of duck BLVRA had 95.3% identity with Gallus gallus, 95.0% with Taeniopygia guttata, 70.0% with Xenopus tropicalis,61.1% with Bos taurus, 60.5% with Homo sapiens and 59.5% with Mus musculus, which indicated that the BLVRA gene was evolutionarily conserved. The relative gene expression level of BLVRA in shell glands of Jinyun ducks with white eggshells was 3 times higher than that in ducks with dark green eggshells (P<0.01). There was a significant positive correlation between reflection coefficient of eggshells and the relative expression of the BLVRA gene (r=0.719, P<0.05). Together, these findings suggest that the BLVRA gene could be a candidate gene for the molecule breeding of ducks with green eggshells.