Genomic structure of the Nile tilapia (Oreochromis niloticus) transferrin gene and a haplotype associated with saltwater tolerance

Two microsatellite markers closely linked to transferrin were genotyped on surviving and non-surviving tilapia siblings kept in saltwater. Statistical analysis detected a significant distortion in segregation between two haplotypes defined by the two microsatellites. Sequence analysis of the transferrin gene detected several SNPs, some of which resulted in amino-acid changes in the transferrin protein. A haplotype of several SNPs segregated together with the two microsatellites and indicated that transferrin could be associated with saltwater tolerance in tilapia. An expression study indicated up-regulation of transferrin when tilapias were exposed to saltwater. These findings suggest that transferrin is involved in saltwater tolerance in tilapia.