In summary, we identified and characterized the duodenase-1
gene in tilapia. The duodenase-1 gene was expressed in all 10 tissues
examined in healthy fish. Its highest expression was in the
intestine. Rapid and sensitive responses of the gene to the infection
with the bacterial pathogen S. agalactiae were observed, suggesting
that the gene plays an important role in innate immune responses
to the bacterial pathogen. We found significant associations between
four SNPs and one haplotype in the duodenase-1 gene and
resistance to the bacterial pathogen S. agalactiae. These SNPs and
haplotypes, which were significantly associated with resistance to
S. agalactiae could facilitate the selection of tilapia resistant against
S. agalactiae. Further experiments on whether SNPs in the
duodenase-1 gene are associated with resistance to other bacteria
and virus in tilapia could be useful in understanding more functions
of the duodenase-1 gene. Using SNP in the duodenase-1 gene for
QTL analysis will understand the relationship between the SNPs
and QTLs