High salinity induced expression profiling of differentially expressed genes in shrimp (Penaeus monodon)

Four suppression subtractive hybridization (SSH) cDNA libraries were constructed to identify differentially expressed salinity stress responsive genes of black tiger shrimp, Penaeus monodon exposed to high (55 ppt) salinity conditions. One each of the forward and reverse SSH cDNA libraries were developed from the gill and gut tissues of shrimp and clones having inserts larger than 300 bp were unidirectionally sequenced. Based on the sequence homology search, the identified genes were categorized for their putative functions related to a wide range of biological roles, such as nucleic acid regulation and replication, immune response, energy and metabolism, signal transduction, cellular process, structural and membrane proteins, stress and osmoregulation. Gene expression levels in response to high salinity conditions at 2 weeks post salinity stress for some of the differentially expressed genes (Na⁺/K⁺-ATPase α-subunit, glutathione peroxidase, intracellular fatty acid binding protein, elongation factor 2, 14-3-3 like protein, penaeidin, translationally controlled tumor protein, transglutaminase and serine proteinase inhibitor B3) identified from SSH cDNA libraries were analysed by real-time RT-PCR. The highest gene expression levels was observed for Na⁺/K⁺-ATPase α-subunit in gill tissues (15.23-folds) and antennal glands (12.01-folds) and intracellular fatty acid binding protein in gut tissues (14.05-folds) respectively. The differential and significant levels of gene expression indicate the functional role of these genes in shrimp salinity stress adaptive mechanisms.