Molecular characterization and functional analysis of the lysosomal gene in red swamp crayfish, .

Aspartic proteinases are one of the four families of proteinase enzymes that are widely present in living organisms. They are involved in various physiological events, such as protein degradation, development, and host defense. However, the characterization and functional roles of aspartic proteinases remain to be elucidated in crustaceans. Here, we characterized a fragment of cDNA from red swamp crayfish, (). The open reading frame of the gene contained 1152 bp, encoding a protein of 383 amino acid residues. We also evaluated the immunological role of the gene in vivo. Spatial distribution analysis revealed that the mRNA was high in the hepatopancreas, followed by the gut, gills, and hemocytes of . The expression levels of the gene increased following challenge with viral (polyinosinic: polycytidylic acid) and bacterial (lipopolysaccharides, peptidoglycan) PAMPs compared with PBS injection. The suppression of the gene by RNA interference significantly increased the expression of immune-associated genes. These results showed that the gene has an essential biological role in innate immune responses because it regulates the expression of immune-associated genes.