Transcriptomic analysis of the black tiger shrimp (Penaeus monodon) reveals insights into immune development in their early life stages

With the rapid growth in the global demand, the shrimp industry needs integrated approaches for sustainable production. A high-quality shrimp larva is one of the crucial key requirements to maximize shrimp production. Survival and growth rates during larval development are often criteria to evaluate larval quality, however many aspects of gene regulation during shrimp larval development have not yet been identified. To further our understanding of biological processes in their early life, transcriptomic analysis of larval developmental stages (nauplius, zoea, mysis, and postlarva) were determined in the black tiger shrimp, Penaeus monodon using next-generation RNA sequencing. Gene clustering and gene enrichment analyses revealed that most of the transcripts were mainly related to metabolic processes, cell and growth development, and immune system. Interestingly, Spätzle and Toll receptors were found in nauplius stage, providing evidence that Toll pathway was a baseline immune system established in early larval stages. Genes encoding pathogen pattern-recognition proteins (LGBP, PL5-2 and c-type lectin), prophenoloxidase system (PPAE2, PPAF2 and serpin), antimicrobial peptides (crustin and antiviral protein), blood clotting system (hemolymph clottable protein) and heat shock protein (HSP70) were expressed as they developed further, suggesting that these immune defense mechanisms were established in later larval stages.