Molecular Characterisation, Ontogeny and Tissue Level Expression Analysis of a Downstream Signalling Molecule of the Toll-Pathway, Dorsal (An NF-ΚB Homologue) in Black Tiger Shrimp (Penaeus monodon)

Abstract

Innate immunity is the first-line of host defense in multi-cellular organisms against pathogens. Innate immune responses are regulated by immune signalling pathways where Toll and IMD (immune deficiency) pathway are the major ones. In shrimp, most homolog components of the Toll/ NF-κB-pathway of Drosophila including Toll-like receptor (TLR), MyD88, TRAF6, Tube/Pelle, Spatzle, Dorsal and Cactus have been identified. Moreover, the expression profiles of genes involved in the Toll pathway have been studied in response to various pathogens especially white spot syndrome virus (WSSV), a devastating pathogen causing huge economic losses to shrimp aquaculture. In the present study, we report partial sequence of Dorsal (NF-κB) from tiger shrimp, Penaeus monodon. The sequence obtained by partial cloning and 5'RACE consisted of 1155 nt with an ORF coding for 339aa with a conserved RHD (Rel homology domain) and an IPT (Ig-like, plexins and transcription factors) domain. Ubiquitous expression of PmDorsal was observed in healthy shrimp, with varying levels. Ontogenetic expression of this gene in different developmental stages of P. monodon was also analysed and found the highest expression of PmDorsal in Zoea 3. The expression of PmDorsal in different larval stages and tissues of P. monodon indicated that it might play potential role in some of the physiological functions during development and also in the immune response of shrimp against diverse pathogens.