Thesis (M.Sc.)--Chulalongkorn University, 2011

Black tiger shrimp (Penaeus monodon) was the most important economic aquatic animals in Thailand. However, the production loss of shrimps caused by viral diseases are still remained a major problem of shrimp farming industries. One of the key to overcome this loss is to understand shrimp immunity. Shrimps immunity relied on innate immune response. Toll or Toll-like receptors have been identified in fruit fly, nematode, and human. Recently, Toll receptors in penaeid shrimps have been discovered and studied their functions, except in black tiger shrimp. The objectives of this study are to clone the full length cDNA of PmToll receptor and characterize its function. The full-length cDNA of PmToll receptor consists of 4,129 nucleotides, which can be encoded to 931 amino acids. PmToll receptor contains the distinct structure/functional motif of the Toll receptor family including an extracellular domain, which consists of leucine-rich repeats (LRRs) flanked by cysteine-rich motifs, a single-pass transmembrane portion, and a cytoplasmic Toll/Interleukin-1 receptor (TIR) domain. The expression of PmToll can be found in several tissues such as gill, heart, lymphoid, muscle, nerve, pleopod, stomach and but less expression can also be found in the hepatopancreas. The analysis of phylogenetic relationship between the deduced amino acid of PmToll and other organisms’ Toll suggests that PmToll is closely related to other shrimp Tolls, especially FcToll. The function of PmToll in black tiger shrimp was studied, by knocking down PmToll using dsRNA-PmToll. The result suggested that the PmToll cannot be suppressed in black tiger shrimp.