The Penaeus monodon Chitinase 1 Gene Is Differentially Expressed in the Hepatopancreas During the Molt Cycle.
We have isolated a full-length chitinase complementary DNA from the tiger shrimp Penaeus monodon that encodes a 621 amino acid protein possessing the functional domains of the chitinase protein family. The Penaeus monodon chitinase 1 (PmChi-1) gene product is 81.8% identical to a chitinase 1 protein expressed in the hepatopancreas of Penaeus japonicus. Analysis by reverse transcription-polymerase chain reaction (RT-PCR) indicates that PmChi-1 messenger RNA is detectable in the hepatopancreas and the gut. PmChi-1 expression during the molt cycle fluctuates markedly, with lowest mRNA levels at stages A(1), C, and D(3); there is a dramatic increase in transcript abundance at the D(2) stage. Using the same tissues and molt stages, RT-PCR analyses of genes encoding other digestive enzymes (trypsin, chymotrypsin, and cathepsin L), a muscle structural protein (tropomyosin II), and housekeeping proteins (elongation factor II and GTP-binding protein) indicate that PmChi-1 is expressed in a distinct tissue-specific and stage-specific manner. The other digestive enzyme genes are expressed in a similar spatiotemporal pattern, but none exhibited a dramatic increase in transcript abundance at stage D(2). Increased expression of PmChi-1 at D(2) suggests that hepatopancreas-expressed chitinase is involved in the degradation of endogenous chitin in the gut peritrophic membrane prior to molting.
Tan
SH
CSIRO Division of Tropical Agriculture, Molecular Animal Genetics Centre, Level 3, Gehrmann Laboratories, Research Road, University of Queensland, St. Lucia, Brisbane, Queensland Q4072, Australia
Degnan
BM
Lehnert
SA