Abstract:
In this study, we focused on the isolation and characterization of apoptosis-related
gene(s) from the black tiger shrimp (P. monodon). In shrimp, apoptosis has been
causally implicated in the death of shrimp from infections by white spot syndrome
virus (WSSV) and yellow head virus (YHV). Several candidate shrimp apoptotic
gene(s) have been reported. From the rapid amplification of cDNA ends and EST
library of P. monodon, we obtained a gene for the enzyme shrimp nuclease, a
defender against apoptotic death (DAD1) and ribophorin I. The analysis of tissue
distribution indicated that shrimp nuclease was always restricted to only the
hepatopancreas even when the level of sensitivity was increased by using nested
RT-PCR, while DAD1 and ribophorin I showed endogenous expression in all
examined tissues. Time-course analysis of shrimp nuclease in shrimp-infected with
WSSV showed up-regulation at the early stage of infection but a return to the base
line level as the gross signs of disease developed. We concluded that this function
was involved in digestion and not in apoptosis. By contrast, DAD1 showed downregulation
and ribophorin I up-regulation after YHV challenge. These expression
patterns were similar to reports for homologues of these genes in previous reports
on apoptosis. The control of apoptosis is complex and involves the interaction of
many proteins and genes, few of which have been characterized for shrimp. Thus,
firm conclusions regarding the role of these transcripts must await the
identification/characterization of these other proteins.