Molecular Characterization and Gene Expression Profiling ... - CUSAT

3.1. Introduction
Chapter 3
The Indian white shrimp, F. indicus is the most dominant shrimp
species in the shallow water shrimp fishery along the west and east coast of
India. F. indicus is an important shrimp species which is cultivated in Pokkali
paddy fields (paddy-cum-shrimp farming) practiced in the wetlands of
Kerala. Antimicrobial peptides (AMPs) widely distributed in the whole
living kingdom, play an important role in the immunological defense
especially in those organisms which lack adaptive immunity (Dimarq et al.,
1998; Bulet et al., 1999., Destoumieux et al., 2000a; Zasloff, 2002; Boman, 2003;
Tincu and Taylor, 2004; Vargas-Albores et al., 2004; Cuthbertson et al., 2008).
In penaeid shrimps, four main families of AMPs have been currently
described and characterized from the haemocytes: penaeidins, crustins, anti-
lipopolysaccharide factors (ALFs) and lysozymes. Penaeidins are mainly
active against gram-positive bacteria, filamentous fungi (Destoumieux et al.,
1999), viruses and protozoans (Bachere, 2003). Whereas ALFs have a broader
antimicrobial spectrum, including gram-negative bacteria (Somboonwiwat et
al., 2005; de la Vega et al., 2008). Conversely, crustins are reported to have a
more-restricted activity spectrum, affecting mainly marine gram-positive
bacteria (Relf et al., 1999; Bartlett et al., 2002; Zhang et al., 2007). A detailed
literature survey on the AMPs in penaeid shrimps is given in chapter 2.
Though studies have been carried out for unraveling the
biochemical aspects of defense mechanisms in F. indicus, no works have
been carried out on AMPs in this species. So far there are no reports on
AMP molecules from F. indicus. Discovery of new AMPs in F. indicus will
Molecular Characterization and Gene Expression Profiling of Antimicrobial Peptides in Penaeid Shrimps
186