Molecular Characterization and Gene Expression Profiling ... - CUSAT

Chapter 2
specific nature like phagocytosis, encapsulation, nodule formation, phenol-
oxidase system, reactive oxygen species and AMPs. AMPs are a major
component of the innate immune defense system in crustaceans, providing
an immediate and broad-spectrum microbicidal activity against pathogenic
microbes. They are considered as endogenous antibiotics, encoded in the
host genome directly. Most AMPs display cationic properties, have a
molecular mass less than 10 kDa, with less than 50 amino acid residues and
adopt an amphipathic structure that is believed to be essential for their
antimicrobial action. In most cases, AMPs were shown to disrupt microbial
membrane by pore formation or detergent effect and cause immediate cell
death. So far more than 800 AMPs have been isolated and more than half of
them have been isolated from Arthropods.
Among crustaceans AMPs have been isolated from artemia,
crayfishes, lobsters, crabs and prawns. AMPs including penaeidins, crustins,
astacidins and anti-lipopolysaccharide factors (ALFs) have been isolated and
characterized from many crustaceans. Among crustaceans, the first described
AMPs were the carcinins, a crustin isolated from C. maenas, and penaeidins
from L. vannamei. Among crustaceans, penaeidins are the most studied
AMPs, being isolated from more than ten penaeid prawn species. Several
ALFs and crustins have also been recently isolated and characterized in
many crustacean species including crabs, lobsters, prawns and crayfishes.
During the past several years, a variety of AMP families were characterized
from shrimps.
In penaeid shrimps, to date, three kinds of antimicrobial peptides
have been fully characterized, namely the crustins (Bartlett et al., 2002),
penaeidins and the anti-lipopolysaccharide factor (ALF) from haemocytes
(Destoumieux et al., 2001; Somboonwiwat, et al., 2005). Penaeidins constitute
an original peptide family, whose molecular structure is unique, composed
of an N-terminal proline–rich region and a C-terminal domain containing six
cysteines forming three intramolecular disulphide bridges (Yang et al., 2003).
Molecular Characterization and Gene Expression Profiling of Antimicrobial Peptides in Penaeid Shrimps
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