Antilipopolysaccharide factor (ALF) of mud crab Scylla paramamosain: Molecular cloning, genomic organization and the antimicrobial activity of its synthetic LPS binding domain

Molecular cloning, genomic organization and functional analysis of an anti-lipopolysaccharide factor from Chinese mitten crab Eriocheir sinensis

“…Considering the constitutively expression of EsALF in haemocytes, the hybrid signals in heart were probably derived from insignificant numbers of contaminant circulating haemocytes. The high expression level of EsALF in haemocytes and gonad was consistent with the results from other arthropods, where haemocytes were the major sites of AMPs synthesis and intestine or gonad was the secondary expression site for AMPs [17,24]. But the present results were not concordant to those from M. japonicus, where ALF could be detected in all tissues including haemocytes, lymphoid organs, hearts, intestines and gills.…”

“…The untreated crabs and crabs that received an injection of 50 ml PBS were used as the blank group and the control group, respectively. The injected crabs were returned to water tanks and three individuals were randomly collected at 2,4,6,8,12,16,24,32,48 and 72 h post-injection. The haemolymphs from the blank, control and challenge groups were collected using a syringe from cheliped in an equal volume of anticoagulant modified Alsever solution (27 mM sodium citrate, 336 mM NaCl, 115 mM glucose, 9 mM EDTA, pH 7.0) [27], and centrifuged at 1000g, 4 1C for 10 min to harvest the haemocytes.…”

“…Subsequent studies indicated that ALF from L. polyphemus exhibited strong antibacterial activity against Gram-negative R-type bacteria through neutralizing the lipid A, a common toxic moiety of LPS [21,22], and also the inhibitory effect on the growth of Gram-positive bacteria. Afterward, similar proteins were identified from the haemocytes of Litopenaeus vannamei [15], T. tridentatus [20], Penaeus monodon [17,18], Fenneropenaeus chinensis [9], Marsupenaeus japonicus [16], Pacifastacus leniusculus [23], and Scylla paramamosain [24], etc. The expression profile of ALFs indicated that the mRNA transcripts for the protein could be induced by Vibrio infection [9,18] or LPS administration [16], suggesting their crucial roles in crustacean innate immunity.…”

Two isoforms of anti-lipopolysaccharide factors identified and characterized from the hemocytes of portunid crabs, Portunus pelagicus and Scylla tranquebarica

“…The mature peptides of PpALF2 and StALF contained the two characteristic conserved cysteine residues forming a disulphide loop, which possess a cluster of positive charges within it. This region of the mature peptide is defined as the LPS-binding domain (Imjongjirak et al, 2007). These conserved cysteine residues were found at the positions C 29 and C 50 in PpALF2 and StALF (Fig.…”

“…Synthetic peptides, corresponding to the ALF putative LPS-binding domain of Limulus have proved to possess an efficient LPS neutralizing activity (Nagoshi et al, 2006). Likewise, similar synthetic peptides, based on ALF sequences of crustaceans have also showed potent antimicrobial activity (Imjongjirak et al, 2007).…”