title: Toll-like receptor of mud crab, Scylla serrata: molecular characterisation, ontogeny and functional expression analysis following ligand exposure, and bacterial and viral infections.
abstract: Toll-like receptors are sentinels of innate immune system, which recognise pathogen-associated molecular patterns, and subsequently activate production of antimicrobial peptides to contain the infection. In the present study, we cloned and characterised a Toll gene from Scylla serrata (SsToll) encoding 1005 amino acids with typical Toll-like receptor domain topology. Phylogenetic analysis revealed that it belongs to insect-type invertebrate Toll family showing 100 % identity with Scylla paramamosain (SpToll). The expression pattern of mRNA in different tissues indicated that SsToll is constitutively expressed in all the tissues examined, with varying expression levels. The expression was also detected in all the life-stages (egg, zoea stages 1-5, megalopa and crab instar) with the highest level observed in zoea 2. In-vitro studies using crab haemocyte culture demonstrated that SsToll transcripts are distinctly modulated in response to ligands such as peptidoglycan and lipopolysaccharide at all time-points. A significant change in SsToll expression was also noticed in haemocytes exposed to poly I:C (3-9 h). On the contrary, the transcription level of SsToll in response to white spot syndrome virus (WSSV) challenge was noticeably different. The change in expression in vitro was not significant at early time-points until 3 h; the transcripts showed a significant up-regulation commencing from 6 h, but not beyond 12 h. However, in vivo expression was unaffected at early time-points of WSSV challenge (until 12 h) and a gradual up-regulation was detected at 24 h. In-vivo challenge with Vibrio parahaemolyticus resulted in delayed up-regulation of the gene. The results obtained in the present study suggest that SsToll might be involved in the innate immunity of mud crab.
authors.affiliation: Central Institute of Fisheries Education, Versova, Andheri West, Mumbai, 400061, India.
authors.forename: R
authors.initials: R
authors.lastname: Vidya
authors.forename: Anutosh
authors.initials: A
authors.lastname: Paria
authors.forename: A
authors.initials: A
authors.lastname: Deepika
authors.forename: K
authors.initials: K
authors.lastname: Sreedharan
authors.forename: M
authors.initials: M
authors.lastname: Makesh
authors.forename: C S
authors.initials: CS
authors.lastname: Purushothaman
authors.forename: Aparna
authors.initials: A
authors.lastname: Chaudhari
authors.forename: P
authors.initials: P
authors.lastname: Gireesh Babu
authors.forename: K V
authors.initials: KV
authors.lastname: Rajendran
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003386:Brachyura / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology / Q000821:virology; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D054884:Host-Pathogen Interactions / Q000235:genetics; D008024:Ligands; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D051193:Toll-Like Receptors / Q000235:genetics* / Q000378:metabolism
chemical_list: D008024:Ligands; D051193:Toll-Like Receptors