English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Background  Big defensin is an antimicrobial peptide composed of a highly hydrophobic N-terminal region and a cationic C-terminal region containing six cysteine residues involved in three internal disulfide bridges. While big defensin sequences have been reported in various mollusk species, few studies have been devoted to their sequence diversity, gene organization and their expression in response to microbial infections.    Findings  Using the high-throughput Digital Gene Expression approach, we have identified in  Crassostrea gigas  oysters several sequences coding for big defensins induced in response to a  Vibrio  infection. We showed that the oyster big defensin family is composed of three members (named  Cg -BigDef1,  Cg -BigDef2 and  Cg -BigDef3) that are encoded by distinct genomic sequences. All  Cg -BigDefs contain a hydrophobic N-terminal domain and a cationic C-terminal domain that resembles vertebrate β-defensins. Both domains are encoded by separate exons. We found that big defensins form a group predominantly present in mollusks and closer to vertebrate defensins than to invertebrate and fungi CSαβ-containing defensins. Moreover, we showed that  Cg-BigDef s are expressed in oyster hemocytes only and follow different patterns of gene expression. While  Cg-BigDef3  is non-regulated, both  Cg-BigDef1  and  Cg-BigDef2  transcripts are strongly induced in response to bacterial challenge. Induction was dependent on pathogen associated molecular patterns but not damage-dependent. The inducibility of  Cg -BigDef1 was confirmed by HPLC and mass spectrometry, since ions with a molecular mass compatible with mature  Cg -BigDef1 (10.7 kDa) were present in immune-challenged oysters only. From our biochemical data, native  Cg -BigDef1 would result from the elimination of a prepropeptide sequence and the cyclization of the resulting N-terminal glutamine residue into a pyroglutamic acid.    Conclusions  We provide here the first report showing that big defensins form a family of antimicrobial peptides diverse not only in terms of sequences but also in terms of genomic organization and regulation of gene expression.

Big Defensins, a Diverse Family of Antimicrobial Peptides That Follows Different Patterns of Expression in Hemocytes of the Oyster Crassostrea gigas