title: Characterization of immune genes from the schistosome host snail Biomphalaria glabrata that encode peptidoglycan recognition proteins and gram-negative bacteria binding protein.
abstract: Peptidoglycan (PGN) recognition proteins (PGRPs) and gram-negative bacteria binding proteins (GNBPs) play an essential role in Toll/Imd signaling pathways in arthropods. The existence of homologous pathways involving PGRPs and GNBPs in other major invertebrate phyla such as the Mollusca remains unclear. In this paper, we report four full-length PGRP cDNAs and one full-length GNBP cDNA cloned from the snail Biomphalaria glabrata, the intermediate host of the human blood fluke Schistosoma mansoni, designated as BgPGRPs and BgGNBP, respectively. Three transcripts are generated from a long form PGRP gene (BgPGRP-LA) by alternative splicing and one from a short form PGRP gene (BgPGRP-SA). BgGNBP encodes a putative secreted protein. Northern blots demonstrated that expression of BgPGRP-SA and BgGNBP was down-regulated in B. glabrata at 6 h after exposure to three types of microbes. No significant changes in expression were observed in snails at 2 days post-exposure (dpe) to the trematodes Echinostoma paraensei or S. mansoni. However, up-regulation of BgPGRP-SA in M line snails at later time points of infection with E. paraensei (i.e., 12 and 17 dpe) was observed. Our study revealed that exposure to either microbes or trematodes did not alter the expression levels of BgPGRP-LAs, which were consistently low. This study provides new insights into the potential pathogen recognition capabilities of molluscs, indicates that further studies of the Toll/Imd pathways in this phylum are in order, and provides additional ways to judge the importance of this pathway in the evolution of internal defense across the animal phyla.
authors.affiliation: Center for Evolutionary and Theoretical Immunology, MSC03 2020, University of New Mexico, Albuquerque, NM 87131, USA. zhangsm@unm.edu
authors.forename: Si-Ming
authors.initials: SM
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Zeng
authors.forename: Eric S
authors.initials: ES
authors.lastname: Loker
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001700:Biomphalaria / Q000235:genetics* / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology; D002352:Carrier Proteins / Q000235:genetics* / Q000276:immunology; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004199:Disease Vectors; D004449:Echinostoma / Q000276:immunology; D004451:Echinostomiasis / Q000635:transmission; D015870:Gene Expression; D006090:Gram-Negative Bacteria / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012550:Schistosoma mansoni / Q000276:immunology; D012555:Schistosomiasis mansoni / Q000635:transmission; D017386:Sequence Homology, Amino Acid