title: Schistosomin from the snail Biomphalaria glabrata: expression studies suggest no involvement in trematode-mediated castration.
abstract: By inhibiting reproductive hormones, the neuropeptide schistosomin produced by the snail Lymnaea stagnalis plays an essential role in parasitic castration mediated by the schistosome parasite Trichobilharzia ocellata during late stage infection. Here we report on the presence and expression of schistosomin in the snail Biomphalaria glabrata, a prominent intermediate host of the parasite Schistosoma mansoni, one of the causative agents of human schistosomiasis. The deduced amino acid (aa) sequences from complementary DNAs (cDNAs) from B. glabrata contain a 17 aa signal peptide and a 79 aa mature peptide with 62 -- 64% identity to schistosomin from L. stagnalis. Ontogenic expression at the protein and mRNA levels showed that schistosomin was in higher abundance in embryos and juveniles relative to mature snails, suggesting that schistosomin is likely involved in developmental processes, not in reproduction. Moreover, expression data demonstrated that infection with two different digenetic trematodes, S. mansoni and Echinostoma paraensei, did not provoke elevated expression of schistosomin in B. glabrata from early stage infection (4 days post-exposure; dpe) to patent infection (up to 60dpe), by which time parasitic castration has been accomplished. In conclusion, our data suggest that a role of schistosomin in parasitic castration cannot be established in B. glabrata infected with either of two trematode species.
authors.affiliation: Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA. zhangsm@unm.edu
authors.forename: Si-Ming
authors.initials: SM
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Nian
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.forename: Eric S
authors.initials: ES
authors.lastname: Loker
authors.forename: Coen M
authors.initials: CM
authors.lastname: Adema
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001700:Biomphalaria / Q000235:genetics / Q000378:metabolism* / Q000469:parasitology*; D015153:Blotting, Western; D004926:Escherichia coli / Q000235:genetics; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D036341:Intercellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009919:Orchiectomy; D010455:Peptides / Q000378:metabolism*; D011994:Recombinant Proteins; D016415:Sequence Alignment; D014200:Trematoda / Q000502:physiology*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D011994:Recombinant Proteins; C054640:schistosomin