Sperm surface beta-N-acetylhexosaminidases are among the molecules mediating early gamete interactions in invertebrates and vertebrates, including man. The plasma membrane of Drosophila spermatozoa contains two beta-N-acetylhexosaminidases, DmHEXA and DmHEXB, which are required for egg fertilization. Here, we demonstrate that three putative Drosophila melanogaster genes predicted to code for P-N-acetylhexosaminidases, Hexo1, Hexo2, and fdl, are all expressed in the male germ line. fdl codes for a homolog of the beta subunit of the mammalian lysosomal beta-N-acetylhexosaminidase Hex A. Hexo1 and Hexo2 encode two homologs of the P-subunit of all known beta-N-acetylhexosaminidases, which we have named beta, and beta 2, respectively. Immunoblot analysis of sperm proteins indicated that the gene products associate in different heterodimeric combinations forming DmHEXA, with an 42 structure, and DmHEXB, with a beta(1)beta(2) structure. Immunofluorescence demonstrated that all the gene products localized to the sperm plasma membrane. Although none of the genes was testis-specific, fdl was highly and preferentially expressed in the testis, whereas Hexo1 and Hexo2 showed broader tissue expression. Enzyme assays carried out on testis and on a variety of somatic tissues corroborated the results of gene expression analysis. These findings for the first time show the in vivo expression in insects of genes encoding beta-N-acetylhexosaminidases, the only molecules so far identified as involved in sperm/egg recognition in this class, whereas in mammals, the organisms where these enzymes have been best studied, only two types of polypeptide chains forming dimeric functional beta-N-acetylhexosaminidases are present in Drosophila three different gene products are available that might generate numerous dimeric isoforms.
Identification and expression analysis of Drosophila melanogaster genes encoding b-hexosaminidases of the sperm plasma membrane / F. Cattaneo, M.E. Pasini, J. Intra, M. Matsumoto, F. Briani, M. Hoshi, M.E. Perotti. - In: GLYCOBIOLOGY. - ISSN 0959-6658. - 16:9(2006 Sep), pp. 786-800. ((Intervento presentato al 19. convegno European Drosophila Research Conference tenutosi a Eger nel 2005.
|Titolo:||Identification and expression analysis of Drosophila melanogaster genes encoding b-hexosaminidases of the sperm plasma membrane|
PASINI, MARIA ENRICA (Secondo)
|Parole Chiave:||fertilization; gamete interactions; fdl; Hexo1; Hexo2|
|Settore Scientifico Disciplinare:||Settore BIO/06 - Anatomia Comparata e Citologia|
Settore BIO/18 - Genetica
|Data di pubblicazione:||set-2006|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1093/glycob/cwl007|
|Appare nelle tipologie:||01 - Articolo su periodico|