Ohresser M. auteur aut IRD Borsa Philippe auteur aut IRD Delsert C. auteur aut IRD text journalArticle eng text/pdf reformatted digital access A novel intron-length polymorphism at the actin gene locus mac-1 is here reported and used as a genetic marker for population studies in mussels of the genus Mytilus. Two closely related genes subsequently identified as alleles, mac-1a1, and mac-1b1, from a genomic library of M. galloprovincialis were partially cloned and sequenced. They mainly differed from each other by a 65-bp insertion within their first intron. Polymerase chain reaction (PCR) primers were designed outside the insertion. The PCR analysis of 166 individual mussels from M. galloprovincialis and M. edulis populations revealed three size-classes of alleles or allelomorphs, two of which were of the expected sizes for mac-1a1 and mac-1b1. One allelomorph was absent from M. edulis samples, although it was present at substantial frequencies in M. galloprovincialis populations. The frequencies of the two other allelomorphs significantly differed between M. galloprovincialis and M. edulis populations. The comparison of six mac-1 intron sequences over 277 bp showed at once that allelomorphs encompassed alleles differing from one another by substantial numbers of mutations, and that identical alleles were present in both M. galloprovincialis and M. edulis individuals, a probable result of the recent introgression between the two species. (Résumé d'auteur) specialized INVERTEBRE AQUATIQUE POLYMORPHISME GENETIQUE TAXONOMIE 034BIOINV03 6 2 123-130 1997 https://www.documentation.ird.fr/hor/fdi:010011003 [F B010011003] https://www.documentation.ird.fr/hor/fdi:010011003 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_6/b_fdi_47-48/010011003.pdf IRD - Base Horizon / Pleins textes 1997-09-22 2018-04-04 fdi:010011003 fre