Characterization of a highly repeated DNA family in tapetinae species (mollusca bivalvia: veneridae).

A repetitive DNA family (phBglII400) was characterized in the clam species Tapes philippinarum (Veneridae Tapetinae). The tandemly repeated sequences are AT-rich and show a mainly pericentromeric localization, as most satellite DNAs do. Sequence analysis of phBglII400 DNA family showed a high level of intraspecific homogeneity. Furthermore a 200 bp subunit motif within the 400 bp monomer was apparent as well as the existence of two main "open reading frames" along the 400 bp sequence.In order to investigate the possible distribution of this DNA family among Veneridae, Southern blot analyses were performed on genomic DNAs of Tapes decussatus, Venerupis aurea and Paphia undulata (Tapetinae), Callista chione (Pitarinae), Chamelea gallina (Chioninae) and Venus verrucosa (Venerinae). The phBglII400 family has been found in two additional Tapetinae, namely V. aurea and P. undulata, but not in T. decussatus or other analyzed species. This pattern of sat-DNA distribution supports the high level of differentiation of T. decussatus observed in the previous gene-allozyme analysis. All of these suggest a better allocation of T. decussatus to a genus different from that of T. philippinarum.