CHARACTERIZATION OF A HIGHLY REPEATED DNA FAMILY IN TAPETINAE SPECIES(MOLLUSCA-BIVALVIA, VENERIDAE)

A repetitive DNA family (phBg/l 1400) was characterized in the clam sp ecies 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 phBg/l 1400 DNA famil y 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 sequen ce. In order to investigate the possible distribution of this DNA fami ly among Veneridae, Southern blot analyses were performed on genomic D NAs of Tapes decussatus, Venerupis aurea and Paphia undulata (Tapetina e), Callista chione (Pitarinae), Chamelea gallina (Chioninae) and Venu s verrucosa (Venerinae). The phBg/l 1400 family has been found in two additional Tapetinae, namely V. aurea and P. undulata, but not in T. d ecussatus or other analyzed species. This pattern of sat-DNA distribut ion supports the high level of differentiation of T decussatus observe d in the previous gene-allozyme analysis. All of these suggest a bette r allocation of T. decussatus to a genus different from that of T phil ippinarum.