title: Cloning and characterization of a highly conserved satellite DNA from the mollusc Mytilus edulis.
abstract: Sperm DNA of the common mussel, Mytilus edulis, has been found to contain a highly repeated sequence identifiable upon restriction with the endonuclease ApaI. The repetitive nucleotide (nt) sequence amounts to 0.63% of the mollusc genome with an estimated copy number of 5.4 x 10(4) copies per haploid complement. The monomer unit with a 173-bp repeat length has been cloned. Progressive DNA digestions with ApaI yield ladder-like banding patterns on agarose gels, indicating that the repeated elements are tandemly arranged in the genome and therefore represent a sequence of satellite DNA. The degree of internal redundancy of the reiterated sequence is deemed negligible, since nt sequence analysis of a random set of cloned monomers has detected the presence of only a few direct repeats while inverted repeated motifs or any other internal substructures appear absent. The homologies found among cloned monomers are strikingly high, averaging 95%. The results suggest that the exceptional sequence homogeneity of this satellite DNA may be attributed either to some homogenizing mechanism or to evolutionary conserved trends.
authors.affiliation: Departamento de Biología Molecular y Celular, Centro de Investigación y Desarrollo, C.S.I.C., Barcelona, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Ruiz-Lara
authors.forename: E
authors.initials: E
authors.lastname: Prats
authors.forename: J
authors.initials: J
authors.lastname: Sainz
authors.forename: L
authors.initials: L
authors.lastname: Cornudella
mesh_terms: D000818:Animals; D001483:Base Sequence; D049872:Bivalvia / Q000235:genetics*; D003001:Cloning, Molecular; D016384:Consensus Sequence / Q000235:genetics; D004276:DNA, Satellite / Q000235:genetics*; D015252:Deoxyribonucleases, Type II Site-Specific; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004276:DNA, Satellite; D015252:Deoxyribonucleases, Type II Site-Specific; C038485:GGGCCC-specific type II deoxyribonucleases