title: Detection and molecular cloning of highly repeated DNA in the sea cucumber sperm.
abstract: A highly reiterated sequence in the sperm DNA of the echinoderm Holothuria tubulosa has been isolated by digestion with EcoRI, and cloned in the phagemid Bluescript. The monomeric unit has a repeat length of 391 bp and is arranged in tandem. The uncloned genomic monomer as well as two independent cloned fragments have been sequenced. The repeated element constitutes about 1.8% of total Holothuria DNA which corresponds to a repetition frequency of about 1.4 x 10(5) copies per haploid complement. The repetitive sequence has a high A + T content (66.8%) characterized by scattered tracts of A and T residues with no apparent internal sub-repeats, although several inverted and direct repeats are present. Heterogeneity between monomers derived from individual clones is low, whereas sequence similarity to known repetitive elements appears to be negligible.
authors.affiliation: Unidad de Química Macromolecular del CSIC, Universitat Politécnica de Catalunya, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Sainz
authors.forename: F
authors.initials: F
authors.lastname: Azorín
authors.forename: L
authors.initials: L
authors.lastname: Cornudella
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D004262:DNA Restriction Enzymes; D004447:Echinodermata / Q000235:genetics*; D006238:Haploidy; D008297:Male; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid; D012616:Sea Cucumbers / Q000235:genetics*; D013094:Spermatozoa
chemical_list: D004247:DNA; D004262:DNA Restriction Enzymes