Nucleotide sequence of satellite DNA contained in the eliminated genome of<i>Ascaris lumbricoides</i>

Abstract

Several restriction endonuclease fragments isolated from highly repetitive satellite DNA of the chromatin eliminating nematode Ascaris lumbricoides var. suum have been cloned. Each type of restriction fragment corresponds to a different variant of the same related ancestral sequence. These variants differ by small deletions, insertions and single base substitutions. Restriction and DBM blot analyses show that members of the same variant class are tandemly linked and therefore are physically separated from other variant classes. A comparison of all the determined sequences establishes a 121 bp long and AT rich consensus sequence. There is evidence for an internal short range periodicity of 11 bp length, indicating that the Ascaris satellite initially may have evolved from an ancestral undecamer sequence. The satellite DNA sequences are mostly but not entirely eliminated from the presumptive somatic cells during chromatin diminution. We have no evidence for transcriptional activity of satellite DNA at any stage or tissue analyzed.