Abstract
A family of highly repetitive DNA elements, the Cla-elements, is present in the genomes of the two sibling speciesChironomus th. thummi andCh. th. piger. These Cla-elements are organized in large tandem repetitive clusters as well as occuring as interspersed monomeric elements, in both subspecies. The analysis of a monomeric Cla-element and several kilobases of its flanking sequences fromCh. th. piger revealed that the short Cla-elements are cotransposed together with adjacent DNA. We found the same association of Cla-elements with specific flanking DNA in clones obtained from the rDNA ofCh. th. thummi and from nonribosomal Cla-DNA ofCh. th. piger. The Cla-element-flanking DNA is clearly also repetitive, but mainly of inter-spersed organization.