title: Clustered and interspersed repetitive DNA sequence family of Chironomus. The nucleotide sequence of the Cla-elements and of various flanking sequences.
abstract: The nucleotide sequence of more than 30 cloned members of the clustered and interspersed repetitive Cla-sequence family present in the genome of various chironomids has been determined. In four cloned Cla-element clusters, the 5' and 3'-flanking sequences including the junctions between the Cla-element clusters and the flanking sequences were also sequenced. The repetitive Cla-elements, which are able to transpose under certain circumstances, have a monomer length ranging from 110 to 119 base-pairs, are very A + T-rich (greater than 80% A + T) and display numerous palindromic sequences. The Cla-elements are organized in small (4 elements) to medium-sized (greater than 30 elements) tandem repetitive clusters, which are dispersed over more than 200 sites of the chromosomes of Chironomus thummi thummi, including the non-transcribed spacer of the ribosomal DNA repeating unit. The tandem repetitive Cla-elements show anomalous behaviour during high-percentage polyacrylamide gel electrophoresis, indicating a bent or globular conformation. The flanking sequences are also repetitive, but the sequenced parts did not reveal any tandem repetitive arrangement. Near the junctions of the Cla-element clusters and the flanking sequences, short duplications are found, ranging from 5 to 12 bases, present in both sides of the Cla-element clusters. The Cla-elements might be involved in the hybrid dysgenesis phenomenon that is observed after crossings between the two subspecies Ch. th. thummi and Ch. th. piger.
mesh_terms: D000818:Animals; D001345:Autoradiography; D001483:Base Sequence; D002683:Chironomidae / Q000235:genetics*; D002875:Chromosomes; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D004262:DNA Restriction Enzymes; D004175:Diptera / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D006824:Hybridization, Genetic; D009690:Nucleic Acid Conformation; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004247:DNA; D004262:DNA Restriction Enzymes