DNA in centromeres of Chironomus pallidivittatus
Research output: Thesis › Doctoral Thesis (compilation)
The centromeres of most higher eukaryotes are embedded within large regions of constitutive heterochromatin and consist of large quantities of highly repetitive DNA. Transposable elements are also found in these regions. However, a detailed mapping of such elements or other nonsatellite DNA embedded within the large blocks of centromeric repetitive DNA has not yet been made. The dipteran Chironomus pallidivittatus provides an excellent experimental model for study of centromeric DNA, because its small genome size, well defined centromeric region and a small number of chromosomes which can develop to giant chromosomes and easily be manipulated using microdissection techniques. We found two types of tandem repetitive DNA which are specific for the centromeric regions of C. pallidivittatus. One type made up of 155 bp repeat unit is present in about 1300 copies in all four centromeres. Another type of repeat, 375 bp long, is restricted to the centromere 3 and is represented by 100 copies. We have also found a third kind of centromeric DNA, a SINE-like mobile element, termed Cp1. A detailed study of the two types of centromeric tandem repeats showed that they share some properties, although they show little sequence homology and it is possible that 375 bp repeats constitute a functional alternative to 155 bp repeats. The Cp1 inserts into 155 bp and 375 bp tandem repeats with identical nine base pairs of target site duplications. It appears to be uniform in the centromeric regions, contrasting with polymorphic and degenerated forms outside of the centromere. The intracentromeric Cp1 contains a large palindrome structure at its left part and a pol III transcription unit at the right end. The palindrome provides specific binding sites for nuclear proteins. Some features of Cp1 have parallels in the functionally identified CEN DNA from yeasts, showing that Cp1 deserves further studies related to a possible functional role.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Award date||1998 Jun 6|
|State||Published - 1998|
Defence details Date: 1998-06-06 Time: 10:15 Place: Lecture hall in Department of Genetics, Sölvegatan 29, 223 62, Lund External reviewer(s) Name: Traut, Walter Title: Professor Affiliation: Medicine university of Lübeck, Germany --- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Genetics (Closed 2011) (011005100)