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Repetitive DNA in search of a function - a study of telomeric and centromeric sequences in Chironomus

Castillejo-Lopez, Casimiro LU (1998)
Abstract
Repetitive DNA is quantitatively the main component of telomeres and centromeres, structures responsible for maintenance of the eukaryotic chromosome. The telomere is the specialized nucleoprotein complex that terminates linear chromosomes. In most species the DNA component consists of short repeats which are generated by the enzyme complex telomerase. However, there are important exceptions such as the Drosophila melanogaster telomeres which are elongated by retrotransposons and, as documented in the present thesis, a third telomeric system in Chironomus pallidivittatus in the form of arrays of 340 bp long complex tandem repeats which extend to the end of their chromosomes. Complex repeats are not elongated by telomerase and one aim of my... (More)
Repetitive DNA is quantitatively the main component of telomeres and centromeres, structures responsible for maintenance of the eukaryotic chromosome. The telomere is the specialized nucleoprotein complex that terminates linear chromosomes. In most species the DNA component consists of short repeats which are generated by the enzyme complex telomerase. However, there are important exceptions such as the Drosophila melanogaster telomeres which are elongated by retrotransposons and, as documented in the present thesis, a third telomeric system in Chironomus pallidivittatus in the form of arrays of 340 bp long complex tandem repeats which extend to the end of their chromosomes. Complex repeats are not elongated by telomerase and one aim of my work has therefore been to elucidate possible regeneration mechanisms for telomeres with such repeats. I have obtained evidence for DNA increase through DNA sequences of nontelomeric origin being inserted into the telomeric repeat array via gene conversion. Immunolocalization of reverse transcriptase related proteins in the telomeric puff of the related species C. thummi revealed, on the other hand, a possible link between the regeneration of Chironomus telomeric complex repeats and mechanisms used by other eukaryotes. Only seven of the eight pairs of chromosome termini in C. pallidivittatus have 340 bp repeats. The remaining telocentric end contains another repeat, the centromeric 155 bp unit, probably extending to the chromosome end. In the arrays of this repeat, a putative homologue of the mammalian centromeric CENP-B box has been found and characterized. Its interspersed distribution and its surrounding direct repeats suggest a mobile origin. It is present in different recombined forms, which could be related to a role in recombination as has been suggested for the human CENP-B box. (Less)
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author
opponent
  • Prof Landegren, Ulf, Dept. of medical genetics. Uppsala. Sweden
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Chironomus, CENP-B box, mobile elements, reverse transcriptase, gene conversion, satellite, repetitive DNA, Telomere, centromere, Genetics, cytogenetics, Genetik, cytogenetik
pages
140 pages
publisher
Department of Genetics, Lund University
defense location
Geniska inst. Lund
defense date
1998-10-28 10:15
external identifiers
  • Other:ISRN: LUNDBDS/NBGE 1031/001-140 (1998)
language
English
LU publication?
yes
id
27440069-49df-4b4d-a26b-a36785221639 (old id 39029)
date added to LUP
2007-06-20 12:19:34
date last changed
2016-09-19 08:45:04
@misc{27440069-49df-4b4d-a26b-a36785221639,
  abstract     = {Repetitive DNA is quantitatively the main component of telomeres and centromeres, structures responsible for maintenance of the eukaryotic chromosome. The telomere is the specialized nucleoprotein complex that terminates linear chromosomes. In most species the DNA component consists of short repeats which are generated by the enzyme complex telomerase. However, there are important exceptions such as the Drosophila melanogaster telomeres which are elongated by retrotransposons and, as documented in the present thesis, a third telomeric system in Chironomus pallidivittatus in the form of arrays of 340 bp long complex tandem repeats which extend to the end of their chromosomes. Complex repeats are not elongated by telomerase and one aim of my work has therefore been to elucidate possible regeneration mechanisms for telomeres with such repeats. I have obtained evidence for DNA increase through DNA sequences of nontelomeric origin being inserted into the telomeric repeat array via gene conversion. Immunolocalization of reverse transcriptase related proteins in the telomeric puff of the related species C. thummi revealed, on the other hand, a possible link between the regeneration of Chironomus telomeric complex repeats and mechanisms used by other eukaryotes. Only seven of the eight pairs of chromosome termini in C. pallidivittatus have 340 bp repeats. The remaining telocentric end contains another repeat, the centromeric 155 bp unit, probably extending to the chromosome end. In the arrays of this repeat, a putative homologue of the mammalian centromeric CENP-B box has been found and characterized. Its interspersed distribution and its surrounding direct repeats suggest a mobile origin. It is present in different recombined forms, which could be related to a role in recombination as has been suggested for the human CENP-B box.},
  author       = {Castillejo-Lopez, Casimiro},
  keyword      = {Chironomus,CENP-B box,mobile elements,reverse transcriptase,gene conversion,satellite,repetitive DNA,Telomere,centromere,Genetics,cytogenetics,Genetik,cytogenetik},
  language     = {eng},
  pages        = {140},
  publisher    = {ARRAY(0x9891068)},
  title        = {Repetitive DNA in search of a function - a study of telomeric and centromeric sequences in Chironomus},
  year         = {1998},
}