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Molecular and Cellular Biology, October 2000, p. 7634-7642, Vol. 20, No. 20
Department of Control of Genetic Processes,
Institute of Gene Biology, Russian Academy of Sciences, 117334 Moscow, Russia
Received 19 June 2000/Accepted 31 July 2000
Drosophila telomeres contain arrays of the
retrotransposonlike elements HeT-A and TART.
Their transposition to broken chromosomal termini has been implicated
in chromosome healing and telomere elongation. The HeT-A
element is attached by its 3' end, which contains the promoter. To
monitor the behavior of HeT-A elements, we used the yellow
gene with terminal deficiencies consisting of breaks in the
yellow promoter region that result in the
y-null phenotype. Attachment of the HeT-A
element provides the promoterless yellow gene with a
promoter that activates yellow expression in bristles. The
frequency of HeT-A transpositions to the yellow terminal deficiency depends on the genotype of the line and varies from
2 × 10
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Attachment of HeT-A Sequences to
Chromosomal Termini in Drosophila melanogaster May
Occur by Different Mechanisms
3 to less than 2 × 10
5.
Loss of the attached HeT-A due to incomplete replication at the telomere leads to inactivation of yellow expression,
which is restored by attachment of a new HeT-A element
upstream of yellow. New HeT-A additions occur
at a frequency of about 1.2 × 10
3. Short DNA
attachments are generated by gene conversion using the homologous
telomeric sequences as templates. Longer DNA attachments are generated
either by conventional transposition of an HeT-A element to
the chromosomal terminus or by recombination between the 3' terminus of
telomeric HeT-A elements and the receding end of
HeT-A attached to the yellow gene.
*
Corresponding author. Mailing address: Institute of
Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 117334 Moscow, Russia. Phone: 7-095-1359734. Fax: 7-095-1354105. E-mail:
pgeorg&biogen.msk.su and
gpg{at}mx.ibg.relarn.ru.
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