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Loss of telomere function in metazoans results in catastrophic damage to the genome, cell cycle arrest, and apoptosis. Here we show that the mustard weed Arabidopsis thaliana can survive up to 10 generations without telomerase. The last five generations of telomerase-deficient plants endured increasing levels of cytogenetic damage, which was correlated with(More)
Telomere lengths and telomerase activity were studied during the development of a model dioecious plant, Melandrium album (syn Silene latifolia). Telomeric DNA consisted of Arabidopsis-type TTTAGGG tandem repeats. The terminal positions of these repeats were confirmed by both Bal31 exonuclease degradation and in situ hybridization. Analysis of terminal(More)
Telomerase is an essential enzyme that maintains telomeres on eukaryotic chromosomes. In mammals, telomerase is required for the lifelong proliferative capacity of normal regenerative and reproductive tissues and for sustained growth in a dedifferentiated state. Although the importance of telomeres was first elucidated in plants 60 years ago, little is(More)
The Ku70/80 heterodimer is a critical component of the non-homologous end-joining (NHEJ) pathway and of the telomere cap in yeast and mammals. We report the molecular characterization of the KU70 and KU80 genes in Arabidopsis and describe the consequences of a Ku70 deficiency. Arabidopsis KU70/80 genes are ubiquitously expressed and their products form(More)
The Mre11/Rad50/Nbs1 complex is involved in many aspects of chromosome metabolism. Aberrant function of the complex is associated with defects in the DNA checkpoint, double-strand break repair, meiosis, and telomere maintenance. In this article, we report the consequences of Mre11 dysfunction for the stability of mitotic and meiotic chromosomes in(More)
Changes in telomere lengths and telomerase activity in tobacco cells were studied during dedifferentiation and differentiation; leaf tissues were used to initiate callus cultures, which were then induced to regenerate plants. While no significant changes in the range of telomere lengths were observed in response to dedifferentiation and differentiation,(More)
End-to-end fusion of critically shortened telomeres in higher eucaryotes is presumed to be mediated by nonhomologous end-joining (NHEJ). Here we describe two PCR-based methods to monitor telomere length and examine the fate of dysfunctional telomeres in Arabidopsis lacking the catalytic subunit of telomerase (TERT) and the DNA repair proteins Ku70 and(More)
Chromosome termini form a specialized type of heterochromatin that is important for chromosome stability. The recent discovery of telomeric RNA transcripts in yeast and vertebrates raised the question of whether RNA-based mechanisms are involved in the formation of telomeric heterochromatin. In this study, we performed detailed analysis of chromatin(More)
Telomeres in mammals and plants are protected by the terminal t loop structure, the formation of which parallels the first steps of intrachromatid homologous recombination (HR). Under some circumstances, cells can also utilize an HR-based mechanism (alternative lengthening of telomeres [ALT]) as a back-up pathway for telomere maintenance. We have found that(More)
A number of X chromosome DNA sequences have been isolated from a dioecious plant, Melandrium album (syn. Silene latifolia),using chromosome microdissection followed by degenerate oligonucleotide-primed polymerase chain reaction (DOP–PCR) amplification. Six DNA clones were selected and further characterized by DNA/DNA hybridization techniques to check their(More)