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Using slot-blot and fluorescent in situ hybridization (FISH), we found no evidence for the presence of the Arabidopsis-type telomeric sequence (TTTAGGG)n at the chromosome termini in any of the Cestrum species we investigated. Probing for the human-type telomere (TTAGGG)n also revealed no signal. However, polymerase chain reaction experiments indicated that there are short lengths of the sequence TTTAGGG dispersed in the genome but that these sequences are almost certainly too short to act as functional telomeres even if they were at the chromosome termini. An analysis of related genera Vestia and Sessea indicates that they too lack the Arabidopsis-type telomere, and the sequences were lost in the common ancestor of these genera. We found that the Cestrum species investigated had particularly large mean chromosome sizes. We discuss whether this is a consequence of alternative telomere end maintenance systems.
Sýkorová et al. (Wed,) studied this question.