Telomeric and interstitial telomeric-like DNA sequences in Orthoptera genomes

A (TTAGG)n-specific telomeric DNA probe was hybridized to 11 orthopteroid insect genomes by fluorescence in situ hybridization. Nine different genera, mainly distributed within two evolutionary branches with male chromosome numbers 2n = 23 and 2n = 17 were included in the analysis. Telomere sequences yielded positive signals in every telomere and there was a considerable number of interstitial telomeric-like sequences, mainly located at the distal end of some, but not all, subterminal chromosome regions. One of the species, Pyrgomorpha conica, showed massive hybridization signals associated with constitutive heterochromatin. The results are discussed along two lines: (i) the chromosomal evolutionary trends within this group of insects and (ii) the putative role that ITs may play in a genome when they are considered telomere-derived, but not telomere-functional, DNA sequences.