Presence of a functional (TTAGG)n telomere-telomerase system in aphids

The structure of the telomeres of four aphid species (Acyrthosiphon pisum, Megoura viciae, Myzus persicae and Rhopalosiphum padi) has been evaluated by Southern blotting and fluorescent in situ hybridization. This revealed that each chromosomal end consists of the (TTAGG)n repeat. The presence of a telomerase coding gene has been successively verified in the A. pisum genome, revealing that aphid telomerase presents a sequence identity ranging from 12 to 18% with the invertebrate and vertebrate homologues and possesses the two main domains involved in telomerase activity. Interestingly, telomerase expression has been verified in different somatic tissues suggesting that in aphids the telomerase activity could be not restricted as in human cells. The study of telomeres in a M. persicae strain with variable chromosome number evidenced that aphid telomerase can initiate the de novo synthesis of telomere sequences at internal breakpoints resulting in the stabilization of the chromosomal fragments.