Consensus inverted terminal repeat sequence of Paramecium lESs: Resemblance to termini of Tc1 -related and Euplotes Tec transposons

Abstract

During the formation of a transcriptionally active macronucleus, ciliated protozoa excise large numbers of interstitial segments of DNA (internal eliminated sequences; lESs) from their chromosomes. In this study we analyze the published sequences of 20 lESs that Interrupt surface protein genes of Paramecium and identify a consensus inverted terminal repeat This sequence is similar to the ends of the Tc1-related transposons found in nematodes and other meta-zoans, as well as to both the ends of the Tec transposons and at least some of the lESs in the distantly related ciliate Euplotes crassus. The results of these analyses bolster previous proposals that lESs were created by transposition. © 1995 Oxford University Press.