A Mutation in Paramecium tetraurelia Reveals Functional and Structural Features of Developmentally Excised DNA Elements

摘要: The excision of internal eliminated sequences (IESs) from the germline micronuclear DNA occurs during differentiation a new macronuclear genome in ciliated protozoa. In Paramecium, IESs are generally short (28–882 bp), AT rich elements that show few conserved sequence features with exception an inverted-terminal-repeat consensus has similarity to ends mariner /Tc1 transposons (Klobutcher and Herrick 1995). We have isolated analyzed mutant cell line cannot excise 370-bp (IES2591) coding region 51A variable surface protein gene. A single C T transition within prevents excision. inability IES2591 revealed 28-bp IES inside larger IES, suggesting reiterative integration these can occur. Together, mutation evidence for support theory Paramecium evolved transposable elements. Unlike previously studied presence this macronucleus does not completely inhibit its wild-type copy through multiple sexual generations.