Control of DNA excision efficiency in Paramecium.

ABSTRACT: Programmed excision of internal eliminated sequences (IESs) occurs at thousands of sites in ciliate genomes. How this is controlled is largely unknown. Here, we report the characterization of the non-efficiently excised 156psiG-11 IES from Paramecium primaurelia strain 156 and that of the efficiently excised 168psiG-11 IES, an allelic variant from strain 168. Then, we report a genetic and molecular analysis of IES excision efficiency in F(1) progeny derived from interstrain crosses and in F(2) homozygous progeny derived from F(1) autogamy. IES 168psiG-11 excision efficiency was approximately 100% in all cases. IES 156psiG-11 excision efficiency was 19 +/- 13% in F(1) progeny and 0.6 +/- 1.1% in F(2) progeny. No trans-excision event between IESs 156psiG-11 and 168psiG-11 was detected within the F(1) progeny. These data demonstrate that the excision efficiency of this IES is variable and controlled by a cis-acting element. This should encompass positions 8 and/or 9 of the right IES end, which display allele differences. Finally, the 30-fold stimulation of IES 156psiG-11 excision efficiency within F(1) progeny relative to F(2) progeny demonstrates that Paramecium IES excision efficiency is sensitive either to a conjugation-specific trans-acting factor provided by the zygotic genome, or to homologous chromosome cross-talk.

SUBMITTER: Dubrana K 

PROVIDER: S-EPMC92537 | biostudies-literature | 2001 Nov

REPOSITORIES: biostudies-literature