Pairing of lacO tandem repeats in Arabidopsis thaliana nuclei requires the presence of hypermethylated, large arrays at two chromosomal positions, but does not depend on H3-lysine-9-dimethylation.

Fluorescent chromatin tagging by the lacO operator/lac repressor system in Arabidopsis thaliana is useful to trace distinct chromatin domains in living cells. Nevertheless, the tandem repeats of the tagging system may alter the spatial organisation of chromatin within nuclei by increasing homologous pairing as well as association with heterochromatin. Efficient homologous pairing occurs if lacO repeat arrays of ∼10 kb are present at two loci, either on the same chromosome or on different chromosomes.

Silencing of retrotransposons in Dictyostelium by DNA methylation and RNAi.

We have identified a DNA methyltransferase of the Dnmt2 family in Dictyostelium that was denominated DnmA. Expression of the dnmA gene is downregulated during the developmental cycle. Overall DNA methylation in Dictyostelium is approximately 0.

A database search for double-strand containing RNAs in Dictyostelium discoideum.

In eukaryotic cells, double-stranded RNA is degraded to 21mers and triggers RNA interference. Using a pattern description language, we have searched the EMBL database for sequences with the potential to form double strands in cis in Dictyostelium discoideum. No extended inverted repeats were found in mRNAs.