Several highly divergent histone H3 genes are present in the hypotrichous ciliate Stylonychia lemnae

In the protozoan Stylonychia lemnae 10 different histone H3 genes were disc overed by polymerase chain reaction (PCR) amplification and sequence analys is. One of them is interrupted by a short intron sequence. These genes code for nine divergent histone H3 proteins. The genetic distances between some of these variants are very high. Most of the substitutions, as well as ins ertions/deletions, were found in the amino-terminal region. One variant sho ws an extremely elongated and altered N-terminus, which did not allow an un ambiguous alignment with other histone H3 variants in this region. Hybridiz ation experiments using the different H3 genes as probes indicate that even more histone H3 variants must exist in this species. (C) 1999 Federation o f European Microbiological Societies. Published by Elsevier Science B.V. Al l rights reserved.