H4 HISTONE IN THE MACRONUCLEUS OF BLEPHARISMA-JAPONICUM (PROTOZOA, CILIOPHORA, HETEROTRICHIDA)

Two clones, obtained by polymerase chain reaction from macronuclear DN A of the unicellular ciliated protist Blepharisma japonicum, were isol ated and sequenced. They correspond to fragments of two different puta tive H4 histone genes. The existence of multiple H4 histone genes was also suggested by Southern blot hybridisation experiments employing on e of the obtained clones as a probe. Two B.japonicum H4 protein fragme nts, which were directly sequenced, show differences in the amino acid sequences too. The comparison of the obtained B. japonicum H4 partial amino acid sequences with each other, and with H4 from other ciliates and from representative microbial and multicellular organisms, highli ghts the larger histone heterogeneity of lower eukaryotes compared to that observed in higher organisms.