Cloning and analysis of the macronuclear gene for histone H1 from Euplotes eurystomus

Euplotes is a hypotrichous ciliate that contains both a macronucleus (MAC) and a micronucleus in the same cell. The DNA in the MAC is composed of small, linear highly amplified fragments, each of which contains one gene, two telomeres and all the necessary regulatory elements. Although there is a large amount of condensed chromatin in the MAC, it appears not to be organized in 30 nm fibers as seen in higher eukaryotes (9). Since histone HI is responsible for the formation of the 30 nm fiber, analysis of this protein in Euplotes may provide some insight into the unique chromatin structure in the MAC. Histone HI from the Euplotes MAC has been previously