In average occurs one nucleosome per 200 base pairs. H1 does not belong to the nucleosome complex but serves to enhance the condensation of the chromatin even further. Non-histones is a collective term for a number of regulators that are acidic when compared to the strongly alkaline histones. Otherwise is their amino acid composition within the usual framework. Clue exists that certain protein fractions bind to certain DNA segments.
Further experiments hint at their possible activation by hormones, metabolites, etc.
Additionally has it shown that the phytochrome system transfers signals to the DNA that enhance the transcription of certain segments selectively. The degree of condensation of the nuclear DNA is variable. Strongly condensed DNA is called heterochromatin , less condensed one euchromatin . Heterochromatin is stained more intense than euchromatin by certain nuclear dyes. Condensation and decondensation of the DNA are at least partially reversible processes.