p237
Not all eukaryotes use histones
Roy S, Morse D, A Full Suite of Histone and Histone Modifying Genes Are Transcribed in the Dinoflagellate Lingulodinium. PLoS ONE 7 e34340 (2012)
[BG] Unlike typical eukaryotes, dinoflagellate chromatin is permanently organized into a cholesteric liquid crystal structure, similar to structures observed in bacteria grown under stress conditions or in sperm cell nuclei.
High concentration of divalent cations, a low ratio (1:10) of basic protein to DNA, and amounts of DNA that can range from 1.5 pg/cell (half that in a haploid human cell) in
Symbiodinium to roughly 200 pg/cell in Lingulodinium . The unique chromatin structure in dinoflagellates is presumably a derived characteristic since nuclei in Perkinsus , a genus thought to be ancestral to the dinoflagellates, have a typical eukaryotic appearance.
All core histone and many histone modifying enzyme sequences are present in the
Lingulodinium transcriptome The abundance of histone mRNA in Lingulodinium is between 5- and 25-fold lower than in the higher plant Solanum chacoense depending on the histone Histone protein accumulation is below current detection limits