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