Figure 3. Linker histone H1 is neurotoxic.

Dissociated cortical neurons were cultured for 48 hrs and histones were applied for a further 24 hrs. Cell death was determined by luminescence to measure protease release and was expressed as relative luminescence units (RLU). For clarity RLU means are expressed as +/- 2 x standard deviation (SD). Histone H1 caused dose-dependent death of cortical neurons ( a) while core histones H2A, H2B, H3 and H4 were without effect up to 200 nM ( b–e). Cell death as measured by luminescence was confirmed directly via phase contrast microscopy of dissociated cortical neurons in culture ( Figure 4).