Editing Staining (section)

=== Hoechst stains ===
[[Hoechst stain|Hoechst]] is a ''bis''-benzimidazole derivative compound that binds to the ''minor groove'' of [[DNA]]. Often used in fluorescence microscopy for DNA staining, Hoechst stains appear yellow when dissolved in aqueous solutions and emit blue light under UV excitation. There are two major types of [[Hoechst stain|Hoechst]]: ''Hoechst 33258'' and ''Hoechst 33342''. The two compounds are functionally similar, but with a little difference in structure. Hoechst 33258 contains a terminal [[hydroxyl]] group and is thus more soluble in aqueous solution, however this characteristics reduces its ability to penetrate the [[plasma membrane]]. Hoechst 33342 contains an [[ethyl group|ethyl]] substitution on the terminal hydroxyl group (i.e. an ethylether group) making it more hydrophobic for easier plasma membrane passage