Cytochemical localisation of NADP-linked glutamate dehydrogenase newly induced in nitrogen-starved mycelia of Coprinus cinereus

Abstract Electron microscopic cytochemistry shows that following transfer of mycelium from nitrogen-rich to nitrogen-free medium, the NADP-linked glutamate dehydrogenase activity, which is known to be derepressed by such treatment, is localised in the vicinity of the cell membrane and the nucleus. Detection of similar cytochemical reaction products in material subjected to lengthened incubation in the original medium, rather than to transfer (which showed no significant change in the level of spectrophotometrically-detectable enzyme activity) implies that regulation of the enzyme may include an activation process which is mimicked by the preparation methods employed for electron microscopy.