OSMOTIC EFFECTS ON THE POLYAMINE PATHWAY OF NEUROSPORA-CRASSA

In bacteria, mammals, and certain plants, the induction of the polyami ne synthetic enzyme, ornithine decarboxylase (ODC), and the accumulati on of its product, putrescine, follows osmotic manipulations of cells. In at least some of these cases, this response is indispensable for s urvival. We wished to determine whether the polyamine pathway of Neuro spora crassa was regulated in response to hyper- or hypoosmotic condit ions. Unlike ODC of most other classes of organisms, the N. crassa enz yme and the accumulation of putrescine appears to be relatively indiff erent to these conditions, either during sudden transitions or in stea dy-state. We conclude that other mechanisms of osmotic adjustment or t olerance have evolved in N. crassa and perhaps other fungi that obviat e the need for putrescine accumulation. (C) 1995 Academic Press, Inc.