DIFFERENTIAL STRESS GENE-EXPRESSION DURING THE DEVELOPMENT OF NEUROSPORA-CRASSA AND OTHER FUNGI

Stress genes are differentially expressed during the development of Ne urospora crassa and other fungi. Large amounts of constitutive heat sh ock protein 70 (HSC70) are found in dormant conidia of N. crassa, wher eas little mRNA of the related glucose-regulated protein (grp78) is de tected. It is, however, not generally clear whether heat shock protein or mRNA is preferentially stored in dormant spores. Germinating spore s of N. crassa increase the level of grp mRNA. During this development al stage, the induction of inducible heat shock protein (hsp) genes ca n be elicited by heat shock only at certain times after the beginning of germination. Exponential growth (proliferation) is paralleled by in creased levels of HSCs. The stationary state is characterized by decre ased levels of some HSCs and increased levels of others. Conidiation i n hi crassa is accompanied by a strong enhancement of the synthesis an d levels of HSCs but also of HSPs after heat shock. This increase may serve a need for additional rounds of replication, for the expression and transport of sporulation-specific proteins or for stabilization of macromolecules in the spores and their preservation for germination. The control mechanisms involved in the differential expression of hsc genes are currently not known. (C) 1998 Federation of European Microbi ological Societies. Published by Elsevier Science B.V. All rights rese rved.