Heat shock gene expression in germinating ascospores of Neurospora tetrasperma.

The activated ascospores of Neurospora tetrasperma were inactive in protein synthesis and did not accumulate transcripts for a constitutive protein until after 90 min of incubation. These spores were blocked even longer in the expression of a gene encoding a heat shock protein, hsp30, which could not be induced until after 300 min of spore germination. Early in germination the ascospores were highly susceptible to damage from moderately high temperatures. At the same time that spores became capable of expressing the hsp30 gene, there was a loss of cytosine methylation from the gene.