Developmental Changes in Translatable RNA Species Associated with Meiosis and Spore Formation in Saccharomyces cerevisiae

Abstract

During Saccharomyces cerevisiae sporulation distinct changes in translatable mRNA species have been detected by two-dimensional gel electrophoresis of the polypeptides produced in a messenger-dependent, cell-free rabbit reticulocyte lysate primed with RNA prepared from a/alpha, a/a, and alpha/alpha isogenic diploids at different stages of sporulation. The availability of functional mRNA increased by about 25% during the first 4 h after transfer of either sporulating (a/alpha), or nonsporulating (a/a and alpha/alpha) diploids to sporulation medium. Thereafter functional mRNA decreased such that in the a/alpha strain after 24 h there was only about 50% of the amount in vegetative cells; a less marked decrease was observed in the a/a and alpha/alpha strains. Of 750 mRNA species detected, 43 underwent alterations only during sporulation in the a/alpha strain, whereas 36 changes were common to all three strains and one mRNA specific to alpha/alpha vegetative cells was detected. Only four of the sporulation-specific changes were due to the de novo appearance of translatable species, and two of these became predominant species of the total population. The majority of the specific changes were due to either permanent or transient increases in the concentration of individual mRNA species; 11 decreases were found. Changes were found at most stages of sporulation, although many occurred in either of two stages, one early (before 2 h) and the other later (between 6 and 8 h) when commitment to meiotic segregation was beginning. The results provide evidence for both quantitative and, to a lesser extent, qualitative transcriptional control of gene expression during sporulation.

TheSPS100Gene ofSaccharomyces cerevisiaeis Activated Late in the Sporulation Process and Contributes to Spore Wall Maturation

“…The SPS100 and SPSJOJ genes define a new class of temporally distinct sporulation-specific genes. Our observations, taken in conjunction with the studies of other investigators (16,21,41,44), suggest that the program of events of meiosis and spore formation reflects the sequential expression of at least four temporally distinct classes of sporulation-specific genes. The SP013 gene is the prototype gene for the earliest class of sporulation-specific genes.…”

“…The transcripts encoded by these genes accumulate before the completion of meiosis (13,16,28). In complementary studies, analyses of the in vitro coding capacities of RNAs isolated from sporulating cells demonstrated the accumulation of an array of sporulationspecific mRNAs most of which also appear before the completion of meiosis (21,44). Two of the sporulationspecific transcripts identified in a study performed by Kurtz and Lindquist, however, begin to accumulate only after spore wall synthesis has begun (22).…”