IME1, a positive regulator gene of meiosis in S. cerevisiae

IMEI (inducer of MEiosis) was cloned due to its high copy number effect: it enabled MAT insufficient strains to undergo meiosis. Disruption of IMEI results in a recessive Spo^- phenotype. Diploids homozygous for the two mutations ime1-0, rmel-1 are also meios deficient. We conclude that IME1 is a positive regultor of meiosis that normally is repressed by RME1. RME is repressed by a complex of MATal and MATα2 gene products. IME1 is also regulated by the environment: no transcripts could be detected in glucose growing cells, in contrast to acetate growing cell. Starvation for nitrogen further induced (6- to 8-fold) transcription of IME1, but, as expected, the induction was found only in MATa/MATα or rmel-l/rme1-1 diploids. Furthermore, the IME1 multicopy plasmids promoted sporulation in rich media.