Eleven novel sep genes of Schizosaccharomyces pombe required for efficientcell separation and sexual differentiation

Genetic analysis of 20 sterile mutants prone to form hyphae revealed 11 nov el ste genes (sep6 to sep16) of Schizosaccharomyces pombe. None of the muta nts was completely mycelial. Most mutants formed branching hyphae and showe d normal septation. Aberrant septal structures and actin distribution were seen only at 36 degrees C. sep9-307, sep14-576 and sep15-598 showed genetic interactions with sep1-1, a mutation in a forkhead transcription factor ho mologue. Additional genetic interactions were detected between sep6-194, se p15-598 and cdc16-116, a mutant allele of an anaphase modulator of p34(cdc2 ). sep9-307 and sep15-598 caused dikaryosis in wee1(-) background. In matin g and sporulation tests, sep6(-), sep7(-), sep9(-), sep10(-), sep11(-) and sep15(-) proved to be defective in conjugation only, whereas sep8(-), sep13 (-) and sep16(-) were also defective in meiosis-sporulation. sep12(-) and s ep14(-) were only partially sterile. All mutants could produce M-factor but sep8(-), sep11(-), sep15(-) and sep16(-) were defective in P-factor produc tion. The mutations in sep8, sep11 and sep16 suppressed the pat1-114-driven meiosis, All mutants were sensitive to the presence of higher concentratio ns of chloride in the medium and to short heat shocks. The diversity of the mutant phenotypes and the pleiotropic effects of the mutations suggest tha t these sep genes might act in, or interact with, a multiple overlapping ne twork of regulatory modules, Copyright (C) 1999 John Wiley & Sons, Ltd.