Escape from Premature Death Due to Nuclear Mutations in Podospora anserina: Repeal versus Respite.
Premature death has been defined as a growth stoppage linked to the accumulation of specific deletions of the mitochondrial genome (mtDNA) in Podospora anserina. This occurs only in strains carrying the AS1-4 mutation which lies in a gene encoding a cytosolic ribosomal protein. Here we describe the isolation and genetic characterization of 10 nuclear mutations which either delay the appearance of this syndrome (respite from premature death) or cause a switch to the classical senescence process (repeal of premature death). These mutations lie in at least six genes. Some cause defects at the levels of ascospore germination, growth rates, and/or sensitivity toward inhibitors of protein syntheses. All modify the onset of senescence in wild-type (AS1+) strains. The role played by these genes is discussed with respect to the control of diseases due to mtDNA rearrangements in filamentous fungi. Copyright 1998 Academic Press.
Institut de Génétique et Microbiologie, de l'Université Paris-Sud, C.N.R.S.-URA 2225, Orsay, 91405, France
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Contamine
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Picard