What triggers senescence in Podospora anserina?

Senescence of Podospora anserina is triggered by a cytoplasmic and infectio us factor (the determinant of senescence) and is always correlated with mit ochondrial DNA modifications, especially with the accumula tion of small ci rcular subgenomic DNA molecules, the senDNAs, Several observations have sug gested that the senDNAs could be the cytoplasmic and infectious determinant , However, we show here (1) that senDNA molecules can be transferred to a y oung culture without the cotransmission of the determinant of senescence an d (2) that the determinant of senescence does not segregate as a mitochondr ial DNA mutation, Overall, our data strongly argue that amplification of se nDNA molecules in the mitochondria is not an intrinsic property of these sm all DNA molecules. They question the nature of the actual determinant of se nescence. (C) 1999 Academic Press.