MITOCHONDRIAL MUTATIONS IMPAIR SIGNAL-TRANSDUCTION IN DICTYOSTELIUM-DISCOIDEUM SLUGS

Subpopulations of mutant mitochondria appear to play important roles i n degenerative processes associated with aging and are characteristic of many mitochondrial diseases. We have generated mutants carrying pla smid insertions in the Dictyostelium discoideum mitochondrial genome a nd have shown that phototaxis and thermotaxis in these mutants is more sensitive than growth and division to the presence of a subpopulation of defective mitochondria. This could result from direct impairment o f a mitochondrial role in signal transduction, or indirectly from the effects of energy depletion. Either way, signal transduction may be th e first cellular activity to be compromised by the accumulation of def ective mitochondria in age-related tissue dysfunction and in mitochond rial disease. (C) 1997 Academic Press.