Previously we discovered an age-associated, genome-wide increase in LOH in yeast that results from the loss of mtDNA and respiratory function in the progeny of aging cells [11]–[12]. Here we used our recently developed MEP [16] to examine LOH in cells that retain respiratory function throughout their life span. Although the MEP strains are in the same S288C strain background as strains used in previous studies, they display a greater capacity to maintain mitochondrial function both in logarithmically growing cultures and during aging [11], [46]. This greater stability of mitochondrial function in the MEP strain is similar to that found for most natural isolates of S. cerevisiae [14]. The faithful maintenance of functional mitochondria depends on over 100 genetic loci [15] and we have not determined the precise genetic basis for the phenotypic differences we observe.
