Do long telomeres affect cellular fitness?

Telomeres protect the chromosome ends and maintain the genome stability; they, therefore, play important roles in aging and cancer. Despite the wide variability in telomere length among eukaryotes, in all telomerase-expressing cells telomere length is strictly controlled within a very narrow range. In humans, telomeres shorten with age, and it has been proposed that telomere shortening may play a causal role in aging. Using yeast strains with genetically or physiologically generated differences in telomere length, we have explored the question of whether having long telomeres affects telomere function and fitness or cellular lifespan. We found no effect of long telomeres on vegetative cell division, meiosis, or in cellular lifespan. No positive or negative effect on fitness was observed either under stressful conditions.