Caloric restriction extends lifespan in long-lived, but not short-lived genotypes in Daphnia
Faculty Mentor
Lev Yampolsky
Mentor Home Department
Biological Sciences
Short Abstract
Caloric restriction (CR) is known to extend life in a variety of organisms including yeasts, worms, flies, mice, and, by some account, primates. Daphnia, a classic model organism for developmental biology and ecophysiology, was one of the first organisms in which the life-extending effect of CR has been demonstrated. However, more recently the magnitude or even existence of the CR effects in Daphnia has been controversial, partly because the effect is known to be stronger in some genotypes than others, and because excessive caloric restriction (e.g., starvation) can have the opposite effect on longevity. We conducted a series of lifespan experiments in 12 different genotypes of D. magna that included both short-lived and long-lived ones, and covering a broad range of food levels, including the level above the ad libitum level. We show that the highest lifespan is observed between food levels of 5x104 and 3x105 algae cells per mL, over which range the lifespan is not changing much, although in most genotypes the longest lifespan is observed at 105 cells/mL. The 4-fold increase in food concentration to 4x105 cells/mL results in a significant (~30%) reduction of lifespan in the long-lived genotypes, but causes no difference in lifespan of short-lived ones. This lifespan difference showed little or no negative correlations with fecundity in each food level, inconsistent with the hypothesis of lifespan reducing effect of elevated reproduction under high food. We hypothesize that lifespan-reducing genomic determinants present in the short-lived clones eliminate the beneficial effects of caloric restriction.
Category
Science, Technology and Engineering
Start Date
5-4-2024 9:10 AM
End Date
5-4-2024 10:10 AM
Location
D.P. Culp Center Room 219
Caloric restriction extends lifespan in long-lived, but not short-lived genotypes in Daphnia
D.P. Culp Center Room 219
Caloric restriction (CR) is known to extend life in a variety of organisms including yeasts, worms, flies, mice, and, by some account, primates. Daphnia, a classic model organism for developmental biology and ecophysiology, was one of the first organisms in which the life-extending effect of CR has been demonstrated. However, more recently the magnitude or even existence of the CR effects in Daphnia has been controversial, partly because the effect is known to be stronger in some genotypes than others, and because excessive caloric restriction (e.g., starvation) can have the opposite effect on longevity. We conducted a series of lifespan experiments in 12 different genotypes of D. magna that included both short-lived and long-lived ones, and covering a broad range of food levels, including the level above the ad libitum level. We show that the highest lifespan is observed between food levels of 5x104 and 3x105 algae cells per mL, over which range the lifespan is not changing much, although in most genotypes the longest lifespan is observed at 105 cells/mL. The 4-fold increase in food concentration to 4x105 cells/mL results in a significant (~30%) reduction of lifespan in the long-lived genotypes, but causes no difference in lifespan of short-lived ones. This lifespan difference showed little or no negative correlations with fecundity in each food level, inconsistent with the hypothesis of lifespan reducing effect of elevated reproduction under high food. We hypothesize that lifespan-reducing genomic determinants present in the short-lived clones eliminate the beneficial effects of caloric restriction.