Physiological Mechanisms of Increased Stress Resistance in Drosophila melanogaster Selected for Postponed Senescence

Abstract

Postponed senescence in Drosophila melanogaster is associated with increased adult resistance to starvation, desiccation, and ethanol vapor. Flies from postponed-senescence populations were compared to flies from control populations with respect to age-specific respiration rate, activity level, and total lipid content. Females from control (short-lived) populations exhibited greater respiration rates and activity levels than did flies from postponed-senescence populations when young. At older ages, there were no differences in respiration rates, and females from postponed-senescence populations were more active than control-population females. The age-specific trends and patterns of differences in respiration rate and activity do not appear to explain the previously observed differences and trends in starvation, desiccation, and ethanol-vapor resistance. Females from postponed-senescence populations had greater proportional lipid content than did females from control populations over the range of ages examined. Lipid content increased with age for both types of populations. Age-specific trends and differences in lipid content appear to explain satisfactorily the increase in starvation resistance with age for females of all populations as well as the greater starvation resistance of females from the postponed-senescence populations.