Abstract
BackgroundThe molecular mechanisms of variations in individual longevity are not well understood, even though longevity can be increased substantially by means of diverse experimental manipulations. One of the factors supposed to be involved in the increase of longevity is a higher stress resistance. To test this hypothesis in a natural system, eusocial insects such as bees or ants are ideally suited. In contrast to most other eusocial insects, ponerine ants show a peculiar life history that comprises the possibility to switch during adult life from a normal worker to a reproductive gamergate, therewith increasing their life expectancy significantly.ResultsWe show that increased resistance against major stressors, such as reactive oxygen species and infection accompanies the switch from a life-history trait with normal lifespan to one with a longer life expectancy. A short period of social isolation was sufficient to enhance stress resistance of workers from the ponerine ant species Harpegnathos saltator significantly. All ant groups with increased stress resistances (reproducing gamergates and socially isolated workers) have lower catalase activities and glutathione levels than normal workers. Therewith, these ants resemble the characteristics of the youngest ants in the colony.ConclusionsSocial insects with their specific life history including a switch from normal workers to reproducing gamergates during adult life are well suited for ageing research. The regulation of stress resistance in gamergates seemed to be modified compared to foraging workers in an economic way. Interestingly, a switch towards more stress resistant animals can also be induced by a brief period of social isolation, which may already be associated with a shift to a reproductive trajectory. In Harpegnathos saltator, stress resistances are differently and potentially more economically regulated in reproductive individuals, highlighting the significance of reproduction for an increase in longevity in social insects. As already shown for other organisms with a long lifespan, this trait is not directly coupled to higher levels of enzymatic and non-enzymatic antioxidants.
Highlights
Animal species differ vastly in how long they live
A number of different pathways have been shown to be involved in the phenomenon, comprising the target of rapamycin (TOR), the AMP-activated protein kinase, those converging onto sirtuin activation and the insulin signalling pathway [7,8]
Among the target genes are those coding for enzymatic antioxidants and chaperones
Summary
Animal species differ vastly in how long they live. Some species have life expectancies of only a few days, whereas others can live for to be several hundred years old. Proteins with a central integrator function within these pathways are e.g. SMK-1, PGC1alpha and FoxO factors [9,10] Activation of these systems is believed to increase stress resistance and life expectancy by changing the transcriptional profile of the cells. Among the target genes are those coding for enzymatic antioxidants and chaperones This would be in line [5,7] one of the earliest molecular theories of ageing, which proposed that reactive oxygen species (ROS) progressively damage macromolecules, leading to a decline in cellular function and, to death [11,12]. One of the factors supposed to be involved in the increase of longevity is a higher stress resistance To test this hypothesis in a natural system, eusocial insects such as bees or ants are ideally suited. In contrast to most other eusocial insects, ponerine ants show a peculiar life history that comprises the possibility to switch during adult life from a normal worker to a reproductive gamergate, therewith increasing their life expectancy significantly
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