Abstract
Avian models have the potential to elucidate basic cellular and molecular mechanisms underlying the slow aging rates and exceptional longevity typical of this group of vertebrates. To date, most studies of avian aging have focused on relatively few of the phenomena now thought to be intrinsic to the aging process, but primarily on responses to oxidative stress and telomere dynamics. But a variety of whole-animal and cell-based approaches to avian aging and stress resistance have been developed—especially the use of primary cell lines and isolated erythrocytes—which permit other processes to be investigated. In this review, we highlight newer studies using these approaches. We also discuss recent research on age-related changes in neural function in birds in the context of sensory changes relevant to homing and navigation, as well as the maintenance of song. More recently, with the advent of “-omic” methodologies, including whole-genome studies, new approaches have gained momentum for investigating the mechanistic basis of aging in birds. Overall, current research suggests that birds exhibit an enhanced resistance to the detrimental effects of oxidative damage and maintain higher than expected levels of cellular function as they age. There is also evidence that genetic signatures associated with cellular defenses, as well as metabolic and immune function, are enhanced in birds but data are still lacking relative to that available from more conventional model organisms. We are optimistic that continued development of avian models in geroscience, especially under controlled laboratory conditions, will provide novel insights into the exceptional longevity of this animal taxon.
Highlights
Researchers focused on the basic biology of aging and longevity in humans and model organisms currently use an intellectual schema that identifies “hallmarks” of aging—key cellular, molecular, and metabolic processes that lead to the loss of homeostasis and resiliency to stress and disease that characterize organismal aging and, death
We focus on -omics data gleaned from the use of avian models that are potentially relevant to geroscience; we highlight how data from birds compare to data collected using more “traditional” animal models
As noted above, when using erythrocytes as source material, several groups have demonstrated that the genetic signature of long-lived birds shows an enrichment of genes involved in stress defense mechanisms, cell growth and proliferation, and immune function
Summary
Researchers focused on the basic biology of aging and longevity in humans and model organisms currently use an intellectual schema that identifies “hallmarks” Naturalistic studies of avian population biology always come with a set of potential confounds, including episodic variation in food availability, extremes of temperature or moisture, predation, or disappearance of individual birds for unknown reasons. When individuals of extreme ages are lost in such studies, mortality cannot clearly be attributed to aging or other intrinsic sources of mortality These potential confounds were investigated in a recent controlled study of captive zebra finches (Taeniopygia guttata), in which food availability and environmental conditions were systematically varied to ascertain their effect on survival [20]. Food availability had no effect on mortality in birds maintained under “benign” conditions This type of study serves as a caution against drawing firm conclusions about avian aging rates and mortality based on data from the field. Laboratory rodent studies have shown that inbreeding significantly lengthens telomeres, and that telomere dynamics can vary in a species or strain-specific manner [31]
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