Telomeres in Aging: Birds

This chapter describes the use of avian species as model organisms for research in telomere biology and aging. Cellular or replicative senescence is often utilized as a model for the aging process because of the hypothesis that cellular aging recapitulates organismal aging. A genomic alteration associated with cellular or replicative senescence in a variety of organisms, including the chicken, is the shortening of telomeres. Telomere arrays have been examined in a wide sampling of avian species, including chicken, using fluorescence in situ hybridization (FISH). A PCR-based technique that can be used to compare the abundance of telomere repeats is quantitative real-time PCR (Q-PCR). This technique quantifies the fold difference between telomere-repeat copy number in an experimental sample compared to a reference DNA sample. Real-time fluorescence-based PCR and RT-PCR have emerged as powerful methods for examining gene expression patterns in many contexts. In traditional PCR, an amplicon, which accumulates after a predetermined number of cycles, is analyzed by gel electrophoresis.