Transgenic biomarkers of aging in drosophila melanogaster

UnrestrictedLife span is currently the best measure of aging rate in Drosophila (and other organisms), however death as an assay endpoint is problematic for two reasons: (i) it takes a long time to measure and makes for slow experiments, and (ii) death of the animal precludes a number of interesting assays and experiments. One goal of the aging field has been to identify aging "biomarkers", i.e. an easily measured indicator of aging that could be used instead of life span. Reliable biomarkers have the potential to greatly increase the pace and scope of aging research in Drosophila and other organisms, and would have medical implications in humans. We have identified transgenic reporter constructs that appear promising as aging biomarkers. Innate immune response gene promoters linked to GFP were assayed longitudinally in individual aging flies and found to be partially predictive for remaining life span. Heat shock protein genes also appear to be promising as biomarkers of aging. Both hsp70 and hsp22 are induced during aging in tissue- and temporal-specific patterns. hsp22 and hsp70 promoters linked to GFP were assayed under different conditions including normal aging, heat stress and pure oxygen atmosphere. Both hsp-GFP reporters were partially predictive of remaining life span under normal aging and stress conditions. The hsp-GFP reporters were also tested in a real-time video tracking system which allowed us to quantify GFP expression and fly activity simultaneously. hsp70 and hsp22 gene reporters were induced during fly aging in circadian patterns (24hr and 18hr periods, respectively), and spiked several hours prior to death of the animal. In conclusion, both immune peptide-GFP and hsp-GFP reporters are promising biomarkers of aging. The real-time video-tracking system could be a powerful tool for further studies on these reporters