Fig. 4: Aged flies receiving the youth impacts maintain better physiological fitness.

a Motor activity (negative geotaxis) was assayed in the 60d-old control Canton-S flies (indicated as 60d Control) and 60d-old aged flies that have been co-housed with 1d-old young Canton-S flies for 20 days (indicated as 60d Co-housed). Each condition included 6 independent replicates and a total of 30 flies. Results were expressed as mean percentages ± SEM. b 60d-old control Canton-S flies (indicated as 60d Control) and 60d-old aged flies that have been co-housed with 1d-old young Canton-S flies for 20 days (indicated as 60d Co-housed) were subjected to desiccation. The mean survival time ± SEM of each condition was calculated and illustrated as the bar graph. P values: ns > 0.1234; <0.0332*. P values of the columns were annotated by the Mann–Whitney test. Each condition included 10 flies. c Protein levels of Ref. ² P, Atg8a-I/Atg8a-II, ubH2A, and GAPDH in the whole animal lysates derived from flies of the indicated condition were examined by the Western blot analyses. Label of each lane was: (1) 10d, Control: 10d-old young Canton-S flies. (2) 60d, Control: 60d-old aged Canton-S flies, (3) 60d, Co-housed: 60-old aged Canton-S flies that have been co-housed with 1d-old young flies for 20 days. Levels of GAPDH were used to normalize total protein input. Each lane contained whole animal lysates from 5 flies. Results from 2 independent experiments (except the case of Atg8a, triplicates were included) were used to quantitate the differences of protein expression (via the ImageJ program). Fold changes of expression level were compared to the value of 10d, Control (the very left lane; assigned as 1) and indicated at the bottom of Western blot. All Western blots derived from the same experiment were processed in parallel.