Fig. 5
High relative humidity (RH) reduces water loss with age and slows innate immune aging. a Water content per adult female, cohorts sampled from age 1 to 7 weeks old; cohorts maintained at 20%, 40%, and 80% RH. Trajectory of water content among RH groups analyzed with Generalized Linear Model Fit by maximum likelihood ratio test. For main effects: age affected water content (χ2 = 102.9, p < 0.0001) but humidity did not (χ2 = 1.23, p = 0.54). For interaction effects: water content declined faster in 20% RH compared to 80% RH (χ2 = 50.0, p < 0.025); no significant difference in water loss rate between 40% and 80% RH (χ2 = 0.625, p = 0.43). All point estimates produced represent the mean from five independent biological samples comprised of 20 pooled females. b Survivorship of yw adult females aged under RH of 20%, 40%, and 80% (25 °C). Log-rank test of mortality: 20% versus 40%, p = 0.0003; 40% versus 80%, p = 0.616. Three cages of 125 flies used for each RH condition. c–e Relative PGRP-LC, EcR, and Defensin mRNA levels in MTs from yw females, mean and SEM, aged at 20%, 40%, and 80% RH (25 °C), sampled at 1, 2, 4, and 6 weeks; three samples of 15 females were censored from demography cages to produce three independent biological samples at each time point and condition. Analysis was performed with Generalized Linear Model Fit by maximum likelihood ratio test for main (age, RH) and interaction (age x RH) effects. PGRP-LC: age, χ2 = 24.3, p < 0.001; RH, χ2 = 13.0, p = 0.0015; age x RH, χ2 = 7.08, p = 0.029. EcR: age, χ2 = 13.3, p < 0.001; RH, χ2 = 11.3, p = 0.0035; age x RH, χ2 = 6.75, p = 0.034. Defensin: age, χ2 = 15.1, p < 0.001; RH, χ2 = 2.79, p = 0.095; age x RH, χ2 = 4.32, p = 0.038