Fig. 4: Bacterial physiology impact stiffness and cuticle senescence with age. | Nature Communications

Fig. 4: Bacterial physiology impact stiffness and cuticle senescence with age.

From: Mechanical properties measured by atomic force microscopy define health biomarkers in ageing C. elegans

Fig. 4

a Lifespan curve of wild-type (WT) C. elegans on untreated control bacteria (blue), heat-treated (green) or UV-treated bacteria (purple) (n = 90, 85 and 106, respectively; log rank test p < 0.001 vs untreated control bacteria) and b longitudinal study of mechanical properties as Young’s Modulus (YM; kPa) until mean lifespan (D18 for WT, D24 for heat-treated, D28 for UV-treated). Error bars indicate 95% CI, dotted lines mark mean YM at day 1 for WT (blue), heat-treated (green) or UV-treated bacteria (purple). Two-tailed unpaired t test for statistical comparison of WT to treatments at chronological age day 10 and mean lifespan. c Lifespan curve of untreated (0 µg/ml) (blue) and trimethoprim (Tmp)-treated (3 µg/ml) (red) WT C. elegans grown on sensitive OP50 (line) or grown on trimethoprim-resistant OP50-TmpR overexpressing a dihydrofolate reductase cassette (dotted line) (n = 83, 70, 100 and 91, respectively; log rank test p < 0.001, p = 0.4094 and p = 0.0206 vs OP50 0 µg/ml) and d mechanical properties as YM (kPa) at chronological age of 16 days. Error bars indicate 95% CI. Two-way ANOVA Tukey’s multiple comparison test for statistical comparison and interaction of terms (green). e Mechanical properties as YM (kPa) at mean lifespan (D18 for WT, D33 for Tmp-treated). Error bars indicate 95% CI. Two-tailed unpaired t test for statistical comparison. f Lifespan curve of WT C. elegans grown on OP50 (blue) or OP50 mutants of the TCA cycle genes gltA (yellow) or sucA (red) (n = 111, 113 and 101, respectively; log rank test p < 0.001 vs OP50), and g mechanical properties as YM (kPa) at chronological age of 14 days or h at mean lifespan (D18 for OP50, D23 for OP50ΔgltA and D26 for OP50ΔsucA). Error bars indicate 95% CI. Two-tailed unpaired t test for statistical comparison of OP50 to bacterial mutants. i Representative AFM cuticle topography images of WT C. elegans at mean lifespan grown on untreated control, heat-treated, UV-treated, carbenicilin-treated (50 µg/ml) and trimethoprim-treated (3 µg/ml) OP50 bacteria or on OP50ΔgltA and OP50ΔsucA bacterial mutants. j Roughness quantification of topographical images presented as RMS roughness Rq ± standard deviation. Two-tailed unpaired t test for statistical comparison of WT with conditions. n represented above the graph, show number of biologically independent worm samples. For lifespan measurements, n represents the number of worms scored as dead. For a summary of YM values and additional statistics for independent trials, see Supplementary Data 1 and for a summary of worm lifespan trials and statistical comparison between genotypes see Supplementary Data 2. Source data are provided as a Source Data file.

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