Fig. 3 | Nature Communications

Fig. 3

From: Time-restricted feeding restores muscle function in Drosophila models of obesity and circadian-rhythm disruption

Fig. 3

Muscle-specific knockout of Sk2 resulted in physiological dysfunction, like the Sk2 mutant. a Flight performance assay. Fly flight paths were recorded and given a numerical value to calculate flight index (F.I.) (see the Methods section). IFM-specific RNAi knock-down of Sk2 using Fln-Gal4;UAS-mito-GFP (referred as Fln/ + ) resulted in a significant reduction in muscle performance in 1-, 3-, and 5-week-old male and female flies compared with age-matched driver control (Fln/+). Age-dependent decline in flight performance is also shown in the Sk2 KD and driver control flies. (n = 100–150 flies were tested at each age in both male and female flies for the Sk2 KD and control flies from three independent experiments). b NLaz RNA was upregulated in the IFM upon KD of Sk2 in the genetically obese flies (both male and female) after 3 weeks. N = 3 independent experiments from 30 flies IFM. c Confocal images of the IFM from 3-week-old females of wild-type (Fln/+ ) and IFM-specific KD of genetically obese Sk2 flies probed with phalloidin (green) and Nile Red (red puncta). More intramuscular lipid (arrows) and actin-containing myofibrillar disorganization was detected in IFM of Sk2 KD (asterisks), compared with age-matched driver control. Scale bar is 20 µm. d Intramuscular lipid area quantification showed significant increase upon KD of Sk2 compare to age-matched driver control. N = 9 from three flies IFM in each genotype. e Confocal images of the IFM of 3-week-old females expressing mito-GFP (green), a reporter for mitochondrial morphology, DAPI (blue) and phalloidin (red). Compared with wild-type, KD of Sk2 flies showed mitochondrial dysmorphology/abnormality (asterisks) and disorganization of actin-containing myofibrils. Scale bar is 4 µm. f Quantification of Sk2 knockdown mitochondrial dysmorphology from three representative experiment shown. N = 9. For panels a, b, d, and f bar graphs (along with dot plots for panels d and f) and error bars presented as mean ± SD, and statistical analysis was performed using one-way ANOVA with post hoc Tukey test, where * p < 0.05, 0.01 p < 0.01, ***  p < 0.001, ns  nonsignificant

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