Figure 4. UNC-68 oxidation causes defective intracellular calcium (Ca²⁺) handling; (A) UNC-68 was immunoprecipitated and immunoblotted using anti-ryanodine receptor (RyR), anti-calstabin, and dinitrophenyl (DNP; marker of oxidation) antibodies in nematodes acutely treated for 0, 15 min, 2 hr, or 4 hr with FK506 or paraquat (treatment was applied for 20 min) at increasing concentration (day 5).

(B–C) Quantification of the band intensity shown in (A): band intensity was defined as the ratio of either DNP (marker of UNC-68 oxidation) or FKB-2 binding over its corresponding /UNC-68’s expression. (D) Contraction-associated Ca²⁺ transients measured in young age-synchronized WT nematodes treated for 15 with FK506 or for 20 min with increasing concentrations of paraquat (day 5). (E) Contraction-associated Ca²⁺ transients measured in FKB-2 KO nematodes treated with the antioxidant N-acetylcysteine (NAC) at 5 mM (day 7). (F) UNC-68 was immunoprecipitated and immunoblotted using anti-RyR, anti-calstabin, and DNP (marker of oxidation) antibodies in WT, the long lived (CLK-1) and the short lived (MEV-1) nematodes at day 2, 7, and 15. (G–H) Quantification of the average band intensity from triplicate experiments: band intensity was defined as the ratio of each complex member’s expression over its corresponding /UNC-68’s expression. (I) Graph showing number of bends recorded for WT vs. CLK-1 and MEV-1 worms at three distinct ages (day 2, 7, and 15). (J) The number of curling events was calculated as a percentage of the overall motility (curls/bends). N ≥ 20 per group. Data are means ± SEM from triplicate experiments. One-way ANOVA shows * p<0.05. Two-way ANOVA was used in panel I and J. SK SR; sarcoplasmic reticulum fraction from mouse skeletal muscle used as external control reference and was not quantified in the bar graphs. The time 0 min refers to untreated worms. Figure 4—source data 1.