Altered metabolism is a hallmark of aging. The tricarboxylic acid cycle (TCA cycle) is an essential metabolic pathway and plays an important role in lifespan regulation. Supplementation of α-ketoglutarate, a metabolite converted by isocitrate dehydrogenase alpha-1 (idha-1) in the TCA cycle, increases lifespan in C. elegans. However, whether idha-1 can regulate lifespan in C. elegans remains unknown. Here, we reported that the expression of idha-1 modulates lifespan and oxidative stress tolerance in C. elegans. Transgenic overexpression of idha-1 extends lifespan, increases the levels of NADPH/NADP⁺ ratio, and elevates the tolerance to oxidative stress. Conversely, RNAi knockdown of idha-1 exhibits the opposite effects. In addition, the longevity of eat-2 (ad1116) mutant via dietary restriction (DR) was reduced by idha-1 knockdown, indicating that idha-1 may play a role in DR-mediated longevity. Furthermore, idha-1 mediated lifespan may depend on the target of rapamycin (TOR) signaling. Moreover, the phosphorylation levels of S6 kinase (p-S6K) inversely correlate with idha-1 expression, supporting that the idha-1-mediated lifespan regulation may involve the TOR signaling pathway. Together, our data provide new insights into the understanding of idha-1 new function in lifespan regulation probably via DR and TOR signaling and in oxidative stress tolerance in C. elegans.

This study introduces decahydronaphthalenes (C₁₀- and C₁₁-decalins; C₀De and C₁De) as a novel class of hydrodesulfurization (HDS)-associated forensic markers. Diesel-contaminated soil residues from 12 gas station spills and fresh ultra-low-sulfur diesel (ULSD) reference samples (2018–2025) in Taiwan were evaluated. The decalin abundances, derived from gas chromatography/mass spectrometry (GC/MS) peak areas, were converted into diagnostic ratios (DRs) using a conserved C₁₅ sesquiterpane (BS3) internal reference. These ratios were correlated with conventional fingerprint parameters and alternative HDS products to support source identification and manufacturing-era estimation. Notably, Pearson correlations revealed that C₀De and C₁De weathering behaviors mimic those of short- (CH-6/CH-7) and medium-chain (CH-9) n-alkylcyclohexanes, respectively. Furthermore, C₁De’s negative correlation with C_xD proxies indicates the premise that rigorous HDS processing lowers sulfur concentration while elevating these hydrogenated side products. Expanding on a framework using dimethylbiphenyls (C₂B) and trimethyltetralins (C₃T), adding these novel decalin markers in principal component analysis (PCA) maintained manufacturer-specific source discrimination, with collinear loading vectors confirming C₁De and C₃T as codependent HDS markers. Cross-validated (CV) linear discriminant analysis (LDA) showed that replacing C₃T with C₀De or C₁De improved discrimination among broad sulfur-regulatory manufacturing-era groups, although residual classification uncertainty remained for strongly weathered samples. These results support C₀De and C₁De as complementary HDS-associated markers for semi-quantitative manufacturing-era assessment rather than exact chronological dating.