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@alicefrolov.bsky.socialOct 6, 2026, 5:00 PM

New visualization: "The oxidative tipping point: ROS output outpaces antioxidant defense across the lifespan"

#RedoxBiology #MitochondrialBioenergetics #OxidativeStress #ReactiveOxygenSpecies #ElectronTransportChain #NRF2Signaling #FreeRadicalBiology

New visualization: "The oxidative tipping point: ROS output outpaces antioxidant defense across the lifespan" Subtitle: Simulated mitochondrial superoxide flux (left) vs enzymatic antioxidant capacity (right) per tissue and age. I am sharing a diverging paired-lollipop balance plot developed to communicate the divergence between mitochondrial reactive oxygen species generation and enzymatic scavenging capacity as a function of chronological age across four representative tissues (myocardium, skeletal muscle, hepatic parenchyma, and cortical neurons). I want to emphasize at the outset that the underlying values are simulated; they are parameterized to reproduce qualitative trends reported in the redox biology literature rather than to represent empirical measurements from a specific cohort. The mirror-lollipop geometry places superoxide flux on the left axis and combined antioxidant capacity (aggregating SOD2, catalase, and glutathione peroxidase activity) on the right, with a shared central baseline. This layout makes the widening asymmetry between the two arms readily interpretable per tissue-age stratum. The left-hand stems model electron leak at Complexes I and III, scaled to reflect the age-associated decline in electron transport chain coupling efficiency and the attendant increase in single-electron reduction of molecular oxygen. The right-hand stems encode declining enzymatic detoxification, incorporating the documented attenuation of NRF2-mediated transcriptional responses with advancing age. The central mechanistic claim rendered by the figure is the crossover point at which ROS output exceeds buffering capacity, initiating a self-amplifying regime of macromolecular oxidation, mtDNA lesion accumulation, and further ETC dysfunction. Post-mitotic tissues (neurons, myocardium) reach this inflection earlier in the simulated trajectory, consistent with their limited mitochondrial turnover.
@alicefrolov.bsky.socialSep 30, 2026, 5:00 PM

"Electron Transport Chain Capacity Erodes Complex-by-Complex with Age"

Subtitle: Simulated OXPHOS complex activity (% of young) across four age groups in skeletal muscle.

#OXPHOS #MitochondrialBioenergetics #Respirometry #MtDNA #SkeletalMuscleMetabolism #ElectronTransportChain #Bioenergetics

"Electron Transport Chain Capacity Erodes Complex-by-Complex with Age" Subtitle: Simulated OXPHOS complex activity (% of young) across four age groups in skeletal muscle. I am sharing a radial polar bar representation designed to communicate the differential, non-uniform decline of individual respiratory chain complexes with advancing age. Each angular segment of the "electron transport chain wheel" corresponds to one of the five OXPHOS complexes (CI: NADH:ubiquinone oxidoreductase; CII: succinate dehydrogenase; CIII: cytochrome bc1; CIV: cytochrome c oxidase; CV: F1Fo-ATP synthase), while radial extent encodes activity normalized to a young reference cohort (100%). Four concentric bands stratify the age groups, permitting rapid visual comparison of complex-specific trajectories. I want to emphasize that the underlying data are simulated. They are not derived from a primary cohort but are parameterized to reproduce trends repeatedly documented in the literature: the disproportionate vulnerability of Complexes I and IV, both of which incorporate mtDNA-encoded subunits and are therefore sensitive to the accumulation of somatic mtDNA deletions and point mutations, clonal expansion of mutant genomes, and impaired mitochondrial proteostasis. Complex II, being entirely nuclear-encoded, is rendered comparatively preserved, consistent with its frequent use as a normalization reference in respirometric and histochemical assays. The polar geometry was chosen deliberately to foreground the coupled, sequential architecture of the respiratory chain rather than to imply independence between complexes. Declining CI and CIII capacity constrains ubiquinone and cytochrome c redox cycling, with downstream consequences for proton-motive force generation and CV throughput. I welcome methodological critique, particularly regarding whether polar encoding introduces perceptual distortion of the radial magnitudes relative to a conventional Cartesian layout.