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alicefrolov.bsky.social
Mitochondrial membrane potential heterogeneity with age

I am sharing a data visualization exploring how mitochondrial membrane potential (Δψm) declines.

#MitochondrialBioenergetics #TMRM #MembranePotential #Mitophagy #SingleCellHeterogeneity #OxidativePhosphorylation #MtDNA
#ProtonMotiveForce
Mitochondrial membrane potential heterogeneity with age I am sharing a data visualization exploring how mitochondrial membrane potential (Δψm) declines and becomes more dispersed across the lifespan. The figure, titled "Mitochondrial membrane potential collapses and disperses with age," presents single-cell TMRM (tetramethylrhodamine methyl ester) intensity across four age groups in three tissues. I want to emphasize at the outset that the underlying dataset is simulated; it is constructed to illustrate a trend that is well grounded in the existing literature rather than to report novel empirical measurements. The chart employs a faceted raincloud design, with each tissue occupying its own facet. Within each facet, the four age cohorts are represented by a combination of a half-density (violin) contour, jittered single-cell points, and an overlaid boxplot. This composite format was chosen deliberately to convey both central tendency and the full distributional structure, which is critical here because the phenomenon of interest is not only a shift in the mean but an expansion of intercellular variance. Two features are salient. First, median TMRM intensity declines monotonically with advancing age across all three tissues, consistent with progressive dissipation of the proton-motive force and diminished electron transport chain coupling efficiency. Second, and more importantly, the distributions broaden with age, indicating increasing cell-to-cell heterogeneity in Δψm. This dispersion is compatible with mosaic accumulation of mtDNA mutations, clonal expansion of dysfunctional mitochondrial populations, and stochastic failure of quality-control mechanisms such as mitophagy. I would welcome discussion regarding appropriate normalization strategies for TMRM intensity, particularly the non-quench versus quench mode distinction, and how these affect interpretation of the observed variance structure.
September 20, 2026 at 5:00 PM
alicefrolov.bsky.social
Figure title: "Mitochondrial membrane potential collapse and dispersion with age"

Subtitle: Per-cell TMRM fluorescence in fibroblasts across four age groups and two tissues

#MitochondrialBioenergetics #TMRM #MembranePotential #SingleCellFunction #mtDNAheteroplasmy #Mitophagy
Figure title: "Mitochondrial membrane potential collapse and dispersion with age" Subtitle: Per-cell TMRM fluorescence in fibroblasts across four age groups and two tissues I am sharing a figure exploring how mitochondrial membrane potential (ΔΨm) distributions shift with donor age at single-cell resolution. The visualization uses a faceted half-violin raincloud design: each facet pairs the smoothed density (the "cloud") of per-cell TMRM fluorescence with jittered raw observations (the "rain"), facilitating simultaneous inspection of central tendency, distributional shape, and the tails that population-averaged assays obscure. Facets are arranged across four age groups and two tissue sources (dermal and pulmonary fibroblasts). A methodological caveat before interpretation: the data are simulated. They are parameterized to reproduce trends reported in the literature rather than to present novel empirical measurements, and are intended to illustrate the analytical framework and expected effect structure. Two features are salient. First, a progressive downward shift in median TMRM signal with age, consistent with age-associated ΔΨm depolarization attributable to declining electron transport chain flux and proton-motive force. Second, and arguably more informative, a marked increase in interquartile spread and bimodality in the older cohorts. This dispersion reflects mitochondrial heterogeneity — the coexistence of polarized and depolarized subpopulations within isogenic cultures — that likely arises from clonal expansion of mtDNA deletions, stochastic mitophagy insufficiency, and asymmetric organelle partitioning across mitotic divisions. I would emphasize that variance itself is a phenotype here. Reporting only mean ΔΨm collapses precisely the signal of interest. The raincloud geometry makes this explicit and, I would argue, should be standard for single-cell functional readouts.
September 8, 2026 at 6:21 PM
nanopharmnc.bsky.social
we also found that NASPM significantly altered the excitability of BNST neurons
Fig. 3 Application of NASPM hyperpolarizes the resting membranepotential and decreases excitability of dlBNST neurons in C57BL/6Jmale mice. a Representative trace of RMP hyperpolarization afterNASPM application from a spontaneously active dlBNST neuron. bRaw change in resting membrane potential before and after NASPM. cAverage magnitude of NASPM-induced hyperpolarization. d NASPMcauses an increase in the rheobase at RMP. e No significant changes inthe number of action potentials fired by dlBNST neurons in response toincreasing 20 pA current steps before and after drug application. Totaln = 13 cells from 6 mice. Asterisks indicate significant differences inpaired t-tests (b,d), one-sample t-tests (c) with a theoretical mean of0, or two-way repeated measures ANOVA with Greenhouse–Geissercorrection (e)
August 22, 2025 at 12:38 AM
alicefrolov.bsky.social
New visualization: Age-Related Erosion of Mitochondrial Membrane Potential Across Tissues

I am sharing a figure intended to communicate a well-documented bioenergetic trend.

#Mitochondria #Bioenergetics #Aging #MembranePotential #TMRM #Senescence #CellBiology #DataVisualization
New visualization: Age-Related Erosion of Mitochondrial Membrane Potential Across Tissues I am sharing a figure intended to communicate a well-documented bioenergetic trend rather than a novel empirical result. The data displayed are simulated, generated to reflect distributional patterns consistently reported in the aging literature; they should not be interpreted as a specific experimental cohort. The figure ("TMRM-based ΔΨm distributions decline and disperse with advancing age (simulated cohort)") uses a violin-style plot to represent mitochondrial membrane potential (ΔΨm) inferred from tetramethylrhodamine methyl ester (TMRM) fluorescence across several tissue compartments and age strata. TMRM accumulates in the mitochondrial matrix as a function of ΔΨm in accordance with the Nernst relationship, providing a ratiometric proxy for the proton-motive force established by the electron transport chain. Two features are deliberately emphasized. First, the central tendency of each distribution shifts toward lower ΔΨm with advancing age, consistent with diminished respiratory chain coupling efficiency, accumulation of mtDNA lesions, and reduced complex I and IV activity. Second, and mechanistically important, the distributions broaden with age, reflecting increased cell-to-cell heterogeneity. This dispersion is compatible with mosaic patterns of mitochondrial dysfunction, in which subpopulations of cells sustain depolarization while others remain relatively preserved, plausibly linked to stochastic clonal expansion of deleterious mtDNA variants. I chose the violin format precisely because boxplots or bar summaries obscure this variance structure, which I regard as biologically informative rather than nuisance noise. Tissue-specific differences in baseline ΔΨm and rate of decline are illustrated to prompt discussion of differential vulnerability in post-mitotic versus proliferative compartments.
July 22, 2026 at 5:11 PM