Biology subjects

Kaplan, C.

Publications and source records attributed to Kaplan, C..

5 recordsLinked to original sources

bioRxiv2026

Functional Connectivity Differences Underly Variable Centralized Symptom Relief After Hysterectomy

Approximately 1 in 4 women with chronic pelvic pain (CPP) report persistent pelvic pain after hysterectomy. Centralized symptoms-fatigue, multisite pain, and sleep disturbance, quantified using the Fibromyalgia Survey Score (FSS)-often co-occur with this risk, but the trajectory of centralized symptom burden after surgery, independent of pelvic pain outcome, is not well understood. Whether presurgical differences in central nervous system pain processing distinguish women whose centralized symptoms improve (improvers) from those whose do not (non-improvers) has not been tested. In this observational study, we assessed whether individuals who do and do not report improvement in FSS scores six months post-operatively differ in their baseline/pre-operative phenotypes and brain function. Sensory sensitivity scores were significantly higher in non-improvers than in improvers at baseline. We identified no significant, presurgical differences in age, average pelvic pain intensity, widespread pain, or pain interference between improvers and non-improvers. Functional connectivity was examined at rest and during the application of a distal, sustained pressure pain. We identified no significant group differences at rest. During sustained pressure pain, non-improvers showed greater connectivity than improvers between primary somatosensory cortex and posterior thalamic seeds with frontal, motor, cerebellar and limbic regions, but lower connectivity between the periaqueductal gray and subgenual cingulate cortex. Non-improvers also showed a greater pain-evoked increase in connectivity between the pelvic and leg representations of the primary sensory cortex and other sensorimotor regions in the pain-versus-rest contrast. Overall, non-improvers showed increased functional connectivity between regions associated with the multisensory integration of ascending pain, and decreased connectivity between regions associated with descending pain modulation. In exploratory analyses, some of these connections were additionally associated with symptom burden: sensory sensitivity, number of painful regions, and pain interference. This work may inform mechanisms of persistent symptom burden and guide surgical decision-making in patients with high central sensitization.

neuroscience↗

bioRxiv2026

Concordance between the fast and efficient mixed-effects algorithm (FEMA) and conventional mixed-effects modeling for whole-brain connectivity in longitudinal chronic pain

Researchers increasingly have access to neuroimaging data with repeated measures within subjects. Linear mixed-effects modeling offers a valuable way to analyze such data, but its application remains limited in the neuroimaging literature due to high computational cost and a lack of mainstream analysis packages. Here we benchmark a recently published algorithm, the Fast and Efficient Mixed-Effects Algorithm (FEMA), against a conventional implementation (MATLAB's fitlme, restricted maximum likelihood) across 94,830 functional connectivity edges. In contrast to the Adolescent Brain Cognitive Development (ABCD) Study Dataset used in the development and testing of FEMA, the dataset used in the current analysis has a smaller sample size (n = 378) and comprises individuals with chronic pelvic pain scanned at up to four visits over three years. Despite these differences, the two implementations produced highly concordant results: fixed-effect estimates and test statistics correlated at r [≥] 0.999 (Lin's concordance correlation coefficient [≥] 0.999), and the two approaches reached the same statistical conclusion for 99.98% of edges. FEMA completed each analysis roughly 20 times faster. Agreement was weaker for the estimated variance components, where FEMA attributed systematically less variance to the participant random effect, yielding a slightly lower intraclass correlation in approximately 82% of edges. We further show that most residual disagreement reflected FEMA's default variance-grid resolution rather than the estimator itself, and could be eliminated at negligible computational cost. These findings support the use of FEMA for connectome-wide analysis of repeated-measures neuroimaging data.

neuroscience↗

bioRxiv2026

Single-stranded telomeric repeats segregate into spatial compartments within ALT-associated PML bodies

Alternative lengthening of telomeres (ALT)-associated PML bodies (APBs) concentrate single-stranded (ss) telomeric DNA and RNA species that are critical for recombination-based telomere maintenance. However, how these species are organized inside APBs has remained invisible at microscopic resolution. Here, we map the nanoscale topology of APB components using 3D MINFLUX super-resolution microscopy combined with multiplexed exchange DNA-PAINT labeling at [~]3 nm localization precision. We discover that ssC-rich and ssG-rich telomeric repeats occupy distinct spatial compartments within a partially open, [~]70 nm thick PML protein shell: ssC-rich repeats concentrate at the inner shell surface, while ssG-rich repeats distribute broadly through the interior alongside TRF1-marked double-stranded telomeric chromatin. The ssG-rich signal is predominantly DNA and frequently colocalizes with POT1 assemblies. Additional TRF1 clusters outside the shell indicate multi-telomere association. Together, these structural constraints motivate a model of ALT in which t-loop resolution generates a C-circle template that drives rolling-circle amplification of telomeric repeats. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/724127v1_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@fdb6a2org.highwire.dtl.DTLVardef@e185c9org.highwire.dtl.DTLVardef@168b12org.highwire.dtl.DTLVardef@44bd0_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LI3D MINFLUX combined with exchange DNA-PAINT resolves APB components at {bsim}3 nm isotropic precision, enabling direct visualization of molecular organization beyond the reach of conventional super-resolution microscopy. C_LIO_LIPML forms a partially open, [~]70 nm thick spherical shell in APBs with reduced molecular density compared to canonical PML nuclear bodies, providing the structural scaffold and coordinate system for mapping internal APB organization. C_LIO_LIDouble-stranded telomeric chromatin (TRF1-marked) fills the APB interior, with additional TRF1 domains outside the shell indicative of multi-telomere clustering at individual APBs. C_LIO_LIssC-rich repeats concentrate in the inner part of the PML shell while ssG-rich DNA repeats distribute broadly through the interior, revealing strand-specific spatial segregation. C_LIO_LIThe ssG-rich single-stranded repeats in APBs predominantly comprise DNA and partially colocalize with POT1, connecting their spatial distribution to single-stranded telomeric DNA substrates. C_LIO_LIThe spatial organization of APB components motivates a mechanistic model in which t-loop processing generates C-circle templates for rolling-circle amplification, while multi-telomere clustering facilitates inter-telomeric recombination. C_LI

cell biology↗

bioRxiv2020

Adaptive actin organization counteracts elevated membrane tension to ensure robust endocytosis

Clathrin-mediated endocytosis (CME) robustness under elevated membrane tension is maintained by actin assembly-mediated force generation. However, whether more actin assembles at endocytic sites in response to increased load, as has been observed in lamellipodia, has not previously been investigated. Here actin network ultrastructure at CME sites was examined under low and high membrane tension. Actin and N-WASP spatial organization indicate that actin polymerization initiates at the base of clathrin-coated pits and that the network then grows away from the plasma membrane. Actin network height at individual CME sites was not coupled to coat shape, raising the possibility that local differences in mechanical load feedback on assembly. By manipulating membrane tension and Arp2/3 complex activity we tested the hypothesis that actin assembly at CME sites increases in response to elevated load. Indeed, in response to elevated membrane tension, actin grew higher, resulting in greater coverage of the clathrin coat, and CME slowed. When membrane tension was elevated and the Arp2/3 complex was inhibited, shallow clathrin-coated pits accumulated, indicating that this adaptive mechanism is especially crucial for coat curvature generation. We propose that actin assembly increases in response to increased load to ensure CME robustness over a range of plasma membrane tensions.

cell biology↗

bioRxiv2019

Direct comparison of clathrin-mediated endocytosis in budding and fission yeast reveals conserved and evolvable features

AbstractConserved proteins drive clathrin-mediated endocytosis (CME), which universally involves a burst of actin assembly. To gain fundamental mechanistic insights into this process, a side-by-side quantitative comparison of CME was performed on two distantly related yeast species. Though endocytic protein abundance in S. pombe and S. cerevisiae are more similar than previously thought, membrane invagination speed and depth are two-fold greater in fission yeast than in budding yeast. In both yeasts, Arp2/3 complex activation drives membrane invagination when triggered by the accumulation of [~]70 WASP molecules. In contrast to budding yeast, WASP-mediated actin nucleation activity plays an essential role in fission yeast endocytosis. Genetics and live-cell imaging revealed core CME spatiodynamic similarities between the two yeasts, though two-zone actin assembly is a fission yeast-specific mechanism, which is not essential for CME. These studies identified conserved CME mechanisms and species-specific adaptations and have broad implications that extend from yeast to humans.

cell biology↗