Biology subjects

Regan, K.

Publications and source records attributed to Regan, K..

8 recordsLinked to original sources

bioRxiv2026

A field method to optimize dried blood spot sampling for mercury biomonitoring

O_LIHeavy metals are pervasive environmental contaminants that can impair the health of organisms globally. As the largest anthropogenic source of the potent neurotoxin mercury (Hg), gold mining has amplified these threats throughout the tropics. Consequently, there is a mounting need to monitor Hg contamination of the richest biological communities on Earth. Venous whole blood provides a reliable, nonlethal measurement of recent dietary and site-derived contamination, but collecting and cold-storing samples can be impractical in field conditions. C_LIO_LITo overcome these challenges, we developed and evaluated a method to assay Hg exposure in vascular organisms by measuring the volume of dried blood spots (DBS) in the field, which can be stored at ambient temperatures until analysis. We explored the methods precision and accuracy in estimating whole blood Hg concentrations by collecting paired whole blood and DBS aliquots from birds (n = 527 individuals, 140 species) along a trophic gradient (i.e., granivores to piscivores) in Belize and Peru. C_LIO_LIUsing a Bayesian linear mixed-effects model, we found a highly precise and unbiased relationship between DBS and whole blood total Hg concentrations that was centered at perfect unity (R2 = 0.99; {beta} = 1.00 {+/-} 0.03; 95% CrI: 0.95-1.05). Agreement between individual paired aliquots was more variable, in which approximately 12% of DBS containing at least 1 ng THg differed from whole blood by more than {+/-}20%. However, DBS accuracy increased at higher THg concentrations, suggesting that disagreement at low concentrations is an expected consequence of higher measurement error near the analytical limit of detection of our instruments. C_LIO_LICompared to whole-blood collection and analysis workflows, DBS offer substantial logistical advantages by eliminating cold-chain dependence and reducing transport burden, laboratory handling time, and overall operational costs. Consequently, volume-measured DBS provide a practical and highly reliable alternative for monitoring Hg contamination in both humans and wildlife, particularly for ecological and population-level applications in remote and resource-limited environments. C_LI

pharmacology and toxicology↗

bioRxiv2026

Neutrophil migration in the lung is altered by alveolar collapse and stretch

RationaleHeterogeneous alveolar collapse is prevalent in inflammatory lung conditions such as chronic obstructive pulmonary disease, acute respiratory distress syndrome, and pneumonia. Although neutrophil-released proteases contribute to the tissue remodeling that leads to alveolar collapse, how this altered mechanical environment in turn affects neutrophil migration remains largely unexplored. ObjectivesIn this study, we investigate how alveolar collapse and stretch influence neutrophil migration and identify the mechanical and biochemical factors that govern regional migration differences. MethodsWe developed a novel precision-cut lung slice platform that generates collapsed vs non-collapsed regions within the same slice. Neutrophils in both regions were longitudinally imaged for up to 5 hours to quantify motility behavior. Migration mechanisms were probed using migration-related inhibitors, collagenase, and cigarette smoke extract. A crystal ribcage system, which preserves intact alveolar shape and the air-liquid interface, was also used to assess the effects of ventilation on neutrophil migration. ResultsNeutrophil migration was faster in the collapsed region compared to not-collapsed regions. This regional difference was eliminated by Rho-associated protein kinase (ROCK) inhibition, which selectively increased migration speed in the non-collapsed region. The regional difference persisted with the addition of collagenase and cigarette smoke extract, both of which significantly increased the migration speed in both regions. In the crystal ribcage, the preserved air-liquid interface and ventilation together enhanced neutrophil migration compared with a collapsed lung. ConclusionsAlveolar collapse and stretch facilitate neutrophil migration, indicating the role of localized tissue remodeling in driving neutrophil activity and further disease progression.

bioengineering↗

bioRxiv2025

Mosaic pattern: lung functional heterogeneity at the alveolus level

Inhaled particles carrying pathogens, pollutants (e.g., microplastics, smoke), therapeutics, and diagnostics are increasingly relevant to public health, yet real-time tracking of aerosol transport in functional alveoli remains challenging. Here, we used the recently developed crystal ribcage to investigate aerosol transport in ex vivo lungs during active ventilation, obtaining the first real-time observations of single aerosol droplet transport and deposition in functional alveoli. We discovered deterministic heterogeneity at both intra- and inter-alveolar levels, with aerosol distribution forming a characteristic "mosaic" pattern in which only specific alveolar clusters received particles. The pattern was consistently formed in vivo during spontaneous breathing and ex vivo using both positive- and negative-pressure ventilation. This pattern was also consistent across a range of aerosols, including small molecules, nanobodies, nanoparticles, microplastics, therapeutics, and pathogens. Additionally, the pattern was observed in murine, porcine, and human lungs, and evolved from birth through aging in mice. The post-deposition stability of the pattern depended on particle type and lung age, lasting from a few minutes for small molecular weight particles to multiple days for cell-binding particles. These alveolar-level heterogeneities may uncover previously unrecognized biological and immunological heterogeneities associated with the mosaic pattern, including its role in postnatal lung development, susceptibility to inhaled airborne hazards such as pollutants and infectious agents, and early pathogenesis and response to inhaled therapeutics in respiratory diseases such as pneumonia, COPD, asthma, and lung cancer.

bioengineering↗

bioRxiv2025

Micromechanics of lung capillaries across mouse lifespan and in positive- vs negative-pressure ventilation

The lung undergoes continuous remodeling throughout normal development and aging, including changes to alveolar and capillary structure and function. While histological methods allow static analysis of these age-related changes, characterizing the changes that occur in response to mechanical stimuli remains difficult, particularly over a dynamic, physiologically relevant range in a functioning lung. Alveolar and capillary distension - the change in diameter of alveoli and capillaries, respectively, in response to pressure changes - is one such process, where dynamically controlling and monitoring the diameter of the same capillary or alveolus is essential to infer its mechanical properties. We overcome these limitations by utilizing the recently developed crystal ribcage to image the alveoli and vasculature of a functional mouse lung across the lifespan in postnatal (6-7 days), young adult (12-18 weeks), and aged (20+ months) mice. Using a range of biologically relevant vascular (0-15 cmH2O) and transpulmonary (3-12 cmH2O) pressures, we directly quantify vascular and alveolar distention in the functional lung as we precisely adjust pulmonary pressures. Our results show differences in age-related alveolar and vascular distensibility: when we increase transpulmonary alveolar or vascular pressure, vessels in postnatal lungs expand less and undergo less radial and axial strain, under each respective pressure type, suggesting stiffer capillaries than in older lungs. However, while vessels in young adult and aged lungs respond similarly to variations in vascular pressure, differences in elasticity start to emerge at the alveolar scale in response to transpulmonary alveolar pressure changes. Our results further indicate that differing effects of ventilation mode (i.e., positive vs negative) present themselves at the capillary level, with vessels under positive pressure undergoing more compression than when under negative-pressure conditions. These findings contribute both to the understanding of the functional changes that occur within the lung across the lifespan, as well as to the debate of ventilation effects on lung microphysiology.

physiology↗

bioRxiv2022

Probing lung function at high spatiotemporal resolution using a novel crystal ribcage

Understanding the dynamic pathogenesis and treatment response in pulmonary diseases requires probing the lung at cellular resolution in real-time. Despite recent progress in intravital imaging, optical imaging of the lung during active respiration and circulation has remained challenging. Here, we introduce the crystal ribcage: a transparent ribcage that (i) allows truly multiscale optical imaging of the lung in health and disease from whole-organ to single cell, (ii) enables the modulation of lung biophysics and immunity through intravascular, intrapulmonary, intraparenchymal, and optogenetic interventions, and (iii) preserves the 3-D architecture, air-liquid interface, cellular diversity, and respiratory-circulatory functions of the lung. Utilizing these unprecedented capabilities on murine models of primary and metastatic lung tumors, respiratory infection, pulmonary fibrosis, emphysema, and acute lung injury we probed how disease progression remodels the respiratory-circulatory functions at the single alveolus and capillary levels. In cancer, we identified the earliest stage of tumorigenesis that compromises alveolar and capillary functions, a key state with consequences on tumor progression and treatment response. In pneumonia, we mapped mutual links between the recruited immune cells and the alveolar-capillary functions. We found that neutrophil migration is strongly and reversibly responsive to vascular pressure with implications for understanding of how lung physiology, altered by disease and anatomical location, affects immune cell activities. The crystal ribcage and its broad applications presented here will facilitate further studies of real-time remodeling of the alveoli and capillaries during pathogenesis of nearly any pulmonary disease, leading to the identification of new targets for treatment strategies.

bioengineering↗

bioRxiv2021

Distinct states of proinsulin misfolding in MIDY

A precondition for efficient proinsulin export from the endoplasmic reticulum (ER) is that proinsulin meets ER quality control folding requirements, including formation of the Cys(B19)-Cys(A20) "interchain" disulfide bond, facilitating formation of the Cys(B7)-Cys(A7) bridge. The third proinsulin disulfide, Cys(A6)-Cys(A11), is not required for anterograde trafficking, i.e., a "lose-A6/A11" mutant [Cys(A6), Cys(A11) both converted to Ser] is well secreted. Nevertheless, an unpaired Cys(A11) can participate in disulfide mispairings, causing ER retention of proinsulin. Among the many missense mutations causing the syndrome of Mutant INS gene-induced Diabetes of Youth (MIDY), all seem to exhibit perturbed proinsulin disulfide bond formation. Here we have examined a series of seven MIDY mutants [including G(B8)V, Y(B26)C, L(A16)P, H(B5)D, V(B18)A, R(Cpep+2)C, E(A4)K], six of which are essentially completely blocked in export from the ER in pancreatic {beta}-cells. Three of these mutants, however, must disrupt the Cys(A6)-Cys(A11) pairing to expose a critical unpaired cysteine thiol perturbation of proinsulin folding and ER export, because when introduced into the proinsulin lose-A6/A11 background, these mutants exhibit native-like disulfide bonding and improved trafficking. This maneuver also ameliorates dominant-negative blockade of export of co-expressed wild-type proinsulin. A growing molecular understanding of proinsulin misfolding may permit allele-specific pharmacological targeting for some MIDY mutants.

biochemistry↗

bioRxiv2019

Environmental selection and spatiotemporal structure of a major group of soil protists (Rhizaria: Cercozoa) in a temperate grassland

Soil protists are increasingly appreciated as essential components of soil foodwebs; however, there is a dearth of information on the factors structuring their communities. Here we investigate the importance of different biotic and abiotic factors as key drivers of spatial and seasonal distribution of protistan communities. We conducted an intensive survey of a 10m2 grassland plot in Germany, focusing on a major group of protists, the Cercozoa. From 177 soil samples, collected from April to November, we obtained 694 Operational Taxonomy Units representing >6 million Illumina reads. All major cercozoan groups were present, dominated by the small flagellates of the Glissomonadida. We found evidence of environmental filtering structuring the cercozoan communities both spatially and seasonally. Spatial analyses indicated that communities were correlated within a range of four meters. Seasonal variations of bactevirores and bacteria, and that of omnivores after a time-lapse, suggested a dynamic prey-predator succession. The most influential edaphic properties were moisture and clay content, which differentially affected each functional group. Our study is based on an intense sampling of protists at a small scale, thus providing a detailed description of the niches occupied by different taxa/functional groups and the ecological processes involved.

ecology↗

bioRxiv2018

Bridging the spatiotemporal scales of macromolecular transport in crowded biomimetic systems

Crowding plays a key role in the transport and conformations of biological macromolecules. Gene therapy, viral infection and transfection require DNA to traverse the crowded cytoplasm, including a heterogeneous cytoskeleton of filamentous proteins. Given the complexity of cellular crowding, the dynamics of biological molecules can be highly dependent on the spatiotemporal scale probed. We present a powerful platform that spans molecular and cellular scales by coupling single-molecule conformational tracking (SMCT) and selective-plane illumination differential dynamic microscopy (SPIDDM). We elucidate the transport and conformational properties of large DNA, crowded by custom-designed networks of actin and microtubules, to link single-molecule conformations with ensemble DNA transport and cytoskeleton structure. We show that actin crowding leads to DNA compaction and suppression of fluctuations, combined with anomalous subdiffusion and heterogeneous transport, whereas microtubules have much more subdued impact across all scales. Interestingly, in composite networks of both filaments, microtubules primarily govern single-molecule DNA dynamics whereas actin governs ensemble transport.

biophysics↗