Biology subjects

Chow, B. Y.

Publications and source records attributed to Chow, B. Y..

6 recordsLinked to original sources

bioRxiv2025

Associations Between Gut Microbiome and 24-Hour Blood Pressure Variability: A Cross-sectional Study Highlighting Sex Differences and Potential Therapeutic Targets

Blood pressure (BP) variability is an independent risk factor for cardiovascular disease (CVD). While gut microbiota (GM) and GM-derived short-chain fatty acids (SCFAs) are recognized to play a key role in BP regulation, their association with BP variability remains poorly understood. This cross-sectional study of 241 community-dwelling individuals from Hong Kong (113 men and 128 women, mean age 54{+/-}6 years) without symptomatic CVD examined the associations of GM, characterized by shotgun sequencing, and plasma SCFAs, with systolic and diastolic blood pressure (SBP/DBP) variability assessed by 24-hour BP monitoring. GM analyses, using covariate-adjusted statistical models, revealed that higher 24-hour SBP CoV associated negatively with GM -diversity (Shannon and Simpsons index, P<0.05) and positively with Firmicutes/Bacteroidetes ratio, driven by the female cohort. Parabacteroides merdae, Bacteroides dorei, Bifidobacterium pseudocatenulatum, Alistipes finegoldii and Bacteroides intestinalis were negatively associated with indices of SBP/DBP variability in a sex-specific manner. Further analysis indicated that B. dorei may mediate SBP CoV via plasma iso-butyric acid in women (bootstrapping 95% CI: -3.6 to -0.19; P<0.05). We demonstrated that higher SBP variability is associated with markers of gut dysbiosis and a reduction in beneficial gut bacteria, particularly in women. Notably, we identified several gut bacterial species with potential therapeutic implications for managing 24-hour SBP/DBP variability, warranting further investigation.

microbiology↗

bioRxiv2022

Optogenetic clustering and membrane translocation of the BcLOV4 photoreceptor

Optogenetic clustering is a versatile method to control protein activity in living cells, tissues, and organisms. Here we show that the BcLOV4 photoreceptor both clusters and translocates to the plasma membrane in response to blue light, representing a new class of light-dependent behavior. We demonstrate that dual translocation and clustering can be harnessed for novel single-component optogenetic tools, including for activation of the entire family of epidermal growth factor receptor (ErbB1-4) tyrosine kinases. We further find that clustering and membrane translocation are causally linked. Stronger clustering increased the magnitude of translocation and downstream signaling, increased sensitivity to light by ~3-4-fold, and decreased the expression levels needed for strong signal activation. Thus light-induced clustering of BcLOV4 provides a strategy to generate a new class of optogenetic tools and to enhance existing ones.

bioengineering↗

bioRxiv2022

High-throughput feedback-enabled optogenetic stimulation and spectroscopy in microwell plates

The ability to perform sophisticated, high-throughput optogenetic experiments has been greatly enhanced by recent open-source illumination devices that allow independent programming of light patterns in single wells of microwell plates. However, there is currently a lack of instrumentation to monitor such experiments in real time, necessitating repeated transfers of the samples to stand-alone analytical instruments, thus limiting the types of experiments that could be performed. Here we address this gap with the development of the optoPlateReader (oPR), an open-source, solid-state, compact device that allows automated optogenetic stimulation and spectroscopy in each well of a 96-well plate. The oPR integrates an optoPlate illumination module with a module called the optoReader, an array of 96 photodiodes and LEDs that allows 96 parallel light measurements. The oPR was optimized for stimulation with blue light and for measurements of optical density and fluorescence. After calibration of all device components, we used the oPR to measure growth and to induce and measure fluorescent protein expression in E. coli. We further demonstrated how the optical read/write capabilities of the oPR permit computer-in-the-loop feedback control, where the current state of the sample can be used to adjust the optical stimulation parameters of the sample according to pre-defined feedback algorithms. The oPR will thus help realize an untapped potential for optogenetic experiments by enabling automated reading, writing, and feedback in microwell plates through open-source hardware that is accessible, customizable, and inexpensive.

synthetic biology↗

bioRxiv2022

Mechanotransductive feedback control of endothelial cell motility and vascular morphogenesis

Vascular morphogenesis requires persistent endothelial cell motility that is responsive to diverse and dynamic mechanical stimuli. Here, we interrogated the mechanotransductive feedback dynamics that govern endothelial cell motility and vascular morphogenesis. We show that the transcriptional regulators, YAP and TAZ, are activated by mechanical cues to transcriptionally limit cytoskeletal and focal adhesion maturation, forming a conserved mechanotransductive feedback loop that mediates human endothelial cell motility in vitro and zebrafish intersegmental vessel (ISV) morphogenesis in vivo. This feedback loop closes in 4 hours, achieving cytoskeletal equilibrium in 8 hours. Feedback loop inhibition arrested endothelial cell migration in vitro and ISV morphogenesis in vivo. Inhibitor washout at 3 hrs, prior to feedback loop closure, restored vessel growth, but washout at 8 hours, longer than the feedback timescale, did not, establishing lower and upper bounds for feedback kinetics in vivo. Mechanistically, YAP and TAZ induced transcriptional suppression of RhoA signaling to maintain dynamic cytoskeletal equilibria. Together, these data establish the mechanoresponsive dynamics of a transcriptional feedback loop necessary for persistent endothelial cell migration and vascular morphogenesis.

cell biology↗

bioRxiv2021

Single-component optogenetic tools for inducible RhoA GTPase signaling

We created optogenetic tools to control RhoA GTPase, a central regulator of actin organization and actomyosin contractility. RhoA GTPase, or its upstream activating GEF effectors, were fused to BcLOV4, a photoreceptor that can be dynamically recruited to the plasma membrane by a light-regulated protein-lipid electrostatic interaction with the inner leaflet. Direct membrane recruitment of these effectors induced potent contractile signaling sufficient to separate adherens junctions in response to as little as one pulse of blue light. Cytoskeletal morphology changes were dependent on the alignment of the spatially patterned stimulation with the underlying cell polarization. RhoA-mediated cytoskeletal activation induced YAP nuclear localization within minutes and subsequent mechanotransduction, verified by YAP- TEAD transcriptional activity. These single-component tools, which do not require protein binding partners, offer spatiotemporally precise control over RhoA signaling that will advance the study of its diverse regulatory roles in cell migration, morphogenesis, and cell cycle maintenance.

bioengineering↗

bioRxiv2018

An Open-Source Plate Reader

Microplate readers are foundational instruments in experimental biology and bioengineering that enable multiplexed spectrophotometric measurements. To enhance their accessibility, we here report the design, construction, validation, and benchmarking of an open-source microplate reader. The system features full-spectrum absorbance and fluorescence emission detection, in situ optogenetic stimulation, and stand-alone touch screen programming of automated assay protocols. The total system costs <$3500, a fraction of the cost of commercial plate readers, and can detect the fluorescence of common dyes down to [~]10 nanomolar concentration. Functional capabilities were demonstrated in context of synthetic biology, optogenetics, and photosensory biology: by steady-state measurements of ligand-induced reporter gene expression in a model of bacterial quorum sensing, and by flavin photocycling kinetic measurements of a LOV (light-oxygen-voltage) domain photoreceptor used for optogenetic transcriptional activation. Fully detailed guides for assembling the device and automating it using the custom Python-based API (Application Program Interface) are provided. This work contributes a key technology to the growing community-wide infrastructure of open-source biology-focused hardware, whose creation is facilitated by rapid prototyping capabilities and low-cost electronics, optoelectronics, and microcomputers.\n\nTable of Contents Graphic\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=91 SRC=\"FIGDIR/small/413781_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (30K):\norg.highwire.dtl.DTLVardef@c26eaborg.highwire.dtl.DTLVardef@efb695org.highwire.dtl.DTLVardef@1bc2f41org.highwire.dtl.DTLVardef@1c25c79_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗