Biology subjects

Barrios, A. M.

Publications and source records attributed to Barrios, A. M..

3 recordsLinked to original sources

bioRxiv2026

A high-throughput all-optical platform for mapping gene perturbations to electrophysiology

Electrical phenotyping remains a bottleneck in linking genes to cellular function. We developed a high-throughput all-optical electrophysiology platform combining an engineered human induced pluripotent stem cell (hiPSC) line, wide-field voltage imaging, and automated analysis. The hiPSC line integrates inducible NGN2, CRISPR interference, and degron-gated expression of Voltron2 and CheRiff, enabling neuronal differentiation, targeted gene knockdown, and optical electrophysiology. The microscope records approximately 1,500 spiking glutamatergic neurons at 800 Hz across a 4x4 mm field, with larger fields supporting approximately 3,000 neurons at 660 Hz. Automated analysis extracts single-cell voltage traces and quantifies firing patterns, action-potential waveforms, and subthreshold dynamics. Arrayed knockdown of five sodium- and potassium-channel genes produced distinct electrophysiological phenotypes. The engineered hiPSC line also supported optical electrophysiology recordings from motor neurons, astrocytes, and cardiomyocytes. These results establish a scalable platform for high-throughput electrophysiological phenotyping and functional genomics in hiPSC-derived cells.

neuroscience↗

bioRxiv2026

Branched-chain amino acid fermentation as an alternative mammalian electron sink

Hypoxia disrupts mitochondrial respiration and increases the NADH/NAD+ ratio, causing reductive stress. To maintain redox homeostasis, mammalian cells divert electrons toward fermentation. While fermentation in mammals typically involves lactate production, we identify the fermentation of branched-chain amino acids (BCAAs) as an alternative electron sink activated by hypoxia. The resulting metabolites are excreted in urine as a distinct mechanism for alleviating reductive stress. BCAA fermentation is catalyzed by lactate dehydrogenase (LDH) enzymes and is highly responsive to the NADH/NAD+ ratio. Consequently, BCAA fermentation products are sensitive biomarkers for reductive stress in human contexts ranging from resistance exercise to severe hypoxemia. Furthermore, we find that mouse sperm have evolved highly efficient BCAA fermentation, providing a specific metabolic strategy to support the anaerobic electron flow that facilitates flagellar hypermotility across mammalian sperm. Our work highlights an under-appreciated fate of BCAAs in response to reductive stress.

cell biology↗

bioRxiv2022

Organ-Specific Fuel Rewiring in Acute and Chronic Hypoxia Redistributes Glucose and Fatty Acid Metabolism

Oxygen deprivation can be detrimental. However, chronic hypoxia is associated with decreased incidence of metabolic syndrome and cardiovascular disease in high-altitude populations. Previously, hypoxic fuel rewiring has primarily been studied in immortalized cells. Here, we describe how systemic hypoxia rewires fuel metabolism to optimize whole-body adaptation. Acclimatization to hypoxia coincided with dramatically lower blood glucose and adiposity. Using in vivo fuel uptake and flux measurements, we found that organs partitioned fuels differently during hypoxia adaption. Acutely, most organs increased glucose uptake and suppressed aerobic glucose oxidation, consistent with previous in vitro investigations. In contrast, brown adipose tissue and skeletal muscle became "glucose savers," suppressing glucose uptake by 3-5-fold. Interestingly, chronic hypoxia produced distinct patterns: the heart relied increasingly on glucose oxidation, and unexpectedly, the brain, kidney, and liver increased fatty acid uptake and oxidation. Hypoxia-induced metabolic plasticity carries therapeutic implications for chronic metabolic diseases and acute hypoxic injuries.

physiology↗