Biology subjects

Syed, S.

Publications and source records attributed to Syed, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Amino Acid Metabolic Signature Links Pediatric Environmental Enteric Dysfunction to Maternal-Fetal Growth Restriction Across Two Independent Cohorts

Environmental Enteric Dysfunction (EED) is a leading contributor to childhood stunting. Most EED literature derives from postnatal pediatric cohorts, leaving unclear how much of the metabolic signature reflects acquired intestinal pathology versus growth restriction originating earlier. We applied genome-scale metabolic modeling to explore whether metabolic features of pediatric EED overlap with those of maternal plasma proteomes associated with adverse early-life growth. Duodenal transcriptomics from the Study of Environmental Enteropathy and Malnutrition (SEEM; 52 children with EED, 24 controls) and maternal plasma proteomics from the Alliance for Maternal and Newborn Health Improvement (AMANHI; n = 2,485 pregnant women) were integrated with the Human1 model using Reaction Inclusion by Parsimony and Transcript Distribution (RIPTiDe), followed by flux sampling and Linear Discriminant Analysis, across five growth-related proxies (small-for-gestational-age, low birth weight, preterm birth, stunting, and wasting). Amino acid and nucleotide metabolism were prominent among the top discriminating reactions in EED and most proxies. Of the 50 reactions distinguishing EED from control, 24 (48%) were among the top reactions in at least one proxy, and 19 (38%) with low birth weight, the largest of any proxy. These exploratory findings suggest shared metabolic pathways across tissues and life stages and motivate longitudinal studies.

systems biology↗

bioRxiv2026

Serum nutritional-metabolic recovery during tuberculosis treatment across BMI-defined undernutrition strata: A longitudinal proteomic reanalysis

Background Tuberculosis remains the leading cause of death from a single infectious agent, and undernutrition is a major modifiable risk factor. Serum proteomics can capture systemic host recovery during therapy, but whether baseline BMI-defined undernutrition alters this trajectory is unclear. Methods We reanalysed processed longitudinal tandem-mass-tag serum proteomics from 30 adults with pulmonary tuberculosis and durable cure sampled at baseline and weeks 8, 17, 26 and 52. Thirteen participants had baseline BMI <18.5 kg/m2 and 17 had BMI >=18.5 kg/m2. Protein-level analyses evaluated baseline differences and week-specific within-participant change; module and recovery-axis models evaluated BMI-by-time interactions, with random-intercept mixed models added as a repeated-measures sensitivity analysis. Three complementary treatment-responsive modules were integrated into an exploratory, nonredundant 36-protein nutritional-metabolic summary axis. Results The reconstructed dataset contained 1,923 quantified features across 150 participant-visits. Inflammatory/acute-phase and metal-handling/nutritional-immunity module scores declined during follow-up, whereas lipid/apolipoprotein-transport, nutritional-carrier and endocrine-immunometabolic scores increased. In the primary week-specific paired-change analyses, no protein-level between-BMI difference in longitudinal change survived false-discovery-rate correction; no curated-module BMI-by-time interaction survived correction. The 36-protein summary axis increased in both BMI strata from week 17 onward. In a random-intercept model without interaction, the BMI <18.5 kg/m2 stratum had a lower average axis score across visits than the BMI >=18.5 kg/m2 comparison stratum, although the confidence interval included zero (difference -1.34, 95% CI -2.76 to 0.08; p = .064). Categorical and continuous BMI-by-time interaction tests did not detect differential axis trajectories. Conclusions Tuberculosis treatment was accompanied by broad longitudinal remodelling of circulating inflammatory and nutritional-metabolic protein systems. An exploratory 36-protein summary axis increased in both baseline BMI strata, while formal interaction tests did not detect BMI-dependent trajectories and remained too imprecise to establish equivalence. BMI should be regarded as an anthropometric proxy rather than a comprehensive measure of nutritional state. The defined axis provides a framework for prospective validation alongside direct measures of body composition, micronutrients, treatment exposure and clinical outcomes.

bioinformatics↗

bioRxiv2026

Glutamatergic and Redox Abnormalities in Major Depressive Disorder: Links to Childhood Maltreatment and Perceived Stress

Background: Childhood sexual abuse (CSA) increases the risk for major depressive disorder (MDD), yet the underlying neurobiological mechanisms remain poorly understood. We examined (1) associations of medial prefrontal cortex (mPFC) glutamatergic metabolites and redox balance with childhood maltreatment and MDD; and (2) whether these neurochemical measures predicted future perceived stress. Methods: Using proton and phosphorus 4T magnetic resonance spectroscopy, we quantified glutamate, glutamine, their sum (Glx), and the NAD/NADH ratio within the same mPFC voxel in 71 women across four groups: healthy controls (HC; n=27), current MDD without CSA (n=14), current MDD with CSA (n=14), and remitted MDD with CSA (n=16). Results: Glutamate and Glx levels were lower in both CSA-exposed groups (n=30) compared with HC (n=27), whereas women with MDD without CSA did not differ significantly from HC. Among CSA-exposed women, greater maltreatment severity was associated with lower glutamine, and greater maltreatment multiplicity with lower glutamate and Glx, specifically in women with current MDD. The association between depressive symptom severity and glutamine differed by CSA history. A significant interaction between baseline NAD/NADH ratio and clinical group predicted perceived stress at 6-month follow-up, adjusting for baseline perceived stress. Specifically, lower baseline NAD/NADH ratio predicted greater subsequent perceived stress in MDD without CSA, but not in the other clinical groups. Conclusions: Our findings suggest that mPFC glutamatergic metabolites and redox balance show distinct patterns of association with CSA history, depression status, and subsequent perceived stress, highlighting neurochemical heterogeneity in MDD and molecular markers of risk.

neuroscience↗

bioRxiv2026

Distinct transcriptional remodeling of immune and metabolic pathways in severe undernutrition during latent tuberculosis infection does not consistently predict tuberculosis progression across independent cohorts

Background: Undernutrition increases tuberculosis (TB) risk, but whether severe undernutrition during latent TB infection (LTBI) produces blood transcriptional changes that resemble active disease or identify future TB remains unclear. Methods: We reanalyzed whole-blood RNA sequencing from adults with LTBI in GSE152218, comparing severe undernutrition (BMI <16 kg/m2; n=16) with adequate nutrition (BMI >=18.5 kg/m2; n=11). Genes and Reactome pathways were evaluated. A seven-module summary was compared with active TB among severely undernourished adults and tested prospectively in GSE79362 and GC6-74/GSE94438 after pathway-representation assessment. Results: No genes reached FDR <0.05 in the primary model; two did only in sensitivity analysis. In contrast, 241 Reactome pathways were significant and directionally concordant in both models (NES rho=0.954), including complement/Fc-receptor, B-cell, phospholipid/phagocytosis, neutrophil, vascular, autophagy, and cytokine-signaling pathways. Most changed opposite to the active-TB comparison (178/241; pathway rho=-0.390). The seven-module score was unrelated to baseline progression in GSE79362 (adjusted OR per SD=1.090; P=0.6922). In GC6, four modules met the prespecified representation criterion; their baseline score was inversely associated with progression (adjusted OR per SD=0.711; P=0.0218), but secondary and longitudinal analyses were non-confirmatory. Conclusions: Severe undernutrition during LTBI is associated with reproducible immune- and metabolism-related transcriptional remodeling that differs from active-TB biology and does not consistently identify future TB progression.

molecular biology↗

bioRxiv2026

WHAT IS NORMAL? MULTIMODAL CHARACTERIZATION OF NON-DISEASED PEDIATRIC DUODENAL BIOPSIES USING MACHINE LEARNING IMAGE ANALYSIS AND TRANSCRIPTOMICS

Pediatric endoscopy is performed only when clinically indicated, limiting access to healthy duodenal tissue. Biopsies with duodenal no pathologic abnormality (NPA) are often used as controls despite the presence of symptoms or inflammatory disease found elsewhere in the gastrointestinal (GI) tract. We characterized pediatric duodenal NPA tissue across clinical, histologic, cellular, and transcriptomic domains. Methods Archival duodenal NPA biopsies were obtained with clinical metadata and hematoxylin-and-eosin whole-slide images (WSIs). Duodenal mRNA-seq data were analyzed from a subset of patients with duodenal NPA. Clinical metadata and WSIs underwent machine-learning analysis, cell populations were quantified from WSIs, and RNA-seq data underwent differential expression and pathway-enrichment analyses. Results The primary cohort included 195 patients with duodenal NPA. Comparisons between patients with non-duodenal GI disease and those with no GI disease showed differences in inflammatory biomarkers and follow-up utilization. Unsupervised clinical clustering identified three clusters with partial enrichment for IBD with colonic inflammation and Eosinophilic Esophagitis (EoE) with esophageal inflammation. Supervised clinical classification showed modest discrimination. WSI clustering showed limited disease-status discrimination, and cell quantification showed no significant group differences. In the separate RNA-seq cohort of 43 patients, differential-expression and pathway-enrichment analyses identified transcriptional and pathway-level differences between disease-status groups. Conclusions This multi-level characterization indicates that pediatric duodenal NPA tissue should not be treated as a uniform control category. Clinical metadata and transcriptomics revealed clinical and molecular heterogeneity, while histologic and cell analyses showed limited disease-status separation, supporting a refined definition of control tissue.

physiology↗

bioRxiv2026

Microglia extract neuronal proteolytic organelles via skoupocytosis

Neurons face unique challenges in maintaining protein homeostasis due to their tortuous morphology and extended processes. Proteolytic organelles are typically transported retrogradely towards their soma for degradation where lysosomes are enriched, but some organelles are larger than these neuronal processes, questioning how these organelles are degraded. Here we show that microglia, the resident immune cells of the brain, extract proteolytic organelles from neurons both in vitro and in vivo. Microglia make transient contact with neuronal membranes where proteolytic organelles are stationed beneath. At these sites of interaction, microglia pinch off a small portion of the neuronal process containing the organelle, leaving the rest of the process intact. We term this process skoupocytosis after the Greek word for garbage. Phosphatidylserine (PS) lipase ABHD16a accumulates near these proteolytic organelles and converts PS into lyso-PS to initiate microglial skoupocytosis. Skoupocytosis bypasses the need for retrograde organelle transport, providing homeostatic advantages for neurons that must maintain function in processes that extend extraordinarily long distances from the cell soma.

neuroscience↗

bioRxiv2026

De Novo Design of Protein Switches with Diffusion-Based Ensemble Sampling

Protein switches are proteins that can respond to biochemical stimuli by rearranging their structural elements, essential for cells to transduce signals. The de novo design of such proteins requires amino acid sequences whose energy landscapes support multiple stimulus-dependent conformations, yet most current de novo protein design pipelines are optimized for single stable structures. Existing multi-state inverse-folding methods can design sequences compatible with multiple backbones, but they assume that suitable backbone ensembles are already available, often requiring expert knowledge. We introduce Diff-Switch, a framework for sampling switch-like backbone ensembles from pretrained protein diffusion models. Given a reference backbone structure and domain decomposition, our method preserves local domain geometry while encouraging diversity in global domain arrangements along user-specified collective variables, inspired by metadynamics. We implement this objective through a controlled diffusion sampler with reward-tilting for local similarity between the ensemble members and history-dependent bias in collective-variable space to avoid repeated sampling of the same global arrangement. The resulting ensembles provide candidate conformational states for downstream multi-state inverse folding. Across our evaluation set of 20 diverse proteins, using conformations from these generated ensembles improves the success rate of finding switch-compatible sequences over baseline sampling. We further apply the method to a real-world protein switch design task and characterize the resulting designs.

bioinformatics↗

bioRxiv2026

A modular, high-bandwidth, bidirectional implantable device for neural interrogation

Modern neuroelectronic interfaces have shown great potential to diagnose conditions, address neurological dysfunction, and advance neuroscientific knowledge. However, neural interface systems today require tethered connections that restrict mobility, prevent testing across ecological contexts, and inhibit clinical translation to at-home use. Fully implantable commercial systems have previously been developed, but exhibit significant constraints, including a bulky design, limited modularity, low bandwidth, or unidirectional communication (e.g. deep brain stimulation systems, DBS; spinal cord stimulation systems, SCS). Here, we have developed the Modular Bionic Interface (MBI), a system composed of a fully implantable device and a worn unit for high-bandwidth, bidirectional interfacing with the nervous system. The MBI can record high fidelity electrophysiological signals and deliver spatiotemporally modulated electrical stimulation for clinical and research purposes through flexible interaction with third party implantable devices. We performed benchtop evaluation to validate the recording and stimulation capabilities of the MBI across a diverse range of inputs and outputs. We then evaluated the MBI system in vivo through chronic implantation within a sheep, where results were stable for the length of evaluation, over three months. While connected to an actively powered, third-party high-resolution spinal cord stimulation electrode array, the MBI system was able to deliver stimulation to evoke lower extremity motor responses and record spinal compound action potentials evoked by peripheral nerve and spinal stimulation. Through rigorous evaluation, we demonstrate a fully implantable system with a small footprint capable of high-resolution, bi-directional communication with the nervous system via modular connections to third-party devices. We expect that modular devices will further our ability to treat complex neurological disease and injury.

neuroscience↗

bioRxiv2024

Distinct roles of the two BRCA2 DNA binding domains in DNA damage repair and replication fork preservation

Homologous recombination (HR) is a highly conserved tool for the removal of DNA double-strand breaks (DSBs) and the preservation of stalled and damaged DNA replication forks. Successful completion of HR requires the tumor suppressor BRCA2. Germline mutations in BRCA2 lead to familial breast, ovarian, and other cancers, underscoring the importance of this protein for maintaining genome stability. BRCA2 harbors two distinct DNA binding domains, one that possesses three oligonucleotide/oligosaccharide binding (OB) folds (known as the OB-DBD), and with the other residing in the C-terminal recombinase binding domain (termed the CTRB-DBD) encoded by the last gene exon. Here, we employ a combination of genetic, biochemical, and cellular approaches to delineate contributions of these two DNA binding domains toward HR and the maintenance of stressed DNA replication forks. We show that OB-DBD and CTRB-DBD confer ssDNA and dsDNA binding capabilities to BRCA2, respectively, and that BRCA2 variants mutated in either DNA binding domain are impaired in the ability to load the recombinase RAD51 onto ssDNA pre-occupied by RPA. While the CTRB-DBD mutant is modestly affected for HR, it exhibits a strong defect in the protection of stressed replication forks. In contrast, the OB-DBD is indispensable for both BRCA2 functions. Our study thus defines the unique contributions of the two BRCA2 DNA binding domains in genome maintenance.

biochemistry↗

bioRxiv2024

Regulation of proteostasis by sleep through autophagy in Drosophila models of Alzheimer's Disease

Sleep and circadian rhythm dysfunctions are common clinical features of Alzheimers Disease (AD). Increasing evidence suggests that in addition to being a symptom, sleep disturbances can also drive the progression of neurodegeneration. Protein aggregation is a pathological hallmark of AD, however the molecular pathways behind how sleep affects protein homeostasis remain elusive. Here we demonstrate that sleep modulation influences proteostasis and the progression of neurodegeneration in Drosophila models of Tauopathy. We show that sleep deprivation enhanced Tau aggregational toxicity resulting in exacerbated synaptic degeneration. In contrast, sleep induction using gaboxadol led to reduced hyperphosphorylated Tau accumulation in neurons as a result of modulated autophagic flux and enhanced clearance of ubiquitinated Tau, suggesting altered protein processing and clearance that resulted in improved synaptic integrity and function. These findings highlight the complex relationship between sleep and autophagy, in regulating protein homeostasis, and the neuroprotective potential of sleep-enhancing therapeutics to slow the progression or delay the onset of neurodegeneration.

neuroscience↗

bioRxiv2024

High-resolution, high-throughput analysis of Drosophila geotactic behavior

Drosophila innate response to gravity, geotaxis, has been previously used to assess the impact of aging and disease on motor performance. Despite its rich history, fly geotaxis continues to be largely measured manually and assessed through simplistic metrics. The manual nature of this assay introduces substantial experimental variability while simplistic metrics provide limited analytic insights into the behavior. To address these shortcomings, we have constructed a fully automated, programable apparatus, and developed a multi-object tracking software capable of following sub-second movements of individual flies, thus allowing reproducible, detailed, and quantitative analysis of geotactic behavior. The apparatus triggers and monitors geotaxis of 10 fly cohorts simultaneously, with each cohort consisting of up to 7 flies. The tracking program isolates cohorts and records individual fly coordinate outputs allowing for simultaneous multi-group, multifly tracks per experiment, greatly improving throughput and resolution. The algorithm tracks individual flies during the entire run with [~]97% accuracy, yielding detailed climbing curve, speed, and movement direction with 1/30 second resolution. Our tracking also allows the construction of multi-variable metrics and the detection of transitory movement phenotypes, such as slips and falls, which have thus far been neglected in geotaxis studies due to limited spatio-temporal resolution. Through a combination of automation and robust tracking, the platform is therefore poised to advance Drosophila geotaxis assay into a comprehensive assessment of locomotor behavior.

neuroscience↗

bioRxiv2023

Context-dependent hyperactivity in syngap1a and syngap1b zebrafish autism models.

Background and AimsSYNGAP1 disorder is a prevalent genetic form of Autism Spectrum Disorder and Intellectual Disability (ASD/ID) and is caused by de novo or inherited mutations in one copy of the SYNGAP1 gene. In addition to ASD/ID, SYNGAP1 disorder is associated with comorbid symptoms including treatment-resistant-epilepsy, sleep disturbances, and gastrointestinal distress. Mechanistic links between these diverse symptoms and SYNGAP1 variants remain obscure, therefore, our goal was to generate a zebrafish model in which this range of symptoms can be studied. MethodsWe used CRISPR/Cas9 to introduce frameshift mutations in the syngap1a and syngap1b zebrafish duplicates (syngap1ab) and validated these stable models for Syngap1 loss-of-function. Because SYNGAP1 is extensively spliced, we mapped splice variants to the two zebrafish syngap1a and b genes and identified mammalian-like isoforms. We then quantified locomotory behaviors in zebrafish syngap1ab larvae under three conditions that normally evoke different arousal states in wild type larvae: aversive, high-arousal acoustic, medium-arousal dark, and low-arousal light stimuli. ResultsWe show that CRISPR/Cas9 indels in zebrafish syngap1a and syngap1b produced loss-of-function alleles at RNA and protein levels. Our analyses of zebrafish Syngap1 isoforms showed that, as in mammals, zebrafish Syngap1 N- and C-termini are extensively spliced. We identified a zebrafish syngap1 1-like variant that maps exclusively to the syngap1b gene. Quantifying locomotor behaviors showed that syngap1ab larvae are hyperactive compared to wild type but to differing degrees depending on the stimulus. Hyperactivity was most pronounced in low arousal settings, with overall movement increasing with the number of mutant syngap1 alleles. ConclusionsOur data support mutations in zebrafish syngap1ab as causal for hyperactivity associated with elevated arousal that is especially pronounced in low-arousal environments.

neuroscience↗

bioRxiv2023

Comparison of image registration techniques in functional ultrasound imaging

Functional Ultrasound Imaging (fUSI) is an emerging hemodynamic-based functional neuroimaging technique that combines high spatiotemporal resolution and sensitivity, as well as extensive brain coverage, enabling a range of applications in both control and disease animal models. Based on power Doppler (pD) imaging, fUSI measures changes in cerebral blood volume (CBV) by detecting the back-scattered echoes from red blood cells moving within its field of view (FOV). However, the expansion of fUSI technology is partly limited by the challenge to co-register pD vascular maps acquired across different sessions or animals to one reference; an approach that could widen the scope of experimental paradigms and enable advanced data analysis tools. In this study, we seek to address this critical limitation. We evaluate six image registration techniques, predominantly used in other neuroimaging studies, using 2D sagittal whole-brain fUSI data from 82 anesthetized mice, and tested the quality of registration using multiple metrics. Our findings indicate a substantial enhancement in the alignment of fUSI images post registration. Among the tested techniques, the non-rigid registration algorithm Imregdeform yielded superior performance. We offer the first comparative study of image registration techniques for a 2D fUSI brain dataset, paving a way for improved utilization of fUSI in future pre-clinical research applications.

neuroscience↗

bioRxiv2023

Membrane mechanics dictate axonal morphology and function

Axons are thought to be ultrathin membrane cables of a relatively uniform diameter, designed to conduct electrical signals, or action potentials. Here, we demonstrate that unmyelinated axons are not simple cylindrical tubes. Rather, axons have nanoscopic boutons repeatedly along their length interspersed with a thin cable with a diameter of [~]60 nm like pearls-on-a-string. These boutons are only [~]200 nm in diameter and do not have synaptic contacts or a cluster of synaptic vesicles, hence non-synaptic. Our in silico modeling suggests that axon pearling can be explained by the mechanical properties of the membrane including the bending modulus and tension. Consistent with modeling predictions, treatments that disrupt these parameters like hyper- or hypo-tonic solutions, cholesterol removal, and non-muscle myosin II inhibition all alter the degree of axon pearling, suggesting that axon morphology is indeed determined by the membrane mechanics. Intriguingly, neuronal activity modulates the cholesterol level of plasma membrane, leading to shrinkage of axon pearls. Consequently, the conduction velocity of action potentials becomes slower. These data reveal that biophysical forces dictate axon morphology and function and that modulation of membrane mechanics likely underlies plasticity of unmyelinated axons.

neuroscience↗

bioRxiv2023

A comprehensive catalog of 3D genome organization in diverse human genomes facilitates understanding of the impact of structural variation on chromatin structure

The human genome is packaged into the three-dimensional (3D) nucleus and organized into functional units known as topologically associating domains (TADs) and chromatin loops. Recent studies show that the 3D genome can be modified by genome structural variants (SVs) through disrupting higher-order chromatin organizations such as TADs, which play an essential role in insulating genes from aberrant regulation by regulatory elements outside TADs. Here, we have developed an integrative Hi-C analysis pipeline to generate a comprehensive catalog of TADs, TAD boundaries, and loops in human genomes to fill the gap of limited resources. We identified 2,293 TADs and 6,810 sub-TADs missing in the previously released TADs of GM12878. We then quantified the impact of SVs overlapping with TAD boundaries and observed that two SVs could significantly alter chromatin architecture leading to abnormal expression and splicing of genes associated with human diseases.

genomics↗

bioRxiv2023

Modulation of protein-DNA binding reveals mechanisms of spatiotemporal gene control in early Drosophila embryos

It is well known that enhancers regulate the spatiotemporal expression of their target genes by recruiting transcription factors (TFs) to the cognate binding sites in the region. However, the role of multiple binding sites for the same TFs and their specific spatial arrangement in determining the overall competency of the enhancer has yet to be fully understood. In this study, we utilized the MS2-MCP live imaging technique to quantitatively analyze the regulatory logic of the snail distal enhancer in early Drosophila embryos. Through systematic modulation of Dorsal and Twist binding motifs in this enhancer, we found that a mutation in any one of these binding sites causes a drastic reduction in transcriptional amplitude, resulting in a reduction in total mRNA production of the target gene. We provide evidence of synergy, such that multiple binding sites with moderate affinities cooperatively recruit more TFs to drive stronger transcriptional activity than a single site. Moreover, a Hidden Markov-based stochastic model of transcription reveals that embryos with mutated binding sites have a higher probability of returning to the inactive promoter state. We propose that TF-DNA binding regulates spatial and temporal gene expression and drives robust pattern formation by modulating transcriptional kinetics and tuning bursting rates.

developmental biology↗

bioRxiv2022

Expanded Multiplexing on Sensor-Constrained Microfluidic Partitioning Systems

Microfluidics can split samples into thousands or millions of partitions such as droplets or nanowells. Partitions capture analytes according to a Poisson distribution, and in diagnostics, the analyte concentration is commonly calculated with a closed-form solution via maximum likelihood estimation (MLE). Here, we present a generalization of MLE with microfluidics, an extension of our previously developed Sparse Poisson Recovery (SPoRe) algorithm, and an in vitro demonstration with droplet digital PCR (ddPCR) of the new capabilities that SPoRe enables. Many applications such as infection diagnostics require sensitive detection and broad-range multiplexing. Digital PCR coupled with conventional target-specific sensors yields the former but is constrained in multiplexing by the number of available measurement channels (e.g., fluorescence). In our demonstration, we circumvent these limitations by broadly amplifying bacteria with 16S ddPCR and assigning barcodes to nine pathogen genera using only five nonspecific probes. Moreover, we measure only two probes at a time in multiple groups of droplets given our two-channel ddPCR system. Although individual droplets are ambiguous in their bacterial content, our results show that the concentrations of bacteria in the sample can be uniquely recovered given the pooled distribution of partition measurements from all groups. We ultimately achieve stable quantification down to approximately 200 total copies of the 16S gene per sample, enabling a suite of clinical applications given a robust upstream microbial DNA extraction procedure. We develop new theory that generalizes the application of this framework to a broad class of realistic sensors and applications, and we prove scaling rules for system design to achieve further expanded multiplexing. This flexibility means that the core principles and capabilities demonstrated here can generalize to most biosensing applications with microfluidic partitioning.

bioengineering↗

bioRxiv2022

Real time, in vivo measurement of neuronal and peripheral clocks in Drosophila melanogaster

Circadian clocks are highly conserved transcriptional regulators that control 24-hour oscillations in gene expression, physiological function, and behavior. Circadian clocks exist in almost every tissue and are thought to control tissue-specific gene expression and function, synchronized by the brain clock. Many disease states are associated with loss of circadian regulation. How and when circadian clocks fail during pathogenesis remains largely unknown because it is currently difficult to monitor tissue-specific clock function in intact organisms. Here, we developed a method to directly measure the transcriptional oscillation of distinct neuronal and peripheral clocks in live, intact Drosophila, which we term Locally Activatable BioLuminescence or LABL. Using this method, we observed that specific neuronal and peripheral clocks exhibit distinct transcription properties. Loss of the receptor for PDF, a circadian neurotransmitter critical for the function of the brain clock, disrupts circadian locomotor activity but not all tissue-specific circadian clocks; we found that, while peripheral clocks in non-neuronal tissues were less stable after the loss of PDF signaling, they continued to oscillate. This result suggests that the presumed dominance of the brain clock in regulating peripheral clocks needs to be re-examined. This result further demonstrates that LABL allows rapid, affordable, and direct real-time monitoring of clocks in vivo.

genetics↗