Biology subjects

Joshi, N.

Publications and source records attributed to Joshi, N..

At least 19 recordsLinked to original sources

bioRxiv2026

Biosynthetic Olfactory System from Multiplexed Engineered Microbes (BOSMEM)

Whole-cell biosensors can detect many types of chemicals in complex environments, but existing designs force a tradeoff in multiplexed sensing: separating sensor strains into individual reservoirs limits how many analytes can be monitored at once, while pooling strains in open co-culture lets faster-growing strains take over within days, corrupting the signal. The microfluidic "mother machine" has been used for over a decade, mostly to study individual bacterial strains with single-cell resolution, but never to house multiple engineered strains simultaneously for sensing applications. We repurpose this device to hold a library of genetically distinct biosensor strains, physically isolating each strain in its own growth channel while continuous flow keeps every strain fed. Each strain reports on a target chemical through a unique combination of three fluorescent proteins, so seven distinguishable signals emerge from only three optical channels. We characterized turn-on and turn-off kinetics of several biosensors in the mother machine. Over a multi-day experiment with repeated chemical exposures, biosensors housed this way matched the expected on/off state and held stable population ratios, while biosensors in an open batch co-culture drifted and lost reliable signal. This establishes mother-machine-based multiplexing as a scalable route to long-term chemical monitoring with living sensors.

bioengineering↗

bioRxiv2026

Plaque-associated oligodendrocyte proteostatic failure underlies myelin loss in Alzheimers disease

Alzheimers disease (AD) features amyloid-{beta} plaques and tau pathology, yet the mechanism underlying early and clinically significant myelin loss remains unresolved. Here, we report human iPSC-derived forebrain organoids with doxycycline-inducible expression of SOX10, OLIG2, and NKX6-2 (SON), which generate robust, mature oligodendrocytes and compact myelin in vitro and in vivo. Introducing amyloid precursor protein (APP) pathogenic mutations produces extracellular amyloid-{beta} plaques and phosphorylated tau, accompanied by reduced myelin basic protein (MBP) expression and disrupted myelin ultrastructure. Single-cell and spatial transcriptomics combined with amyloid plaque imaging reveal that oligodendrocytes in plaque-dense regions show pathological changes in calcium signaling, immune activation, lipid remodeling, and protein catabolic pathways. Notably, MBP protein is reduced despite elevated myelin-related transcription, suggesting plaque-induced degradation of myelin proteins. Consistent with this, proteasomal inhibition restores MBP protein levels and improves compact myelin ultrastructure in AD organoids. In human AD brain tissue, protein catabolic pathways are similarly upregulated with increasing plaque density. Together, these findings identify plaque-associated oligodendrocyte proteostatic failure as a candidate mechanism of myelin loss and a potential therapeutic pathway in AD.

neuroscience↗

bioRxiv2026

Systematic Engineering of Intra-Articular Drug Release Profiles Reveals a Key Determinant of Disease-Modifying Efficacy in Post-Traumatic Osteoarthritis

Post-traumatic osteoarthritis (PTOA) is a progressive joint disease for which no disease-modifying osteoarthritis drugs (DMOADs) have been approved. Although injectable drug delivery systems can prolong therapeutic retention within the joint, it remains unclear whether local drug release kinetics influence disease-modifying efficacy. Here, we developed a modular platform of injectable supramolecular hydrogels using biocompatible, generally recognized as safe (GRAS) amphiphilic molecules and systematically engineered a range of degradation and drug release profiles. Using the cathepsin-K inhibitor L-006235 as a model DMOAD, we generated hydrogels with distinct release kinetics and evaluated their therapeutic performance in PTOA. Hydrogels exhibiting slower degradation and more sustained drug release like Sucrose Stearate (SS hydrogel) showed prolonged intra-articular retention and improved therapeutic outcomes. In a destabilization of the medial meniscus (DMM) mouse model, sustained-release formulations significantly reduced cartilage degeneration, preserved aggrecan expression, improved joint histopathology, and enabled effective monthly dosing. In contrast, formulations with faster degradation and release kinetics required more frequent administration to achieve comparable benefits. To our knowledge, this is the first study to establish local drug release kinetics as a critical determinant of disease-modifying efficacy in PTOA. This work provides one of the clearest demonstrations to date that engineering intra-articular release kinetics, rather than merely prolonging residence time, can improve disease-modifying outcomes. Our findings establish local release kinetics as a key design parameter for osteoarthritis therapeutics and highlight the potential of tunable supramolecular hydrogels for long-acting drug delivery.

bioengineering↗

bioRxiv2026

Genomic-Adjusted Radiation Dose from Bulk RNA Sequencing for Personalized Radiotherapy

Radiotherapy is delivered to more than half of all patients with cancer yet is prescribed using uniform physical doses despite well-established interpatient variability in biological response. The genomic-adjusted radiation dose (GARD), derived from the radiosensitivity index (RSI), integrates tumor transcriptomics with radiation dose to estimate patient-specific treatment effect, and has been clinically validated as a predictor of radiotherapy benefit across diverse disease sites, including breast, lung, head and neck, glioma, sarcoma, rectal, and endometrial cancers. However, further clinical validation and deployment has been limited by reliance on microarray-based expression. Here we develop an RNA sequencing-based formulation of RSI (RSI-seq) and show that it preserves the functional properties of the original model across measurement platforms. RSI-seq maintains concordance with microarray RSI, including preservation of patient rank ordering (pooled Spearman{rho} = 0.86), and, when integrated into GARD, reproduces predicted changes in biological effect under clinically relevant dose perturbations (R2 [≥] 0.78 for {Delta}GARD in both directions). This preservation of interventional prediction is robust to expression noise and invariant to normalization strategy, enabling consistent application across RNA-seq pipelines. Application across the TCGA pan-cancer transcriptomic atlas demonstrates scalability across tumor types, with cohort medians agreeing closely with previously published microarray RSI medians (Spearman{rho} = 0.68, Pearson r = 0.85 across 20 matched cohorts). By bringing a clinically validated radiogenomic dose model into the RNA-sequencing era, RSI-seq makes biologically personalized radiotherapy directly accessible, retrospectively in existing RNA-seq cohorts and prospectively in modern clinical sequencing workflows, across the full range of tumor types treated with radiation.

genomics↗

bioRxiv2026

Wavelength induced cultivar specific enrichment of essential amino acids and phenolics in Amaranthus tricolor

Light wavelengths modulate plant growth, metabolism, and physiology. Amaranthus, a C4 underutilized climate resilient crop with promising nutritional properties remained unexplored in terms of metabolite enrichment under monochromatic light wavelengths of visible spectrum. In current study, two cultivars of Amaranthus tricolor (green and red) were exposed to seven light regimes of photosynthetically active radiation (PAR; 400-700 nm): deep blue, blue, green, amber, red, deep red, far red, and their metabolic responses were captured using Gas Chromatography-Mass Spectrometry. The metabolic analysis revealed wavelength-specific reprogramming in the levels of organic acids, sugars, amino acids, fatty acids as well as phenolics. In both the green and red Amaranthus, branched-chain amino acids and phenylalanine, which are nutritionally essential, were significantly elevated under far-red light. While the phenolics such as caffeic acid and ferulic acid were elevated under green and deep blue light respectively in green Amaranthus, amber light wavelengths enhanced these phenolics in red Amaranthus. The study highlighted cultivar-specific metabolic rewiring triggered by specific wavelengths. Altogether, these findings provides insights into metabolic adaptation and demonstrate the ability of light wavelength to specifically enrich the targeted metabolite of nutritional relevance in Amaranthus. It offers strategies to improve the nutritional value of crops in controlled agriculture systems. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=167 HEIGHT=200 SRC="FIGDIR/small/714947v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@8de67forg.highwire.dtl.DTLVardef@17a03corg.highwire.dtl.DTLVardef@118d18corg.highwire.dtl.DTLVardef@6568f3_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2026

Neuromodulatory Control of Cortical Function: Cell-Type Specific Regulation of Neuronal Information Transfer

Neuromodulatory systems such as dopamine and acetylcholine enable cortical circuits to rapidly shift between behavioral states, yet it remains unclear how receptor-specific signaling reshapes what single neurons compute. Here we combined whole-cell recordings from excitatory and inhibitory neurons in layer 2/3 of mouse somatosensory cortex with information-theoretic analyses under frozen-noise stimulation. We quantified stimulus-to-spike information transfer and profiled each neuron across four functional domains: passive membrane biophysics, action potential dynamics, intrinsic adaptation currents, and input feature selectivity captured by spike-triggered averages. Activation of D1, D2, or M1 receptors produced cell-type and receptor-specific changes in fractional information and firing output, demonstrating that neuromodulators regulate encoding beyond simple gain control. Unsupervised clustering revealed that receptor activation reshapes neuronal functional identities, consistent with a dynamic computational phenotype. To identify the organizing principle underlying these transitions, we applied multi-set correlation and factor analysis and found that neuromodulation systematically reorganizes covariance among functional domains. In excitatory neurons, dopaminergic activation led to a decreased coordination between input feature selectivity and other functional properties while strengthening coordination among response based features such as spike dynamics and adaptation. Inhibitory neurons, by contrast, generally exhibited increased coordination across domains. These findings identify neuromodulation as a reconfiguration signal that reshapes not only individual cellular properties but also the architecture linking them, thereby dynamically expanding the computational repertoire of cortical circuits.

neuroscience↗

bioRxiv2026

Reinnervation of Muscle Targets Enhances the Separability of Motor Unit Signals Following Peripheral Nerve Transfers

After amputation, advanced prosthetic limbs offer a promising means of restoring motor function. However, state-of-the-art prostheses often rely on aggregate electromyogram (EMG) signals to decode motor intention, which limits their ability to replicate natural limb movements. Decomposing EMG signals into individual motor unit components has shown potential for more natural control, but distinguishing between individual units can be challenging when nearby signals overlap. This study demonstrates that muscle target reinnervation surgeries can naturally increase physical separation between motor unit signals, thereby mitigating this overlap. Reinnervation of individual motor units is evaluated in a rodent hindlimb model after direct nerve-to-muscle implantation. Histological and electrophysiological analyses reveal that structural changes following reinnervation surgery result in beneficial motor unit signal changes, particularly improving spatial separation between motor unit signals compared to those in intact muscle. This spatial separation contributed to fewer instances of complex, overlapping signals in reinnervated muscle recordings. Motor unit signals were leveraged to provide a proof-of-concept of precise control of a virtual prosthesis for the first time after direct nerve-to-muscle implantation surgery. These findings highlight the potential of reinnervated muscle targets as key biological interfaces that facilitate motor unit separation, reducing the burden on decomposition algorithms and improving prosthetic control.

bioengineering↗

bioRxiv2025

An H3K79 Methylation-Dependent Checkpoint Blocks Holliday Junction Resolution and Meiotic Divisions under Heat Stress

Meiosis, the specialized cell division that produces haploid gametes from diploid precursors, is markedly more sensitive to heat stress than mitosis in a wide range of organisms, despite the two processes utilizing largely overlapping cellular machinery. The mechanistic basis of meiotic heat sensitivity has remained unclear. Here, we show that in budding yeast, even moderate heat stress impairs the processing of programmed double-strand breaks into crossovers, resulting in permanent meiotic division arrest. This arrest depends on methylation of histone H3 at lysine 79 (H3K79) by Dot1, and a subset of other components of the meiotic recombination checkpoint. Thus, in contrast to the canonical heat shock response that adapts mitotically dividing cells to elevated temperatures, meiotic arrest is triggered by stalled recombination intermediates in the context of the H3K79 chromatin modification. These findings suggest a conserved epigenetic pathway responsible for heat-induced meiotic failure across eukaryotes. Genetically enhancing the heat tolerance of meiotic chromosome metabolism may increase reproductive resilience of organisms facing rising global temperatures, bridging the gap until mitigation strategies are in place. Significance StatementMeiosis generates haploid gametes through a specialized cell division that involves crossovers between homologous chromosomes. Crossovers promote genetic diversity and ensure proper chromosome segregation during meiosis I. In many organisms, meiosis stalls under moderate heat stress at temperatures permissive for mitosis, a phenomenon with implications for crop fertility and stability of ecosystems. Using yeast, we discovered that heat stress blocks meiosis at Holliday junctions - the four-armed DNA intermediates that resolve into crossovers - while alternative non-crossovers form normally. Arrest depends on the H3K79 methylation-dependent checkpoint involving Dot1. Thus, heat sensitivity of meiosis stems from checkpoint surveillance of impaired chromosome interactions. Modulating the underlying mechanism could enhance reproductive resilience to a warming climate.

genetics↗

bioRxiv2025

A Precisely Controlled Long-Acting Immunosuppression Platform Enables Prolonged Survival of Vascularized Composite Allografts

Vascularized composite allotransplantation (VCA) restores complex tissue defects but demands lifelong systemic immunosuppression. Oral tacrolimus (TAC) is limited by a narrow therapeutic window, pharmacokinetic variability, adherence challenges, and toxicity. Local delivery could mitigate these issues, yet clinical translation has been hindered by burst release, short duration, and the inability to co-deliver agents. We developed PRECISE (Programmable, REtrievable, Controlled ImmunoSuppression Encapsulator), an injectable, in-situ-forming PLGA depot that achieves long-acting, tightly controlled TAC release via structure-guided co-formulation with drug-binding agents (DBAs). GRAS small molecules (e.g., EGCG, maltotriose) identified by in silico docking and in vitro screening suppressed burst and modulated solvent efflux. Notably, rapamycin (RAPA) served dually as an mTOR inhibitor and a TAC-binding excipient, enabling synchronized dual-agent delivery. PRECISE eliminated burst in vitro and produced coordinated TAC+RAPA release with clinically compatible injectability. In rats, monthly intragraft dosing maintained systemic TAC/RAPA within the therapeutic window ([~]5-10 ng/mL) for >300 days, prolonged hindlimb allograft survival, expanded Tregs, and induced donor-specific hyporesponsiveness. Surgical retrieval of the depot triggered rapid TAC decline, demonstrating reversibility. In a stringent, fully MHC-mismatched porcine VCA model, PRECISE maintained on-target drug levels and extended graft survival beyond 90 days with minimal rejection and preserved vascular integrity. PRECISE is, to our knowledge, the first retrievable, injectable platform to deliver long-acting, dual-agent immunosuppression with controlled kinetics, rapid attainment of therapeutic steady state, and sustained graft protection. Its modular, structure-guided design enables clinical translation across VCA and solid-organ transplantation, delivering precise, durable, and safer immunosuppression.

bioengineering↗

bioRxiv2025

SPACE: spatially resolved multiomic analysis for high-throughput CRISPR screening in 3D models

Current spatial CRISPR screening technologies are limited by targeted readouts and high costs, restricting the scope of biological discovery. Here we present SPAtial Cell Exploration (SPACE), a spatial CRISPR screening platform that integrates whole-transcriptome profiling ([~]18,000 genes), multiplexed protein detection ([~]68 markers), and CRISPR perturbation mapping at subcellular resolution. SPACE significantly reduces whole-transcriptome profiling costs compared to sequencing methods while preserving spatial context. We demonstrate SPACE by screening 43 CRISPR knockouts (KOs) across [~]100,000 cells in hundreds of cancer-associated fibroblast (CAF)-tumor spheroids, obtaining whole-transcriptome and multiplexed protein readout from the same exact cells. SPACE revealed previously unknown regulatory mechanisms on tumor extracellular matrix (ECM) remodeling, and identified spatially-resolved ligand-receptor interactions and perturbation-specific spatial gene signatures that are not detectable with dissociation-based methods. This scalable, cost-effective platform provides a transformative framework for high-throughput spatial perturbation studies in complex tissue models.

cell biology↗

bioRxiv2025

Profibrotic monocyte-derived alveolar macrophages as a biomarker and therapeutic target in systemic sclerosis-associated interstitial lung disease

Interstitial lung disease (ILD) is present in over 60% of patients with systemic sclerosis (SSc) and is the leading cause of SSc-related deaths. Profibrotic monocyte-derived alveolar macrophages (MoAM) play a causal role in the pathogenesis of pulmonary fibrosis in animal models where their persistence in the niche requires signaling through Colony Stimulating Factor 1 Receptor (CSF1R). We hypothesized that the presence and proportion of MoAM in bronchoalveolar lavage (BAL) fluid from patients with SSc-ILD may be a biomarker of ILD severity. To test this hypothesis, we analyzed BAL fluid from 9 prospectively enrolled patients with SSc-ILD and 13 healthy controls using flow cytometry and single-cell RNA sequencing. Patients with SSc-ILD had more MoAM and interstitial macrophages in BAL fluid than healthy controls, and their abundance was associated with lung fibrosis severity. We identified changes in the MoAM transcriptome as a function of treatment with mycophenolate, an effective therapy for SSc-ILD. In SSc-ILD lung explants, spatial transcriptomics identified an expanded population of interstitial macrophages spilling into the alveolar space. Our findings suggest that the proportion of profibrotic MoAM and interstitial macrophages in BAL fluid may serve as a biomarker of SSc-ILD and credential them as possible targets for therapy.

immunology↗

bioRxiv2025

Targeting Leishmania donovani Sphingosine Kinase 1 using PF-543 enhances immune response and limits parasite load

BackgroundSphingosine-1-phosphate (S1P) is a bioactive lipid mediator regulating apoptosis, proliferation, and immune responses. While S1Ps presence in Leishmania donovani phagolysosomes has been reported, the role of sphingosine kinases, especially SphK1, in parasite survival and host immune modulation remains underexplored. This study investigates the molecular and functional role of L. donovani SphK1 (LdSphK1) and evaluates the antileishmanial potential of PF-543, a specific SphK1 inhibitor. MethodsLdSphK1 and human SphK1 (rhSphK1) were cloned, expressed in E. coli, purified, and analyzed by SDS-PAGE. Enzymatic activity and inhibition by PF543 were assessed using NBD-S1P-based fluorometric assays. Protein-ligand interactions were analyzed using Microscale Thermophoresis (MST). Leishmania promastigotes overexpressing LdSphK1 were studied via confocal microscopy, and their viability and infectivity were assessed in vitro. THP-1 macrophages infected with L. donovani were treated with PF543 alone or with Amphotericin B and analyzed by MTT assay, RT-PCR, Giemsa staining, ELISA and immunoblotting. In vivo efficacy was tested in L. donovani-infected Swiss mice. ResultsrLdSphK1 ([~]102 kDa) and rhSphK1 ([~]50 kDa) were enzymatically active and significantly inhibited by PF-543. MST confirmed high-affinity binding of PF-543 (KD [~]29 microMolar). In L. donovani SphK1 overexpressor (LdSphKa) promastigotes, PF543 inhibited SphK1 activity and reduced parasite infectivity, more than in wildtype L. donovani promastigotes. Notably, PF543 treatment reduced parasite infectivity in vitro, lowered amastigote load by [~]40%, and promoted a pro-inflammatory cytokine shift ({uparrow}IL-12, {uparrow}TNF-, {downarrow}IL-10). Inhibition of ceramide synthesis and S1P supplementation revealed that S1P rescues ceramide-induced parasite death, implicating SphK1 in parasite survival. PF543 and Amphotericin B demonstrated synergistic anti-parasitic effects both in vitro and in vivo, with >90% reduction in parasite burden in mice. ConclusionPF543 is a potent inhibitor of SphK1, impairing parasite survival and modulating host immune responses. When combined with Amphotericin B, it offers a synergistic therapeutic strategy against visceral leishmaniasis, warranting further clinical exploration. Author SummaryLeishmaniasis, a neglected tropical disease, has limited available treatments and is becoming more resistant to medications. In this study, we explored the therapeutic potential of PF-543, a potent sphingosine kinase 1 (SphK1) inhibitor (demonstrated anticancer effects in various preclinical models) against Leishmania donovani. We successfully cloned and purified both Leishmania and human SphK1 proteins and confirmed PF-543 binding through biochemical and biophysical assays. Overexpression of LdSphK1 in parasites enhanced their survival and infectivity. In vitro, PF-543 treatment of infected macrophages decreased amastigote burden, shifted cytokine profiles towards a pro-inflammatory state, and enhanced host cell apoptosis. Notably, PF-543 acted synergistically with Amphotericin B, the current clinical drug, both in vitro and in vivo in Swiss mice, drastically lowering parasite burden. This study highlights the possibility of combination therapy and finds PF-543 to be a promising irresistible host-targeted antileishmanial drug. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/652326v2_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@1926575org.highwire.dtl.DTLVardef@4305f4org.highwire.dtl.DTLVardef@3c10c7org.highwire.dtl.DTLVardef@171801e_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2024

Understanding Neuronal Diversity: Role of Input Dynamics and Selectivity

Neuronal classification based on morphology, electrophysiology, and molecular markers is often considered static. Here, we challenge this view, showing that functional classification depends on input patterns. Using single-cell recordings from layer 2/3 barrel cortex neurons in mice, we compared responses to step-and-hold versus dynamic frozen noise inputs that mimic presynaptic activity. Action potential and waveform-based classifications varied significantly, highlighting the dynamic nature of neuronal identity. To assess the contribution of input versus neuronal attributes toward classification, we analyzed four attribute sets, namely action potential, passive biophysical, adaptation currents, and linear input filters derived via spike-triggered averages (STA). Our findings revealed that the STA, which captures a neurons selective responsiveness to presynaptic activity, explained the most variance within the population. This highlights input-driven dynamics as key to functional identity, emphasizing the need for physiologically relevant inputs in defining neuronal classes and shifting the focus from static properties to dynamic functional diversity.

neuroscience↗

bioRxiv2024

A collection of split-Gal4 drivers targeting conserved signaling ligands in Drosophila

Communication between cells in metazoan organisms is mediated by a remarkably small number of highly conserved signaling pathways. Given the relatively small number of signaling pathways, the existence of multiple related ligands for many of these pathways is thought to represent a key evolutionary innovation for encoding complexity into cell-cell signaling. Relatedly, crosstalk and other interactions between pathways is another critical feature which allows a modest number pathways to ultimately generate an enormously diverse range of outcomes. It would thus be useful to have genetic tools to identify and manipulate not only those cells which express a given signaling ligand, but also those cells that specifically co-express pairs of signaling ligands. Here, we present a collection of split-Gal4 knock-in lines targeting many of the ligands for highly conserved signaling pathways in Drosophila (Notch, Hedgehog, FGF, EGF, TGF{beta}, JAK/STAT, JNK, and PVR). We demonstrate that these lines faithfully recapitulate the endogenous expression pattern of their targets, and that they can be used to specifically identify the cells and tissues that co-express pairs of signaling ligands. As a proof of principle, we demonstrate that the 4th chromosome TGF{beta} ligands myoglianin and maverick are broadly co-expressed in muscles and other tissues of both larva and adults, and that the JAK/STAT ligands upd2 and upd3 are partially co-expressed from cells of the midgut following gut damage. Together with our previously collection of split-Gal4 lines targeting the seven Wnt ligands, this resource allows Drosophila researchers to identify and genetically manipulate cells that specifically express pairs of conserved ligands from nearly all the major intercellular signaling pathways.

genetics↗

bioRxiv2024

LCN2 promotes focal adhesion formation and invasion by stimulating Src activation.

Previous work has demonstrated that Lipocalin2 (LCN2) expression promotes invasion and migration in multiple tumor types. The mechanisms by which LCN2 promotes invasion and migration remain unclear. Previous work from our laboratory demonstrated that LCN2 promotes actin filament formation by inhibiting actin glutathionylation. In this report, we demonstrate that in addition to inhibiting actin glutathionylation, LCN2 stimulates invasion by promoting the formation of focal adhesions, which is independent of the ability of LCN2 to bind iron. LCN2 promotes focal adhesion formation by promoting the activation of c-Src by stimulating the expression of the transcription factor ETS1. ETS1 activates the expression of the protein phosphatase, PTP1B, resulting in the auto-activation of c-Src and increased paxillin phosphorylation leading to focal adhesion formation. These results demonstrate that LCN2 has iron-dependent and independent functions in promoting invasion and highlight the multiple mechanisms by which LCN2 promotes invasion and suggest that c-Src inhibitors could be used to treat invasive colorectal cancer. SUMMARYExpression of LCN2 is elevated in invasive colorectal cancer. We demonstrate that LCN2 promotes invasion by stimulating the formation of focal adhesions by promoting Src activation.

cell biology↗

bioRxiv2024

Temporal Coherence Shapes Cortical Responses to Speech Mixtures in a Ferret Cocktail Party

Segregation of complex sounds such as speech, music and animal vocalizations as they simultaneously emanate from multiple sources (referred to as the "cocktail party problem") is a remarkable ability that is common in humans and animals alike. The neural underpinnings of this process have been extensively studied behaviorally and physiologically in non-human animals primarily with simplified sounds (tones and noise sequences). In humans, segregation experiments utilizing more complex speech mixtures are common; but physiological experiments have relied on EEG/MEG/ECoG recordings that sample activity from thousands of neurons, often obscuring the detailed processes that give rise to the observed segregation. The present study combines the insights from animal single-unit physiology with segregation of speech-like mixtures. Ferrets were trained to attend to a female voice and detect a target word, both in presence or absence of a concurrent, equally salient male voice. Single neuron recordings were obtained from primary and secondary ferret auditory cortical fields, as well as frontal cortex. During task performance, representation of the female words became more enhanced relative to those of the (distractor) male in all cortical regions, especially in the higher auditory cortical field. Analysis of the temporal and spectral response characteristics during task performance reveals how speech segregation gradually emerges in the auditory cortex. A computational model evaluated on the same voice mixtures replicates and extends these results to different attentional targets (attention to female or male voices). These findings are consistent with the temporal coherence theory whereby attention to a target voice anchors neural activity in cortical networks hence binding together channels that are coherently temporally-modulated with the target, and ultimately forming a common auditory stream.

neuroscience↗

bioRxiv2024

A Mechanically Resilient Soft Hydrogel Improves Drug Delivery for Treating Post-Traumatic Osteoarthritis in Physically Active Joints

Intra-articular delivery of disease-modifying osteoarthritis drugs (DMOADs) is likely to be most effective in early post-traumatic osteoarthritis (PTOA) when symptoms are minimal and patients are physically active. DMOAD delivery systems therefore must withstand repeated mechanical loading without affecting the drug release kinetics. Although soft materials are preferred for DMOAD delivery, mechanical loading can compromise their structural integrity and disrupt drug release. Here, we report a mechanically resilient soft hydrogel that rapidly self-heals under conditions resembling human running while maintaining sustained release of the cathepsin-K inhibitor L-006235 used as a proof-of-concept DMOAD. Notably, this hydrogel outperformed a previously reported hydrogel designed for intra-articular drug delivery, used as a control in our study, which neither recovered nor maintained drug release under mechanical loading. Upon injection into mouse knee joints, the hydrogel showed consistent release kinetics of the encapsulated agent in both treadmill-running and non-running mice. In a mouse model of aggressive PTOA exacerbated by treadmill running, L-006235 hydrogel markedly reduced cartilage degeneration. To our knowledge, this is the first hydrogel proven to withstand human running conditions and enable sustained DMOAD delivery in physically active joints, and the first study demonstrating reduced disease progression in a severe PTOA model under rigorous physical activity, highlighting the hydrogels potential for PTOA treatment in active patients.

bioengineering↗

bioRxiv2024

Yes Associated Transcriptional Regulator 1 (YAP1) and WW Domain Containing Transcription Regulator (WWTR1) are required for murine pregnancy initiation

Endometrial stromal cell decidualization is required for pregnancy success. Although this process is integral to fertility, many of the intricate molecular mechanisms contributing to decidualization remain undefined. One pathway that has been implicated in endometrial stromal cell decidualization in humans in vitro is the Hippo signaling pathway. Two previously conducted studies showed that the effectors of the Hippo signaling pathway, YAP1 and WWTR1, were required for decidualization of primary stromal cells in culture. To investigate the in vivo role of YAP1 and WWTR1 in decidualization and pregnancy initiation, we generated a Progesterone Cre mediated partial double knockout (pdKO) of Yap1 and Wwtr1. Female pdKOs exhibited subfertility, a compromised decidualization response, partial interruption in embryo transport, blunted endometrial receptivity, delayed implantation and subsequent embryonic development, and a unique transcriptional profile. Bulk mRNA sequencing revealed aberrant maternal remodeling evidenced by significant alterations in extracellular matrix proteins at 7.5 days post-coitus in pdKO dams and enrichment for terms associated with fertility-compromising diseases like pre-eclampsia and endometriosis. Our results indicate a required role for YAP1 and WWTR1 for successful mammalian uterine function and pregnancy success.

molecular biology↗