Biology subjects

Datta, P.

Publications and source records attributed to Datta, P..

At least 19 recordsLinked to original sources

bioRxiv2026

The phage shock protein A (PspA) maintains membrane potential and supports NADH dehydrogenase function in mycobacteria

Maintenance of membrane integrity and proton motive force (PMF) is critical for bacterial survival. The phage shock protein (Psp) system, conserved across bacterial species, stabilizes the membrane, maintains PMF, and protects against envelope damage. However, how the conserved effector PspA contributes to PMF maintenance remains unclear. Here, using the mycobacterial Psp system as a genetically tractable model, we provide mechanistic insight into this process. We show that PspA and the accessory protein PspM jointly sustain membrane potential, with PspM required to maintain a ~70 kDa PspA isoform at the membrane during envelope stress. Loss of PspA increases susceptibility to thioridazine, which targets type II NADH dehydrogenase (NDH-2), and to Ro 48-8071, an inhibitor of menaquinone biosynthesis. Notably, hypersusceptibility to thioridazine is rescued by exogenous menaquinone. Consistent with these phenotypes, a pspA-deficient mutant exhibits impaired NADH dehydrogenase activity despite unchanged abundance of NDH-2 and menaquinone (MK-9). Together, these findings identify a functional link between PspA and NADH dehydrogenase-dependent respiration and suggest that PspA contributes to PMF maintenance by supporting respiratory electron transfer.

molecular biology↗

bioRxiv2026

Reconciling fast Hepatitis B evolutionary rates with ancient co-divergence

Estimating evolutionary rates and divergence times for hepatitis B virus (HBV) has long been complicated by conflicting calibration approaches and extensive rate variation. To unlock the full potential of ancient and modern HBV genomic data, we develop a Bayesian mixed-effects molecular clock model that accounts for various sources of rate variation including time-dependent rate decay. Our analyses reveal a pronounced decline in evolutionary rates over time, reconciling HBV divergence estimates with human migration events across both deep and more recent timescales. We show that HBV spread into Europe through both Neolithic farming expansions and later steppe migrations, paralleling patterns proposed for Indo-European language origins. Phylogeographic reconstructions suggest that the Neolithic-associated lineage dispersed at approximately 1 km/year, consistent with archaeological estimates, while genotype D expanded during the Bronze Age at an almost threefold higher rate, plausibly driven by technological innovations underlying steppe expansions. Historical overlap between these lineages facilitated recombination, giving rise to genotype E, which has become a dominant HBV genotype in Africa. These findings demonstrate that ancient viral genomes, when analyzed with models capturing complex rate dynamics, provide a powerful lens on human prehistory and the processes shaping pathogen diversity.

evolutionary biology↗

bioRxiv2026

Transcription Factor-Mediated Reprogramming of Cancer-Associated Fibroblasts Reveals Targetable Vulnerabilities in Solid Tumors

Cancer-associated fibroblasts (CAFs) contribute to immune exclusion and therapy resistance in solid tumors, limiting the efficacy of chimeric antigen receptor (CAR) T cell and immune cell therapy. To overcome this, we developed a transcription factor (TF)-based strategy to reprogram prostate-derived CAFs (pCAFs) into normal fibroblast-like cells (NFs). We prioritized TFs enriched in quiescent stellate cells--Vitamin D receptor (VDR), Peroxisome Proliferator-Activated Receptor gamma (PPAR{gamma}), and p53--and selected VDR for proof-of-concept studies. Lentiviral VDR expression in pCAFs produced VDR-reprogrammed NFs (VDR-rpNFs) with reduced CAF markers, increased ATP, and suppressed TGF-{beta} and IL6, indicating phenotypic and metabolic reversion. In both in vitro 3D co-cultures and in vivo, VDR-rpNFs disrupted tumor architecture, enhanced CAR T cell infiltration, and reduced necrosis. PPAR{gamma}- and p53-rpNFs showed similar reprogramming effects. These results suggest TF-guided fibroblast reprogramming as a viable strategy to remodel the tumor microenvironment and improve CAR T cell efficacy in solid tumors.

cancer biology↗

bioRxiv2026

Imaging Synaptic Vesicle Protein SV2C with 18F-UCB-F: An In Vitro Autoradiography and In Vivo NHP PET Study

The synaptic vesicle protein SV2C, predominantly found in the basal ganglia, has been associated with Parkinsons disease through genetic studies. It plays a crucial role in regulating dopamine release and has been shown to be disrupted in PD animal models and brain tissues from PD patients. In the context of PD-related synaptopathy, SV2C may serve as a potential imaging target for monitoring disease progression and response to treatment. [18F]UCB-F is a radioligand binding to SV2C developed by UCB. Preliminary autoradiography and PET studies in rats showed that [18F]UCB-F displays a brain distribution consistent with the expression of SV2C in vitro but does not display any specific binding in vivo. This study was therefore designed to further investigate the affinity and selectivity of [18F]UCB-F for SV2C and to examine the in vitro and in vivo properties of the radioligand in non-human primates. In vitro binding studies were performed to measure the affinity of UCB-F to SV2A, SV2B, and SV2C. Insilico modeling was used to assess the binding mode and energy of UCB-F. Autoradiography studies on rat and non-human primate (NHP) brain tissues were performed to confirm that [18F]UCB-F showed similar distribution in rat and NHP tissue. Finally, PET studied in NHPs were performed to examine the in vivo pharmacokinetic properties of [18F]UCB-F. [18F]UCB-F was successfully synthesized from the corresponding precursor with high yield. Autoradiography on brain slices from rats and NHPs demonstrated specific binding of [18F]UCB-F in the pallidum, striatum, substantia nigra, and brainstem, consistent with the known brain expression of SV2C. In NHPs, [18F]UCB-F rapidly crossed the blood-brain barrier, reaching peak uptake values of 2.8 %ID in NHP1 and 2.1 %ID in NHP2 at 4 minutes post-injection. The tracer wasrapidly washed out from the brain, with no clear regional distribution. Radiometabolite analysis revealed the formation of only more polar radiometabolites, with approximately 15% of unchanged radioligand remaining in plasma at 15 minutes post-injection. In vitro and in-silico studies demonstrated that the affinity of [18F]UCB-F decreased by approximately one factor of magnitude with increase of temperature from 4{degrees} to 37{degrees} C. This temperature-related decrease of the affinity for SV2C together with rapid in vivo radiometabolism might explain the discrepancy between in vitro and in vivo performance of [18F]UCB-F. Overall, these findings suggest that [18F]UCB-F is not a suitable PET radioligand for imaging SV2C. Further research is needed to identify alternative candidates with improved in vivo stability and brain retention.

neuroscience↗

bioRxiv2025

Tripartite AAV Systems for EYS Retinal Gene Therapy

Mutations in the Eyes Shut Homolog (EYS) gene are a leading cause of autosomal recessive retinitis pigmentosa, a progressive retinal degenerative disease for which no effective treatment currently exists. However, the large size of the EYS coding sequence ([~]9.4 kb) exceeds the packaging limit of adeno-associated virus (AAV) vectors, posing a major barrier to gene replacement therapy. To address this challenge, we developed a tripartite AAV vector system that enables delivery and reconstitution of the full-length EYS gene using a Cre-lox-based unidirectional DNA recombination strategy, Uni-STAR (Uni-directional and Site-specific Transgene Assembly by Recombination). The system consists of three AAV constructs carrying discrete EYS segments flanked by engineered, non-compatible lox sites that drive ordered and unidirectional recombination in target cells. We validated this system in vitro by demonstrating successful reconstitution and expression of full-length EYS protein in HEK293T cells. In vivo, subretinal co-injection of the three AAV vectors into mouse eyes led to precise reconstitution and expression of full-length EYS protein in the retina. These findings establish the feasibility of using a tripartite AAV system to deliver the complete EYS gene and provide a foundation for future therapeutic development targeting EYS-associated retinal degenerations.

genetics↗

bioRxiv2025

AI-Driven and 3D-Bioprinted New Approach Methodology (NAM) Identifies NEO100 as Potent Ultrasound-Activated Therapeutic for Primary and Metastatic Brain Tumors

Primary and metastatic brain tumors are among the deadliest and treatment-resistant cancers, mainly because of their inherent resistance to chemoradiation and limited drug delivery across the blood-brain barrier (BBB). Identifying molecules that can cross the BBB and serve as sonosensitizers is crucial for developing noninvasive, targeted therapies such as sonodynamic therapy (SDT). To overcome the limitations of traditional low-throughput screening, a New Approach Methodology (NAM) was developed, starting with AI-driven molecular discovery. A positive-unlabeled neural network, trained on over 200 molecular descriptors, was used to predict compounds likely to respond to focused ultrasound (FUS), penetrate the BBB, and mediate therapeutic sonodynamic activity. While AI helps prioritize potent candidates, effective SDT also depends on clinically scalable FUS delivery. Low-intensity FUS enables noninvasive activation of small molecules in the brain and has been validated in several clinical settings. Therefore, AI-guided predictions were combined with ultrasound-based sonodynamic testing using parameters relevant to human therapy. A major challenge in SDT development is the lack of rapid, physiologically relevant tumor models, as traditional 3D organoids take weeks to mature, delaying validation. To address this, a magnetic bioprinting platform was used to produce uniform 3D tumor spheroids within hours, enabling high-throughput screening of SDT. These spheroids replicate key microenvironmental gradients, supporting reliable ultrasound-driven cytotoxicity testing. Through this combined NAM pipeline, AI identified NEO100--an ultrapure, pharmaceutical-grade perillyl alcohol currently in Phase 2a clinical trials--as a promising sonosensitizer candidate. These predictions were validated in rapidly 3D bioprinted tumor models representing glioblastoma, Group 3 pediatric medulloblastoma, meningioma, and breast-to-brain and lung-to-brain metastases. In all tumor types, ultrasound activation significantly increased NEO100s cytotoxicity. Given its established safety profile in humans and ability to cross the BBB, NEO100 demonstrates how integrating AI-based molecular discovery, accelerated 3D bioprinting, and clinically relevant ultrasound parameters can rapidly advance precision sonodynamic therapies for various primary and metastatic brain cancers.

cancer biology↗

bioRxiv2025

TXA11114: Discovery of an in vivo efficacious efflux pump inhibitor in Pseudomonas aeruginosa

Multi-drug resistance in Pseudomonas aeruginosa is often associated with overexpression of drug efflux pumps which limit antibiotics exposure. So far, successful development of efflux pump inhibitors (EPIs) has been plagued by undesirable toxicities and inconsequential in vivo efficacy. TAXIS Pharmaceuticals Inc. has discovered an effective anti-pseudomonal therapy involving a novel indole carboxamide class of EPI, TXA11114, with a fluorine substituted diamine sidechain, as an adjunctive to levofloxacin. TXA11114 has demonstrated excellent potentiation of levofloxacin MIC by [≥] 8-fold in 90% of Walter-Reed and CDC multi-drug resistant (MDR) isolates. Biophysical and genetic studies with TXA11114 support efflux inhibition while ruling out membrane disruption as a mechanism of action. TXA11114 enhanced the levofloxacin killing and diminished the frequency of resistance emergence to levofloxacin to undetectable levels. Moreover, in murine thigh and lung P. aeruginosa infection models, the TXA11114-levofloxacin combination showed pronounced killing compared to levofloxacin alone, achieving a validated in vivo efficacy milestone that previous EPIs could not. Most importantly, TXA11114 exhibits a safe toxicology profile when screened for cytotoxicity, hERG channel inhibition, in vitro nephrotoxicity, and acute toxicity. Further, pharmacokinetic (PK) parameters of TXA11114 have a complementary profile with that of levofloxacin in plasma and bronchoalveolar lavage fluid (BALF) samples of infected mice, maximizing pharmacodynamic (PD) benefits. Overall, studies on the TXA11114-levofloxacin combination highlight its potential as an anti-pseudomonal agent for combating multidrug-resistant infections.

microbiology↗

bioRxiv2025

PET imaging of an antisense oligonucleotide in the living non-human primate brain using click chemistry

Determination of a drugs biodistribution is critical to ensure it reaches the target tissue of interest. This is particularly challenging in the brain where invasive sampling methods may not be possible. Here, a pretargeted imaging methodology is disclosed that utilizes bioorthogonal click chemistry to determine the distribution of an antisense oligonucleotide in the living brain following intrathecal dosing. A novel PET tracer, [18F]BIO-687, bearing a click-reactive trans-cyclooctene (TCO) was discovered and tested in conjunction with a Malat1 antisense oligonucleotide (ASO) conjugated with a methyltetrazine (MeTz). PET imaging in rats demonstrated that the tracer possesses good kinetic properties for CNS imaging and can react to form a covalent linkage with high specificity to the MeTz-conjugated-ASO in vivo. Further, the amount of tracer reacted by cycloaddition with the Tz was determined to be dependent on the concentration of ASO-MeTz in tissue, as determined through comparison of the imaging signal with the LC-MS of the tissue homogenate. The system was evaluated in cynomolgus monkeys, with PET imaging showing favorable tracer kinetics and specific binding to the ASO in vivo. These results demonstrate that the tracer [18F]BIO-687 can image intrathecally-delivered ASO distribution in the brain, and future studies should leverage this technology to evaluate ASO distribution in human subjects to study distribution. One Sentence SummaryDistribution of an intrathecally administered antisense oligonucleotide can be imaged using a pretargeted approach in the living brains of non-human primates.

neuroscience↗

bioRxiv2024

Identification of Ephrin type-B receptor 4 as a critical mediator of tissue fibrosis

Pulmonary fibrosis (PF) is a pathology associated with interstitial lung diseases (ILDs), including idiopathic pulmonary fibrosis (IPF). Fibrosis promotes continual secretion of extracellular matrix (ECM), producing non-functional scar tissue and causing organ failure. This study investigated the tyrosine kinase receptor Ephrin type-B receptor 4 (EphB4) as a mediator of PF. To this end, we generated mice with conditional Col1a2-driven deletion of Ephb4 and used a preclinical mouse model of PF, total and single nuclei RNA (snRNA) sequencing, NanoString, previously published single cell data, computational analysis, and functional assays of mouse and human healthy control and IPF lung fibroblasts. Col1a2-CreERT-driven Ephb4 deletion, or EphB4 inhibition via NVP-BHG712, markedly protected against bleomycin-induced PF. Total RNA-sequencing of fibroblasts isolated from Ephb4-deficient fibrotic mouse lungs exhibited reduced expression of ECM, ER Cargo, and protein trafficking-related genes. NVP-BHG712 reduced expression of these identified genes in mouse lung fibroblasts under fibrotic conditions in vitro. SnRNA sequencing of mouse lungs treated with NVP-BHG712 identified transcriptomic changes of ECM genes in specific fibroblast subpopulations. RNA sequencing, computational, and functional assays using mouse and human IPF fibroblasts identified elastin as a key mediator involved in EphB4 signaling. Combined, our data show that EphB4 is a crucial mediator of PF.

pathology↗

bioRxiv2024

Delivering large genes using adeno-associated virus and the CRE-lox DNA recombination system

Adeno-associated virus (AAV) is a safe and efficient gene delivery vehicle for gene therapies. However, its relatively small packaging capacity limits its use as a gene transfer vector. Here, we describe a strategy to deliver large genes that exceed the AAVs packaging capacity using up to four AAV vectors and the CRE-lox DNA recombination system. We devised novel lox sites by combining non-compatible and reaction equilibrium-modifying lox site variants. These lox sites facilitate sequence-specific and near-unidirectional recombination of AAV vector genomes, enabling efficient reconstitution of up to 16 kb of therapeutic genes in a pre-determined configuration. Using this strategy, we have developed AAV gene therapy vectors to deliver IFT140, PCDH15, CEP290, and CDH23 and demonstrate efficient production of full-length proteins in cultured mammalian cells and mouse retinas. Notably, this approach significantly surpasses the trans-splicing and split-intein-based reconstitution methods in efficiency, requiring lower doses, minimizing or eliminating the production of truncated protein products, and offering flexibility in selecting splitting positions. The CRE-lox approach described here provides a simple and effective platform for producing AAV gene therapy vectors beyond AAVs packaging capacity.

molecular biology↗

bioRxiv2023

Immune Correlates of Hyperglycemia and Vaccination in a Non-human Primate Model of Long-COVID

Hyperglycemia, and exacerbation of pre-existing deficits in glucose metabolism, are major manifestations of the post-acute sequelae of SARS-CoV-2 (PASC). Our understanding of lasting glucometabolic disruptions after acute COVID-19 remains unclear due to the lack of animal models for metabolic PASC. Here, we report a non-human primate model of metabolic PASC using SARS-CoV-2 infected African green monkeys (AGMs). Using this model, we have identified a dysregulated chemokine signature and hypersensitive T cell population during acute COVID-19 that correlates with elevated and persistent hyperglycemia four months post-infection. This persistent hyperglycemia correlates with elevated hepatic glycogen, but there was no evidence of long-term SARS-CoV-2 replication in the liver and pancreas. Finally, we report a favorable glycemic effect of the SARS-CoV-2 mRNA vaccine, administered on day 4 post-infection. Together, these data suggest that the AGM metabolic PASC model exhibits important similarities to human metabolic PASC and can be utilized to assess therapeutic candidates to combat this syndrome.

immunology↗

bioRxiv2022

The role of consciously timed movements in shaping and improving auditory timing

Our subjective sense of time is intertwined with a plethora of perceptual, cognitive, and motor functions, and likewise, the brain is equipped to expertly filter, weight, and combine these signals for seamless interactions with a dynamic world. Until relatively recently, the literature on time perception has excluded the influence of motor activity, yet, it has been found that motor circuits in the brain are at the core of most timing functions. Several studies have now identified that concurrent movements exert robust effects on perceptual timing estimates, but critically, have not assessed how humans consciously judge the duration of their own movements. This creates a gap in our understanding of the mechanisms driving movement-related effects on sensory timing. We sought to address this gap by administering a sensorimotor timing task in which we explicitly compared the timing of isolated auditory tones and arm movements, or both simultaneously. We contextualized our findings within a Bayesian cue combination framework, in which separate sources of temporal information are weighted by their reliability and integrated into a unitary time estimate that is more precise than either unisensory estimate. Our results revealed differences in accuracy between auditory, movement, and combined trials, and crucially, that combined trials were the most accurately timed. Under the Bayesian framework, we found that participants combined estimates were more precise than isolated estimates in a way that trended towards optimality, while being overall less optimal than the models prediction. These findings elucidate previously unknown qualities of conscious motor timing, and proposes computational mechanisms that can describe how movements combine with perceptual signals to create unified, multimodal experiences of time.

neuroscience↗

bioRxiv2022

Knockout of Bbs10 results in lack of cone electrical function and progressive retinal degeneration of rods and cones

Bardet Biedl Syndrome (BBS) is an autosomal recessive disorder caused by mutations in at least 22 different genes. A constant feature is early onset retinal degeneration leading to blindness, with variable central obesity, polydactyly, renal failure, and developmental anomalies. BBS type 10 (BBS10) is a common form caused by mutations in the BBS10 gene encoding a chaperonin-like protein. There are currently no treatments for the progressive vision loss. To aid in treatment development, a BBS10 mouse model was developed by knocking out the Bbs10 gene. Using optical coherence tomography (OCT), electroretinography (ERG), and a visually guided swim assay (VGSA), we demonstrate that Bbs10-/- mice have progressive retinal degeneration. Cone electrical function was absent although cones were anatomically present on histology and retained partial function based on VGSA. The retinal outer nuclear layer (photoreceptor nuclei) progressively thinned as demonstrated on OCT and histology, and rod electrical activity decreased over time on ERG. These phenotypes are more rapidly progressive than retinal degeneration in the Bbs1M390R/M390R knock-in mouse. They are consistent with a cone-rod dystrophy distinct from typical rod-cone degeneration in retinitis pigmentosa and recapitulate aspects of retinal degeneration observed in humans with BBS10. This study has implications for BBS10 gene therapy.

genetics↗

bioRxiv2021

Possible Interference in Protein - Protein interaction as a new approach in microinhibition of respiratory pathogens on nasal- oral epithelium: An early on-screen study with reference toSARS-Cov-2-ACE2 binding interference

Upper and lower respiratory pathogens - both microbes and viruses -are responsible for very high morbidity, man-hour loss, residual long term clinical conditions and even mortality. In india only, high incidence of annual respiratory infections - both UT and LT - demands prophylactic intervention in addition to all therapeutic interventions available.The issue of respiratory infections is more pronounced now in the backdrop of nearly uncontrolled high incidences of SARS-Cov-2 affection resulting in death and damage of human lives to the extent of hundreds of millions spreading over entire world, with incidence variations from country to country. After the initial unanswered phase of spread of SARS-Cov-2 virus with attendant unseen mortalities, quickest invention of a series of unusual vaccines have stemmed the lethal progress to a very significant extent, although vaccinating each and every human subject - nearly 8 to 9 bn in supremely divided world -economically-- is an unthinkable proposition where economic disparity dictates vaccine availability and implementation.Moreover, being of highly unstable nucleic acid composition, the original virus, by now has a thick set of variants around the globe with variable clinical outcome. Given this complex background of scanty availability and inefficient implementation, there always is a need of a preventive approach which can possibly micro-fix the pathogens, including SARS-2 on nasal epithelium so as to interfere with viral [or any pathogen] entry through specified receptor gate[s] or any other ways. The present formulation is under study -- as a candidate of interference on nasal / oral mucosa for all respiratory pathogens. This brief report describes dry on-screen studies of protein - protein interaction as well as its possible interference by an amino acid Lysine. Phospholipid bilayerresponses in presence of added loads of the same essential amino acid -Lysine - showed unusual and unexplained behavior both in structural integrity as well in spatial orientation.

biochemistry↗

bioRxiv2021

Characterisation of a novel ACE2-based therapeutic with enhanced rather than reduced activity against SARS-CoV2 variants

The human angiotensin-converting enzyme 2 acts as the host cell receptor for SARS-CoV-2 and the other members of the Coronaviridae family SARS-CoV-1 and HCoV-NL63. Here we report the biophysical properties of the SARS-CoV-2 spike variants D614G, B.1.1.7 and B.1.351 with affinities to the ACE2 receptor and infectivity capacity, revealing weaknesses in the developed neutralising antibody approaches. Furthermore, we report a pre-clinical characterisation package for a soluble receptor decoy engineered to be catalytically inactive and immunologically inert, with broad neutralisation capacity, that represents an attractive therapeutic alternative in light of the mutational landscape of COVID-19. This construct efficiently neutralised four SARS-CoV-2 variants of concern. The decoy also displays antibody-like biophysical properties and manufacturability, strengthening its suitability as a first-line treatment option in prophylaxis or therapeutic regimens for COVID-19 and related viral infections.

immunology↗

bioRxiv2021

Differential requirement of NPHP1 for compartmentalized protein localization during photoreceptor outer segment development and maintenance

Nephrocystin (NPHP1) is a ciliary transition zone protein and its ablation causes nephronophthisis (NPHP) with partially penetrant retinal dystrophy. However, the precise requirements of NPHP1 in photoreceptors are not well understood. Here, we characterize retinal degeneration in a mouse model of NPHP1 and show that NPHP1 is required to prevent infiltration of inner segment plasma membrane proteins into the outer segment during the photoreceptor maturation. We demonstrate that Nphp1 gene-trap mutant mice, which were previously described as null, are in fact hypomorphs due to the production of a small quantity of functional mRNAs derived from nonsense-associated altered splicing and skipping of two exons including the one harboring the gene-trap. In homozygous mutant animals, inner segment plasma membrane proteins such as syntaxin-3 (STX3), synaptosomal-associated protein 25 (SNAP25), and interphotoreceptor matrix proteoglycan 2 (IMPG2) accumulate in the outer segment when outer segments are actively elongating. This phenotype, however, is spontaneously ameliorated after the outer segment elongation is completed. Retinal degeneration also occurs temporarily during the photoreceptor maturation but stops afterward. We further show that Nphp1 genetically interacts with Cep290, another NPHP gene, and that a reduction of Cep290 gene dose results in retinal degeneration that continues until adulthood in Nphp1 mutant mice. These findings demonstrate that NPHP1 is required for the confinement of inner segment plasma membrane proteins during the outer segment development, but its requirement diminishes as photoreceptors mature. Our study also suggests that additional mutations in other NPHP genes may influence the penetrance of retinopathy in human NPHP1 patients.

neuroscience↗

bioRxiv2020

A vision prosthesis based on electrical stimulation of the primary visual cortex using epicortical microelectrodes

Prostheses that can restore limited vision in the profoundly blind have been under investigation for several decades. Studies using epicortical macroelectrodes and intracortical microelectrodes have validated that electrical stimulation of primary visual cortical can serve as the basis for a vision prosthesis. However, neither of these approaches has resulted in a clinically viable vision prosthesis. Epicortical macroelectrodes required high levels of electrical current to evoke visual percepts, while intracortical microelectrodes faced challenges with longevity and stability. We hypothesized that epicortical microelectrodes could evoke visual percepts at lower currents than macroelectrodes and provide improved longevity and stability compared with intracortical microelectrodes. To test this hypotheses we implanted epicortical microelectrode arrays over the primary visual cortex of a nonhuman primate. Electrical stimulation via this array was used to evaluate the ability of epicortical microstimulation to evoke differentiable visual percepts. Visual percepts were evoked using the epicortical microelectrode array, and at electrical currents notably lower than those required to evoke visual percepts on macroelectrode arrays. The electrical current thresholds for evoking visual percepts on the epicortical microelectrode array were consistent across multiple array implants and over several months. Normal vision of light perception was not impaired by multiple array implants or chronic electrical stimulation, demonstrating that no gross visual deficit resulted from the experiments. We specifically demonstrate that epicortical microelectrode interfaces can serve as the basis for a vision prosthesis and more generally may provide an approach to evoking perception in multiple sensory modalities. One Sentence SummaryElectrical stimulation of the brain via microelectrodes resting on the surface of primary visual cortex can evoke multiple differentiable visual percepts.

bioengineering↗

bioRxiv2020

Phage-shock-protein (Psp) Envelope Stress Response: Evolutionary History and Discovery of Novel Players

Bacterial phage shock protein (PSP) systems stabilize the bacterial cell membrane and protect against envelope stress. These systems have been associated with virulence, but despite their critical roles, PSP components are not well-characterized outside proteobacteria. Using comparative genomics and protein sequence-structure-function analyses, we systematically identified and analyzed PSP homologs, phyletic patterns, domain architectures, and gene neighborhoods. This approach underscored the evolutionary significance of the system, revealing that the core PspA gene (Snf7 in ESCRT outside bacteria) was present in the Last Universal Common Ancestor (LUCA), and that this ancestral functionality has since diversified into multiple novel, distinct PSP systems across life. Several novel partners of the PSP system were identified: (i) the Toastrack domain, likely facilitating assembly of sub-membrane stress-sensing and signaling complexes, (ii) the newly-defined HAAS-PadR-like transcriptional regulator pair system, and (iii) multiple independent associations with ATPase, CesT/Tir-like chaperone, and Band-7 domains in proteins thought to mediate sub-membrane dynamics. Our work also uncovered links between the PSP components and other domains, such as novel variants of SHOCT-like domains, suggesting roles in assembling membrane-associated complexes of proteins with disparate biochemical functions. Results are available at https://jravilab.org/psp. ImportancePhage shock proteins (PSP) are virulence-associated, cell membrane stress-protective systems. They have mostly been characterized in proteobacteria and firmicutes. We now show that PSP systems were present in the Last Universal Common Ancestor, and that homologs have evolved and diversified into newly identified functional contexts. Recognizing the conservation and evolution of PSP systems across bacterial phyla contributes to our understanding of stress response mechanisms in prokaryotes. Moreover, the newly discovered PSP modularity will likely prompt new studies of lineage-specific cell-envelope structures, lifestyles, and adaptation mechanisms. Finally, our results validate use of domain architecture and genetic context for discovery in comparative genomics.

evolutionary biology↗