Biology subjects

De, S.

Publications and source records attributed to De, S..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

Structures of Naked Mole-Rat, Tuco-Tuco, and Guinea Pig Ribosomes: Is rRNA Fragmentation Linked to Translational Fidelity?

Ribosomes are central to protein synthesis in all organisms. Among mammals, the ribosome functional core is highly conserved. Remarkably, two rodent species, the naked mole-rat (NMR) and tuco-tuco display fragmented 28S rRNA, coupled with high translational fidelity and long lifespan. The unusual ribosomal architecture in the NMR and tuco-tuco has been speculated to be linked to high translational fidelity. Here we show, by single-particle cryo-electron microscopy (cryo-EM), that despite the fragmentation of their rRNA, NMR and tuco-tuco ribosomes retain their core functional architecture. Compared to ribosomes of the guinea pig, a phylogenetically related rodent without 28S rRNA fragmentation, ribosomes of NMR and tuco-tuco exhibit poorly resolved, certain expansion segments. In contrast, the structure of the guinea pig ribosome shows high similarity to human ribosome. Enhanced translational fidelity in the NMR and tuco-tuco may stem from subtle, allosteric effects in dynamics, linked to rRNA fragmentation.

biochemistry↗

bioRxiv2025

Membrane potential bistability in human breast cancer MDA-MB-231 cells: A 'Hodgkin-Huxley type' model

The plasma membrane voltage (Vm) is well known to have significant involvement in a wide range of cellular functions including cancer progression. Voltage imaging revealed that Vm of MDA-MB-231 breast cancer cells is bistable with hyperpolarising voltage transients (HVTs). Here, we formulate a model of Vm incorporating the ion channels Nav1.5, Cav3.2, and KCa1.1. Vm is governed by the Hodgkin-Huxley formalism coupled to intracellular Ca2+ dynamics, via Ca2+ influx through Cav3.2 and Ca2+-dependent efflux of K+ through KCa1.1. Stochastic fluctuations--arising from sparse ion channel expression and Ca2+-induced Ca2+ release (CICR)--drive Vm transitions between the otherwise stable depolarised and hyperpolarised states. The model qualitatively reproduces the key experimental observations of HVTs, and their suppression by specific inhibitors of Nav1.5 or KCa1.1. It is predicted that inhibition of CICR should also lead to suppression of HVTs. Our model promises to help the understanding of the dynamic electrical activity of the MDA-MB-231 cell model and its functional consequences, and may inspire future bioelectricity-based cancer diagnosis and therapy.

cancer biology↗

bioRxiv2025

Comparative evaluation on the fermentative potential of single and assorted fruit and vegetable waste for production of bioethanol

Fruit and vegetable waste (FVW) constitute a large part of municipal solid waste (MSW) and create significant environmental challenges by emitting the greenhouse gas methane. In contrast, these are a big source of fermentable sugar to produce bioenergy. Therefore, in this study, the Scanning Electron Microscopy (SEM), Attenuated total reflectance-fourier-transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and biochemical quantification of -cellulose and acid-insoluble lignin contents were carried out to compare fermentative potential between single (potato peel vs. orange peel) and assorted vegetable and fruit wastes. Collectively, the study indicates that assorted vegetable waste holds enormous biofuel potential by having low moisture content (6.78 %), moderately low decomposition temperature (Tmax: 299.36 {degrees}C), low crystallinity index (CrI: 19.12%), and high -cellulose contents (32.35 - 47.73 gm%) yielding high sugar (325.65 mg/g). The study also optimized several key fermentation parameters such as pH, sugar concentration and the time to produce bioethanol. It was observed that maximum production of ethanol (2.14%) was achieved at 28{degrees}C, at pH 6.3 with a higher initial sugar concentration of 200mg/g by using Saccharomyces cerevisiae strain NCIM 3594. This study supports the likely utility of unsorted vegetable waste to obtain bioethanol at a mass scale.

plant biology↗

bioRxiv2025

AlphaGenome: advancing regulatory variant effect prediction with a unified DNA sequence model

Deep learning models that predict functional genomic measurements from DNA sequence are powerful tools for deciphering the genetic regulatory code. Existing methods trade off between input sequence length and prediction resolution, thereby limiting their modality scope and performance. We present AlphaGenome, which takes as input 1 megabase of DNA sequence and predicts thousands of functional genomic tracks up to single base pair resolution across diverse modalities - including gene expression, transcription initiation, chromatin accessibility, histone modifications, transcription factor binding, chro- matin contact maps, splice site usage, and splice junction coordinates and strength. Trained on human and mouse genomes, AlphaGenome matches or exceeds the strongest respective available external models on 24 out of 26 evaluations on variant effect prediction. AlphaGenomes ability to simultaneously score variant effects across all modalities accurately recapitulates the mechanisms of clinically-relevant variants near the TAL1 oncogene. To facilitate broader use, we provide tools for making genome track and variant effect predictions from sequence.

bioinformatics↗

bioRxiv2025

The global proteome of Streptococcus pneumoniae EF3030 under nutrient-defined in vitro conditions

Streptococcus pneumoniae is a pathobiont that colonises the upper respiratory tract of humans without causing symptoms but can cause a range of life-threatening diseases including pneumonia, sepsis, and meningitis. It also causes less severe, non-invasive infections such as otitis media and sinusitis. This bacterium thrives in the nasopharynx, where nutrient availability is limited, and has adapted to this environment by developing mechanisms to survive host stress and regulate protein abundance. To study the molecular biology of S. pneumoniae under in vitro and infection-related conditions, a suitable cultivation medium is essential for reproducible experiments. In this study, we optimized a chemically-defined minimal medium that mimics the in vivo nutrient-limited condition and used it for proteome analysis. This optimized medium not only shortened the lag phase but also improved the growth of S. pneumoniae clinical isolates and other streptococcal species. We applied this medium to analyse the global proteome of the pneumococcal colonising strain EF3030, focusing on the transition from the early to late log phase. Our proteomic analysis revealed distinct patterns of protein abundance in different functional categories including metabolism, amino acid synthesis, natural competence, RNA synthesis, cell wall synthesis, protein degradation, and stress responses. Notably, choline-binding protein CbpD, competence factors ComGA and ComEA as well as proteins involved in processing internalized single-stranded DNA (ssDNA) such as Dpr and DprA were higher in abundance in the late log phase. This proteomic profiling provides valuable insights into the pathophysiology of strain S. pneumoniae EF3030 under defined nutrient conditions.

microbiology↗

bioRxiv2025

Revisiting the cancer microbiome using PRISM

Recent controversy around the cancer microbiome highlights the need for improved microbial analysis methods for human genomics data. We developed PRISM, a computational approach for precise microorganism identification and decontamination from low-biomass sequencing data. PRISM removes spurious signals and achieves excellent performance when benchmarked on a curated dataset of 62,006 known true- and false-positive taxa. We then use PRISM to detect microbes in 8 cancer types from the CPTAC and TCGA datasets. We identify rich microbiomes in gastrointestinal tract tumors in CPTAC and identify bacteria in a subset of pancreatic tumors that are associated with altered glycoproteomes, more extensive smoking histories, and higher tumor recurrence risk. We find relatively sparse microbes in other cancer types and in TCGA, which we demonstrate may reflect differing sequencing parameters. Overall, PRISM does not replace gold-standard controls, but it enables higher-confidence analyses and reveals tumor-associated microorganisms with potential molecular and clinical significance.

genomics↗

bioRxiv2024

Passage through micro-sprayer increases functional activity-implications for activity assays in time-resolved cryo-EM

This study examines the validity of an assay that is used to report on the retainment of functional competence by ribosomes as they pass a micro-sprayer. We find a reproducible increase, rather than the expected decrease in GFP production as monitored by fluorescence, which suggests heterogeneity or partial aggregation of ribosomes in solution. An even larger increase in functional activity is observed when sonication is used, pointing to mechanical agitation as the decisive factor in both scenarios. The results have a bearing on the design and interpretation of validation experiments in time-resolved cryo-EM based on microfluidic chips.

biophysics↗

bioRxiv2024

A Comprehensive Method on Black-legged Tick Larvae and Nymph Feeding on Mice to Study Lyme Disease Transmission and Acquisition

Tick-borne diseases are a growing public health concern in the United States, with cases rising steadily each year. Lyme borreliosis, or Lyme disease, remains the most prevalent, affecting approximately 476,000 individuals annually. Human-driven changes in climate and ecosystems have expanded the habitat of pathogen-carrying ticks, facilitating the spread of these infections. Additionally, increased instances of tick-borne diseases transmission through human tissues have been reported. Despite ongoing efforts to manage these infections, their incidence continues to rise. To develop effective control measures against these diseases and prevent the transmission of tick-borne infections through human and animal tissues, it is very important to develop detection assays and understand the transmission mechanisms of tick-borne infections. In this study, we provide detailed descriptions and visual references for larval and nymphal tick feeding on mice, focusing on the transmission and acquisition of Borrelia burgdorferi (sensu stricto). These methodologies can be applied to study other tick-borne diseases, tick vectorial capacity, and tick biology, aiding in the development of detection strategies to combat these infections.

molecular biology↗

bioRxiv2024

The circadian gene Dec2 promotes pancreatic cancer dormancy by regulating tumor cell antigen presentation to facilitate immune evasion

The mechanisms that regulate cancer dormancy remain poorly understood. Using a mouse model of resectable pancreatic adenocarcinoma (PDAC), we identified Dec2 as a gene that was upregulated in metastatic dormant tumor cells. Deletion of Dec2 from tumor cells substantially increased mouse survival after resection due to an immune-mediated mechanism as the survival benefit was abrogated in immunodeficient conditions. Dec2 promoted immune evasion by repressing multiple components of the MHC-I dependent antigen presentation pathway in tumor cells. Dec2 is a regulator of circadian rhythms, and we found several components of the antigen presentation pathway oscillated in a circadian manner that was lost upon deletion of Dec2. Moreover, T-cell mediated tumor cell killing varied depending on the time of day. We suggest that lowered MHC-I presentation of antigens during rest phase is a natural effect of the circadian clock, which is exploited by Dec2-overexpressing pancreatic tumors to evade the immune system.

cancer biology↗

bioRxiv2024

Disruptive changes in tissue microenvironment prime oncogenic processes at different stages of carcinogenesis in lung

Carcinogenesis is characterized not only by the uncontrolled growth of malignant cells but also by the disruption of the normal balance of cellular processes and intercellular interactions in the microenvironment that overcome the constraints of tissue homeostasis and support malignant growth. We profiled benign pulmonary dysplasia, carcinoma in situ, and invasive lung carcinomas at single-cell resolution to identify composite changes in cellular processes, signaling, and interactions among tumor-immune-stromal cells in the microenvironment in progressively advanced disease stages. We developed OncoTerrain, a hyperparameter-tuned model that captured synergistic multimodal signatures of an increasingly perturbed microenvironment in malignant disease stages and identified composite microenvironmental changes that supported cancer hallmarks. Key cancer-related changes in transcriptional states, cellular processes, and intercellular interactions involving immune, fibroblast, and stromal cell types preceded tumor initiation and were often synergistic. The microenvironment of increasingly malignant tissues was characterized by immune avoidance, ECM remodeling, and altered cell mobility. There were changes in cell states in fibroblasts, macrophages, and their inter-cellular interactions with other cell types, whereas T-cell activation occurred late. The in-situ carcinomas showed variations in the composite microenvironmental states that corroborated their pathology, which was not apparent at the genome level. A subset of those harbored populations of tumor and non-tumor cells with aggressive characteristics in some but not all aspects of hallmarks of carcinogenesis in the lung. We suspect that the variation in the coordination of microenvironmental cues may influence why some but not all in-situ tumors progress to the advanced stages.

genomics↗

bioRxiv2024

Deconstructing evolutionary histories of complex genomic rearrangements in lung malignancies

Somatic genomic rearrangements are hallmarks of cancer. Complex genomic rearrangements (CGRs) involving multiple intertwined structural alterations are often present in tumor genomes. CGRs frequently harbor oncogenic drivers, but their genomic architectures and etiologies are poorly understood. We used deep-coverage optical mapping technology to profile the genomic landscapes of normal lung tissues, benign pulmonary lesions, carcinoma in situ, and advanced carcinomas to examine the patterns of genome disorganization and instability in different stages of carcinogenesis in lung. Large rearrangements and CGRs were prevalent in the carcinomas. We developed omcplR to resolve the architecture of CGRs and predict their genesis from optical mapping data using genome-graph concept. We found that CGRs often arose from hierarchical combinations of multiple, localized simple structural variations, and harbored allelic heterogeneity at the affected loci. Rearrangement patterns and associated genomic signatures suggested that chromoanasynthesis was a likely prevalent mechanism driving complex genomic rearrangements. The early rearrangement junctions in intra-chromosomal CGRs were usually localized within the same chromatin domains, but the late junctions in advanced tumors had more heterogeneous contexts suggesting progressive organizational heterogeneity. The CGRs, especially the late events therein were under positive selection. A composite signature of genomic alterations including the CGRs captured the trajectory of progressive genomic disorganization and instability with carcinogenesis in lung and underscored the extent of genomic structural heterogeneity among the in-situ tumors.

genomics↗

bioRxiv2024

Molecular determinants of protein pathogenicity at the single-aggregate level

Determining the structure-function relationships of protein aggregates is a fundamental challenge in biology. These aggregates, whether formed in vitro, within cells, or in living organisms, present significant heterogeneity in their molecular features such as size, structure, and composition, making it difficult to determine how their structure influences their functions. Interpreting how these molecular features translate into functional roles is crucial for understanding cellular homeostasis and the pathogenesis of various debilitating diseases like Alzheimers and Parkinsons. In this study, we introduce a bottom-up approach to explore how variations in protein aggregates size, composition, post-translational modifications and point mutations profoundly influence their biological functions. Applying this method to Alzheimers and Parkinsons associated proteins, we uncover the mechanism of novel disease-relevant pathways and demonstrate how subtle alterations in composition and morphology can shift the balance between healthy and pathological states. Our findings establish a broadly applicable framework for investigating protein dysfunctions in various proteinopathies.

biochemistry↗

bioRxiv2024

Telmisartan impedes JEV infection predominately via AT1/PPARγ axis

Japanese encephalitis, caused by Japanese encephalitis virus (JEV) is a vector born disease for which no specific therapeutics are available yet. Binding of angiotensin II (Ang II) to angiotensin II type 1 (AT1) receptor induces release of inflammatory cytokines associated with viral encephalitis. Accordingly, Ang II receptor blockers (ARBs) have been proposed to manage encephalitis. Since Telmisartan (TM, antagonist of AT1 and agonist of PPAR{gamma}) has relatively better brain access than other ARBs, this investigation aims to evaluate its anti-JEV efficacy in vitro and in vivo. TM reduced JEV titer, RNA and protein (NS3) significantly in the BHK-21 cells with IC50 of 24.68M and CC50 of >350 M (Selectivity Index >14.18) indicating its potential of repurposing against JEV. The anti-JEV efficacy of TM was further observed in macrophages (RAW264.7) and neuronal (SH-SY5Y) cells. Interestingly, the viral load was reduced significantly in pre, co and post-treatment conditions of TM, however most efficiently (80%) in post treatment. In presence of GW (PPAR{gamma} antagonist) and AG (AT1 agonist), viral infection was increased remarkably while AT1 was upregulated and PPAR{gamma} was downregulated. Whereas, TM treatment reversed the levels of AT1 and PPAR{gamma} during infection. Further, reduction of inflammatory markers like p-IRF-3, COX-2 and p-NF-{kappa}B was observed after TM treatment in RAW264.7 cells suggesting its immunomodulation through the AT1/PPAR{gamma} axis. Finally, the anti-JEV potential of TM was validated in mice model through the reduction of disease score, viral protein and histological changes. Thus, the preclinical efficacy of TM suggests its suitability for repurposing against JEV.

microbiology↗

bioRxiv2024

Zika and Dengue Viruses Differentially Modulate Host mRNA Processing Factors Defining Its Virulence

Rising global temperatures coupled with increasing international travel, and trade are contributing to spread of vectors such as ticks and mosquitoes, resulting in a surge of vector-borne flavivirus infection in human population. Furthermore, this increase in flavivirus infection pose threat to the safety of biologics such as cell and gene therapy products as human-derived materials are commonly used during manufacturing of these drug products. In this study, we conducted time-course transcriptomic and protein analyses to uncover the host molecular factors driving the virulence of Zika virus (ZIKV) and Dengue virus (DENV) in the context of host defense mechanisms, as these two viruses have caused the most recent and significant flavivirus outbreaks. Compared to DENV, ZIKV exhibited stronger virulence and cytopathic effects. RNA sequencing analysis revealed differential expression of various cellular factors, including RNA processing factors. Further investigation identified cell-type and time-dependent upregulation nonsense-mediated RNA decay (NMD), RNA degradation factors and nuclear pore complex (NPC) transcripts. Protein analysis showed that ZIKV, unlike DENV, degrades NMD factors in host cells, which along with mis-regulation of RNA degradation factors resulted in accumulation in host intronic transcripts as revealed by RNA-seq data. We also found that active nuclear transport is required for ZIKV replication, suggesting that therapeutic targeting of the NPC could potentially be effective in controlling ZIKV infection. Furthermore, from our findings we hypothesize that, ZIKV, but not DENV, drives early host cell cytopathy through targeted protein degradation. Current studies are underway to develop novel strategies to detect ZIKV, DENV and other flaviviruses in biologics based on transcriptomics and proteomics. TeaserExploring the molecular basis of flavivirus virulence in host cells.

genomics↗

bioRxiv2024

Inconsistencies in the published rabbit ribosomal rRNAs: a proposal for uniformity in sequence and site numbering

Examination of all publicly available Oryctolagus cuniculus (rabbit) ribosome cryo-EM structures reveals numerous confusing inconsistencies. First, there are a plethora of single nucleotide differences among the various rabbit 28S and 18S rRNA structures. Second, two nucleotides are absent from the NCBI Reference Sequence for the 18S rRNA gene. Moving forward, we propose using the Broad Institutes rabbit whole genome shotgun sequence and numbering to reduce modeling ambiguity and improve consistency between ribosome models.

biophysics↗

bioRxiv2024

Polyphenol-rich fraction of Bergenia ligulata (Wall.) Engl. sensitizes colon and breast cancer metastasis in vivo: Evidence of cell-type specific mechanism

BackgroundColon and breast cancer are one of the leading causes of mortality worldwide. Limited efficacies of present treatments highlighted an urgent need for improvement. Bergenia ligulata is known for its anticancer properties in Indian traditional and folk medicine though the molecular basis of its effects, particularly its anti-metastatic properties, is not well understood. Anti-prostate cancer activity of a LCMS defined polyphenol-rich fraction from Bergenia ligulata (PFBL) rhizome extract has already been published showing promising results in preclinical models. PurposeThe present study aims to explore anti-cancer activity and anti-metastatic potentials of PFBL against colon and breast cancers in both in vitro and preclinical settings. Study design and methodsPFBL alone or in synergy with standard chemotherapeutic drugs was tasted in CT26 and 4T1 subcutaneous solid tumors in BALB/c mice. The effect of PFBL was analyzed in terms of changes in tumor mass and different molecular marker levels. Anti-metastatic potential of PFBL was evaluated in CT26 and 4T1 lung metastasis model in mice focusing on the number of lung nodules and lung size. ResultsOur results evidenced that PFBL efficiently regressed both CT26 and 4T1-induced solid tumors alone and in combination with 5FU/doxorubicin without affecting the health of normal host. Notably, PFBL suppressed lung metastasis of 4T1 and CT26 cells in mice with great efficacy. Analysis of tumor and cell extracts suggested that colon cancer cells died by autophagy, while breast cancer cells majorly died by caspase-dependent apoptosis. PFBL actions involved AMPK-dependent inhibition of mTORC1 and subsequent increase in LC3II, PARP1, CDK4 and Cyclin D1 levels in both HCT116 and MCF7 cells; an elevation of intracellular ROS level was the major cause of death in both the cancer types. PFBL treatment also reversed the EMT marker expressions in in vivo and in vitro. ConclusionPFBL regressed colon and breast cancer metastasis through distinct mechanisms with little effect on healthy mice. The present study underscored PFBL as a novel anti-tumor and anti-metastasis candidate warranting further testing in clinical settings.

cancer biology↗

bioRxiv2024

Evolutionary history with chronic malnutrition enhances pathogen susceptibility at older ages

Juvenile malnutrition is a global public health concern that negatively impacts the development and maturation of the immune system, leading to increased susceptibility to infectious diseases. Such adverse effects on immunity might increase with ageing, worsening disease conditions later in life. Furthermore, malnutrition may persist across generations, imposing strong natural selection to survive the nutrient shortage. However, it is unclear how the evolutionary history of ancestral generations with chronic malnutrition could influence pathogen resistance and infection susceptibility, as well as their age-specific changes in extant generations. To address this, we used Drosophila melanogaster populations adapted against chronic juvenile malnutrition and exposed them to a bacterial pathogen, Providencia rettgeri, during their early and late adulthood. Surprisingly, we observed that in populations adapted to chronic malnutrition, young flies survived infection better by tolerating the infection, while control flies displayed higher infection susceptibility despite carrying a similar pathogen load. However, this pattern in post-infection survival is reversed with ageing. There was no change in pathogen resistance, but evolved flies succumbed more to infection than control flies regardless of the input infection doses. Our study thus revealed new evolutionary insights into the development of contrasting early vs late-life immune strategies and age-specific vulnerabilities to infection as a function of early-life malnutrition.

evolutionary biology↗

bioRxiv2024

Integrative single-cell analysis of neural stem/progenitor cells reveals epigenetically dysregulated interferon response in progressive multiple sclerosis

Progressive multiple sclerosis (PMS) is characterized by a primary smouldering pathological disease process associated with a superimposed inflammatory activity. Cellular and molecular processes sustaining the pathobiology of PMS remain to be identified. We previously discovered senescence signatures in neural stem/progenitor cells (NSCs) from people with PMS. Applying direct reprogramming to generate directly induced NSCs (iNSCs) from somatic fibroblasts, we retain epigenetic information and observe hypomethylation of genes associated with lipid metabolic processes and IFN signalling only in PMS lines. Single-cell/nucleus transcriptomic and epigenetic profiling reveal an inflammatory, senescent-like, IFN-responsive radial glia (RG)-like cell subcluster mainly in PMS iNSCs that is driven by IFN-associated transcription factors. Lastly, we identify a population of senescent, IFN-responsive, disease-associated RG-like cells (DARGs) in the PMS brain that share pseudotime trajectories with iNSCs in vitro. We describe the existence of a non-neurogenic, dysfunctional DARG population that has the potential to fuel smouldering inflammation in PMS.

neuroscience↗