Biology subjects

Mukherjee, N.

Publications and source records attributed to Mukherjee, N..

At least 19 recordsLinked to original sources

bioRxiv2026

Mathematical genomics of SRY proteins and their associated HMG-Box domains across mammals

Male sex determination in mammals depends on sex-determining region Y (SRY), a transcription factor whose high-mobility group box (HMG box) binds and bends DNA to activate SOX9. The divergent N- and C-terminal domains lack sequence homology and have been dismissed as passive linkers, yet alignment-based homology cannot reveal whether they retain a hidden compositional grammar. We applied quantitative genomics to 65 full-length mammalian SRY proteins and 38 HMG-box subsequences across 75 mammals, integrating amino acid and dipeptide compositions, Shannon entropy, dominant-residue profiles, hydropathy-based n-gram spectra, longest hydropathy stretches, and cumulative proximity. The HMG box is tightly constrained: basic residues dominated, cysteine was nearly absent, entropy clustered near 4.0, polar content averaged 58.44\%, and 25 of 38 HMG boxes shared 57.97\% polar residues, whereas full-length SRY varied more, with rodents showing high polar and glutamine-rich profiles and cetaceans low polar content. Proximity-based clustering was more taxonomically consistent at the HMG level, while terminal regions blurred domain-level signals. Across 65 SRY proteins and 38 HMG domains, intrinsic disorder was the dominant predicted state, and a polyQ-rich rodent SRY illustrated how low-complexity repeats can produce misleading ordered predictions, underscoring the need for consensus disorder analysis in rapidly evolving intrinsically disordered regions. Cumulative proximity analysis identified \textit{Bos taurus} and \textit{Bos grunniens} as the only pair proximally clustered at both the full-length SRY and SRY-HMG levels, establishing multivariate proximity as a stringent criterion of compositional similarity satisfied by a single mammalian pair. These results suggest that SRY and its HMG box each carry a distinct compositional grammar, quantifiable only through alignment-independent signatures, with compositional individuality being the rule rather than the exception. These quantitative signatures provide a framework for interpreting SRY variation, assessing clinical mutations, and understanding evolutionary pressures shaping sex determination. Denser taxon sampling, structural modeling, and experimental tests are needed to clarify whether HMG-box drift and terminal-region variation affect DNA binding, bending, or reproductive function.

bioinformatics↗

bioRxiv2026

Hepatobiliary Progenitor-like Reprogramming in Liver Metastases

Metastatic progression requires cancer cells to adapt to the unique constraints of distant organ microenvironments, yet the mechanisms that drive organ-specific adaptations remain poorly understood. Here, we show that the liver actively rewrites metastatic cancer cell identity, driving tumor cells toward a hepatobiliary progenitor-like state. Through integrated transcriptomic, proteomic, metabolomic, and epigenomic analyses of patient-derived rapid-autopsy samples and experimental models, we identify this state as selectively enriched in liver metastases. It is characterized by co-activation of hepatic and biliary/progenitor regulators HNF4A and SOX9 and is observed across multiple epithelial cancers, indicating a conserved response to the hepatic niche. Mechanistically, hepatocyte-derived TGF-{beta} and hypoxia converge to activate a HIF-1-ACLY axis, increasing nuclear acetyl-coenzyme A availability and histone acetylation at hepatic lineage regulatory elements to drive hepatobiliary reprogramming. This coordinated niche-response program can be captured transcriptionally and is associated with inferior overall survival. Disruption of this pathway suppresses hepatic reprogramming and impairs liver metastatic fitness. These findings identify the liver as an active determinant of metastatic cell fate, linking microenvironmental signaling to metabolic and chromatin remodeling programs that enable lineage plasticity. More broadly, they reveal organ-specific reprogramming as a fundamental principle of metastasis and a therapeutic vulnerability in liver metastases.

cancer biology↗

bioRxiv2026

Isoform-Specific Localization Diversifies Human MSI2 Function

Musashi-2 (MSI2) is an RNA-binding protein implicated in stem cell regulation and cancer, yet reports of its regulatory activity span translational activation, repression, and effects on mRNA stability, sometimes within the same cellular context. The basis for this diversity has remained unclear. Here, we identify alternative splicing as a determinant of MSI2 regulatory activity, acting through isoform-specific subcellular localization. Using a tethered reporter assay, we show that the canonical MSI2-328 isoform promotes translation without changing mRNA abundance. Truncation and mutation analysis identify a 40-amino-acid region (residues 194-234) as necessary and sufficient for cytoplasmic localization and necessary for translational activation. In contrast, the alternatively spliced MSI2-324 isoform localizes predominantly to the nucleus and fails to promote translation. We map this difference to an 18-amino-acid sequence introduced by an alternative 3 splice acceptor in exon 12; this sequence is sufficient to direct nuclear localization, and its removal restores MSI2-328-like cytoplasmic localization and translational activation. Consistent with these compartmental differences, the two isoforms associate with distinct protein networks, MSI2-328 with translation factors and ribosomal proteins, and MSI2-324 with chromatin and pre-mRNA processing factors. These isoform-specific activities are conserved across cell types, and the relative abundance of MSI2 isoforms shifts toward MSI2-324 in several cancers. Altogether, alternative splicing controls MSI2 subcellular localization, interaction networks, and regulatory output, providing a mechanistic framework for the context-dependent roles of MSI2 in gene regulation.

molecular biology↗

bioRxiv2026

A digital twin of pancreatic islet differentiation predicts cell fate

The controlled generation of mature stem cell-derived islets (SC-islets) remains a barrier to scalable cell therapy for diabetes. Here, we develop a predictive digital model defining the cell-state-specific regulatory logic governing fate specification during human SC-islet differentiation. We integrate 400,603 cells from 9 original single-cell multiomic datasets and 52 public single-cell RNA-seq and ATAC-seq datasets across 4 cell lines and 7 differentiation protocols. This model resolves transcriptional and chromatin accessibility dynamics while enabling time-resolved inference and in silico perturbation of cell-state-specific gene regulatory networks. We identify regulators across trajectories from endoderm progenitors to pancreatic exocrine and endocrine lineages, nominating new candidate regulators. Among these candidates, we validate previously unreported roles for STAT1 as an exocrine driver and ZEB1 as a dynamic regulator of early endocrine specification and later off-target serotonergic islet cell fate. This work provides an experimentally supported predictive framework and an interactive resource comprising 1,116 simulations to prioritize transcription factors and intervention windows for refining SC-islet differentiation.

cell biology↗

bioRxiv2026

Proviral dynamics and HIV-1C viral diversity in the context of HIV-TB co-infection

BackgroundART effectively suppresses HIV replication and restores CD4+ T cells; however, long-lived HIV latent reservoirs enable viral persistence. Tuberculosis (TB) co-infection further impacts HIV latency and enhances viral replication. Given the high prevalence of latent TB infection (LTBI) in TB-endemic settings, understanding its impact on HIV biology is critical. Our study aims to investigate the influence of TB co-infection on HIV reservoir dynamics, viral diversity, and drug resistance mutations in ART-naive individuals. MethodologySamples from 90 ART-naive HIV-1C individuals, stratified based on IGRA and TB diagnosis, were used in this study. Plasma and PBMCs were isolated for viral RNA and DNA extraction respectively. Total proviral DNA was quantified using gag PCR. Full-length env and pol genes were amplified, purified and sequenced using ONT and Illumina platforms. Pol sequences were subjected to Drug Resistance Mutation (DRM) analysis via Stanford HIVdb with a minimum threshold mutation frequency of [≥]10%. Full length env sequences were used for phylogenetic analysis by aligning with Indian Subtype C reference sequence and phylogenetic tree was generated using ggplot2. ResultProviral load analysis showed no significant differences across HIV+LTBI-, HIV+LTBI+, and HIV+TB+ groups, although a trend toward higher levels was observed in HIV+TB+ individuals. Correlation analysis revealed distinct immune associations, with HIV+LTBI+ individuals showing positive correlations with activation and PD-1 expression. Longitudinal analysis of proviral loads demonstrated a modest decline in proviral load post-ART but remained persistent for up to 18-20 months following initiation of ART accompanied by low level ongoing viral replication. DRM analysis revealed a 33% prevalence in ART-naive individuals, with higher occurrence in HIV+LTBI+ group. Of the identified DRMs, 38% (5/13) and 71% (5/7) in sequences obtained from PBMC and plasma respectively were attributed to polymorphic mutations associated with Integrase strand transfer inhibitors (INSTIs). DRMs within plasma and PBMC derived viruses showed high concordance. Phylogenetic analysis of env sequences indicated overlapping viral populations between the 3 groups, with greater diversity in PBMCs compared to plasma. ConclusionThe study highlights that HIV reservoir dynamics, drug resistance, and viral diversity are significantly influenced by TB co-infection. While proviral loads were comparable, LTBI-associated immune activation and granuloma niches may have driven viral diversification and DRM emergence. High concordance between compartments and presence of transmitted resistance underscore the need for baseline screening, multi-compartment analysis, and sustained surveillance.

microbiology↗

bioRxiv2026

Genomic and Evolutionary Determinants of Two-hit Frequencies in Tumor Suppressor Genes

While biallelic or "two-hit" inactivation is a central organizing principle for tumor suppressor genes (TSGs), large-scale cancer genomic data reveal substantial heterogeneity in the frequency of such events across genes. This variability reflects diverse selective constraints on allelic disruption, whose biological determinants remain incompletely characterized. Here, we present a comprehensive, allele-specific analysis of TSG two-hit alterations across [~]9,000 tumors from The Cancer Genome Atlas, focusing on loss of heterozygosity (LOH) arising from the co-occurrence of point mutation and deletion. We show that two-hit frequencies vary widely across TSGs and scale with the functional impact and selection strength of point mutations. Integrating mutation position with zygosity reveals distinct patterns consistent with dominant versus recessive modes of action, enabling a zygosity-informed framework for variant interpretation. We further demonstrate that chromosomal context strongly shapes two-hit frequencies, reflecting aneuploidy biases across chromosome arms and selective trade-offs imposed by neighboring loci, including the co-deletion of synergistic TSGs. Extending the LOH analysis beyond diploid tumors, we find that equivalent "all-hit" frequencies are largely preserved in polyploid cancers following whole-genome doubling, consistent with early acquisition of LOH during clonal evolution. Collectively, our results uncover multiple determinants of adherence to the two-hit model, providing new insight into long-standing heterogeneity in TSG behavior and its potential clinical relevance.

genomics↗

bioRxiv2026

Quantitative Deciphering of Mammalian Histamine Receptors through Mathematical Genomics

Histamine receptors (HRH1-HRH4) are G-protein coupled receptors (GPCRs) that mediate essential physiological functions, including neurotransmission, gastric acid secretion, immune regulation, and presynaptic autoregulation. Despite their importance, systematic comparative analyses across mammalian histamine receptor sequences remain scarce. In this study, we performed a comprehensive evaluation of HRH1-HRH4 across multiple mammalian species, integrating sequence homology, invariant residue mapping, amino acid substitutions, compositional frequencies, Shannon entropy, polystring distributions, intrinsic disorder profiling, and phylogenetic clustering. HRH2 and HRH1 were highly conserved among primates, HRH3 showed strong cohesion within rodents, while HRH4 exhibited pronounced divergence consistent with immune-related specialization. Invariant residues localized to transmembrane helices and activation motifs (D107, W428/Y431, NPxxY), underscoring strict evolutionary constraints on ligand binding, receptor stability, and G-protein coupling. Substitutions were confined to non-essential lipid-facing and loop regions, predominantly conservative in nature, enabling diversification without disrupting the GPCR fold. Amino acid frequency and entropy analyses revealed hydrophobic dominance with subtype-specific enrichment of polar residues, while disorder profiling identified HRH1 as the most dynamic and HRH2 as the most structurally constrained. Polystring analysis highlighted conserved motifs (WWW, PP) alongside subtype- and species-specific repeats, reflecting evolutionary strategies balancing receptor stability with adaptive flexibility. Phylogenetic clustering confirmed subtype-specific cohesion, with HRH3 and HRH4 forming compact clades, HRH1 showing moderate dispersion, and HRH2 forming the most isolated cluster. Collectively, these findings demonstrate that mammalian histamine receptor evolution is governed by conserved biophysical cores and selective variability, offering insights into structural conservation, functional diversification, and translational relevance for drug design and model selection.

bioinformatics↗

bioRxiv2025

Protective IFIH1 variant reduces immune-mediated islet stress and dysfunction in a type 1 diabetes genetic background

Genome-wide association studies (GWAS) have linked dozens of genetic loci to type 1 diabetes (T1D). The IFIH1 gene, which encodes the double-stranded RNA sensor MDA5, is one such locus. The E627* single nucleotide polymorphism (SNP) in IFIH1 is associated with protection against T1D, while the A946T variant is linked to increased risk. While the E627* variant has been shown to result in a truncated protein and dampen type I interferon (IFN) signaling, its specific role in human pancreatic islet health and function remains unclear. We hypothesized that MDA5627* would protect islet cells from stress-induced dysfunction, identity loss, and cell death. Using CRISPR-Cas9 technology, we introduced the E627* and A946T variants into human pluripotent stem cells (hPSCs) derived from a T1D patient. We differentiated these hPSCs into stem cell-derived islets (SC-islets) and treated them with IFN, poly(I:C), and coxsackievirus B3, an enterovirus implicated in T1D pathogenesis. Using single-cell RNA sequencing and an array of functional assays, we investigated the variant impact on both whole SC-islets and their individual cell populations. Our analysis revealed that SC-islets, and their {beta}, , and {delta} cell subpopulations, harboring the MDA5627* variant exhibit an attenuated immune response to the various stressors compared to MDA5946T cells. We also report unique, cell-type-specific transcriptional responses that vary across variants. Notably, MDA5627* SC-islets showed reduced apoptosis rates and viral genome expression, as well as attenuated negative effects on mitochondrial function and insulin secretion in response to stress. Overall, our findings demonstrate that a clinically relevant MDA5 variant confers protection by dampening stress-mediated transcriptional responses, reducing cell dysfunction, and preventing apoptosis. These insights provide a mechanistic framework for understanding T1D pathogenesis and offer new avenues for developing preventative therapies.

cell biology↗

bioRxiv2025

The Ingestive Response Reflects Neural Dynamics in Gustatory Cortex

Upon delivery of a taste onto the tongue, gustatory neural activity determines whether the stimulus is ingested or rejected. While some work in rodents has been devoted to investigating the neural activity leading to the rejection decision and its associated orofacial movements, little is known about what behaviors lead to ingestion of palatable tastes (and what neural activity is associated with that decision), largely because identifying ingestion-related behaviors is a difficult challenge--and probably undoable with video analysis given that the behaviors are largely intraoral. To address this gap in our understanding, we analyzed simultaneously-collected electromyographic (EMG) activity of the jaw opener muscle and the firing of gustatory cortical (GC) ensembles. We developed a machine-learning classifier to identify individual orofacial movements from EMG signals, demonstrating that it outperforms previously developed methods and using the technique to reveal three novel subtypes of ingestion-related tongue/mouth movements. Investigating the dynamics of these behaviors, we found that the frequency of occurrence of each type subtype shifts significantly at the time of the consumption decision, and is both tightly coupled with and reliably follows the transition in GC population activity into the state reflecting the tastants emotional/hedonic value. However, rather than the onset of single "ingestion" movement (as occurs for rejection decisions in the form of gapes), we show that the transition to ingestion is instead characterized by a collective change in the frequencies all ingestion-related behaviors. These findings demonstrate a direct link between neural dynamics in GC and the orchestration of the physical movements that define ingestive behavior, highlighting GCs general role in taste perception, decision making, and the control of motor actions.

neuroscience↗

bioRxiv2025

RIPK1 regulates beta-cell fate via actions on gene expression and kinase signaling in a mouse model of beta-cell self-reactivity

Type 1 diabetes (T1D) is characterized by autoimmune destruction of pancreatic {beta}-cells, insulin insufficiency, and hyperglycemia. Receptor interacting protein kinase 1 (RIPK1) is a multifunctional regulator of cell fate with kinase and scaffolding functions, and we previously identified RIPKs as regulators of {beta}-cell cytotoxicity in vitro. Here we report that Ripk1 expression is increased in islets from aged non-obese diabetic (NOD) mice and {beta}-cells from T1D donors, suggesting that RIPK1 may drive cytokine- and autoimmune-mediated {beta}-cell demise in T1D. Using NIT-1 {beta}-cells derived from NOD mice, we observed that TNF+IFN{gamma} increase RIPK1 phosphorylation, caspase 3/7 activity, and cell death. In contrast, this cytotoxicity was blocked with small molecule RIPK1 inhibition or in Ripk1 gene-edited (Ripk1{Delta}) {beta}-cells. Co-labeling of caspase 3/7 activation and cell death in single cells revealed protection from caspase-dependent and -independent forms of death in Ripk1{Delta} cells. RNAseq uncovered differential cell death-, immune-, and identity-related gene expression, and kinome profiling identified changes in MAPK, Eph, JAK, and other kinase activity associated with protection from cell death in RIPK1 deficient {beta}-cells. Furthermore, in vitro co-culture assays and in vivo adoptive transfer experiments revealed that NIT-1 Ripk1{Delta} cells were protected from autoimmune destruction by splenocytes isolated from diabetic NOD mice. Collectively, our findings indicate that RIPK1 promotes {beta}-cell demise in response to cytokine and autoimmune stress via actions on gene expression and kinase signaling. Therapeutics targeting RIPK1 may provide novel opportunities for prevention or treatment of autoimmune diabetes.

cell biology↗

bioRxiv2025

A Mathematical Genomics Perspective on the Moonlighting Role of Glyceraldehyde-3-Phosphate Dehydrogenase (GAPDH)

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a well-conserved enzyme across Archaea, Bacteria, and Eukarya, known not only for its canonical role in glycolysis, but also for diverse moonlighting functions including transcription regulation, host-pathogen interactions, and immune modulation. Studying GAPDH quantitatively is crucial for understanding how subtle variations at the sequence and structural levels drive such functional diversity across evolutionary lineages. In this study, 165 GAPDH protein sequences from 158 organisms were analyzed to uncover conserved and divergent features underlying multifunctionality. While core catalytic residues were strongly preserved, selective enrichment of small non-polar residues such as valine and alanine suggested a structural basis for flexibility and adaptive potential. The balanced distribution of order- and disorder-promoting residues and the avoidance of long homopolymeric stretches indicated evolutionary selection for both structural coherence and local flexibility. Spatial distribution of amino acids in GAPDH sequences revealed low fractal variance across sequences, with moderate differences in residue clustering patterns pointing to localized adaptations without compromising overall organization. These findings demonstrate that GAPDH multifunctionality is encoded through compositional signatures and conserved spatial architecture, allowing the coexistence of metabolic stability and regulatory plasticity. The results have broad implications for understanding protein evolution, structural adaptability in extreme environments, and functional versatility in pathogenic contexts. This study establishes GAPDH as a model for exploring principles of protein moonlighting and highlights the potential of quantitative compositional analysis in uncovering hidden functional layers.

genomics↗

bioRxiv2025

eIF3d and eIF3e mediate selective translational control of hypoxia that can be inhibited by novel small molecules

Exposure to hypoxia is linked to increased cellular plasticity and enhanced metastasis; effects which are primarily attributed to the transcriptional activation of large gene programs downstream of hypoxia inducible factors (HIFs). However, translational effects in hypoxia, that likely precede transcriptional effects, have remained largely unexplored. Using ribosome-profiling, we uncovered a selective translational response in acute hypoxia that is eIF3d/eIF3e-dependent and controls downstream hypoxic responses including HIF1a accumulation and cellular invasion. We further demonstrated that eIF3e copy number and an eIF3e-expression signature are associated with worsened outcomes for breast cancer patients. Finally, we identified a class of novel small molecules that target eIF3e specifically, reducing the translational response to hypoxia and to ER stress, another stressor that is dependent on eIF3d/eIF3e-mediated translation. Our data uncover critical functions for eIF3d/eIF3e in the hypoxic response and identify a potential means to inhibit stress-induced translation, and potentially plasticity and metastasis, mediated by eIF3e.

cancer biology↗

bioRxiv2024

Target deconvolution of an insulin hypersecretion-inducer acting through VDAC1 with a distinct transcriptomic signature in beta-cells

Obesity, insulin resistance, and a host of environmental and genetic factors can drive hyperglycemia, causing {beta}-cells to compensate by increasing insulin production and secretion. In type 2 diabetes (T2D), {beta}-cells under these conditions eventually fail. Rare {beta}-cell diseases like congenital hyperinsulinism (HI) also cause inappropriate insulin secretion, and some HI patients develop diabetes. However, the mechanisms of insulin hypersecretion and how it causes {beta}-cell dysfunction are not fully understood. We previously discovered small molecules (e.g. SW016789) that cause insulin hypersecretion and lead to a loss in {beta}-cell function without cell death. Here, we uncover the protein target of SW016789 and provide the first time-course transcriptomic analysis of hypersecretory responses versus thapsigargin-mediated ER stress in {beta}-cells. In mouse MIN6 and human EndoC-{beta}H1 {beta}-cells, we identified and validated VDAC1 as a SW016789 target using photoaffinity proteomics, cellular thermal shift assays, siRNA, and small molecule inhibitors. SW016789 raises membrane potential to enhance Ca2+ influx, potentially through VDAC1. Chronically elevated intracellular Ca2+ appears to underpin the negative impacts of hypersecretion, as nifedipine protected against each small molecule hypersecretion inducer we tested. Using time- course RNAseq, we discovered that hypersecretion induced a distinct transcriptional pattern compared to ER stress. Clustering analyses led us to focus on ER-associated degradation (ERAD) as a potential mediator of the adaptive response. SW016789 reduced the abundance of ERAD substrate OS-9 and pharmacological inhibition of ERAD worsened {beta}-cell survival in response to hypersecretory stress. Changes in other ERAD components in MIN6 and EndoC-{beta}H1 at the protein level were minor with either SW016789 or thapsigargin. However, immunostaining for core ERAD components SEL1L, HRD1, and DERL3 in non-diabetic and T2D human pancreas revealed altered distributions of SEL1L/HRD1 and SEL1L/DERL3 rations in {beta}-cells of T2D islets, in alignment with altered ERAD in stressed {beta}-cells. We conclude that hypersecretory stimuli, including SW016789- mediated VDAC1 activation, cause enhanced Ca2+ influx and insulin release. Subsequent differential gene expression represents a {beta}-cell hypersecretory response signature that is reflected at the protein level for some, but not all genes. A better understanding of how {beta}-cells induce hypersecretion and the mechanisms of negative feedback on secretory rate may lead to the discovery of novel therapeutic targets for T2D and HI.

cell biology↗

bioRxiv2024

Novel nanopore sequencing method for determining Human Papillomavirus integrations in tumors without the need for whole genome sequencing

Human papillomaviral (HPV) integrations into host human genome, a key event in cervical carcinogenesis, are currently mapped through laborious and expensive sequencing methodologies. We developed and validated a novel library preparation strategy for nanopore sequencing to generate long targeted reads with HPV and human chimeric sequences. Using this strategy, we validated known HPV integrations in HeLa (HPV18) and SiHa (HPV16) cell lines. We also mapped integration sites in five HPV+ cervical cancer patients, which were confirmed by whole genome and Sanger sequencing. Our nanopore-based method provides a precise and efficient strategy to capture HPV integrations crucial for understanding tumorigenesis.

genomics↗

bioRxiv2024

The RNA binding protein HNRNPA2B1 regulates RNA abundance and motor protein activity in neurites

RNA molecules are localized to subcellular regions through interactions between localization-regulatory cis-elements and trans-acting RNA binding proteins (RBPs). However, the identities of RNAs whose localization is regulated by a specific RBP as well as the impacts of that RNA localization on cell function have generally remained unknown. Here, we demonstrate that the RBP HNRNPA2B1 acts to keep specific RNAs out of neuronal projections. Using subcellular fractionation, high-throughput sequencing, and single molecule RNA FISH, we find that hundreds of RNAs demonstrate markedly increased abundance in neurites in HNRNPA2B1 knockout cells. These RNAs often encode motor proteins and are enriched for known HNRNPA2B1 binding sites and motifs in their 3' UTRs. The speed and processivity of microtubule-based transport is impaired in these cells, specifically in their neurites. HNRNPA2B1 point mutations that increase its cytoplasmic abundance relative to wildtype lead to stronger suppression of RNA mislocalization defects than seen with wildtype HNRNPA2B1. We further find that the subcellular localizations of HNRNPA2B1 target RNAs are sensitive to perturbations of RNA decay machinery, suggesting that it is HNRNPA2B1s known role in regulating RNA stability that may explain these observations. These findings establish HNRNPA2B1 as a negative regulator of neurite RNA abundance and link the subcellular activities of motor proteins with the subcellular abundance of the RNAs that encode them.

molecular biology↗

bioRxiv2024

Comparative analysis of 43 distinct RNA modifications by nanopore tRNA sequencing

Transfer RNAs are the fundamental adapter molecules of protein synthesis and the most abundant and heterogeneous class of noncoding RNA molecules in cells. The study of tRNA repertoires remains challenging, complicated by the presence of dozens of post transcriptional modifications. Nanopore sequencing is an emerging technology with promise for both tRNA sequencing and the detection of RNA modifications; however, such studies have been limited by the throughput and accuracy of direct RNA sequencing methods. Moreover, detection of the complete set of tRNA modifications by nanopore sequencing remains challenging. Here we show that recent updates to nanopore direct RNA sequencing chemistry (RNA004) combined with our own optimizations to tRNA sequencing protocols and analysis workflows enable high throughput coverage of tRNA molecules and characterization of nanopore signals produced by 43 distinct RNA modifications. We share best practices and protocols for nanopore sequencing of tRNA and further report successful detection of low abundance mitochondrial and viral tRNAs, providing proof of concept for use of nanopore sequencing to study tRNA populations in the context of infection and organelle biology. This work provides a roadmap to guide future efforts towards de novo detection of RNA modifications across multiple organisms using nanopore sequencing.

molecular biology↗

bioRxiv2024

The global fish and invertebrate abundance value of mangroves

Mangroves are a critical coastal habitat that provides a suite of ecosystem services and supports livelihoods. We undertake the first global analysis to estimate density and abundance of 37 commercially important fish and invertebrates that are known to extensively use mangroves. Geomorphic mangrove type, sea surface salinity and temperature, and length of mangrove forest edge were important in predicting the density of commercial fish and invertebrates, with deltaic systems supporting the highest densities. The model predicted high densities throughout parts of southeast Asia, the northern coast of South America, the Red Sea, and the Caribbean and Central America. Application of our model onto the global mangrove extent, estimates that mangroves support the annual abundance of nearly 800 billion young-of-year fish and invertebrates contained in our model. Our results confirm the critical role of mangroves globally in supporting fish and fisheries, and further builds the case for their conservation and restoration.

ecology↗

bioRxiv2024

A reaction-diffusion model captures the essence of liquid-liquid phase separation

In this work we propose the formulation of a continuum model for liquid-liquid phase separation (LLPS) using reaction diffusion framework. We consider a well mixed liquid consisting of three phases, the dense droplet phase, the dilute phase and the remaining part to be solvent phase. As a key feature, the model includes both the spatial and temporal aspects and a free energy functional between dense and dilute phase that is physically motivated by reference molecular simulation. The exhaustive numerical simulations of model captures the dynamical formation of droplets and existence of LLPS. As the time progresses, simulation reveal that smaller droplets gradually vanish, and a single droplet undergoes continuous growth until it reaches a stable size. The model predicts that that extent of diffusivity of dense and dilute phase as well as their mutual interaction would modulate the kinetics of droplet formation. Finally we show that introduction of fluctuation in the model accelerate the phase separation process.

biophysics↗