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mhryu@live.com
Today, 1:30 AM
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Extracellular vesicles (EVs) are membranous nanoparticles released by cells that help shape the extracellular environment, remove cellular waste, and mediate cell-to-cell communication. Their release is ubiquitous across kingdoms, species, and cell types, highlighting their functional importance. Nearly as evolutionarily widespread and heterogeneous is the release of viruses, which have evolved to co-opt the host’s cellular machinery to facilitate their replication and spread within all branches of life. Nearly all viruses, enveloped or not, repurpose EVs to modulate infection dynamics, while EVs also play a crucial role in the host’s response to infection. This review explores the interplay between EVs and viruses across the phylogenetic diversity of virus species. We urge virologists and EV biologists to look beyond a single infection model and learn from the unique concepts and shared commonalities observed between close, as well as distantly related viruses, whether they infect mammals, vertebrates, insects, plants, bacteria, or more. To facilitate these efforts, we provide a comprehensive, taxonomical overview of the current knowledge regarding DNA and RNA virus families, and discuss recurring motifs in EV release and function during infection.
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mhryu@live.com
Today, 1:17 AM
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Thanks to the standard microbiology protocols of isolation and culturing, hundreds of strains have been isolated from fermented foods throughout the last decades, and phenotypic traits linked with pro-technological properties and health claims have been investigated. However, culture-independent metagenomic analyses have revealed an unexpected microbial diversity in foods fermented spontaneously or by undefined starter cultures. Here, we report the most groundbreaking advancements in the understanding of fermented foods ecology by presenting case studies where metagenomics has been applied, contributing to identifying novel species in silico or to deciphering the microbiome structure associated with spontaneous fermentations. We also highlight the potential of metagenomics in supporting the identification of potential probiotics and discuss the future ahead, particularly focusing on the integration of multi-omics approaches.
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mhryu@live.com
Today, 12:25 AM
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Programmable composition of complex systems is a longstanding goal of biological research. Generative modeling has improved the reliability of computational design, but existing methods are highly specialized and are difficult to extend or compose. Here, we introduce Proto, a high-level programming language for generative biology. By composing a small set of abstract primitives into structured programs, Proto encodes generative design campaigns across diverse modalities and scales, spanning DNA, RNA, proteins, ligands, and their interactions. Proto readily incorporates predictive models into generative workflows, which we leveraged to design alternatively spliced introns with experimental validation in human cell lines. Proto is natively multi-objective, enabling the design of promoter-repressor pairs with leading experimental success rates for synthetic protein-DNA design. Alongside AI agents, Proto enables the specification of complex pathways and regulatory logic through natural language instructions. We openly release Proto, including software infrastructure and user interfaces, to enable widespread access to generative biological programming.
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mhryu@live.com
June 23, 11:51 PM
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Cobamides, including vitamin B12, are essential cofactors exchanged between organisms across diverse ecosystems including oceans, soils, and the mammalian gut. Although most organisms depend on cobamides only a minority of prokaryotes perform their metabolically costly biosynthesis. This has led to vitamin B12 uptake from the environment as a common acquisition strategy, but does not explain why B12 producers would allow B12 to become extracellularly available. Our work reconciles this inconsistency, showing that bacteriophages can facilitate the release of intracellular B12 at physiologically relevant concentrations. Phages are viruses that infect and often lyse their targeted bacteria, which may externalizes intracellular material along with progeny phages. In this work, we aimed to determine whether phage-mediated lysis promotes the externalization of vitamin B12, thereby supporting the growth of B12 dependent bacteria. To test this, we first used genetically well-defined B12-Producer and B12-User bacteria, and found that phage-mediated lysis of the producers releases sufficient B12 to support the growth of the users in co-culture. Next, we show that phage-mediated lysis of the B12-producer can similarly support the growth of various commensal gut bacteria that are also B12-dependent, in co-culture. B12 released by phage-mediated cell lysis induced significant compositional changes among the non-targeted bacteria including an increased diversity that was muted by supplementing B12 in the medium. Collectively, these findings suggest that phage-mediated bacterial lysis is a significant contributor to nutrient externalization in microbial communities, leading to broad compositional changes beyond their host range.
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mhryu@live.com
June 23, 11:22 PM
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Transfer RNA (tRNA) molecules serve as essential adapters during protein translation. While direct RNA sequencing (DRS) via Oxford Nanopore Technologies has emerged as a powerful platform for systematic tRNAome profiling, we currently lack a simple and robust statistical framework for nanopore tRNA data analyses. Here, we address this gap by developing AMaNITA (Abundance, Modifications, and Nanopore Intensity Toolbox Application), an end-to-end bioinformatic workflow that enables simplified, robust, and scalable analyses of nanopore native tRNA sequencing datasets. AMaNITA streamlines the entire analytical trajectory: from upstream processing (basecalling, mapping, filtering, batch effect correction) to downstream assessment of differential tRNA abundance and modification stoichiometry. The workflow generates an interactive HTML report for data exploration and analysis, allowing the user to download the source data files and resulting plots. AMaNITA can be executed using Singularity from the command line, without requiring installation of dependencies.
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mhryu@live.com
June 23, 5:01 PM
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Neisseria gonorrhoeae and Mycoplasma genitalium infect more than 150 million people each year and are rapidly acquiring antimicrobial resistance (AMR), to all available treatments. PCR tools used for diagnosis and test-of-cure, amplify nucleic acids regardless of microbial viability, leading to false positives and subsequent overuse of antibiotics. Assays that accurately assess microbial viability and replication after exposure to antibiotics and other stimuli are needed to improve diagnostics. In this study, we present a flow cytometric method to quantitatively assess N. gonorrhoeae and M. genitalium viability and replication. We utilised a membrane exclusion dye (Fixable Viability Stain 700) to differentiate live and dead cells and a cell trace dye (CellTrace Violet) to track cell replication. The flow cytometry assay was assessed with and without nutrient starvation and inactivation (permeabilisation or UV exposure) to validate the assays' ability to resolve replicating, non-replicating, and non-viable bacterial populations. The outcomes of flow cytometry were compared to qPCR assays and culture-based approaches. Whereas qPCR overestimated viable cell counts (two-to-four-fold overestimation) and could not distinguish between viable and non-viable cells (p > 0.05), flow cytometry could reliably distinguish these populations, as well as replicating and non-replicating subpopulations. This novel flow cytometry method can be used to improve upon existing techniques for in vitro experimentation such as antimicrobial sensitivity testing and could be further utilised for cell sorting, enabling downstream analyses at the single-cell and population level, providing a basis for the discovery of viability targets for diagnostic tools.
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mhryu@live.com
June 23, 4:28 PM
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Nanobody–antigen molecular recognition underpins nanobody discovery and development, necessitating accurate determination of binding occurrence, interface residues, and affinity. Current predictors are architecturally designed for the massive, heterogeneous spectrum of general protein–protein interactions, diluting the limited, complementarity-determining region (CDR)-dominated nanobody–antigen interaction (NAI) data and masking the decisive CDR signal. The scarcity of experimental affinity data precludes direct regression-based estimation of binding affinity. Here, we present NanoBind, a mechanism-driven deep learning framework that embeds the CDR-dominated binding pattern within its encoder, enabling robust prediction of binding occurrence and interface residues from limited NAI data. Constrained by scarce affinity data, NanoBind generates quantitative affinity ranges for nanobody–antigen pairs without extra experiments. Systematic benchmarking demonstrates that NanoBind surpasses state-of-the-art methods in accuracy and robustness, and interpretability analyses confirm that the model’s decisions align with the CDR-dominated binding mechanism. When million-sequence immune repertoires are screened against 4 antigens, NanoBind reduces candidate nanobodies to fewer than 100 per target. For the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike receptor-binding domain (RBD)–nanobody F2 complex, NanoBind correctly predicts binding occurrence, matches experimentally validated interface residues, and generates an affinity range quantitatively supported by molecular dynamics simulations. A server is available at http://liulab.top/NanoBind/server.
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mhryu@live.com
June 23, 4:15 PM
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Machine learning (ML) has the potential to revolutionize antibody design and selection, but its success depends on access to well-curated datasets of antibody-antigen interactions. We developed a synthetic Fab yeast display library optimized for seamless integration with ML processes, focusing on sequence diversity within the complementary determining region heavy chain CDRH3 loop. The library incorporates key sequence features derived from human B cell repertoires captured in a compact antigen recognition module (ARM) format. Built with the VH1-69 heavy chain and four light chains, the library was evaluated against ten human and murine cell surface antigens, including programmed cell death ligand 1 (PD-L1), T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT), and roundabout guidance receptor 1 (ROBO1). This approach yielded hundreds of antibodies with robust biophysical properties, some of which were validated by flow cytometry and immunohistochemistry. Furthermore, ML analysis identified additional antibodies for ROBO2 and PD-L2 from the aggregate sequencing data. The publicly available dataset establishes an ML-compatible framework designed to accelerate and streamline antibody discovery and development.
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mhryu@live.com
June 23, 3:58 PM
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The fermented food microbiome comprises live microorganisms, their genetic elements and their metabolites, and represents an established dietary approach for modulating host–microbiome interactions through the consumption of fermented foods. Fermentation enhances food preservation and nutrient bioavailability, and supplies the host with probiotics, prebiotic substrates and postbiotic metabolites. These bioactive compounds can influence the oral and gut microbiota, modulate immune function and support metabolic resilience. Fibre-rich, plant-based fermented foods retain such components within structured matrices that enhance microbial viability and mucosal interactions more consistently than do fermented dairy foods. This Review explores how the fermented food microbiome affects the oral–gut axis via both transient microbial exposure and metabolite-mediated signalling. Drawing on clinical and preclinical evidence, we examine how fermented food intake alters resident microbiota and host physiology throughout the digestive tract. Despite growing evidence, the mechanisms through which fermented food might promote health remain insufficiently defined in humans owing to strain variability, inconsistency in microbial composition across fermented foods, heterogeneous clinical outcomes and regulatory ambiguity. Taking into account these limitations, we propose a roadmap to integrate the fermented food microbiome into precision nutrition as a feasible, personalized, diet-based strategy to promote health and prevent disease. The bioactive compounds and microbial consortia contained in plant-based fermented foods support oral and gut microbiota, host immune function and metabolic resilience. This Review describes the impact of the fermented food microbiome on the oral–gut axis and identifies a strategic roadmap to integrate this edible microbiome into precision nutrition practices to promote health.
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mhryu@live.com
June 23, 3:33 PM
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Precise, reversible control of gene expression from self‑amplifying RNA (saRNA) remains difficult, limiting the therapeutic flexibility of this otherwise potent platform. Although alphavirus‑derived saRNAs encode non‑structural proteins that drive RNA replication and offer an intrinsic regulatory point, no existing approach has enabled direct, drug‑dependent control of this machinery for high‑fidelity modulation of expression. Here we engineer saRNA constructs whose replication is activated by the approved small‑molecule drug trimethoprim, using drug‑responsive degradation domains fused to individual non‑structural proteins to regulate self‑amplification. As each replication protein contributes differently to RNA copying, we systematically screened fusion configurations and identified an optimal design combining modified replication proteins with a regulated payload. This construct achieved more than a 104‑fold difference between on and off states with negligible background expression. In mice, oral trimethoprim enabled tunable, reversible and temporally programmed expression patterns. When encoding a human immunodeficiency virus antigen, an escalating trimethoprim regimen enhanced germinal centre responses, a key determinant of antibody affinity maturation. This drug‑regulated saRNA platform provides a controllable and clinically compatible strategy for vaccines, immunotherapies and gene therapies. A self-amplifying RNA circuit whose replication is activated by an FDA-approved small molecule enables precise, reversible and programmable control of RNA amplification and antigen expression for improved therapeutic and vaccine design.
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mhryu@live.com
June 23, 12:52 AM
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The engineered Photorhabdus virulence cassette (PVC) enables precise protein delivery but has not yet achieved RNA packaging and injection delivery. In this study, we achieved intraluminal RNA loading via the U1A RNA-binding domain, anchoring it to the PVC inner tube and establishing DART (PVC Docker-based All-purpose RNA Injection Delivery Tool). This enabled the protective loading of diverse RNAs, including Pepper RNA, guide RNA, siRNA, miRNA, and mRNA. Through the co-delivery of Cas9 in vitro, DART also drove effective knockouts of enhanced green fluorescent protein gene (EGFP), Kirsten rat sarcoma viral oncogene homolog (KRAS), and programmed death-ligand 1 (PD-L1), representing reporter, oncogenic, and immune-related targets for evaluating DART-mediated gene editing. Notably, DART-mediated KRAS knockout produced a significant antitumor effect in a subcutaneous mouse tumor model. Complementary to the external spike-surface fusion strategy of SPEAR (a PVC system termed spike engineering and retargeting), as an intraluminal nanosyringe platform, DART employs internal engineering to expand PVC from protein to RNA delivery.
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mhryu@live.com
June 23, 12:38 AM
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The microbiome actively influences antimicrobial resistance (AMR) dynamics by shaping both ecological and evolutionary processes. However, the extent of its role in resistance emergence, transmission and persistence remains unclear. Traditional AMR research has mainly focused on genetic mechanisms and pathogen-level dynamics. In contrast, the intersection of AMR and the microbiome, including resistance-gene reservoirs, microbial competition and community-mediated selection, remains poorly represented, especially in a modelling context. Here we present a structured framework for incorporating microbiome–AMR interactions into predictive models. We identify key microbiome-mediated processes shaping AMR across different levels of complexity, describe how these can be quantitatively integrated into models, and identify critical data gaps that limit current approaches. By bridging microbiome ecology, AMR biology and mathematical modelling, we set out research priorities and strategies to improve resistance prediction and guide microbiome-targeted interventions. The microbiome plays a significant yet underexplored role in antimicrobial resistance by influencing ecological and evolutionary processes. This Perspective proposes a framework to integrate microbiome–AMR interactions into predictive models while highlighting key mechanisms and data gaps to improve resistance understanding and interventions.
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mhryu@live.com
June 22, 11:37 PM
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Microbial inoculants are increasingly promoted as sustainable alternatives or complements to conventional agricultural inputs, yet their field performance remains highly variable. This review examines how ecological processes governing root microbiome assembly constrain inoculant establishment, persistence, and function across agricultural systems. We synthesize current evidence on the roles of environmental filtering, host-mediated selection, microbial interactions, and context dependency in shaping inoculant outcomes. We further evaluate the promise and limitations of core-microbiome concepts and synthetic communities as emerging strategies for microbiome-informed inoculant design, emphasizing that their practical translation remains challenged by methodological variability, ecological complexity, formulation constraints, and regulatory barriers. By integrating ecological theory with applied microbiology, this review highlights why many inoculants fail to deliver consistent agronomic benefits and outlines a more potential framework for developing context-aware, field-relevant microbiome-based solutions for sustainable agroecosystem management.
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mhryu@live.com
Today, 1:24 AM
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The realization of long-term manned space exploration and extraterrestrial habitation hinges on microbial-based extraterrestrial domestic wastewater (EDW) treatment technology to achieve sustainedly closed-loop water recycling. This perspective recaps the challenges and potential of integrating microbial technology as a sustainable and low-energy alternative for treating EDW compared to physicochemical water recovery systems. Of note, traditional microbial technologies are not directly transferable due to EDW’s unique constraints, including high ammonium, low C/N ratio, and multiple stresses. We proposed how synthetic microbiology integrated with single-cell Raman spectroscopy (SCRS) offers a promising approach to engineer stable, efficient microbiomes tailored for EDW treatment. SCRS coupled with stable isotope probing can enable precise identification and isolation of stress-tolerant functional microorganisms at the single-cell level, bypassing lengthy enrichment methods. SCRS can also serve as a real-time monitoring tool for system optimization and early warning, enabling resilient, intelligently monitored biological systems for extraterrestrial water recycling.
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mhryu@live.com
Today, 1:03 AM
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Lactate's role in biochemistry and physiology has attracted considerable biochemical interest for over a century. Beyond its classical description as a glycolytic byproduct, lactate is now recognized as a central energy metabolite, a redox shuttle, and a signaling molecule. Modern advances in mass spectrometry have uncovered yet another dimension of lactate biology: lactate as a chemical modification on proteins and metabolites. Covalent conjugation of lactate to the ε-amine of a protein lysine side chain generates a posttranslational modification (lysine lactylation); in a related reaction on metabolites, conjugation of lactate to the α-amine of free amino acids produces a class of bioactive lactate-modified amino acids (the N-lactoyl amino acids). These lactate modifications represent a fundamental mechanism by which transient increases in glycolytic flux are translated into durable downstream effectors. Here, we review the detection, regulation, and function of these lactate-derived modifications in cellular and organismal homeostasis.
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Scooped by
mhryu@live.com
Today, 12:22 AM
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Cellular metabolism is widely understood as an integrated network of redox reactions, energy conservation, and biosynthetic pathways. Here we show that across diverse prokaryotic lineages, loss of redox-associated functions is coupled with loss of nucleotide biosynthesis, raising a fundamental question of how such metabolically reduced organisms sustain cell growth. One of the most widespread and diverse lineages of prokaryotes, Minisyncoccota or Patescibacteriota, constitutes the majority of lineages exhibiting this pattern. To investigate how such organisms persist, we cultivated and characterized a representative of this lineage from a deep aquifer. The organism attaches to and penetrates growing bacterial host cells, and directly uptakes host RNA, concomitant with its depletion in the host. The metabolically reduced parasite cleaves host-derived RNA to directly supply cellular energy currencies and precursors for RNA/DNA synthesis, NTPs, without invoking canonical metabolic pathways. Codon usage in the parasite is complementary to that of its host, potentially minimizing translation of host-derived mRNA. Comparative genomics and phylogenetics indicate that these features are widespread and likely ancestral across the lineage. Exploitation of host RNA as a metabolic resource reveals a previously unrecognized metabolic strategy that demonstrates cellular metabolism can be sustained through direct utilization of informational macromolecules and thereby taps into an omnipresent energy reservoir, potentially supporting the environmental ubiquity of the metabolically reduced lineage.
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mhryu@live.com
June 23, 11:48 PM
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Bacterial chitin degradation contributes to global carbon cycling, particularly in marine environments where it is a highly abundant polysaccharide. Despite the taxonomic diversity of co-occurring chitin-degrading bacteria, the influence of individual traits on interactions between them remains poorly understood. Here, we measured key physiological traits of seven chitin degraders and investigated how these traits shape interaction outcomes and chitin degradation in pairwise cocultures. We found mainly negative and neutral interactions among degraders, contrasting with the synergistic dynamics observed with other complex polysaccharides. However, chitin degradation was not consistently diminished. These interaction types could be attributed to the limited partitioning of degradation products, alongside variations in enzyme repertoires and attachment behaviors that help some degraders to prevail over others. Further, we showed that one degrader can strongly inhibit the growth of others, even those possessing favorable physiological traits, likely due to the secretion of inhibitory compounds. These findings extend our understanding of the breadth of interactions among primary polysaccharide degraders and their implications for the degradation process.
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mhryu@live.com
June 23, 5:04 PM
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The scaffold protein NifU plays a central role in assembling the precursor [Fe4S4] clusters required for nitrogenase to function. The synthesis of these precursors depends on a catalytic [Fe2S2] group within NifU core ferredoxin domain. Here, we show that the monothiol glutaredoxin GrxD is one of the proteins delivering this cluster to the NifU scaffold protein. Consistently, grxD mutants have reduced nitrogenase activity, the result of altered iron allocation to this enzyme due to a suboptimal [Fe2S2] cluster occupancy of the core NifU domain in the cell. These results also indicate the existence of additional pathways to provide NifU with its core [Fe2S2] group. Biochemical assays show that GrxD unidirectionally transfers [Fe2S2] to NifU through protein-protein interaction. This allows GrxD to restore apo-NifU functionality, enabling proper [Fe4S4] synthesis, and NifH activation. These findings are crucial to understand how iron is allocated to nitrogenase for biological nitrogen fixation.
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mhryu@live.com
June 23, 4:38 PM
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The Type VI CRISPR-Cas13 system, evolved from prokaryotic immunity, has become a versatile, programmable RNA-targeting platform with broad biotechnological potential. Guided by CRISPR RNA (crRNA), Cas13 cleaves single-stranded RNA via higher eukaryotic and prokaryotic nucleotide-binding domains, exerting specific (cis) and nonspecific (trans) collateral cleavage, which enables ultrasensitive nucleic acid detection while introducing cytotoxicity risks in eukaryotic cells. Diversification of Cas13 subtypes, including compact variants, enhances targetability and delivery compatibility, and inhibitory strategies (anti-CRISPR proteins, crRNA mimicry/degradation) enable activity modulation for improved safety. Building on mechanistic foundations, Cas13 is repurposed for targeted RNA knockdown, nucleic acid diagnostics, live-cell RNA imaging with catalytically inactive variants, programmable RNA base editing through deaminase fusions, splicing regulation, epitranscriptomic editing of multiple RNA chemical marks, interaction mapping of RNA–protein and RNA–RNA networks, and translational control, with preliminary clinical translation in antiviral therapies, pathogenic transcript correction, and cancer therapy. Furthermore, Cas13-integrated diagnostics and functional genomics are accelerating biomarker discovery and personalized treatment. Nevertheless, successful clinical translation hinges on overcoming critical bottlenecks, including tissue-specific delivery, mitigation of collateral cytotoxicity, and management of host immunogenicity. This review synthesizes Cas13 classification, structure–function principles, regulatory inhibitors, application modalities, and translational challenges to inform next-generation engineering and responsible deployment of RNA-targeted technologies.
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mhryu@live.com
June 23, 4:22 PM
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Natural biological CO2 fixation converts atmospheric CO2 to energy-dense carbohydrates, thereby providing an alternative to fossil fuels and contributing to the restoration of carbon balance. Recent advancements in the mechanisms of biological CO2 fixation have led to innovative architectures of CO2 fixation pathways and energy systems that exceed the efficiency of natural carbon assimilation. Synthetic CO2 bioconversion systems (SCBS) have been designed and reprogrammed for the carbon-neutral or carbon-negative biomanufacturing of chemicals from CO2 by integrating multi-carbon biosynthesis with various energy conversion methods, including light, electrical, and chemical processes. In this review, we systematically analyze how to achieve efficient matching of CO2 fixation modules with energy supply modules, aiming to establish scalable SCBS for addressing the pressing issue of atmospheric CO2 overload. Then, we propose a systematic framework for designing next-generation biomanufacturing with enzymatic or microbial CO2 bioconversion systems, facilitating the construction and optimization of SCBS towards carbon-neutral or carbon-negative bioproduction. Furthermore, we emphasize transformative SCBS technologies, such as photo-biohybrid systems for converting light into chemical energy, electro-biohybrid systems for transducing electrical energy into chemical forms, and enzyme cascade systems for repurposing chemical energy, all of which aim to achieve unprecedented efficiency in powering biosynthesis from CO2. Finally, we propose a strategic roadmap for carbon-negative biomanufacturing ecosystems, wherein bioinspired CO2 fixation platforms can synergistically integrate with the principles of a circular economy to facilitate the industrial transition to net-zero emissions.
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mhryu@live.com
June 23, 4:06 PM
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Traditional proximity biotinylation approaches require extensive genetic engineering or intricate purification steps. Here, we introduce FISH+, a ready-to-use RNA proximity labeling method that relies on the recruitment of peroxidase to RNA targets, and facilitates in situ proximity biotinylation in fixed cells. This method permits concurrent visualization of RNA molecules and identification of RNA-interacting proteins. Using this method, we visualized 45S and NEAT1 RNA, and captured their proximal proteins, demonstrating the capability to concurrently visualize RNA and identify proximal proteins. By targeting PNCTR (~36 copies per cell), we observed distinctly bright RNA dots, representing the combined biotinylation signals from both RNA and proximal proteins in situ. This indicates the potential of the FISH+ method for enhanced RNA visualization. We further generalized the FISH+ method to explore XIST-interacting proteins, a number of reported interactors were significantly enriched, such as SPEN, CIZ1 and RBM15. Using quantitative mass spectrometry, we show that FISH+ correctly identifies known RNA-protein interactions in the nucleus of human cells. Overall, we established a watch-and-catch punctate RNA method through the integration of RNA fluorescence in situ hybridization (FISH) with proximity biotinylation. This method provides additional spatial information for the characterization of RNA-centric interactions in fixed, genetically unperturbed samples. FISH+ extends RNA FISH from visualization to protein identification through a simple, robust and highly accessible “watch-and-catch” proximity labeling method for punctate RNAs.
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mhryu@live.com
June 23, 3:54 PM
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Biomolecular condensates are emerging structures that organize cell biochemistry. RNA-protein (RNP) condensates have raised huge interest in the field of RNA biology due to their potential to impact gene expression. Although RNP condensate biophysical properties and assembly mechanisms have been extensively studied, leading to major breakthroughs, their contribution to biological processes remains debated. In this perspective, we review the current knowledge on the functions of cytoplasmic RNP condensates in mRNA regulation. Particularly, we highlight recent technological and conceptual advances that revealed the unexpected function of RNP condensates in mRNA translation. We discuss the mechanisms and biophysical bases that reconcile RNP condensate dual function in translational repression and activation. We propose emerging future directions to further address translation at RNP condensates and decode their functional compartmentalization linked to their biophysical properties. We also highlight the importance of this new function of condensates in translation for improved RNA-based therapeutics.
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mhryu@live.com
June 23, 1:00 AM
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The bacterial 16S rRNA gene is widely used to characterize host-associated and environmental microbiomes, most commonly through sequencing short hypervariable regions. Recent improvements in PacBio sequencing chemistry and concatenation approaches can now enable high-throughput, full-length 16S rRNA gene sequencing with high accuracy and depth. However, errors introduced during library preparation remain a major limitation, particularly during PCR amplification of full-length amplicons, where error accumulation may be elevated due to longer sequence lengths. These challenges are amplified when samples vary widely in microbial biomass, making it difficult to select a single optimal number of PCR cycles. Here, we evaluated PCR cycle autonormalization for PacBio Kinnex full-length 16S rRNA gene sequencing across seven agriculturally relevant specimen types. We compared conventional fixed-cycle PCR protocols (20, 24, and 30 cycles) with an autonormalization approach in which individual reactions were terminated during exponential amplification based on real-time fluorescence thresholds. Under the workflow tested here, autonormalized libraries generally retained a high proportion of sequences following denoising and chimera removal, exhibited low residual error rates (<0.005%), and yielded relatively even read distributions across heterogeneous sample inputs. Overamplified reactions (30 cycles) showed elevated residual error rates and greater sequence loss, particularly in samples with higher microbial biodiversity, whereas low-cycle libraries produced more variable read output among specimens. Importantly, the PCR protocol had relatively minor effects on overall community composition compared with specimen type. These results support PCR cycle autonormalization as a useful workflow strategy for heterogeneous full-length 16S library preparation, while also highlighting the importance of library design, pooling strategy, and downstream processing in shaping technical outcomes.
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mhryu@live.com
June 23, 12:42 AM
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RNA polymerase catalyzes transcription, the first step of gene expression. In bacteria, numerous regulatory proteins and signaling molecules fine-tune RNAP activity in a promoter-specific manner. The resultant changes in gene expression allow cells to acclimate to an ever-changing environment. In addition to phenotypic adaptation, increases in cell fitness can also result from changes in the genome. Here, we explore how mutations in RNAP structural genes benefit cells under diverse selection pressures, with a focus on antibiotics. Selection for resistance to rifampicin (RIF), an antibiotic that binds near the catalytic center of RNAP, leads almost exclusively to amino acid substitutions in the large β subunit that modify the RIF binding site. RIFR mutations have pleiotropic effects and can lead to increased or decreased sensitivity to other antibiotics. In addition, mutations in RNAP are linked to resistance to β-lactams, antibiotics that target peptidoglycan synthesis. Mutations in RNAP can act by altering the interaction with key regulators, including the sigma (σ) factors required for promoter recognition, transcription factors, or signaling molecules that bind to RNAP. RNAP mutations also affect catalysis with impacts on promoter recognition and clearance, elongation, and termination. We consider illustrative examples of changes in RNAP that alter the transcriptional landscape to facilitate the emergence of antibiotic tolerance and resistance, both in the laboratory and during the clinical course of treatment in patients.
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mhryu@live.com
June 22, 11:47 PM
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The twin-arginine translocation (Tat) system is a mechanistically unique protein transport pathway moving folded proteins across membranes. It is found in all domains of life and is essential for bacterial virulence and plant photosynthesis. The membrane proteins, TatA, TatB and TatC form a core complex to which substrate proteins bind, triggering the recruitment of additional TatA protomers to form the transport site. Here we present cryo-electron microscopy structures of the prototypical TatBC complex from E. coli and the atypical complexes from Nitratifactor salsuginis and Myxococcus xanthus in a resting state, alongside TatAC substrate-bound TatBC and TatABC complexes from E. coli in the early stages of transport. These structures demonstrate that substrate proteins associate with the core complex solely through their N-terminal signal peptides. The Tat targeting sequences of the signal peptides make specific contacts with TatC, and the peptide body is clamped by TatB. The core complex contains highly tilted transmembrane helices that drive extreme local membrane thinning. On the basis of our structures and biochemical and functional analyses, we propose a model for the early steps in Tat transport. Cryo-EM structural, biochemical and functional analyses of the bacterial twin-arginine translocation system for protein transport across membranes reveal mechanisms of substrate binding.
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