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bioRxiv2024

Reliable amplification of highly repetitive or low complexity sequence DNA enabled by superhelicase-mediated isothermal amplification

PCR is a cornerstone of molecular biology, but many biologically important DNA templates remain difficult to amplify. Long tandem repeats, low-complexity tracts, and sequences with extreme base composition often yield low product levels, smeared bands, stutter products, or truncated amplicons. These failures can arise because repeated cycles of thermal denaturation and reannealing promote off-register annealing, polymerase slippage, secondary-structure formation, and incomplete extension. Previously, we developed SSB-Helicase Assisted Rapid PCR (SHARP), an isothermal amplification method in which an engineered superhelicase and single-stranded DNA-binding protein replace the thermal melting step of PCR with enzymatic strand separation. Here, we tested whether SHARP can improve amplification of templates that are refractory to conventional PCR. SHARP robustly amplified up to six identical tandem repeats of the Widom 601 nucleosome-positioning sequence and up to 35 identical ankyrin repeats, targets that were poorly amplified by conventional PCR under the conditions tested. SHARP also amplified templates with extreme base composition, including a 95% AT-rich template and GC-rich templates (up to ~95% GC), as well as a 99-repeat CGG tract associated with Fragile X syndrome and a CAG/CAA repeat tract from mutant HTT exon 1 associated with Huntington disease. Together, these results show that helicase-driven isothermal amplification can expand access to repetitive and compositionally extreme DNA sequences that are challenging for conventional thermocycling-based PCR.

bioengineering↗

bioRxiv2024

Direct Feature Identification from Raman Spectra and Precise Data-driven Classification of Phytopathogens at Single Conidium-Species Level

Conidia can cause outbreaks of fungal plant diseases, resulting in significant losses in crop yield and economy. Traditional diagnosis of phytopathogenic conidia based on morphology and molecular biology is time-consuming, labor-intensive, and often fails to differentiate fungal conidia. To overcome these challenges, a new classification approach was developed in this study by integrating Raman spectroscopy with data-driven modeling. Eight fungal species were selected and characterized using Raman spectra. Three characteristic Raman wavenumbers at 1003 to 1005 cm-1, 1153 to 1157 cm-1, and 1515 to 1522 cm-1 shared a consistent pattern across species and could be attributed to carotenoids. Clustering of the Raman spectra using principal component analysis (PCA) showed substantial overlap, indicating inaccurate classification of conidia. Three data-driven models, support vector machines (SVMs), decision trees (DTs), and eXtreme Gradient Boosting Forest (XGBoost) were trained with three categories of features (number of peaks, maximum peak, and curve roughness) identified within eight characteristic wavenumber ranges, The optimal SVM, DT, and XGBoost determined by hyperparameter tuning achieved prediction precision of 0.88, 0.88, and 0.96, respectively. PCA-XGBoost trained by feeding principal components of PCA to XGBoost achieved prediction precision of 0.94, suggesting that features extracted from the raw datasets outperformed those extracted with PCA in terms of data-driven classification. This study has demonstrated the great potential of Raman spectroscopy combined with data-driven modeling for classification of phytopathogenic conidia.

microbiology↗

bioRxiv2024

Evolutionary Constraints on Positional Sequence, Collective Properties and Sequence Style of Tropoelastin Dictated by Fundamental Requirements for Formation and Function of the Extracellular Elastic Matrix

Elastin is an unusual extracellular matrix protein responsible for the properties of extension and energy-efficient elastic recoil of large blood vessels, heart valves, lung parenchyma and many other vertebrate tissues requiring such resilience. Polymeric elastin is assembled from monomeric tropoelastin by a process involving liquid-liquid phase separation, followed by maturation into an extended elastic matrix, covalently cross-linked through the side chains of lysine residues in the protein and producing a robust biomaterial with the structural integrity to withstand hundreds of millions of cycles of extension and recoil without mechanical failure. Elastin functions as an entropic elastomer, whose properties are the direct result of the inability of the protein to fold into a fixed, stable structure. Previous investigations of how the unusual properties of polymeric elastin arise from the sequence of tropoelastin have depended primarily on modeling using molecular biological and biophysical methodologies. This study takes a unique alternative approach, using a well-curated database of tropoelastin sequences from more than 80 representative species of Amniotes to identify characteristics that are conserved over more than 300 million years of evolution in order to provide assembly and conformational flexibility requirements of elastins. Conserved characteristics included preservation not only of regions of linear or positional sequence, but also of collective or compositional characteristics, derived from the sequence but not strictly dependent on positional sequence. A plausible overall consensus sequence for Amniote tropoelastins allowed quantification of residue-by-residue, domain-by-domain and region-by-region levels of sequence conservation, identifying distinct regions of high and low positional sequence conservation. Regions of low positional sequence conservation nevertheless maintained a recognizable, low complexity sequence style characterized by tandem repeats and partial repeats of short, non-polar motifs. Analysis of these motifs indicated hPGhGG, with numerous mutations, insertions and deletions, as the underlying repeating unit in all Amniote tropoelastins. Together these data identify significant evolutionary constraints dictated by fundamental requirements for formation and functionality of the extracellular elastin matrix. Mutations/polymorphisms in human tropoelastin affecting such well-conserved characteristics might be expected to have phenotypic consequences.

biochemistry↗

bioRxiv2024

StreptoCAD: An open-source software toolbox automating genome engineering workflows in streptomycetes

Streptomycetes hold immense potential for discovering novel bioactive molecules for applications in medicine or sustainable agriculture. However, high-throughput exploration is hampered by the current Streptomyces genetic engineering methods that involve the manual design of complex experimental molecular biological engineering strategies for each targeted gene. Here, we introduce StreptoCAD, an open-source software toolbox that automates and streamlines the design of genome engineering strategies in Streptomyces, supporting various CRISPR-based and gene overexpression methods. Once initiated, StreptoCAD designs all necessary DNA primers and CRISPR guide sequences, simulates plasmid assemblies (cloning) and the resulting modification of the genomic target(s), and further summarizes the information needed for laboratory implementation and documentation. StreptoCAD currently offers six design workflows, including the construction of overexpression libraries, base-editing, including multiplexed CRISPR-BEST plasmid generation, and genome engineering using CRISPR-Cas9, CRISPR-Cas3, and CRISPRi systems. In addition to automating the design process, StreptoCAD further secures compliance with the FAIR principles, ensuring reproducibility and ease of data management via standardized output files. To experimentally demonstrate the design process and output of StreptoCAD, we designed and constructed a series of gene overexpression strains in Streptomyces Go40/10, underscoring the tools efficiency and user-friendliness. This tool simplifies complex genetic engineering tasks and promotes collaboration through standardized workflows and design parameters. StreptoCAD is set to transform genome engineering in Streptomyces, making sophisticated genetic manipulations accessible for all and accelerating natural product discovery. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=170 SRC="FIGDIR/small/629370v1_ufig1.gif" ALT="Figure 1000"> View larger version (56K): org.highwire.dtl.DTLVardef@42a7deorg.highwire.dtl.DTLVardef@1aef57org.highwire.dtl.DTLVardef@574e59org.highwire.dtl.DTLVardef@1d8dd3d_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2024

SLC35A2 loss of function variants affect glycomic signatures, neuronal fate, and network dynamics

SLC35A2 encodes a UDP-galactose transporter essential for glycosylation of proteins and galactosylation of lipids and glycosaminoglycans. Germline genetic SLC35A2 variants have been identified in congenital disorders of glycosylation and somatic SLC35A2 variants have been linked to intractable epilepsy associated with malformations of cortical development. However, the functional consequences of these pathogenic variants on brain development and network integrity remain elusive. In this study, we use an isogenic human induced pluripotent stem cell-derived neuron model to comprehensively interrogate the functional impact of loss of function variants in SLC35A2 through the integration of cellular and molecular biology, protein glycosylation analysis, neural network dynamics, and single cell electrophysiology. We show that loss of function variants in SLC35A2 result in disrupted glycomic signatures and precocious neurodevelopment, yielding hypoactive, asynchronous neural networks. This aberrant network activity is attributed to an inhibitory/excitatory imbalance as characterization of neural composition revealed preferential differentiation of SLC35A2 loss of function variants towards the GABAergic fate. Additionally, electrophysiological recordings of synaptic activity reveal a shift in excitatory/inhibitory balance towards increased inhibitory drive, indicating changes occurring specifically at the pre-synaptic terminal. Our study is the first to provide mechanistic insight regarding the early development and functional connectivity of SLC35A2 loss of function variant harboring human neurons, providing important groundwork for future exploration of potential therapeutic interventions.

neuroscience↗

bioRxiv2025

MLC1 alteration in iPSCs give rise to disease-like cellular vacuolation phenotype in the astrocyte lineage

BackgroundMegalencephalic leukoencephalopathy with subcortical cysts (MLC), a rare and progressive neurodegenerative disorder involving the white matter, is not adequately recapitulated by current disease models. Somatic cell reprogramming, along with advancements in genome engineering, may allow the establishment of in-vitro human models of MLC for disease modeling and drug screening. In this study, we utilized cellular reprogramming and gene-editing techniques to develop induced pluripotent stem cell (iPSC) models of MLC to recapitulate the cellular context of the classical MLC-impacted nervous system. MethodsSomatic cell reprogramming of peripheral patient-derived blood mononuclear cells (PBMCs) was used to develop iPSC models of MLC. CRISPR-Cas9 system-based genome engineering was also utilized to create the MLC1 knockout model of the disease. Directed differentiation of iPSCs to neural stem cells (NSCs) and astrocytes was performed in a 2D cell culture format, followed by various cellular and molecular biology approaches, to characterize the disease model. ResultsMLC iPSCs established by somatic cell reprogramming and genome engineering were well characterized for pluripotency. iPSCs were subsequently differentiated to disease-relevant cell types: neural stem cells (NSCs) and astrocytes. RNA sequencing profiling of MLC NSCs revealed a set of differentially expressed genes related to neurological disorders and epilepsy, a common clinical finding within MLC disease. This gene set can serve as a target for drug screening for the development of a potential therapeutic for this disease. Upon differentiation to the more disease relevant cell type-astrocytes, MLC-characteristic vacuoles were clearly observed, which were distinctly absent from controls. This emergence recapitulated a distinguishing phenotypic marker of the disease. ConclusionThrough the creation and analyses of iPSC models of MLC, our work addresses a critical need for relevant cellular models of MLC for use in both disease modeling and drug screening assays. Further investigation can utilize MLC iPSC models, as well as generated transcriptomic data sets and analyses, to identify potential therapeutic interventions for this debilitating disease.

cell biology↗

bioRxiv2025

Human REXO4 is Required for Cell Cycle Progression

Human REXO4 is a poorly characterized exonuclease that is overexpressed in human cancers. To better understand the function of REXO4 and its relationship to cellular proliferation, we have undertaken multidisciplinary approaches to characterize its cell cycle phase-dependent subcellular localization and the cis determinants required for this localization, its importance to cell cycle progression and cell viability, its protein-protein association network, and its activity. We show that the localization of REXO4 to the nucleolus in interphase depends on an N-terminal nucleolar localization sequence and that its localization to the perichromosomal layer of mitotic chromosomes is dependent on Ki67. Depletion of REXO4 led to a G1/S cell cycle arrest, and reduced cell viability. REXO4 associated with ribosome components and other proteins involved in rRNA metabolism. We propose a model where REXO4 is important for proper rRNA processing, which is required for ribosome biogenesis, cell cycle progression, and proliferation. SIGNIFICANCE STATEMENTO_LIREXO4 is a putative RNA exonuclease with limited characterization. The authors used in silico, cell, and molecular biology approaches to characterize its localization, associations, regulation, and function. C_LIO_LIThey found that during interphase, REXO4 localizes to the nucleolus through an N-terminal nucleolar localization sequence. Whereas during mitosis, REXO4 localized to the perichromosomal layer in a Ki67-dependent manner. REXO4 was required for proper cell cycle progression, and viability. C_LIO_LIThese results indicated that REXO4 is important for regulating cell proliferation. C_LI

cell biology↗

bioRxiv2025

Characterizing Oligodendrocyte-Lineage Cells and Myelination in the Basolateral Amygdala: Insights from a Novel Methodology in Postmortem Human Brain

The basolateral amygdala (BLA) plays a key role in the pathophysiology of depressive disorders and trauma, yet oligodendrocyte-lineage cells and myelin in this brain region remain understudied in humans. This may be due, at least in part, to the lack of a cost-effective, antibody-based method to isolate oligodendrocytes (OL) and OL precursor cells (OPC) from postmortem brain tissue that is compatible with molecular biology applications. This study aimed to 1) create and validate a method for isolating OPC and OL nuclei from frozen postmortem grey matter; 2) compare OPC and OL gene expression in the BLA between individuals with depression who died by suicide (with or without a history of childhood abuse) and matched controls; and 3) provide histological characterizations of OPC, OL, and myelin in the BLA. Frozen left-hemisphere BLA samples were obtained from brain donors with well-characterized phenotypic information. Immunolabeled nuclei were sorted into OPC (SOX10+/CRYAB-) and OL (SOX10+/CRYAB+) populations, and RNA was measured using a custom Nanostring codeset. Fluorescence in situ hybridization was used to determine OPC (PDGFR+) and OL (MYRF+) densities, and immunofluorescence was used to label axons (NF-H) and myelin (MBP) for myelin area fraction. The method successfully isolated OPC and OL nuclei with correct transcriptomic profiles. In the OL fraction, MOBP was found to be significantly decreased in depressed individuals with a history of child abuse compared to controls, but no other genes showed significant group differences in either fraction. However, significant age-related patterns were observed in both fractions. Furthermore, no significant differences in cell densities or myelin coverage were observed across groups. Lastly, a strong significant correlation between OL density and myelin area fraction was identified. This study provides a novel sorting method and a comprehensive characterization of OL-lineage gene expression, cell densities, and myelin in the human BLA.

neuroscience↗

bioRxiv2025

Identification and classification of abundant RNA-binding proteins in the mouse lens and interactions of Carhsp1, Igf2bp1/ZBP1, and Ybx1 with crystallin and β-actin mRNAs

RNA-binding proteins (RBPs) are critical regulators of mRNAs controlling all processes such as RNA transcription, transport, localization, translation, mRNA:ncRNA interactions, and decay. Cellular differentiation is driven by tissue-specific and/or tissue-preferred expression of proteins needed for the optimal function of mature cells, tissues and organs. Lens fiber cell differentiation is marked by high levels of expression of crystallin genes encoding critical proteins for lens transparency and light refraction. Herein we performed proteomic and transcriptomic analyses of RBPs in differentiating mouse lenses to identify the most abundant RBPs and establish dynamic changes of their expression in differentiating lens. Expression analyses include highly abundant RBPs, including Carhsp1, Igf2bp1/ZBP1, Ybx1, Pabpc1, Ddx39, and Rbm38. Binding sites of Carhsp1, Ybx1, and Igf2bp1/ZBP1 were predicted in various crystallin and {beta}-actin mRNAs. Immunoprecipitations using antibodies against Carhsp1, Igf2bp1/ZBP1, and Ybx1 confirmed their interactions with A-, B-, and {gamma}A-crystallin mRNAs. A combination of single molecule RNA FISH (smFISH) and immunofluorescence was used to probe in vivo interactions of these RBPs with A-, B-crystallin, and {beta}-actin mRNAs in cytoplasm and nucleoplasm of cultured mouse lens epithelial cells. Together, these results open new avenues to perform comprehensive genetic, cell, and molecular biology studies of individual RBPs in the lens.

developmental biology↗

bioRxiv2025

Ceratopteris richardii U6 promoters and plants expressing Cas9 endonuclease as tools for efficient genome editing in a fern

Ferns and their allies (monilophytes) represent the second most species-rich group of land plants and are of considerable ecological importance. As a sister group of seed plants (including flowering plants) they are also of great evolutionary interest. Compared to flowering plants, however, much less is known about the developmental and molecular biology of ferns. Among the most important reasons have been the huge genome sizes of ferns and technical obstacles such as the lack of an efficient transformation system. In recent years the situation has improved considerably, however. For the fern model system Ceratopteris richardii a whole genome sequence has been published, and an efficient transformation system has been developed. To further facilitate studies on fern biology we aim at simplifying genome engineering of C. richardii with the CRISPR-Cas9 system. We report C. richardii plants that express Cas9 nuclease under control of the strong CaMV 35S promoter. For efficient expression of single guide RNA (sgRNA) by RNA polymerase III we identified C. richardii U6 promoters. These technical improvements may foster many fields of fern physiology, development and evolution.

plant biology↗

bioRxiv2025

Asparagine endopeptidase promotes radioresistance in breast cancer through ATR pathway modulation

BackgroundTumor resistance represents a major challenge in the current oncology landscape. Asparagine endopeptidase (AEP) overexpression correlates with worse prognosis and reduced overall survival in most human solid tumors. However, the underlying mechanisms of the connection between AEP and reduced overall survival in cancer patients remain unclear. MethodsHigh-throughput proteomics, cellular and molecular biology approaches and clinical data from breast cancer (BC) patients were used to identify novel, biologically relevant AEP targets. Immunoblotting and qPCR analyses were used to quantify mRNA and protein levels. Flow cytometry, confocal microscopy, chemical inhibitors, siRNA- and shRNA-silencing and DNA repair assays were used as functional assays. In-silico analyses using the TCGA BC dataset and immunofluorescence assays in an independent cohort of invasive ductal (ID) BC patients were used to validate the clinical relevance of our findings. ResultsHere we showed a dual role for AEP in genomic stability and radiotherapy resistance in BC patients by suppressing ATR and PPP1R10 levels. Reduced ATR and PPP1R10 levels were found in BC patients expressing high AEP levels and correlated with worst prognosis. Mechanistically, AEP suppresses ATR levels, reducing DNA damage-induced cell death, and PPP1R10 levels, promoting Chek1/P53 cell cycle checkpoint activation, allowing BC cells to efficiently repair DNA. Functional studies revealed AEP-deficiency results in genomic instability, increased DNA damage signaling, reduced Chek1/P53 activation, impaired DNA repair and cell death, with phosphatase inhibitors restoring the DNA damage response in AEP-deficient BC cells. Furthermore, AEP inhibition sensitized BC cells to the chemotherapeutic reagents cisplatin and etoposide. Immunofluorescence assays in an independent cohort of IDBC patients showed increased AEP levels in ductal cells. These analyses showed that higher AEP levels in radioresistant IDBC patients result in ATR nuclear eviction, revealing AEPhigh/ATRlow protein levels as an efficient predictive biomarker for the stratification of radioresistant patients. ConclusionThe newly identified AEP/ATR/PPP1R10 axis plays a dual role in genomic stability and radiotherapy resistance in BC. Our work provides new clues to the underlying mechanisms of tumor resistance and strong evidence validating the AEP/ATR axis as a novel predictive biomarker and therapeutic target for the stratification and treatment of radioresistant BC patients.

cancer biology↗

bioRxiv2025

A suite of pre-assembled, pET28b-based Golden Gate vectors for efficient protein engineering and expression

Expression and purification of recombinant proteins in E. coli is a bedrock technique in biochemistry and molecular biology. Expression optimization requires testing different combinations of solubility tags, affinity purification techniques, and site-specific proteases. This optimization is laborious and time consuming as these features are spread across different vector series and require different cloning strategies with varying efficiencies. Modular cloning kits based on the Golden Gate system exist, but are overly complicated for many applications, such as undergraduate research or simple screening of protein purification features. An ideal solution is for a single gene synthesis or PCR product to be compatible with a large series of pre-assembled Golden Gate vectors containing a broad array of purification features at either the N or C-terminus. To our knowledge, no such system exists. To fulfill this unmet need, we Golden Gate domesticated the pET28b vector and developed a suite of 21 vectors with different combinations of purification tags, solubility domains, visualization/labeling tags, and protease sites. We also developed a completely scarless vector series with 9 different N-terminal tags. The system is modular, allowing users to easily customize the vectors with their preferred combinations of features. To allow for easy visual screening of cloned vectors, we optimized constitutive expression of the fluorescent protein mScarlet3 in the reverse strand, resulting in a red to white color change upon successful cloning. Testing with the model protein sfGFP shows the ease of visual screening, high efficiency of cloning, and robust protein expression. These vectors provide versatile, high-throughput solutions for protein engineering and functional studies in E. coli.

biochemistry↗

bioRxiv2025

Sequencing and assembling complete plasmids on Oxford Nanopore Technology Sequencers using R2C2 and Chopper

Plasmids are ubiquitous tools in molecular biology which are used for a large variety of experiments within academic and commercial labs. Both new and old plasmids have to undergo sequencing-based analysis to determine whether or not they are functional, i.e. contain the correct insert in the correct backbone. While traditional Sanger sequencing based analysis was most often limited to the inserts, new high-throughput sequencing based methods and services can now provide the complete sequence of a plasmid. Currently available methods and services vary in throughput and cost. Here, we adapted the Oxford Nanopore Technologies-based R2C2 sequencing method to - rapidly and at low cost - sequence complete plasmids, either individually or in a pool. We also developed an analysis pipeline, Chopper, that produces full-length plasmid sequences. We tested our workflow with commonly used plasmids we ordered from Addgene and produced highly accurate sequences for each plasmid from both their individual and pooled sequencing runs.

bioinformatics↗

bioRxiv2025

Optimizing Transfection Efficiency in Primary Human Splenic Fibroblast Cells

Transfection, a fundamental molecular biology technique, is crucial in introducing foreign DNA into cells. Despite its pivotal importance, mastering this technique remains a formidable challenge. In this study, we employed the calcium phosphate reagent and conducted a systematic exploration through time-dependent experiments to assess its impact on human primary splenic fibroblast cells (HSFC). The results precisely delineate optimal time frames for achieving enhanced transfection efficiency, offering conclusive evidence for the efficacy of calcium phosphate in transient transfection within the cells. The data significantly advances our comprehension of HSFC reactions, contributing to refining transfection methodologies with broader implications for biomedical applications.

cell biology↗

bioRxiv2025

Standardized Residue Numbering and Secondary Structure Nomenclature in the Class D β-Lactamases

Over 1370 class D {beta}-lactamases are currently known, and they pose a serious threat to the effective treatment of many infectious diseases, particularly in some pathogenic bacteria where evolving carbapenemase activity has been reported. Detailed understanding of their molecular biology, enzymology and structural biology are critically important but the lack of a standardized residue numbering scheme and inconsistent secondary structure annotation has made comparative analyses sometimes difficult and cumbersome. Compounding this, in the post-AlphaFold world where we currently find ourselves, an extraordinary wealth of detailed structural information on these enzymes is literally at our fingertips, therefore it is vitally important that a standard numbering system is in place to facilitate the accurate and straightforward analysis of their structures. Here we present a residue numbering and secondary structure scheme for the class D enzymes and apply it to test targets to demonstrate ease at which it can be used.

biochemistry↗

bioRxiv2025

Genome-wide identification of genes involved in beetle odoriferous defensive stink gland function recognizes Laccase2 as the phenoloxidase responsible for toxic para-benzoquinone synthesis

Exocrine glands have evolved several times independently in Coleoptera to produce defensive chemical compounds with repellent, antimicrobial, or toxic effects. Research on such glands had focused on morphological or chemical ecology methods. However, modern genetic approaches were missing to better understand this biological process. With the rise of the red flour beetle, Tribolium castaneum, as a model for studies of development and pest biology, molecular genetic tools are now available to also study the safe generation of toxic compounds in defensive stink glands. Using the RNA-interference-based, genome-wide, phenotypic screen "iBeetle" and the re-analysis of gland-specific transcriptomics based on a significantly improved genome annotation, we could identify 490 genes being involved in odoriferous stink gland function. In the iBeetle screen, 247 genes were identified, of which we present here 178 genes identified during iBeetles 3rd phase, while the transcriptomics analyses identified 249 genes, with six genes being identified in both functional genomics approaches. Of these 490 genes, only about 40% of these genes have molecularly characterized homologs in the vinegar fly, while for 213 genes no fly homologs were recognized and for 13 genes no gene ontology at all was identified. This highlights the importance of genome-wide gene identification in tissues that have not been previously analyzed to recognize potentially new gene functions. Gene ontology analysis revealed "SNARE interactions in vesicular transport", "Lysosome", "Pancreatic secretion", and "MAPK signaling pathway - fly" as key pathways. Additionally, many of the genes are encoding enzymes, transcription factors, transporters, or are involved in membrane trafficking. As the phenoloxidase responsible for generating the toxic para-benzoquinones in the stink glands of the beetle, we could identify laccase2, which is expressed in the last secretory cell in contact with the cuticule-lined organelle, where the toxic compounds are safely produced before being released into the gland reservoir. Author summaryCertain beetles produce toxic substances to defend themselves against microorganisms or predators. For the generation of such chemicals, the beetles have specialized glands, which are organized in a way that they can produce and store the toxic compounds without harming themselves. The morphology and biochemistry of such glands had been intensively studied. However, the genes that are involved in this process had not been recognized. Here we present the identification of about 500 genes that are involved in the function of beetle defensive glands, which presents a starting point for a detailed molecular understanding of the process of safe production of toxic substances. A key feature for the production is the use of non-harmful precursors that are only finally processed by a specifically secreted enzyme called Laccase2 to become toxic in a cuticle-shielded organelle.

genetics↗

bioRxiv2025

In a pathophysiologic state due to SARS-CoV-2, viscosity and cholesterol are two-edged swords.

Much attention has been paid to the genetic composition and molecular biology of viral particles, infection, and micro-anatomical impacts that culminate in fatalities; vaccines have been in continuous development and production; less attention is paid to the fundamental issues of thermodynamics and activation energy characterization of viral RNA replication and cell death. The study aimed at deriving equations that can be fitted to both theoretically and empirically derived data for the quantitation of other thermodynamic parameters and its cognate dimensionless equilibrium constant; some of the derived equations addressed the issue of viscosity and the concentration of cholesterol in particular as they affect translational velocity needed for the delivery of biomolecules to the site of need. The instantaneous velocities before terminal velocity are: [~] 0.046674 m/s (cytosol); 0.141837 m/s (water). The terminal velocities were approximately equal to 3.548614 nm/s for the cytosol and 99.590626 nm/s for the water; these values were computed using literature values of translational diffusion coefficients (Di) of glucose in cytoplasm and in water. The value in water is higher than in the cytosol because of higher cytosolic viscosity than aqueous viscosity. These support the view that cholesterol and viscosity have a dual-edged effect on the pathophysiologic state orchestrated by SARS-CoV-2; higher viscosities in the membrane and in the cytoplasm enhance binding and infection and can diminish the progress of infection, respectively. Higher feasibility and rates were observed at lower thermodynamic temperatures than at higher ones, according to the outcome of the analysis of the viral binding free energy and activation energy, respectively. The dimensionless constant values were higher at the earlier time of the infection and decreased with time, exhibiting a power law relationship. It is advised, among others, that pharmaceuticals (including airborne surfactants) and drugs in solution be given at temperatures above body temperature. Swab testing should be performed on a regular basis to detect significant infections early. Future in vitro and in vivo studies on viral infection might focus on various time periods at different temperatures, above and below body temperature. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/638432v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1262294org.highwire.dtl.DTLVardef@a836a0org.highwire.dtl.DTLVardef@19a5f6forg.highwire.dtl.DTLVardef@1ef86c6_HPS_FORMAT_FIGEXP M_FIG C_FIG With vaccine and/or drug the viral infection can regress; without treatment there could be infection and progression into disease state; discontinuation of treatment can cause a reinfection.

biophysics↗

bioRxiv2025

MBCO PathNet: Integration and visualization of networks connecting functionally related pathways predicted from transcriptomic and proteomic datasets

Our desktop application MBCO PathNet allows for quick and easy integration and visualization of networks of functionally related pathways predicted from numerous gene and protein lists using the Molecular Biology of the Cell Ontology (MBCO) and other ontologies. Within networks of hierarchical parent-child relationships or functional relationships, pathways are visualized as pie charts where each slice represents a dataset that predicted that pathway. Sizes of pies and slices can be selected to represent statistical significance or other quantitative measures. In addition, MBCO PathNet can generate bar diagrams, heatmaps and timelines. Availability and implementationmbc-ontology.org github.com/SBCNY/Molecular-Biology-ofthe-Cell iyengarlab.org/mbcpathnet Contact: jens.hansen@mssm.edu

bioinformatics↗