title: Community review: a robust and scalable selection system for resource allocation within open science and innovation communities

abstract: Resource allocation is essential to the selection and implementation of innovative projects in science and technology. With large stakes involved in concentrating large fundings over a few promising projects, current "winner-take-all" models for grant applications are time-intensive endeavours that mobilise significant researcher time in writing extensive project proposals, and rely on the availability of a few time-saturated volunteer experts. Such processes usually carry over several months, resulting in high effective costs compared to expected benefits. Faced with the need for a rapid response to the Covid19 pandemic in 2020, we devised an agile "community review" system to allocate micro-grants for the fast prototyping of innovative solutions. Here we describe and evaluate the implementation of this community review across 147 projects from the "OpenCOVID19" and "Helpful Engineering" open research communities. The community review process uses granular review forms and requires the participation of grant applicants in the review process. Within a year, we organised 7 rounds of review, resulting in 614 reviews from 201 reviewers, and the attribution of 48 micro-grants of up to 4,000 euros. We show that this system is fast, with a median process duration of 10 days, scalable, with a median of 4 reviewers per project independent of the total number of projects, and fair, with project rankings highly preserved after the synthetic removal of reviewers. We investigate the potential bias introduced by involving applicants in the process, and find that review scores from both applicants and non-applicants have a similar correlation of r=0.28 with other reviews within a project, matching previous observations using traditional approaches. Finally, we find that the ability of projects to apply to several rounds allows to both foster the further implementation of successful early prototypes, as well as provide a pathway to constructively improve an initially failing proposal in an agile manner. Overall, this study quantitatively highlights the benefits of a frugal, community review system acting as a due diligence for rapid and agile resource allocation in open research programs, with particular implications for decentralised communities.


title: Calcium determines Lactiplantibacillus plantarum intraspecies competitive fitness

abstract:
The importance of individual nutrients for microbial strain robustness and coexistence in habitats containing different members of the same species is not well understood. To address this for Lactiplantibacillus plantarum in food fermentations, we performed comparative genomics and examined the nutritive requirements and competitive fitness for L. plantarum strains B1.1 and B1.3 isolated from a single sample of teff injera fermentation batter. Compared to B1.1 and other L. plantarum strains, B1.3 has a smaller genome, limited biosynthetic capacities, and large mobilome. Despite these differences, B1.3 was equally competitive with B1.1 in a suspension of teff flour. In commercially-sourced, nutrient-replete MRS (cMRS) medium, strain B1.3 reached three-fold higher numbers than B1.1 within two days of passage. Because B1.3 growth and competitive fitness was poor in mMRS, a modified MRS lacking beef extract, we used mMRS to identify nutrients needed for robust B1.3 growth. No improvement was observed when mMRS was supplemented with nucleotides, amino acids, vitamins, or monovalent metals. Remarkably, the addition of divalent metal salts increased the growth rate and cell yields of B1.3 in mMRS. Metal requirements were confirmed by Inductively Coupled Plasma Mass Spectrometry, showing that total B1.3 intracellular metal concentrations were significantly (up to 2.7-fold) reduced compared to B1.1. Supplemental CaCl2 conferred the greatest effect, resulting in equal growth between B1.1 and B1.3 over successive five passages in mMRS. Moreover, calcium supplementation reversed a B1.3 strain-specific stationary phase, flocculation phenotype. These findings show how L. plantarum calcium requirements affect competitive fitness at the strain level.

ImportanceEcological theory states that the struggle for existence is stronger between closely related species. Contrary to this assertion, fermented foods frequently sustain conspecific individuals, despite their high levels of phylogenetic relatedness. Therefore, we investigated two isolates of Lactiplantibacillus plantarum B1.1 and B1.3 randomly selected from a single batch of teff injera batter. These strains spanned the known genomic and phenotypic range of the L. plantarum species, and in nutrient-replete, laboratory culture medium, strain B1.3 exhibited poor growth and was outcompeted by the more robust strain B1.1. Despite those differences, B1.1 and B1.3 were equally competitive in teff flour. This result shows how these bacteria have adapted for co-existence in that environment. The capacity for the single macronutrient calcium to restore B1.3 competitive fitness in laboratory culture medium suggests that L. plantarum intraspecies diversity found in food systems is fine-tuned to nutrient requirements at the strain level.

category: microbiology


title: Single-cell tracking data aimed for big data analyses

abstract: This work proposes initial refinements of data from tracking single cells in video from many experiments and at a scale assumed large enough to be meaningful for big data analyses. The present examples of data processing are for illustration only, and caution must be exercised not to consider this contribution as a stand-alone laboratory study. The authors conjecture that computer assisted comparison between cellular behavior in many and diverse experiments can constitute a new source of information. A main intention here is therefore to promote such comparison based on methods employing simplicity, transparency, low-cost and sensor independence as well as independence of software or alternative online services. Indicating the potential value of simple cell positional observations (tracks), can pave the way towards contributions to already established biological databases. This can help to accumulate experience and facilitate big data analyses to search for new phenotypic signatures. Data can be spin-off from special analyses. Simple perturbation of the raw data can help to check for robustness of parameters derived from it. The present example data are from tracking clonal (A549) cells during several cycles while they grow in two-dimensional (2D) monolayers. The results from its processing reflect heterogeneity among the cells as well as inheritance in their response to treatments. The present illustrations include parametrization of population growth curves, aimed to simplify computerized search for similarities in large sets of single-cell tracking data. Other types of statistics, which can promote synergy between experiments, are from temporal development of cell speed in family trees with and without cell death, correlations between sister cells, development of single cell average displacements and the tendency of clustering. These are examples of parameters for further development to utilize information in large collections of data from cell behavior.

category: cell biology


title: Biophysical, Molecular and Proteomic profiling of Human Retinal Organoids derived Exosomes

abstract: Extracellular vesicles (EVs) are phospholipid bilayer-bound particles released by cells that play a role in cell-cell communication, signal transduction, and extracellular matrix remodeling. There is a growing interest in EVs for ocular applications as therapeutics, biomarkers, and drug delivery vehicles. EVs secreted from mesenchymal stem cells (MSCs) have shown to provide therapeutic benefits in ocular conditions. However, very little is known about the properties of bioreactors cultured-3D human retinal organoids secreted EVs. This study provides a comprehensive morphological, nanomechanical, molecular, and proteomic characterization of retinal organoid EVs and compares it with human umbilical cord (hUC) MSCs. Nanoparticle tracking analysis indicated the average size of EV as 100-250 nm. Atomic force microscopy showed that retinal organoid EVs are softer and rougher than the hUCMSC EVs. Gene expression analysis by qPCR showed a high expression of exosome biogenesis genes in late retinal organoids derived EVs (>120 days). Immunoblot analysis showed highly expressed exosomal markers Alix, CD63, Flotillin-2, HRS and Hsp70 in late retinal organoids compared to early retinal organoids EVs (<120 days). Protein profiling of retinal organoid EVs displayed a higher differential expression of retinal function-related proteins and EV biogenesis/marker proteins than hUCMSC EVs, implicating that the use of retinal organoid EVs may have a superior therapeutic effect on retinal disorders. This study adds supplementary knowledge on the properties of EVs secreted by retinal organoids and suggests their potential use in the diagnostic and therapeutic treatments for ocular diseases.

category: bioengineering


title: Building a novel nuclear-organelle genomic framework for the fever tree (Cinchona pubescens Vahl) through short and long-read DNA data assemblies

abstract:
BackgroundThe Andean fever tree (Cinchona L.; Rubiaceae) is the iconic source of bioactive quinine alkaloids which have been key to treating malaria for centuries. In particular, C. pubescens Vahl has been an important source of income for several countries in its native range in north-western South America. However, the genomic resources required to place Cinchona species in the tree of life and to explore the evolution and biosynthesis of alkaloids are meagre.

FindingsUsing a combination of ~120 Gb of long sequencing reads derived from the Oxford Nanopore PromethION platform and 142 Gb of short read Illumina data, we address this gap by providing the first highly contiguous nuclear and organelle genome assemblies and their corresponding annotations. Our nuclear genome assembly consists of 603 scaffolds comprising a total length of 903 Mb, representing ~85% of the genome size (1.1 Gb/1C). This draft genome sequence was complemented by annotating 72,305 CDSs using a combination of de novo and reference-based transcriptome assemblies. Completeness analysis revealed that our assembly is highly complete, displaying 83% of the BUSCO gene set, and a small fraction of genes (4.6%) classified as fragmented. We demonstrate the utility of these novel genomic resources by placing C. pubescens in the Gentianales order using plastid and nuclear datasets.

ConclusionsOur study provides the first genomic resource for C. pubescens thus opening new research avenues, including the unravelling of the gene toolkit for alkaloid biosynthesis in the fever tree.

category: bioinformatics


title: Transcriptional atlas of the human immune response to 13 vaccines reveals a common predictor of vaccine-induced antibody responses

abstract: Systems biology approaches have been used to define molecular signatures and mechanisms of immunity to vaccination. However, most such studies have been done with single vaccines, and comparative analysis of the response to different vaccines is lacking. We integrated temporal transcriptional data of over 3,000 samples, obtained from 820 healthy adults across 28 studies of 13 different vaccines and analyzed vaccination-induced signatures associated with the antibody response. Most vaccines induced similar kinetics of shared transcriptional signatures, including signatures of innate immunity occurring 1-3 days post-vaccination, as well as the canonical plasmablast and cell cycle signatures appearing 7 days post-vaccination. However, the yellow fever vaccine YF-17D uniquely induced an early transient signature of T and B cell activation at Day 1, followed by delayed antiviral/interferon and plasmablast signatures that peaked at Days 7 and 14-21, respectively. Thus, despite the shared transcriptional response to most vaccines, at any given time point there was no evidence for a "universal signature" that could be used to predict the antibody response to all vaccines. However, accounting for the asynchronous nature of responses led to the identification of a time-adjusted signature that improved prediction antibody of responses across vaccines. These results provide a transcriptional atlas of the human immune response to vaccination and define a common, time-adjusted signature of antibody responses to vaccination.

category: immunology


title: Synergistic protection against secondary pneumococcal infection by human monoclonal antibodies targeting distinct epitopes

abstract:
Streptococcus pneumoniae persists as a leading cause of bacterial pneumonia despite the widespread use of polysaccharide-based vaccines. The limited serotype coverage of current vaccines has led to increased incidence of non-vaccine serotypes, as well as an increase in antibiotic resistance among these serotypes. Pneumococcal infection often follows a primary viral infection such as influenza virus, which hinders host defense and results in bacterial spread to the lungs. We previously isolated human monoclonal antibodies (mAbs) against the conserved surface antigen pneumococcal histidine triad protein D (PhtD), and we demonstrated that mAbs to this antigen are protective against lethal pneumococcal challenge prophylactically and therapeutically. In this study, we elucidated the mechanism of protection of a protective anti- pneumococcal human mAb, PhtD3, which is mediated by the presence of complement and macrophages in a mouse model of pneumococcal infection. Treatment with mAb PhtD3 reduced blood and lung bacterial burden in mice, and mAb PhtD3 is able to bind to bacteria in the presence of the capsular polysaccharide, indicating exposure of surface PhtD on encapsulated bacteria. In a mouse model of secondary pneumococcal infection, protection mediated by mAb PhtD3 and another mAb targeting a different epitope, PhtD7, was reduced, however, robust protection was restored by combining mAb PhtD3 with mAb PhtD7, indicating a synergistic effect. Overall, these studies provide new insights into anti-pneumococcal mAb protection and demonstrate for the first time that mAbs to pneumococcal surface proteins can protect against secondary pneumococcal infection in the mouse model.

Author SummaryThe persistence of Streptococcus pneumoniae as a leading cause of bacterial pneumonia despite numerous approved pneumococcal vaccines is a serious threat to public health globally. Currently, prophylactic and therapeutic options for Streptococcus pneumoniae are constrained by the limited serotype coverage of vaccines and the emergence of antibiotic resistant strains. An additional hurdle to overcome is the incidence of secondary pneumococcal infection following a viral infection, which leads to increased mortality. Here, we determined the mechanism of action of a monoclonal antibody (mAb) that targets Streptococcus pneumoniae. We found that mAb PhtD3 operates through macrophage and complement mediated functions. mAb PhtD3 was also discovered to reduce bacterial titers in the lungs and blood and bind to a related antigen PhtE. We also tested additional mAbs and discovered that two unique mAbs to the antigen PhtD conferred protection in a pneumococcal-influenza virus co-infection model. Our study provides new insights into the mechanisms and therapeutic potential of mAbs targeting conserved proteins of Streptococcus pneumoniae.


title: A Coxiella burnetii effector interacts with the host PAF1 complex and suppresses the innate immune response

abstract:
Intracellular bacteria such as the pathogen Coxiella burnetii inject effector proteins into the host cell that promote productive infection. One common strategy of pathogen effectors is to suppress host immune responses to enable pathogen replication. The C. burnetii type IV secretion system translocates a large number of effectors into host cells that collectively promote intracellular bacterial replication, but the individual functions of most of these effectors are poorly understood. In this study, we describe a C. burnetii effector, CBU1314, that localizes to the nucleus and inhibits NF-{kappa}B-, MAPK-, and type I IFN-dependent gene expression. Mechanistically, we find that CBU1314 interacts with the PAF1 complex (PAF1C), a central host transcriptional complex that regulates expression of inflammatory genes in innate immune cells. Notably, we find that PAF1 promotes immune gene expression in response to various immune agonists and C. burnetii infection. Moreover, we find that PAF1 is critical for restricting intracellular C. burnetii replication. Overall, our findings uncover PAF1C as a host target of a C. burnetii effector and reveal new insight into how intracellular bacterial pathogens subvert cell- intrinsic innate defenses.

SignificanceIntracellular bacteria often employ secreted effector proteins to modulate cellular processes and survive intracellularly. The study of these effectors can provide valuable insight into microbial pathogenesis and host biology. Here, we describe a Coxiella burnetii effector that inhibits multiple host signaling pathways and modulates the innate immune response. This effector interacts with the host PAF1 complex (PAF1C), a central regulator of transcription. Furthermore, we show that PAF1 is necessary for maximal gene expression downstream of various innate immune receptors and restricts bacterial replication during infection. Overall, our study elucidates the function of a C. burnetii effector in evading the immune response and provides insight into the role of PAF1C in cell-intrinsic defense against bacterial pathogens.


title: The shifting importance of abiotic and biotic factors across the life cycles of wild pollinators

abstract:
O_LIOrganisms living in seasonal environments are exposed to different environmental conditions as they transition from one life stage to the next across their life cycle. How different life stages respond to these varying conditions is a fundamental aspect of biology and is critical for understanding how organisms will respond to environmental change.
C_LIO_LIDespite the importance of animal pollinators, we lack a basic understanding of the influence of different environmental factors across their life cycles. We investigated the relative importance of climate conditions, food availability, and previous life stage abundance in a community of wild bumble bee species, asking: how do these three factors influence bee abundance at each life stage?
C_LIO_LIWe used a 7-year dataset to examine the importance of environmental conditions on the abundance of life stages in seven wild bumble bee species. We monitored climate conditions, the abundance of floral resources, and abundances of bees in each life stage across the active colony life cycle in a highly seasonal subalpine ecosystem in the Colorado Rocky Mountains, USA.
C_LIO_LIBee abundance at different life stages responded to environmental conditions in a consistent manner across the seven species. The survival and recruitment stage of the life cycle (assessed as abundance of overwintered queens) responded negatively to longer winters; the growth stage (assessed as abundance of workers) responded positively to floral resource availability; and the reproductive stage (assessed as abundance of males) was positively related to the abundance of the previous life stage (workers).
C_LIO_LIOur long-term examination of annual bumble bees reveals a consistent set of responses in the abundance of each life stage to climate conditions, floral resource availability, and previous life stage abundance. Across species, these three factors each influenced a distinct life stage, illustrating how their relative importance can shift throughout the life cycle. The life-cycle approach we have taken with wild bumble bees highlights that important details about pollinator demography are overlooked without considering life stage-specific responses. Ultimately, it is these life-stage specific responses that shape population outcomes, not only for animal pollinators, but for many organisms living in seasonal environments.
C_LI

category: ecology


title: First direct observation of 'elongated' conformational states in α-synuclein upon liquid-liquid phase separation

abstract: -Synuclein (-syn) is an intrinsically disordered protein (IDP) that undergoes liquid-liquid phase separation (LLPS), fibrillation, and forms insoluble intracellular Lewys bodies in neurons, which are the hallmark of Parkinsons Disease (PD). Neurotoxicity precedes the formation of aggregates and is probably related to LLPS of -syn in the cell. The molecular mechanisms underlying the early stages of LLPS are still elusive. To obtain structural insights into -syn upon LLPS, we take advantage of cross-linking/mass spectrometry (XL-MS) and introduce an innovative approach, termed COMPASS (COMPetitive PAiring StatisticS). COMPASS unravels transient interactions between -syn molecules in liquid droplets. In this work, we show that the conformational ensemble of -syn shifts from a  hairpin-like structure towards more  elongated conformational states upon LLPS. We obtain insights into the critical initial stages of PD and establish a novel mass spectrometry-based approach that will aid to solve open questions in LLPS structural biology.

category: biochemistry


title: Shape driven confluent rigidity transition in curved biological tissues

abstract: Collective cell motions underlie structure formation during embryonic development. Tissues exhibit emergent multicellular characteristics such as jamming, rigidity transitions, and glassy dynamics, but there remain questions about how those tissue scale dynamics derive from local cell level properties. Specifically, there has been little consideration of the interplay between local tissue geometry and cellular properties influencing larger scale tissue behaviours. Here we consider a simple two dimensional computational vertex model for confluent tissue monolayers, which exhibits a rigidity phase transition controlled by the shape index (ratio of perimeter to square root area) of cells, on a spherical surface. We show that the critical point for the rigidity transition is a function of curvature such that more highly curved systems are more likely to be in a less rigid, more fluid, phase. A phase diagram we generate for the curvature and shape index constitutes a testable prediction from the model. The curvature dependence is interesting because it suggests a natural explanation for more dynamic tissue remodelling and facile growth in regions of higher surface curvature, without invoking the need for biochemical or other physical differences. This has potential ramifications for our understanding of morphogenesis of budding and branching structures.

category: biophysics


title: Top-down modulation of the retinal code via histaminergic neurons of the hypothalamus

abstract: The mammalian retina is considered an autonomous circuit, yet work dating back to Ramon y Cajal indicates that it receives inputs from the brain. How such inputs affect retinal processing has remained unknown. We identified brain-to-retina projections of histaminergic neurons from the mouse hypothalamus, which densely innervated the dorsal retina. Histamine application, or chemogenetic activation of histaminergic axons, altered spontaneous and light-evoked activity of various retinal ganglion cells (RGCs), including direction-selective RGCs. These cells exhibited broader directional tuning and gained responses to high motion velocities. Such changes could improve vision when objects move fast across the visual field (e.g. while running), which fits with the known increased activity of histaminergic neurons during arousal. In humans, an antihistamine drug non-uniformly modulated visual sensitivity across the visual field, indicating an evolutionary conserved function of the histaminergic system. Our findings expose a previously unappreciated role for brain-to-retina projections in modulating retinal function.

category: neuroscience


title: Strong basal/tonic TCR signals are associated with negative regulation of naive CD4+ T cells

abstract: Tonic TCR signaling occurs constitutively in response to self-peptides presented by MHC (pMHC). Tonic TCR signal intensity correlates with Nur77-GFP reporter transgene expression. A broad range of Nur77-GFP is first detectable in post-selection thymocytes and persists in mature T cells. Nur77-GFPHI Ly6C- CD4+ T cells experience the strongest tonic TCR signaling and exhibit functional hypo-responsiveness to foreign pMHC stimulation. Gene expression analyses suggest similarities between the programs induced by strong tonic TCR signaling and T cell activation. However, the strongest tonic TCR signals also appear to induce expression of negative regulators, including coinhibitory receptors. Analysis of chromatin accessibility similarly suggest that strong tonic TCR signaling correlates with differentially higher accessibility of over 3000 chromatin regions in or near genes that encode positive and negative regulators of T cell activation. We propose that very strong tonic TCR signaling induces mechanisms of negative feedback to recalibrate T cell sensitivity.


title: Mutational impact of APOBEC3B and APOBEC3A in a human cell line

abstract: A prominent source of mutation in cancer is single-stranded DNA cytosine deamination by cellular APOBEC3 enzymes, which results in C-to-T and C-to-G mutations in TCA and TCT motifs. Although multiple enzymes have been implicated, reports conflict and it is unclear which enzyme(s) are responsible. Here we develop a selectable system to quantify genome mutation and compare the mutagenic activities of three leading candidates - APOBEC3A, APOBEC3B, and APOBEC3H. The human cell line, HAP1, was engineered to express the thymidine kinase (TK) gene of HSV-1, which confers sensitivity to ganciclovir. Clonal expression of APOBEC3A and APOBEC3B, but not catalytic mutant controls or APOBEC3H, triggered elevated DNA damage responses and increased frequencies of TK mutation. Mutant TK DNA sequences revealed nearly indistinguishable cytosine mutation patterns. Whole genome sequences from TK mutant clones confirmed these results and enabled broader bioinformatic analyses. Most importantly, comparisons of "pure" APOBEC3A- and APOBEC3B-inflicted mutation signatures from this system and the actual APOBEC3 signature from breast cancer indicated that most tumors manifest a composite signature. These studies help resolve a long-standing etiologic debate in the cancer field and indicate that future diagnostic and therapeutic efforts should focus on both APOBEC3A and APOBEC3B.

category: cancer biology


title: A cocktail containing two synergetic antibodies broadly neutralizes SARS-CoV-2 and its variants including Omicron BA.1 and BA.2

abstract: Neutralizing antibodies (NAbs) can prevent and treat infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, continuously emerging variants, such as Omicron, have significantly reduced the potency of most known NAbs. The selection of NAbs with broad neutralizing activities and the identification of conserved critical epitopes are still urgently needed. Here, we identified an extremely potent antibody (55A8) by single B-cell sorting from convalescent SARS-CoV-2-infected patients that recognized the receptor-binding domain (RBD) in the SARS-CoV-2 spike (S) protein. 55A8 could bind to wild-type SARS-CoV-2, Omicron BA.1 and Omicron BA.2 simultaneously with 58G6, a NAb previously identified by our group. Importantly, an antibody cocktail containing 55A8 and 58G6 (2-cocktail) showed synergetic neutralizing activity with a half-maximal inhibitory concentration (IC50) in the picomolar range in vitro and prophylactic efficacy in hamsters challenged with Omicron (BA.1) through intranasal delivery at an extraordinarily low dosage (25 g of each antibody daily) at 3 days post-infection. Structural analysis by cryo-electron microscopy (cryo-EM) revealed that 55A8 is a Class III NAb that recognizes a highly conserved epitope. It could block angiotensin-converting enzyme 2 (ACE2) binding to the RBD in the S protein trimer via steric hindrance. The epitopes in the RBD recognized by 55A8 and 58G6 were found to be different and complementary, which could explain the synergetic mechanism of these two NAbs. Our findings not only provide a potential antibody cocktail for clinical use against infection with current SARS-CoV-2 strains and future variants but also identify critical epitope information for the development of better antiviral agents.


title: Structural basis of human LRRK2 membrane recruitment and activation

abstract: Mutations in LRRK2 are the most common genetic cause of late-onset Parkinsons disease (PD). LRRK2 encodes the leucine-rich repeat kinase 2 (LRRK2), whose kinase activity is regulated by Rab29, a membrane-anchored GTPase. However, molecular mechanisms underlying Rab29-dependent recruitment and activation of LRRK2 remain unclear. Here we report cryo-EM structures of LRRK2-Rab29 complexes in three oligomeric states, illustrating snapshots of key steps during LRRK2 membrane recruitment and activation. Rab29 binds to the ARM domain of LRRK2, and disruption at the interface abrogates LRRK2 kinase activity. Activation of LRRK2 is underpinned by the formation of an unexpected Rab29-induced super-assembly containing two central kinase-active and two peripheral kinase-inactive LRRK2 protomers. Central protomers undergo pronounced oligomerization-associated rearrangements and adopt an active conformation. Our work reveals the structural mechanism for LRRK2s spatial regulation controlled by Rab GTPases, provides mechanistic insights into pathogenic mutations and identifies new opportunities to design LRRK2 inhibitors for PD treatment.


title: Log-order improved in trans hammerhead ribozyme turnover rates: reevaluating therapeutic space for small catalytic RNAs

abstract: We discovered an enhanced functionality hammerhead ribozyme (EhhRz), designed to act in trans against human rod opsin (RHO) mRNA, with turnover activity >300 nM min-1 under substrate-excess conditions and physiological Mg2+ levels (1 mM). We developed a real-time moderate-throughput fluorescence quantitative hhRz kinetic assay, which is linear with substrate and product moles and supported by gel-based measures. The EhhRz targets a CUC{downarrow} cleavage site in a substrate with no predicted secondary/tertiary structure and demonstrates classic Michaelis-Menten turnover behavior when the substrate is in 10-fold excess (Vmax/Km up to 1.60 x 108 min-1 M-1), which is comparable to RNase A. EhhRzs show cooperative titration with a Kd of 0.73 {+/-} 0.02 mM at cellular Mg2+ concentrations and a Hill coefficient of 1.73 {+/-} 0.07. The upstream EhhRz antisense flank (bound to a downstream substrate flank) interacts with stem-loop II, and examinations of different variants revealed that a U7 residue in the downstream flank of the substrate is not essential for enhanced activity. Under single-turnover conditions with substrate pre-annealed to enzyme, reaction rates exceeded 1,000 min-1. These findings show that RNA catalysis approaches the efficiency of the ribosome and suggests EhhRz in trans is a druggable nucleic acid therapeutic.

category: pharmacology and toxicology


title: A 3-Dimensional bioprinted human gut-liver axis model for studying Alcoholic Liver Disease

abstract:
Gut-liver axis is the interaction between the gut, its microbiome and the liver. The crosstalk and interaction between these organs plays an important role in their individual health and disease. Alcoholic liver disease (ALD) is a case in point where dysfunction of intestine actively promotes liver damage by alcohol. A flashpoint in ALD is the breach of intestinal integrity caused by gut bacteria Enterococcus faecalis (E.Faecalis). More specifically, Cytolysin, a toxin secreted by this bacteria may have a central role in the genesis of ALD. 3-D bioprinted human simulations of the gut-liver axis may help better understand the genesis of ALD.

Here we developed a 3 dimensional bioprinted in vitro model composed of human origin intestinal and liver cells to explore the role of Cytolysin and ethanol in intestinal and liver damage. We find that neither Cytolysin or ethanol are sufficient for cell damage but a combination of the two act in concert to cause maximum breach in intestinal integrity. Secondly we find that enhanced transport of macromolecules thru the intestinal layer is not caused by overt cell toxicity but occurs through potentially paracellular/transcellular pathways. Our model will be used to test repurposed and new drugs/ biologics for treatment of ALD as well as other intestinal inflammatory diseases.


title: Pseudomonas aeruginosa Elicits Sustained IL-1β Upregulation in Alveolar Macrophages from Lung Transplant Recipients

abstract:
BackgroundIsolation of Pseudomonas aeruginosa (PsA) is associated with increased BAL (bronchoalveolar lavage) inflammation and lung allograft injury in lung transplant recipients (LTR). However, the effect of PsA on macrophage responses in this population is incompletely understood. We examined human alveolar macrophage (AM) responses to PsA and Pseudomonas dominant microbiome in healthy lung transplant recipients (LTR).

MethodsWe stimulated THP-1 derived macrophages (THP-1M) and human AM from LTR with different bacteria and LTR BAL derived microbiome characterized as Pseudomonas-dominant. Macrophage responses were assessed by high dimensional flow cytometry, including their intracellular production of cytokines (TNF-, IL-6, IL-8, IL-1{beta}, IL-10, IL-1RA, and TGF-{beta}). Pharmacological inhibitors were utilized to evaluate the role of the inflammasome in PsA-macrophages interaction.

ResultsWe observed upregulation of pro-inflammatory cytokines (TNF-, IL-6, IL-8, IL-1{beta}) following stimulation by PsA compared to other bacteria (Staphylococcus aureus, Prevotella melaninogenica, Streptococcus pneumoniae) in both THP-1 derived and LTR AM, predominated by IL-1{beta}. IL-1{beta} production from THP-1 was sustained after PsA stimulation for up to 96 hours and 48 hours in LTR AM. Treatment with the inflammasome inhibitor BAY11-7082 abrogated macrophage IL-1{beta} and IL-18 production after PsA exposure. BAL Pseudomonas-dominant microbiota elicited an increased IL-1{beta}, similar to PsA, an effect abrogated by the addition of antibiotics.

ConclusionPsA and PsA-dominant lung microbiota induce sustained IL-1{beta} production in LTR AM. Pharmacological targeting of the inflammasome reduces PsA-macrophage-IL1{beta} responses, underscoring their use in lung transplant recipients.


title: Anti-SARS-Cov-2 S-RBD IgG formed after BNT162b2 vaccination can bind C1q and activate complement

abstract:
IntroductionActivation of the classical complement pathway through C1q binding to immunoglobulins (Ig) contributes to pathogen neutralization, thus, the ability of Ig produced after vaccination to bind C1q could affect vaccine efficacy. In this study, we investigated C1q binding and subsequent complement activation by anti-spike (S) protein receptor-binding domain (RBD) specific antibodies produced following vaccination with either the mRNA vaccine BNT162b2 or the inactivated vaccine BBIBP-CorV.

MethodsSerum samples were collected in the period July 2021-March 2022. Participants demographic data, type of vaccine, date of vaccination, as well as adverse effects of the vaccine were recorded. The serum samples were incubated with S protein RBD-coated plates. Levels of human IgG, IgM, and C1q, that were bound to the plate, as well as formed C5b-9, were compared between different groups of participants.

ResultsA total of 151 samples were collected from vaccinated (n=116) and non-vaccinated (n=35) participants. Participants who received either one or two doses of BNT162b2 formed higher levels of anti-RBD IgG than participants who received BBIBP-CorV. The anti-RBD IgG formed following either vaccine bound C1q, but significantly more C1q binding was observed in participants who received BNT162b2. Subsequently, C5b-9 formation was significantly higher in participants who received BNT162b2, while no significant difference in C5b-9 formation was found between the non-vaccinated and BBIBP-CorV groups. Formation of C5b-9 was strongly correlated to C1q binding, additionally, the ratio of formed C5b-9/ bound C1q was significantly higher in the BNT162b2 group.

ConclusionAnti-RBD IgG formed following vaccination can bind C1q with subsequent complement activation, the degree of terminal complement pathway activation differed between vaccines, which could play a role in in the protection offered by COVID-19 vaccines. Further investigation into the correlation between vaccine protection and the ability of vaccine generated antibodies to activate complement is required.


title: 2,4-Diacetylphloroglucinol Against Candida albicans: Biofilm Formation, Aspartyl Protease Production and Ultrastructure Changes

abstract:
The dimorphic fungus Candida albicans is the one of the most important opportunistic pathogen of human. The use of fungicides against candida encounters sub-inhibitory effects, which are fungal stress response and undesirable for the host. In this work we investigated antifungal action of 2,4-diacetylphloroglucinol against Candida albicans ATCC 10231 with focus on they biofilm forming ability under the treatment.

It was found that 2,4-DAPG reduced ability of candida cells to form biofilm, but complete inhibition or irradiation did not achieve. Moreover, Candida albicans cells in the adherent state have been characterized by reduced susceptibility to 2,4-DAPG comparing to planktonic cells.

Investigation of mechanisms which could be explain the antibiofilm action of 2,4-DAPG has revealed the reduction in cells surface hydrophobicity and inhibition of yeast-to-hyphae transition. Biofilms formed under the sub-inhibitory concentrations of 2,4-DAPG were depleted in protein and carbohydrate content. Furthermore, we microscopically visualized the treated biofilms and have revealed numerous cannels localized on hyphae and associated with secretion of aspartyl proteases (Sap).

We assumed what excretion of Sap is triggered by reactive oxygen generated upon affecting of mitochondrion respiration by 2,4-DAPG. Introducing of antioxidant Trolox simultaneously with 2,4-DAPG lead to reducing of Sap production. Thus, production of aspartyl proteases is a one of undesirable side effect of Candida albicans treatment, but using 2,4-DAPG in combination with antioxidants is the solution to overcome it.


title: Nonlytic cellular release of hepatitis A virus requires dual capsid recruitment of the ESCRT-associated Bro1 domain proteins HD-PTP and ALIX

abstract:
Although picornaviruses are conventionally considered  nonenveloped, members of multiple picornaviral genera are released nonlytically from infected cells in extracellular vesicles. The mechanisms underlying this process are poorly understood. Here, we describe interactions of the hepatitis A virus (HAV) capsid with components of host endosomal sorting complexes required for transport (ESCRT) that play an essential role in release. We show release of quasi-enveloped virus (eHAV) in exosome-like vesicles requires a conserved export signal located within the 8 kDa C-terminal VP1 pX extension that functions in a manner analogous to late domains of canonical enveloped viruses. Fusing pX to a self-assembling engineered protein nanocage (EPN-pX) resulted in its ESCRT-dependent release in extracellular vesicles. Mutational analysis identified a 24 amino acid peptide sequence located within the center of pX that was both necessary and sufficient for nanocage release. Deleting a YxxL motif within this sequence ablated eHAV release, resulting in virus accumulating intracellularly. The pX export signal is conserved in non-human hepatoviruses from a wide range of mammalian species, and functional in pX sequences from bat hepatoviruses when fused to the nanocage protein, suggesting these viruses are released as quasi-enveloped virions. Quantitative proteomics identified multiple ESCRT-related proteins associating with EPN-pX, including ALG2-interacting protein X (ALIX), and its paralog, tyrosine-protein phosphatase non-receptor type 23 (HD-PTP), a second Bro1 domain protein linked to sorting of ubiquitylated cargo into multivesicular endosomes. RNAi-mediated depletion of either Bro1 domain protein impeded eHAV release. Super-resolution fluorescence microscopy demonstrated colocalization of viral capsids with endogenous ALIX and HD-PTP. Co-immunoprecipitation assays using biotin-tagged peptides and recombinant proteins revealed pX interacts directly through the export signal with N-terminal Bro1 domains of both HD-PTP and ALIX. Our study identifies an exceptionally potent viral export signal mediating extracellular release of virus-sized protein assemblies and shows release requires non-redundant activities of both HD-PTP and ALIX.

Authors SummaryMechanisms underlying nonlytic release of canonical nonenveloped viruses from infected cells are poorly understood. We show here that release of hepatitis A virus from cells in exosome-like vesicles requires nonredundant activities of two distinct Bro1-domain proteins associated with host cell machinery (ESCRT) for endosomal sorting, HD-PTP and ALIX. We demonstrate both Bro1 domain proteins are recruited to the viral capsid by the pX segment of the 1D capsid protein, and that they act in a non-redundant manner to mediate virus release. Fusing pX to a self-assembling nanocage protein resulted in ESCRT-dependent release mediated by a short pX peptide sequence conserved in hepatoviruses from bats to humans. Mutations within the pX sequence ablate release and result in noncytolytic virus accumulating intracellularly. Our study identifies an exceptionally potent viral export signal mediating extracellular release of virus-sized protein assemblies and shows nonlytic release of quasi-enveloped virus is an ancient evolutionary trait of hepatoviruses.


title: Whole genome sequencing of three mesorhizobia isolated from northern Canada to identify genomic adaptations promoting nodulation in cold climates

abstract: The N2-fixing symbiosis between rhizobia and legumes is negatively impacted by numerous stresses, including low temperatures. To identify genomic features and biochemical pathways of rhizobia that could foster improved symbiotic function under low temperatures, we isolated and characterized three Mesorhizobium strains from legume nodules collected at two distant northern Canadian sites. Whereas the classical determinants of nodulation and nitrogen fixation are located on the chromosome of most mesorhizobia, whole genome sequencing revealed that these genes are on a large symbiotic megaplasmid in all three of the newly isolated strains. A pangenome-wide association study identified 25 genes putatively associated with mesorhizobia isolated from arctic or subarctic environments, with the genomic location of many of these genes implying a relationship with legume symbiosis. Phylogenetic and sequence analyses of the common nodulation genes revealed alleles that are highly conserved amongst mesorhizobia isolated from northern climates but uncommon in mesorhizobia isolated from similar plant hosts in other climatic regions, suggesting potential functional adaptive differences and the horizontal transfer of these alleles between northern rhizobia. We speculate that nod sequence divergence was driven by climatic factors, and that the encoded proteins may be particularly stable and/or active at low temperatures.


title: Interpreting and de-noising genetically engineered barcodes in a DNA virus

abstract: The concept of a nucleic acid barcode applied to pathogen genomes is easy to grasp and the many possible uses are straightforward. But implementation may not be easy, especially when growing through multiple generations or assaying the pathogen long-term. The potential problems include: the barcode might alter fitness, the barcode may accumulate mutations, and construction of the marked pathogens may result in unintended barcodes that are not as designed. Here, we generate approximately 5000 randomized barcodes in the genome of the prototypic small DNA virus murine polyomavirus. We describe the challenges faced with interpreting the barcode sequences obtained from the library. Our Illumina NextSeq sequencing recalled much greater variation in barcode sequencing reads than the expected 5000 barcodes - necessarily stemming from the Illumina library processing and sequencing error. Using data from defined control virus genomes cloned into plasmid backbones we develop a vetted post-sequencing method to cluster the erroneous reads around the true virus genome barcodes. These findings may foreshadow problems with randomized barcodes in other microbial systems and provide a useful approach for future work utilizing nucleic acid barcoded pathogens.


title: LaeA-dependent production of small molecules of Aspergillus niger that compete with specific antibodies that bind to human immune receptors

abstract: Microorganisms secrete a variety of compounds into their environment such as proteins, carbohydrates, and secondary metabolites. These molecules play diverse roles in the interaction of microbes with their abiotic and biotic environment. Little is known about secreted fungal molecules mediating immune evasion. Here we screened culture media of three Aspergilli to assess whether these fungi secrete molecules that can compete with specific antibodies that bind to human immune receptors. Culture media of Aspergillus fumigatus Af293, Aspergillus tubingensis CBS 133792 and the non-acidifying mutant strain Aspergillus niger D15#26 contained components that showed competition for binding to a total of 13 receptors, of which PSGL-1, CXCR1, and CXCR2, were shared between the three species. Filtration experiments showed that most, if not all, interacting components were [≤] 3 kDa. Production of the components that competed with antibodies to bind to CD88 and CXCR2 was shown to be regulated by LaeA. The component(s) that competed for binding to CXCR1 was not only produced in the non-acidifying strain Aspergillus niger D15#26 but also in the non-acidifying oahA deletion strain of Aspergillus niger. Together, these data show that Aspergillus species might produce small molecules that interact with human immune receptors.


title: Targeted genomic sequencing with probe capture for discovery and surveillance of coronaviruses in bats

abstract:
Public health emergencies like SARS, MERS, and COVID-19 have prioritized surveillance of zoonotic coronaviruses, resulting in extensive genomic characterization of coronavirus diversity in bats. Sequencing viral genomes directly from animal specimens remains a laboratory challenge, however, and most bat coronaviruses have been characterized solely by PCR amplification of small regions from the best-conserved gene. This has resulted in limited phylogenetic resolution and left viral genetic factors relevant to threat assessment undescribed.

In this study, we evaluated whether a technique called hybridization probe capture can achieve more extensive genome recovery from surveillance specimens. Using a custom panel of 20,000 probes, we captured and sequenced coronavirus genomic material in 21 swab specimens collected from bats in the Democratic Republic of the Congo. For 15 of these specimens, probe capture recovered more genome sequence than had been previously generated with standard amplicon sequencing protocols, providing a median 6.1-fold improvement (ranging up to 69.1-fold). Probe capture data also identified five novel alpha- and betacoronaviruses in these specimens, and their full genomes were recovered with additional deep sequencing. Based on these experiences, we discuss how probe capture could be effectively operationalized alongside other sequencing technologies for high-throughput, genomics-based discovery and surveillance of bat coronaviruses.


title: A de novo transcription-dependent TAD boundary underpins critical multiway interactions during antibody class switch recombination

abstract: Conflicts between transcription and cohesin-mediated loop extrusion can majorly influence 3D chromatin architecture but whether these structural changes affect biological function is unknown. Here, we show that a critical step in antibody class switch recombination (CSR) in activated B cells, namely, the juxtaposition (synapsis) of donor and acceptor switch (S) recombination sequences at the immunoglobulin heavy chain locus (Igh), occurs at the interface of a de novo topologically associating domain (TAD) boundary formed via transcriptional activity at acceptor S regions. Using Tri-C to capture higher-order multiway chromatin conformations, we find that synapsis occurs predominantly in the proximity of distal 3 CTCF-binding sites and that this multiway conformation is abolished upon downregulation of transcription and loss of the TAD boundary at the acceptor S region. Thus, an insulating de novo TAD boundary created by the conflict between transcription and loop extrusion plays a direct role in the mechanism of CSR.

category: molecular biology


title: Allosteric links between the hydrophilic N-terminus and transmembrane core of human Na+/H+ antiporter NHA2

abstract: The human Na+/H+ antiporter NHA2 (SLC9B2) transports Na+ or Li+ across the plasma membrane in exchange for protons, and is implicated in various pathologies. It is a 537 amino acids protein with an 82 residues long hydrophilic cytoplasmic N-terminus followed by a transmembrane part comprising 14 transmembrane helices. We optimized the functional expression of HsNHA2 in the plasma membrane of a salt-sensitive Saccharomyces cerevisiae strain and characterized a set of mutated or truncated versions of HsNHA2 in terms of their substrate specificity, transport activity, localization and protein stability. We identified a highly conserved proline 246, located in the core of the protein, as being crucial for ion selectivity. The replacement of P246 with serine or threonine resulted in antiporters with altered substrate specificity and increased resistance to the HsNHA2-specific inhibitor phloretin that were not only highly active at an acidic pH of 4.0 (like the native antiporter), but also at neutral pH. We also experimentally confirmed the importance of a putative salt bridge between E215 and R432 for antiporter function and structural integrity. Truncations of the first 50 - 70 residues of the N-terminus doubled the transport activity of HsNHA2, whilst changes in the charge at positions E47, E56, K57, or K58 decreased the antiporters transport activity. Thus, the hydrophilic N-terminal part of the protein appears to allosterically autoinhibit its cation transport. Our data also show this in vivo approach to be useful for a rapid screening of SNPs effect on HsNHA2 activity.


title: The Drosophila Fab-7 boundary element modulates Abd-B gene activity in the genital disc by guiding an inversion of collinear chromatin organization and alternative promoter use

abstract: Hox genes encode transcription factors that specify segmental identities along the Antero-Posterior body axis. These genes are organized in clusters, where their order corresponds to their activity along the body axis, an evolutionary conserved feature known as collinearity. In Drosophila, the BX-C cluster contains the three most posterior Hox genes, where their collinear activation incorporates progressive replacement of histone modifications, reorganization of 3D chromatin architecture and sequential activation of boundary elements and cis-regulatory regions. To dissect functional hierarchies, we compared chromatin organization in larvae and in cell lines, with a focus on the Abd-B gene. Our work establishes the importance of the Fab-7 boundary element for insulation between 3D domains marked by different histone modifications. Interestingly, we detected a non-canonical inversion of collinear chromatin dynamics at the Abd-B gene, with the active histone domain decreasing in size. This chromatin organization differentially instructed alternative Abd-B promoter use, thereby expanding the possibilities to regulate transcriptional output.

category: developmental biology


title: Relative abundance data can misrepresent heritability of the microbiome

abstract: Host genetics can shape microbiome composition, but to what extent it does, remains unclear. Like any other complex trait, this question can be addressed by estimating the heritability (h2) of the microbiome - the proportion of variance in the abundance of each taxon that is attributable to host genetic variation. However, unlike most complex traits, microbiome heritability is typically based on relative abundance data, where taxon-specific abundances are expressed as the proportion of the total microbial abundance in a sample. We derived an analytical approximation for the heritability that one obtains when using such relative abundances and we uncovered three problems: 1) The interdependency between taxa leads to imprecise heritability estimates. 2) Large sample size leads to high false discovery rates, overestimating the number of heritable taxa. 3) Microbial co-abundances lead to biased heritability estimates. We conclude that caution must be taken when interpreting heritability estimates and comparing values across studies.

category: evolutionary biology


title: Detection of low numbers of bacterial cells in pharmaceutical drug product using Raman Spectroscopy and PLS-DA multivariate analysis.

abstract: Sterility testing is a laborious and slow process to detect contaminants present in drug products. Raman spectroscopy is a promising label-free tool to detect microorganisms and thus gaining relevance as future alternative culture-free method for sterility testing in pharmaceutical industry. However, reaching detection limits similar to standard procedures while keeping a high accuracy remains challenging, due to weak bacterial Raman signal. In this work, we show a new non-invasive approach focusing on detect different bacteria in concentrations below 100 CFU/ml within drug product containers using Raman spectroscopy and multivariate data analysis. Even though Raman spectra form drug product with and without bacteria are similar, a partial least squared discriminant analysis (PLS-DA) model shows great performance to distinguish samples with bacteria contaminants in limits below 10 CFU/ml. We use spiked samples with bacteria spores for independent validation achieving a detection accuracy of 99%. Our results indicate a great potential of this rapid, and cost-effective approach to be use in quality control of pharmaceutical industry.


title: An outstanding bacterial membranome requires CRISPR-Cas systems to avoid the intervention of phages

abstract: Antimicrobial resistance is widely recognized as a serious global public health problem. To combat this threat, a thorough understanding of bacterial genomes is necessary. The current wide availability of bacterial genomes provides us with an in-depth understanding of the great variability of dispensable genes and their relationship with antimicrobials. Some of these accessory genes are those involved in CRISPR-Cas systems, which are acquired immunity systems that are present in part of bacterial genomes. They prevent viral infections through small DNA fragments called spacers. But the vast majority of these spacers have not yet been associated with the virus they recognize, and this has been named CRISPR dark matter (spacers without associated recognized sequence). By analyzing the spacers of tens of thousands of genomes from six bacterial species highly resistant to antibiotics, we have been able to reduce the CRISPR dark matter from 80-90% to 15% in some cases. In addition, we have observed that, when a genome presents CRISPR-Cas systems, this is accompanied by particular collections of membrane proteins. Our results suggest that when a bacterium presents membrane proteins that make it compete better in its environment, and these proteins are in turn receptors for specific phages, it would be forced to acquire CRISPR-Cas immunity systems to avoid infection by these phages.


title: The EGFR-STYK1-FGF1 axis sustains functional drug tolerance to EGFR inhibitors in EGFR-mutant non-small cell lung cancer

abstract: Non-small cell lung cancer (NSCLC) patients harboring activating mutations in epidermal growth factor receptor (EGFR) are sensitive to therapy with EGFR tyrosine kinase inhibitors (TKI). Despite remarkable clinical responses using EGFR TKI, surviving drug tolerant cells serve as a reservoir from which drug resistant tumors may emerge. This study addresses the need for improved efficacy of EGFR TKI by identifying targets involved in functional drug tolerance against them. To this aim, a high-throughput siRNA kinome screen was performed using two EGFR TKI-sensitive EGFR-mutant NSCLC cell lines in the presence/absence of the second-generation EGFR TKI afatinib. From the screen, Serine/Threonine/Tyrosine Kinase 1 (STYK1) was identified as a target that when downregulated potentiates the effects of EGFR inhibition in vitro. We found that chemical inhibition of EGFR combined with the siRNA-mediated knockdown of STYK1 led to a significant decrease in cancer cell viability and anchorage-independent cell growth. Further, we show that STYK1 selectively interacts with mutant EGFR and that the interaction is disrupted upon EGFR inhibition. Finally, we identified fibroblast growth factor 1 (FGF1) as a downstream effector of STYK1 in NSCLC cells. Accordingly, downregulation of STYK1 counteracted the afatinib-induced upregulation of FGF1. Altogether, we unveil STYK1 as a valuable target to repress the pool of surviving drug tolerant cells arising upon EGFR inhibition. Co-targeting of EGFR and STYK1 could lead to a better overall outcome for NSCLC patients.


title: Cancer stem cell-derived extracellular vesicles preferentially target MHCII- macrophages and PD1+ T cells in the tumor microenvironment

abstract: Immunotherapy is an approved treatment option for head and neck squamous cell carcinoma (HNSCC). However, the response rate to immune checkpoint blockade is only 13% for recurrent HNSCC, highlighting the urgent need to better understand tumor-immune interplay, with the ultimate goal of improving patient outcomes. HNSCC present high local recurrence rates and therapy resistance that can be attributed to the presence of cancer stem cells (CSC) within tumors. CSC exhibit singular properties that enable them to avoid immune detection and eradication. The immune cell types that directly engage with CSC to allow immune escape and cancer recurrence are still unknown. Here, we genetically engineered CSC-derived extracellular vesicles (EVs) to perform sortase-mediated in vivo proximity labeling. We identified specific immune cell subsets recruited into the CSC niche. We demonstrated that unmanipulated CSC-EVs preferentially target MHC-II- macrophages and PD1+ T cells, and that such EV-mediated intercellular communication between CSC and these immune cells contributed to the observed spatial interactions and niche sharing. These results suggest that combination therapies targeting CSC, tumor macrophages and PD1 may synergize and lower local recurrence rates in HNSCC patients.


title: SWAP1-SFPS-RRC1 splicing factor complex modulates pre-mRNA splicing to promote photomorphogenesis in Arabidopsis

abstract:
Light signals perceived by a group of photoreceptors have profound effects on the physiology, growth, and development of plants. The red/far-red light absorbing phytochromes modulate these aspects by intricately regulating gene expression at multiple levels. Previously, we reported that two splicing factors SFPS (SPLICING FACTOR FOR PHYTOCHROME SIGNALING) and RRC1 (REDUCED RED LIGHT RESPONSES IN CRY1CRY2 BACKGROUND 1), interact with photoactivated phyB to regulate light-mediated pre-mRNA alternative splicing (AS). Here, we report the identification and functional characterization of an RNA binding splicing factor, SWAP1 (SUPPRESSOR-OF-WHITE-APRICOT/SURP RNA-BINDING DOMAIN-CONTAINING PROTEIN1). Loss-of-function swap1-1 mutant is hyposensitive to red light and exhibits a day light-independent early flowering phenotype. SWAP1 physically interacts with both SFPS and RRC1 in a light-independent manner and forms a ternary complex. In addition, SWAP1 also physically interacts with photoactivated phyB and colocalizes with nuclear phyB photobodies. Deep RNA-seq analyses show that SWAP1 regulates the gene expression and pre-mRNA alternative splicing of a large number of genes including those involved in plant responses to light signaling. A comparison with SFPS- and RRC1-regulated events shows that all three splicing factors coordinately regulate the alternative splicing of a subset of genes. Collectively, our study uncovered the function of a new splicing factor, which interacts with photoactivated phyB, in modulating light-regulated development in plants.

SIGNIFICANCERegulation of transcription and pre-mRNA alternative splicing is essential for the transcript diversity and modulation of light signaling in plants. Although several transcription factors involved in light signaling have been discovered and characterized in-depth, only a few splicing factors have been shown to be involved in the regulation of light signaling pathways. In this study, we describe the identification and characterization of a new splicing factor SWAP1, which interact with two previously characterized splicing factors, SFPS and RRC1, forming a ternary complex. We show that, like SFPS and RRC1, SWAP1 also interacts with photoactivated phyB, and consistently, swap1 seedlings are hyposensitive to red light. SWAP1 modulates alternative splicing of a large number of genes and a subset of these genes are coordinately regulated by SFPS, RRC1 and SWAP1. These results highlight the importance of not only the transcription factors but also the phyB-interacting splicing factors in light-regulated plant development.

category: plant biology


title: Shuffled ATG8 interacting motifs form an ancestral bridge between UFMylation and C53-mediated autophagy

abstract: UFMylation mediates the covalent modification of substrate proteins with UFM1 (Ubiquitin-fold modifier 1) and regulates the selective degradation of endoplasmic reticulum (ER) via autophagy (ER-phagy) to maintain ER homeostasis. Specifically, collisions of the ER-bound ribosomes trigger ribosome UFMylation, which in turn activates C53-mediated autophagy that clears the toxic incomplete polypeptides. C53 has evolved non-canonical shuffled ATG8 interacting motifs (sAIMs) that are essential for ATG8 interaction and autophagy initiation. Why these non-canonical motifs were selected during evolution, instead of canonical ATG8 interacting motifs remains unknown. Here, using a phylogenomics approach, we show that UFMylation is conserved across the eukaryotes and secondarily lost in fungi and some other species. Further biochemical assays have confirmed those results and showed that the unicellular algae, Chlamydomonas reinhardtii has a functional UFMylation machinery, overturning the assumption that this process is linked to multicellularity. Our conservation analysis also revealed that UFM1 co-evolves with the sAIMs in C53, reflecting a functional link between UFM1 and the sAIMs. Using biochemical and structural approaches, we confirmed the interaction of UFM1 with the C53 sAIMs and found that UFM1 and ATG8 bound to the sAIMs in a different mode. Conversion of sAIMs into canonical AIMs prevented binding of UFM1 to C53, while strengthening ATG8 interaction. This led to the autoactivation of the C53 pathway and sensitized Arabidopsis thaliana to ER stress. Altogether, our findings reveal an ancestral toggle switch embodied in the sAIMs that regulates C53-mediated autophagy to maintain ER homeostasis.


title: p75NTR prevents the onset of cerebellar granule cell migration via RhoA activation

abstract:
Neuronal migration is one of the fundamental processes during brain development. Several neurodevelopmental disorders can be traced back to dysregulated migration. Although substantial efforts have been placed in identifying molecular signals that stimulate migration, little is known about potential mechanisms that restrict migration. These restrictive mechanisms are essential for proper development since it helps coordinate the timing for each neuronal population to arrive and establish proper connections. Moreover, preventing migration away from a proliferative niche is necessary to maintain a pool of proliferating cells until the proper number of neuronal progenitors is attained.

Here, we identify an anti-migratory role for the p75 neurotrophin receptor (p75NTR) in cerebellar development. Our results show that granule cell precursors robustly express p75NTR in the external granule layer (EGL) when they are proliferating during postnatal development, however, they do not express p75NTR when they migrate either from the rhombic lip during embryonic development or from the EGL during postnatal development. We show that p75NTR prevented GCP migration by maintaining elevated levels of active RhoA. The expression of p75NTR was sufficient to prevent the migration of the granule cells even in the presence of BDNF, a well-established chemotactic signal for this cell population. Our findings suggest that the expression of p75NTR might be a critical signal that stops and maintains the GCPs in the proliferative niche of the EGL, promoting the clonal expansion of cerebellar granule neurons.


title: Human Cytomegalovirus induces neuronal enolase to support virally-mediated metabolicremodeling

abstract:
Viruses depend on cellular metabolic resources to supply the energy and biomolecular building blocks necessary for their replication. Human Cytomegalovirus (HCMV), a leading cause of birth defects and morbidity in immunosuppressed individuals, induces numerous metabolic activities that are important for productive infection. However, many of the mechanisms through which these metabolic activities are induced and how they contribute to infection are unclear. We find that HCMV infection of fibroblasts induces a neuronal gene signature, as well as the expression of several metabolic enzyme isoforms that are typically expressed in other tissue types. Of these, the most substantially induced gene was the neuron-specific isoform of enolase (ENO2). Induction of ENO2 expression is important for HCMV-mediated glycolytic activation, as well as for the virally-induced remodeling of pyrimidine-sugar metabolism, which provides the glycosyl subunits necessary for protein glycosylation. Inhibition of ENO2 expression or activity reduced UDP-sugar pools, attenuated the accumulation of viral glycoproteins, and induced the accumulation of non-infectious viral particles. In addition, our data indicate that the induction of ENO2 expression depends on the HCMV UL38 protein. Collectively, our data indicate that HCMV infection induces a tissue atypical neuronal glycolytic enzyme to activate glycolysis and UDP-sugar metabolism to provide the glycosyl building blocks necessary for viral protein glycosylation and the production of infectious virions.

Significance StatementViruses are obligate parasites that obtain energy and mass from their host cell. Control over the metabolic resources of the cell has emerged as an important host-pathogen interaction that can determine infectious outcomes. We find that the Human Cytomegalovirus (HCMV), a major cause of birth defects and morbidity in immunosuppressed patient populations, induces a neuronal gene signature in fibroblasts including the expression of neuronal-specific enolase (ENO2). Our data indicate that ENO2 is important for HCMV-mediated metabolic remodeling including glycolytic activation and the production of pyrimidine sugars, as well as for viral infectivity. These findings indicate that viruses are capable of tapping into alternative tissue-specific metabolic programs to support infection, highlighting an important viral mechanism of metabolic modulation.


title: Donor strand complementation, isopeptide bonds and glycosylation stabilise highly resilient archaeal thread filaments

abstract: Pili are ubiquitous filamentous surface extensions that play crucial roles for bacterial and archaeal cellular processes such as adhesion, biofilm formation, motility, cell-cell communication, DNA uptake and horizontal gene transfer to name a few. Here we report on the discovery and structure of the archaeal thread - a remarkably stable archaeal pilus that belongs to a so-far largely unknown class of protein filaments. We find that the filament is highly glycosylated and interconnected via donor strand complementation, as well as isopeptide bonds, reminiscent of bacterial type I pili. Despite striking structural similarity with bacterial type-1 pili, archaeal threads appear to have evolved independently and are likely assembled by a markedly distinct mechanism.


title: Upregulation of Somatostatin Receptor Type 2 in a Receptor-Deficient In Vivo Pancreatic Neuroendocrine Tumor Model Improves Tumor Response to Targeted 177Lu-DOTATATE

abstract:
PurposeThe goal of this study was to test whether histone deacetylase inhibitors (HDACis) restore somatostatin receptor type 2 (SSTR2) expression in models of high-grade pancreatic neuroendocrine tumors (PNETs), thereby facilitating effective treatment with 177Lu-DOTATATE therapy.

MethodsTo assess tumor grade correlation with SSTR2 expression, we assessed human SSTR2 promoter methylation and expression levels in 96 NIH patient samples and merged the GSE149395 and GSE117852 datasets. We used three NET cell lines (QGP-1, BON-1, GOT-1) characterized by variable SSTR2 expression profiles for functional in vitro studies using HDACis. Finally, the QGP-1 xenograft mouse model, with low basal SSTR2 expression, was used to analyze the therapeutic efficacy of combined HDACi and 177Lu-DOTATATE therapies.

ResultsHuman PNET SSTR2 promoter methylation showed a significant positive correlation with higher tumor grades (P = 0.000014). We also found a significant negative correlation (P < 0.0001) between SSTR2 promoter methylation and SSTR2 expression in three NET cell lines. In vitro, SSTR2 expression increased significantly in BON-1 and QGP-1 cells at 48 and 72 hours in a dose-dependent fashion using two different HDACis, valproic acid and CI-994. In vivo studies demonstrated a significant increase in 177Lu-DOTATATE tumor uptake in QGP-1-engrafted mice after 10 days of CI-994 pretreatment (P = 0.0175). Treatment with 177Lu-DOTATATE reduced tumor size in mice pretreated with CI-994 compared to 177Lu-DOTATATE alone (at 15 days, P = 0.0028).

ConclusionHDACis increase SSTR2 surface expression in models of high-grade, SSTR2-deficient PNETs. This approach has the potential to improve tumor response to targeted therapy with 177 Lu-DOTATATE in patients with receptor-negative, metastatic PNETs.

Translational Relevance StatementPancreatic neuroendocrine tumors (PNETs) express high levels of somatostatin receptor type 2 (SSTR2), a unique target for both tumor imaging and therapy. Unfortunately, high-grade PNETs lose SSTR2 surface expression and thus become ineligible for SSTR2-targeted 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT). Restoring SSTR2 expression through the reversal of inhibitory epigenetic gene silencing mechanisms has the potential for improving tumor responsiveness to PRRT. We demonstrate that histone deacetylase inhibitors (HDACis) upregulate SSTR2 surface expression in three NET cell lines in vitro. In an in vivo PNET xenograft model with low basal SSTR2 expression, our studies validate a significantly higher tumor uptake of SSTR2-targeted 177Lu-DOTATATE in animals pretreated with HDACis compared to controls. Furthermore, we show that this higher tumor uptake results in significant anti-tumor response when compared to standard PRRT alone. Our preclinical results thus provide a rationale for utilizing HDACi pretreatment to improve targeted radionuclide therapy in patients with SSTR2-negative, metastatic PNETs.


title: Investigating the impact of database choice on the accuracy of metagenomic read classification for the rumen microbiome

abstract: Microbiome analysis is quickly moving towards high-throughput methods such as metagenomic sequencing. Accurate taxonomic classification of metagenomic data relies on reference sequence databases, and their associated taxonomy. However, for understudied environments such as the rumen microbiome many sequences will be derived from novel or uncultured microbes that are not present in reference databases. As a result, taxonomic classification of metagenomic data from understudied environments may be inaccurate. To assess the accuracy of taxonomic read classification, this study classified metagenomic data that had been simulated from cultured rumen microbial genomes from the Hungate collection. To assess the impact of reference databases on the accuracy of taxonomic classification, the data was classified with Kraken 2 using several reference databases. We found that the choice and composition of reference database significantly impacted on taxonomic classification results, and accuracy. In particular, NCBI RefSeq proved to be a poor choice of database. Our results indicate that inaccurate read classification is likely to be a significant problem, affecting all studies that use insufficient reference databases. We observe that adding cultured reference genomes from the rumen to the reference database greatly improves classification rate and accuracy. We also demonstrate that metagenome-assembled genomes (MAGs) have the potential to further enhance classification accuracy by representing uncultivated microbes, sequences of which would otherwise be unclassified or incorrectly classified. However, classification accuracy was strongly dependent on the taxonomic labels assigned to these MAGs. We therefore highlight the importance of accurate reference taxonomic information and suggest that, with formal taxonomic lineages, MAGs have the potential to improve classification rate and accuracy, particularly in environments such as the rumen that are understudied or contain many novel genomes.

category: genomics


title: Evaluation of CA repeat arrays as targets for MeCP2 function in the brain

abstract: AO_SCPLOWBSTRACTC_SCPLOWThe DNA binding protein MeCP2 is reported to bind methylated cytosine in CG and CA motifs in genomic DNA, but it was recently proposed that arrays of tandemly repeated CA containing either methylated or hydroxymethylated cytosine are the primary targets for MeCP2 binding and function. Here we investigated the predictions of this hypothesis using a range of published datasets. We failed to detect enrichment of cytosine modification at genomic CA repeat arrays in mouse brain regions and found no evidence for preferential MeCP2 binding at CA repeats. Moreover, we did not observe a correlation between the CA repeat density near genes and their degree of transcriptional deregulation when MeCP2 was absent. Our results do not provide support for the hypothesis that CA repeats are key mediators of MeCP2 function. Instead, we found that CA repeats are subject to CAC methylation to a degree that is typical of the surrounding genome and contribute modestly to MeCP2-mediated modulation of gene expression in accordance with their content of this canonical target motif.


title: The metabolite-controlled ubiquitin conjugase Ubc8 promotes mitochondrial protein import by enhancing assembly of the TOM complex

abstract: Mitochondria are essential organelles that play a key role in cellular energy metabolism. Transitions between glycolytic and respiratory conditions induce considerable adaptations of the cellular proteome. These metabolism-dependent changes are particularly pronounced for the protein composition of mitochondria. Here we show that the yeast cytosolic ubiquitin conjugase Ubc8 plays a crucial role in the remodeling process when cells transition from respiratory to fermentative conditions. Ubc8 is a conserved and well-studied component of the catabolite control system that is known to regulate the stability of gluconeogenesis enzymes. Unexpectedly, we found that Ubc8 also promotes the assembly of the translocase of the outer membrane of mitochondria (TOM) and stabilizes its cytosol-exposed receptor subunit Tom22. Ubc8 deficiency results in a compromised protein import into mitochondria and a subsequent accumulation of mitochondrial precursor proteins in the cytosol. Our observations show that Ubc8, which is controlled by the prevailing metabolic conditions, promotes the switch from glucose synthesis to glucose usage in the cytosol and induces the biogenesis of the mitochondrial TOM machinery in order to improve mitochondrial protein import during phases of metabolic transition.


title: Conditional covalent lethality driven by oncometabolite accumulation

abstract: Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is a cancer predisposition syndrome driven by mutation of the tumor suppressor fumarate hydratase (FH). Inactivation of FH causes accumulation of the electrophilic oncometabolite fumarate. In the absence of methods for reactivation, tumor suppressors can be targeted via identification of synthetic lethal interactions using genetic screens. Inspired by recent advances in chemoproteomic target identification, here we test the hypothesis that the electrophilicity of the HLRCC metabolome may produce unique susceptibilities to covalent small molecules, a phenomenon we term conditional covalent lethality. Screening a panel of chemically diverse electrophiles we identified a covalent ligand, MP-1, that exhibits FH-dependent cytotoxicity. Synthesis and structure-activity profiling identified key molecular determinants underlying the molecules effects. Chemoproteomic profiling of cysteine reactivity together with clickable probes validated the ability of MP-1 to engage an array of functional cysteines, including one lying in the Zn-finger domain of the tRNA methyltransferase enzyme TRMT1. TRMT1 overexpression rescues tRNA methylation from inhibition by MP-1 and partially attenuates the covalent ligands cytotoxicity. Our studies highlight the potential for covalent metabolites and small molecules to synergistically produce novel synthetic lethal interactions and raise the possibility of applying phenotypic screening with chemoproteomic target identification to identify new functional oncometabolite targets.


title: On the Prediction of non-CG DNA Methylation

abstract: DNA cytosine methylation is an epigenetic modification that has a critical role in gene regulation and genome stability. DNA methylation can be detected and measured using sequencing instruments after sodium bisulfite conversion, but experiments can be expensive for large eukaryotic genomes. Sequencing non-uniformity and mapping biases can leave parts of the genome with low or no coverage, thus hampering the ability of obtaining DNA methylation levels for all cytosines. To address these limitations, several computational methods have been proposed that can predict DNA methylation from the DNA sequence around the cytosine, or from the methylation level of nearby cytosines. Most of these methods are, however, entirely focused on CG methylation in humans and other mammals. In this work, we study for the first time the problem of predicting cytosine methylation for CG, CHG, and CHH contexts on five plant species, either from the DNA primary sequence around the cytosine or the methylation levels of neighboring cytosines. In this framework, we also study (1) the cross-species prediction problem, i.e., the classification performance when training on one species and testing on another species, and the (2) the cross-context prediction problem, i.e., the classification performance when training on one context and testing on another context (within the same species). Finally, we show that providing the classifier with gene annotation information allows our classifier to outperform the prediction accuracy of state-of-the-art methods.


title: Trimethylamine N-oxide (TMAO) enhances substrate mechanical stability probed by single molecule magnetic tweezers

abstract: Trimethylamine N-oxide (TMAO) is a well-known osmolyte to stabilize the folded proteins through a variety of mechanisms. Since mechanical strength of proteins is a critical determinant of its stabilization, TMAO might play a relevant role by favoring its folding dynamics or by enhancing its mechanical stability. To address this question, we have performed the single-molecule magnetic tweezers experiment to explore the TMAO effect on two structurally distinct substrates-protein L and talin. We observed that TMAO increases the mechanical stability of these proteins through increasing their unfolding force. Additionally, we are able to demonstrate that TMAO retards the unfolding kinetics, while accelerating the refolding kinetics under force; which eventually tilts the energy landscape towards the folded state. Interestingly, this TMAO-enhanced protein folding generates mechanical work output upto [~]67 zJ, allowing the protein folding under higher force regime. Overall this TMAO-enhanced mechanical stability provides a significant implication to folding-induced structural stability of proteins.


title: Pervasive transcription enhances the accessibility of H-NS-silenced promoters and generates bistability in Salmonella virulence gene expression

abstract: In Escherichia coli and Salmonella, many genes silenced by the nucleoid structuring protein H-NS are activated upon inhibiting Rho-dependent transcription termination. This response is poorly understood and difficult to reconcile with the view that H-NS acts mainly by blocking transcription initiation. Here we have analysed the basis for the upregulation of H-NS-silenced Salmonella Pathogenicity Island 1 (SPI-1) in cells depleted of Rho-cofactor NusG. Evidence from genetic experiments, semi-quantitative 5 RACE-Seq and ChiP-Seq shows that transcription originating from spurious antisense promoters, when not stopped by Rho, elongates into a H-NS-bound regulatory region of SPI-1, displacing H-NS and rendering the DNA accessible to the master regulator HilD. In turn, HilDs ability to activate its own transcription triggers a positive feedback loop that results in transcriptional activation of the entire SPI-1. Significantly, single-cell analyses revealed that this mechanism is largely responsible for the coexistence of two subpopulations of cells that, although genetically identical, either express or dont express SPI-1 genes. We propose that cell-to-cell differences produced by stochastic spurious transcription, combined with feedback loops that perpetuate the activated state, can generate bimodal gene expression patterns in bacterial populations.


title: Mycobacterium tuberculosis transcriptional regulator Rv1019 is upregulated in hypoxia and negatively regulates Rv3230c-Rv3229c operon encoding enzymes in the oleic acid biosynthetic pathway

abstract: The main obstacle in eradicating tuberculosis is the ability of Mycobacterium tuberculosis to remain dormant in the host, and then to get reactivated even years later under immuno-compromised conditions. Transcriptional regulation in intracellular pathogens plays an important role in adapting to the challenging environment inside the host cells. Previously, we demonstrated that Rv1019, a putative transcriptional regulator of M. tuberculosis H37Rv, is an autorepressor. We showed that, Rv1019 is cotranscribed with Rv1020 (mfd) and Rv1021 (mazG) encoding DNA repair proteins and negatively regulates the expression of these genes. In the present study, we show that Rv1019 also regulates the expression of the genes Rv3230c and Rv3229c (desA3) which form a two-gene operon in M. tuberculosis. Constitutive expression of Rv1019 in M. tuberculosis significantly downregulated the expression of these genes. Employing Waynes hypoxia-induced dormancy model of M. tuberculosis, we show that Rv1019 is upregulated (3-fold) under hypoxia. Finally, by reporter assay, using M. smegmatis as a model, we validate that Rv1019 is recruited to the promoter of Rv3230c-Rv3229c during hypoxia and negatively regulates this operon which is involved in the biosynthesis of oleic acid.


title: Assessing pyrethroid resistance status in the Culex pipiens complex (Diptera: Culicidae) from the northwest suburbs of Chicago, Illinois using Cox regression of bottle bioassays and other detection tools

abstract: Culex pipiens complex is an important vector of epizootic and zoonotic pathogens, including West Nile virus. Chicago, Illinois and its suburbs have suffered high incidence of human West Nile virus infections in the past. This makes abatement programs in and around the Chicago area an essential service. The control of Cx. pipiens is often complicated by rapidly evolving resistance to pyrethroids, which are the most widely used chemical class in US mosquito abatement programs. The present study assessed Sumithrin(R) resistance in Cx. pipiens collected from five locations around Cook County, Illinois, neighboring the city limits of Chicago. According to CDC guidelines, samples from all five locations demonstrated some resistance to Sumithrin(R). When assessed with Anvil(R), a formulated product made of Sumithrin(R) synergized with piperonyl butoxide, susceptibility was rescued in mosquitoes from three out of the five locations, suggesting involvement of mixed-function oxidases and/or carboxylesterases in Sumithrin(R) resistance at these locations. Not all locations had susceptibility rescued by Anvil(R), but these locations had relatively low knockdown resistance allele frequencies, suggesting that mechanisms other than knockdown resistance may be involved. Enzyme activities did not reveal any marked trends that could be related back to mortality in the bottle bioassays, which highlights the need for multiple types of assays to infer enzymatic involvement in resistance. Future directions in pyrethroid resistance management in Chicago area Cx. pipiens are discussed.


title: Fear engrams and NPYergic circuit in the dorsal dentate gyrus determine remote fear memory generalization.

abstract: Generalization is a critical feature of aversive memories and significantly contributes to post-traumatic stress disorder (PTSD) pathogenesis. While fear memories over time tend to generalize across differences in the contextual background and even to novel contextual settings, this effect can be counteracted by exposure to controlled reminder sessions even at remote time points. Using Pavlovian fear conditioning in mice, we show that generalization to a novel context of remote memory is associated with a loss of cellular engram activation in the dorsal dentate gyrus (dDG) and can be effectively counteracted by a preceding contextual reminder session. In addition to engram cells activation in response to a novel context, the reminder session also leads to a recovery of neuropeptide Y (NPY) function in the dDG and dDG-CA3 neurotransmission. In line with a proposed role of NPY as a resilience factor, we found that chronic viral knockdown of NPY in the dDG and blockage of its activity-dependent expression in NPYergic dDG interneurons with dominant-negative CREBS133A both increase remote memory generalization. With chemogenetic silencing of these interneurons, we could localize their critical involvement to a time window during and immediately following the fear memory acquisition. Together, these findings suggest that NPYergic interneurons of the dDG, shaping the memory engram during fear learning and early consolidation, determine fear generalization.


title: Achieving improved accuracy for imputation of ancient DNA

abstract: Genotype imputation has the potential to increase the amount of information that can be gained from the often limited biological material available in ancient samples. As many widely used tools have been developed with modern data in mind, their design is not necessarily reflective of the requirements in studies of ancient DNA. Here, we investigate if an imputation method based on the full probabilistic Li and Stephens model of haplotype frequencies might be beneficial for the particular challenges posed by ancient data. We present an implementation called prophaser, and compare imputation performance to two alternative pipelines that have been used in the ancient DNA community based on the Beagle software. Considering empirical ancient data downsampled to lower coverages as well as present-day samples with artificially thinned genotypes, we show that the proposed method is advantageous at lower coverages, where it yields improved accuracy and ability to capture rare variation. The software prophaser is optimized for running in a massively parallel manner and achieved reasonable runtimes on the experiments performed when executed on a GPU.


title: Assessment of local potato cultivars found in Cis-Himalayan region of West Bengal through morphology and biochemical profiling

abstract: Potato is a major global food crop grown for tubers (underground storage stems) that are high in carbohydrates, minerals, and vitamins. The presence of anthocyanins in tuber skin and flesh can have a significant impact on customer preferences. Potatoes are also high in resistant starches, which have a variety of health benefits, including enhanced fullness, cholesterol reduction, and a reduced risk of colon cancer etc. In West Bengal, diabetes is prevalent. Similarly, according to ICMR studies, colon cancer affects 8.9% of all cancer patients in West Bengal cancer which is caused by ill eating habits or the consumption of foods that are low in antioxidants. 5-10% of colon cancers are genetically caused, while the remainder are caused by poor eating habits or the consumption of foods that are low in antioxidants. To address these issues, one strategy is to eat foods with a low glycemic index and high antioxidant content as a staple food. The tuber tissues of the potato (S. tuberosum L.) accumulate various quantities of anthocyanins, which are commonly consumed around the world. Anthocyanins are pigments that range in colour from red to purple and are found throughout the plant kingdom. Anthocyanins are powerful antioxidants that are water soluble. The red skin potato is well-known among the general public. The epidermal layer contains a high quantity of red anthocyanins, which causes the skin to be red. With this background the present study has been undertaken to address the following objectives morphological (quantitative and qualitative traits) and biochemical characterization of local potato cultivars and identification of most stable genotypes based on the anthocyanin content and tuber yield of local potato cultivars. For our recent research 14 local potato cultivar from North Bengal were collected and evaluated for DUS characterization showed wide range of variability with respect to different phenotypic variants of ten characters. Overall predominant DUS characters of local potato cultivars found in North Bengal are medium sized apical length of sprout, short stem height, compact foliage structure, open leaf structure, ovate lanceolate type leaflet shape, purple leaf sprout predominant colour, spherical leaf sprout shape, medium intensity of anthicyanin coloraton at the base, light intensity of anthicyanin coloraton at the tip and weak nature of light sprout pubescence base. The results of the present investigation suggest that local potato cultivars collected from the northern part of West Bengal showed a high level of genetic variation. The differences between genotypes were highly significant at the 1% and 5% alpha level for all characters like tuber yield, length and weight of tuber, length of sprout, chlorophyll content, canopy temperature, and number of tuber per plant, according to the analysis of variance. Three quantitative traits namely tuber yield, tuber breadth, tuber length played major role in the genetic variance. Anthocyanin content had more contribution to diversify the local potato cultures according to biochemical characterization AMMI analysis suggested that Jalpai from CoochBehar is the most stable potato cultivars in respect to anthocyanin content and tuber yield per plant.


title: Evolutionarily conserved effects of Notch signaling drive intestinal graft-versus-host disease in mice and non-human primates

abstract:
Notch signaling promotes T-cell pathogenicity and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT) in mice, with a dominant role for the Delta-like ligand DLL4. To assess if Notchs effects are evolutionarily conserved and identify key mechanisms, we studied antibody-mediated DLL4 blockade in a non-human primate model similar to human allo-HCT. Short-term DLL4 blockade improved post-transplant survival with striking, durable protection from gastrointestinal GVHD, out of proportion to other disease sites. Unlike prior immunosuppressive strategies, anti-DLL4 interfered with a T-cell transcriptional program associated with intestinal infiltration. In cross-species investigations, Notch inhibition decreased surface abundance of the gut-homing integrin a4b7 in conventional T-cells via b1 competition for a4 binding, while preserving a4b7 in regulatory T-cells. Thereby, DLL4/Notch blockade decreased effector T-cell infiltration into the gut, with increased regulatory to conventional T-cell ratios early after allo-HCT. Our results identify a conserved, biologically unique and targetable role of DLL4/Notch signaling in GVHD.

One Sentence SummaryNotch signaling promotes pathogenic effector T cell infiltration of the intestine during acute graft-versus-host disease.


title: Boid Inclusion Body Disease (BIBD) Is Also a Disease of Wild Boa Constrictors

abstract:
Reptarenaviruses cause Boid Inclusion Body Disease (BIBD), a potentially fatal disease, occurring in captive constrictor snakes boas and pythons worldwide. Classical BIBD, characterized by the formation of pathognomonic cytoplasmic inclusion bodies (IBs), occurs mainly in boas, whereas in pythons, for example, reptarenavirus infection most often manifests as central nervous system signs with limited IB formation. The natural hosts of reptarenaviruses are unknown, although wild constrictor snakes are among the suspects. Here, we report BIBD with reptarenavirus infection in indigenous captive and wild boid snakes in Costa Rica using histology, immunohistology, transmission electron microscopy, next-generation sequencing (NGS), and RT-PCR. The snakes studied represented diagnostic post mortem cases of captive and wild caught snakes since 1989. The results from NGS on archival paraffin blocks confirm that reptarenaviruses have been present in wild boa constrictors in Costa Rica already in the 1980s. Continuous sequences de novo assembled from the low-quality RNA obtained from paraffin embedded tissue allowed the identification of a distinct pair of reptrarenavirus S and L segments in all studied animals; in most cases reference assembly could recover almost complete segments. Sampling of three prospective cases in 2018 allowed examination of fresh blood or tissues, and resulted in identification of additional reptarenavirus segments and hartmanivirus co-infection. Our results show that BIBD is not only a disease of captive snakes, but also occurs in indigenous wild constrictor snakes in Costa Rica, suggesting boa constrictors to play a role in natural reptarenavirus circulation.

IMPORTANCEThe literature describes cases of boid inclusion body disease (BIBD) in captive snakes since the 1970s, and in the 2010s, others and we identified reptarenaviruses as the causative agent. BIBD affects captive snakes globally, but the origin and the natural host of reptarenaviruses remains unknown. In this report, we show BIBD and reptarenavirus infections in two native Costa Rican constrictor snake species, and by studying archival samples, we show that both the viruses and the disease have been present in wild snakes in Costa Rica at least since the 1980s. The diagnosis of BIBD in wild boa constrictors suggests that this species plays a role in the circulation of reptarenaviruses. Additional sample collection and analysis would help to clarify this role further and the possibility of e.g. vector transmission from an arthropod host.