Biology subjects

Tan, J.

Publications and source records attributed to Tan, J..

At least 109 records · Page 6Linked to original sources

bioRxiv2023

Trophic interactions in microbiomes influence plant host population size and ecosystem function

Plant microbiomes that comprise diverse microorganisms, including prokaryotes, eukaryotes, and viruses are the key determinant of plant population dynamics and ecosystem function. Despite their importance, little is known about how interactions, especially trophic interactions, between microbes from different domains modify the importance of microbiomes for plant hosts and ecosystems. Using the common duckweed Lemna minor, we experimentally examined the effects of predation (by bacterivorous protozoa) and parasitism (by bacteriophage) within microbiomes on plant population size and ecosystem phosphorus removal. Our results revealed that predation increased plant population size and phosphorus removal whereas parasitism showed the opposite pattern. The structural equation modeling further pointed out that predation and parasitism affected plant population size and ecosystem function via distinct mechanisms that were both mediated by microbiomes. Our results highlight the importance of understanding microbial trophic interactions for predicting the outcomes and ecosystem impacts of plant-microbiome symbiosis.

microbiology↗

bioRxiv2022

Lab evolution, transcriptomics, and modeling reveal mechanisms of paraquat tolerance

Relationships between the genome, transcriptome, and metabolome underlie all evolved phenotypes. However, it has proved difficult to elucidate these relationships because of the high number of variables measured. A recently developed data analytic method for characterizing the transcriptome can simplify interpretation by grouping genes into independently modulated sets (iModulons). Here, we demonstrate how iModulons reveal deep understanding of the effects of causal mutations and metabolic rewiring. We use adaptive laboratory evolution to generate E. coli strains that tolerate high levels of the redox cycling compound paraquat, which produces reactive oxygen species (ROS). We combine resequencing, iModulons, and metabolic models to elucidate six interacting stress tolerance mechanisms: 1) modification of transport, 2) activation of ROS stress responses, 3) use of ROS-sensitive iron regulation, 4) motility, 5) broad transcriptional reallocation toward growth, and 6) metabolic rewiring to decrease NADH production. This work thus reveals the genome-scale systems biology of ROS tolerance. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/521246v1_ufig1.gif" ALT="Figure 1"> View larger version (83K): org.highwire.dtl.DTLVardef@187f455org.highwire.dtl.DTLVardef@ba0798org.highwire.dtl.DTLVardef@148b175org.highwire.dtl.DTLVardef@17a8f8c_HPS_FORMAT_FIGEXP M_FIG C_FIG

systems biology↗

bioRxiv2022

Label-free and high-throughput removal of residual undifferentiated cells from iPSC-derived spinal-cord progenitor cells

The transplantation of spinal cord progenitor cells (SCPCs) derived from human induced pluripotent stem cells (iPSCs) has beneficial effects on treating spinal cord injury (SCI). However, the presence of residual undifferentiated iPSCs amongst their differentiated progeny poses a high risk as it can develop teratomas or other types of tumors post-transplantation. Despite the need to remove these residual undifferentiated iPSCs, no specific surface markers can identify them for subsequent removal. By profiling the size of SCPCs after a 10-day differentiation process, we found that the large-sized group contains significantly more cells expressing pluripotent markers. In this study, we employed a sized-based, label-free separation using an inertial microfluidic-based device to remove tumor-risk cells. The device can reduce the number of undifferentiated cells from an SCPC population with high throughput (i.e., > 3 million cells per minute) without affecting cell viability and functions. The sorted cells were verified with immunofluorescence staining, flow cytometry analysis, and colony culture assay. We demonstrated the capabilities of our technology to reduce the percentage of OCT4-positive cells. Our technology has great potential for the downstream processing of cell manufacturing workflow, ensuring better quality and safety of transplanted cells.

bioengineering↗

bioRxiv2022

Enhancing detectable fluorescence fluctuation for high-throughput and four-dimensional live-cell super-resolution imaging

Super-resolution (SR) imaging with high-throughput is invaluable to fast and high-precision profiling in a wide range of biomedical applications. However, prevalent SR methods require sophisticated acquisition devices and specific imaging control, and may cost a fairly long time on a single field-of-view. These essentially increase the construction difficulty, including challenges in imaging throughput, system establishment, and automation. Using the natural photophysics of fluorescence, fluctuation-based microscopy techniques can routinely break the diffraction limit with no need for additional optical components, but its long acquisition time still poses a challenge for high-throughput imaging or visualizing transient organelle dynamics. Here, we propose an SR method based on the Auto-Correlation with two-step Deconvolution (SACD) that reduces the number of frames required by maximizing the detectable fluorescence fluctuation behavior in each measurement, with further removal of tunable parameters by a Fourier ring correlation analysis. It only needs 20 frames for twofold lateral and axial resolution improvements, while the SR optical fluctuation imaging (SOFI) needs more than 1000 frames. By capturing raw images for [~]10 minutes, we record an SR image with [~]128 nm resolution that contains 2.4 gigapixels covering an area of [~]2.0 mm x 1.4 mm, including more than 2,000 cells. Beyond that, by applying continuity and sparsity joint constraint, the Sparse deconvolution-assisted SACD enables 4D live-cell SR imaging of events such as mitochondrial fission and fusion. Overall, as an open-sourced module, we anticipate SACD can offer direct access to SR, which may facilitate the biology studies of cells and organisms with high-throughput and low-cost.

biophysics↗

bioRxiv2022

Quantitatively mapping local quality of super-resolution microscopy by rolling Fourier ring correlation

In fluorescence microscopy, computational algorithms have been developed to suppress noise, enhance contrast, and even enable super-resolution (SR). However, the local quality of the images may vary on multiple scales, and these differences can lead to misconceptions, which is especially intractable in emerging deep-learning ones. Current mapping methods fail to finely estimate the local quality, challenging to associate the SR scale content. Here, we develop a rolling Fourier ring correlation (rFRC) framework to evaluate the reconstruction uncertainties down to SR scale. To visually pinpoint regions with low reliability, a filtered rFRC is combined with a modified resolution scaled error map (RSM), offering a comprehensive and concise map for further examination. We demonstrate their performances on various SR imaging modalities, and the resulting quantitative maps enable better SR images integrated from different reconstructions. Beyond that, we provide a strategy for learning-based restorations, allowing a direct detection of both data and model uncertainties, and expect the representative cases can inspire further advances in this rapidly developing field.

biophysics↗

bioRxiv2022

Beta tACS over rIFG and preSMA Improves Stopping Ability for Younger but not Older Adults

A growing body of research suggests that changes in both structural and functional connectivity in the aging brain contribute to declines in cognitive functions such as response inhibition. In recent years, transcranial alternating current stimulation (tACS) has garnered substantial research interest as a potential tool for the modulation of functional connectivity. Here, we report the findings from a double-blind crossover study that investigated the effects of dual-site beta tACS over the right inferior frontal gyrus (rIFG) and pre-supplementary motor area (preSMA) on functional connectivity measured with electroencephalography and response inhibition (stop-signal task performance) of healthy young (n = 18, aged 18-34 years) and older (n =15, aged 61-79 years) adults. Two tACS conditions were administered in separate sessions: in-phase tACS, where electrical currents delivered to the rIFG and preSMA had a 0{degrees} phase difference, and anti-phase tACS, where currents had a 180{degrees} phase difference. Stop-signal task performance was assessed before and after tACS. We found significant improvements in response inhibition that were not due to the phase of the tACS applied. There were also no significant changes in rIFG-preSMA phase connectivity in either age group from in- or anti-phase tACS. Furthermore, we did not observe significant differences in rIFG-preSMA phase connectivity between successful and unsuccessful inhibition, which suggests that rIFG-preSMA phase-coupling might not underlie effective response inhibition. The results offer insight into the neurophysiology of response inhibition and contribute to the future development of non-pharmacological interventions aimed at alleviating age-related declines in cognitive function.

neuroscience↗

bioRxiv2022

Oxygen is a critical regulator of cellular metabolism and function in cell culture

Cell culture is generally considered to be hyperoxic. However, the importance of cellular oxygen consumption is often underappreciated, with rates of oxygen consumption often sufficient to cause hypoxia at cell monolayers. We initially focused on cultured adipocytes as a terminally differentiated cell-type with substantial oxygen consumption rates to support diverse cellular functions. Under standard conditions, cultured adipocytes are hypoxic and highly glycolytic. Increasing oxygen diverted glucose flux toward mitochondria and resulted in thousands of gene expression changes that pointed toward alleviated physiological transcriptional responses to hypoxia. Phenotypically, providing more oxygen increased adipokine secretion and rendered adipocytes more sensitive to insulin and lipolytic stimuli. The functional benefits of increasing pericellular oxygen were transferable to other cellular systems including hPSC-derived hepatocytes and cardiac organoids. Our findings suggest that oxygen is limiting in many terminally-differentiated cell culture systems, and that controlling oxygen availability can improve the quality and translatability of cell models.

cell biology↗

bioRxiv2022

QCR7 affects the virulence of Candida albicans and the uptake of multiple carbon sources present in different host niches

BackgroundCandida albicans is a commensal yeast that may cause life-threatening infections. Studies have shown that the cytochrome b-c1 complex subunit 7 gene (QCR7) of C. albicans encodes a protein that forms a component of the mitochondrial electron transport chain complex III, making it an important target for studying the virulence of this yeast. However, to the best of our knowledge, the functions of QCR7 have not yet been characterized. MethodsA QCR7 knockout strain was constructed using SN152, and BALb/c mice were used as model animals to determine the role of QCR7 in the virulence of C. albicans. Subsequently, the effects of QCR7 on mitochondrial functions and use of carbon sources were investigated. Next, its mutant biofilm formation and hyphal growth maintenance were compared with those of the wild type. Furthermore, the transcriptome of the qcr7{Delta}/{Delta} mutant was compared with that of the WT strain to explore pathogenic mechanisms. ResultsDefective QCR7 attenuated the virulence of C. albicans infection in vivo. Furthermore, the mutant influenced the use of multiple alternative carbon sources that exist in several host niches. Moreover, it led to mitochondrial dysfunction. Furthermore, the QCR7 knockout strain showed defects in biofilm formation or the maintenance of filamentous growth. The overexpression of cell-surface-associated genes (HWP1, YWP1, XOG1, and SAP6) can restore defective virulence phenotypes and the carbon-source utilization of qcr7{Delta}/{Delta}. ConclusionThis study provides new insights into the mitochondria-based metabolism of C. albicans, accounting for its virulence and the use of variable carbon sources that promote C. albicans to colonize host niches.

microbiology↗

bioRxiv2022

Immunity induced by vaccination with recombinant influenza B virus neuraminidase protein breaks viral transmission chains in guinea pigs in an exposure intensity-dependent manner

Mucosal vaccines and vaccines that block pathogen transmission are under-appreciated in vaccine development. However, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has shown that blocking viral transmission is an important attribute of efficient vaccines. Here, we investigated if recombinant influenza virus neuraminidase (NA) vaccines delivered at a mucosal site could protect from onward transmission of influenza B viruses in the guinea pig model. We tested four different scenarios in which sequential transmission was investigated in chains of four guinea pigs. The variables tested included a low and a high viral inoculum (104 vs 105 plaque forming units) in the initial donor guinea pig and variation of exposure/cohousing time (1 day vs 6 days). In three out of four scenarios - low inoculum-long exposure, low inoculum-short exposure and high inoculum-short exposure - transmission chains were efficiently blocked. Based on this data we believe an intranasal recombinant NA vaccine could be used to efficiently curtail influenza virus spread in the human population during influenza epidemics. ImportanceVaccines that can slow respiratory virus transmission in the population are urgently needed for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza virus. Here we describe how a recombinant neuraminidase-based influenza virus vaccines reduces transmission in vaccinated guinea pigs in an exposure-intensity based manner.

microbiology↗

bioRxiv2022

Parallel processing relies on a distributed, low-dimensional cortico-cerebellar architecture

A characteristic feature of human cognition is our ability to multi-task - performing two or more tasks in parallel - particularly when one task is well-learned. How the brain supports this capacity remains poorly understood. Most past studies have focussed on identifying the areas of the brain - typically the dorsolateral prefrontal cortex - that are required to navigate information processing bottlenecks. In contrast, we take a systems neuroscience approach to test the hypothesis that the capacity to conduct effective parallel processing relies on a distributed architecture that interconnects the cerebral cortex with the cerebellum. The latter structure contains over half of the neurons in the adult human brain, and is well-suited to support the fast, effective, dynamic sequences required to perform tasks relatively automatically. By delegating stereotyped within-task computations to the cerebellum, the cerebral cortex can be freed up to focus on the more challenging aspects of performing the tasks in parallel. To test this hypothesis, we analysed task-based fMRI data from 50 participants who performed a task in which they either balanced an avatar on a screen ( Balance), performed serial-7 subtractions ( Calculation) or performed both in parallel ( Dual-Task). Using a set of approaches that include dimensionality reduction, structure-function coupling and time-varying functional connectivity, we provide robust evidence in support of our hypothesis. We conclude that distributed interactions between the cerebral cortex and cerebellum are crucially involved in parallel processing in the human brain.

neuroscience↗

bioRxiv2022

Emerging Evidence for Poxvirus-Mediated Unfolded Protein Response: Lumpy Skin Disease Virus Maintains Self-replication by Activating PERK and IRE1

The cytoplasmic replication of poxviruses requires extensive protein synthesis, challenging the capacity of the endoplasmic reticulum (ER). However, the role of the ER in the life cycle of poxviruses is unclear. In this study, we demonstrate that infection with the lumpy skin disease virus (LSDV), a poxvirus, causes ER stress in vivo and in vitro, further facilitating the activation of the unfolded protein response (UPR). Although UPR activation aids in the restoration of the cellular environment, its significance in the LSDV life cycle remains unclear. Furthermore, the role of ER imbalance for viral replication is also unknown. We show that LSDV replication is hampered by an unbalanced ER environment. In addition, we verify that the LSDV replication depends on the activation of PERK-eIF2 and IRE1-XBP1 signaling cascades rather than ATF6, implying that global translation and XBP1 cleavage are deleterious to LSDV replication. Our findings suggest that LSDV engages all UPR signaling sensors, and that activation of PERK and IRE1 sensors is indispensable to maintaining its own replication. IMPORTANCEAlthough numerous viruses cause ER stress and employ endogenous UPR components to control viral growth, there is no such evidence for poxviruses. Recent real-world epidemics of poxviruses such as monkeypox and LSDV indicated a lack of available coping strategies. Our findings show that LSDV encoding up to 156 open reading frames (ORFs) causes pressure to the stabilization of ER, triggers ER stress, and further promotes the activation of all three UPR signaling pathways. However, inhibiting PERK-eIF2 and IRE1-XBP1 was not conducive for LSDV replication. Since LSDV efficiently utilizes UPR components to assist its own replication, signal-blocking agents of PERK and IRE1 may be useful in the treatment of LSDV. More evidence for the efficacy of such therapy for LSDV, even monkeypox, could come from a clearer characterization of the ER stress-mediated viral replication process.

microbiology↗

bioRxiv2022

Peripheral Auditory Nerve Impairment in a Mouse Model of Syndromic Autism

Dysfunction of the peripheral auditory nerve (AN) contributes to dynamic changes throughout the central auditory system, resulting in abnormal auditory processing, including hypersensitivity. Altered sound sensitivity is frequently observed in autism spectrum disorder (ASD), suggesting that AN deficits and changes in auditory information processing may contribute to ASD-associated symptoms, including social communication deficits and hyperacusis. The MEF2C transcription factor is associated with risk for several neurodevelopmental disorders, and mutations or deletions of MEF2C produce a haploinsufficiency syndrome characterized by ASD, language and cognitive deficits. A mouse model of this syndromic ASD (i.e., Mef2c+/- or Mef2c-Het) recapitulates many of the MEF2C Haploinsufficiency syndrome-linked behaviors including communication deficits. We show here that Mef2c-Het mice exhibit functional impairment of the peripheral AN and a modest reduction in hearing sensitivity. We find that MEF2C is expressed during development in multiple AN and cochlear cell types, and in Mef2c-Het mice, we observe multiple cellular and molecular alterations associated with the AN, including abnormal myelination, neuronal degeneration, neuronal mitochondria dysfunction, and increased macrophage activation and cochlear inflammation. These results reveal the importance of MEF2C function in inner ear development and function and the engagement of immune cells and other non-neuronal cells, which suggests that microglia/macrophages and other non-neuronal cells might contribute, directly or indirectly, to AN dysfunction and ASD-related phenotypes. Finally, our study establishes a comprehensive approach for characterizing AN function at the physiological, cellular, and molecular levels in mice, which can be applied to animal models with a wide range of human auditory processing impairments. Significance StatementThis is the first report of peripheral auditory nerve (AN) impairment in a mouse model of human MEF2C haploinsufficiency syndrome that has well-characterized ASD related behaviors including communication deficits, hyperactivity, repetitive behavior, and social deficits. We identify multiple underlying cellular, sub-cellular, and molecular abnormalities that may contribute to peripheral AN impairment. Our findings also highlight the important roles of immune cells (e.g., cochlear macrophages) and other non-neuronal elements (e.g., glial cells and cells in the stria vascularis) in auditory impairment in ASD. The methodological significance of the study is the establishment of a comprehensive approach for evaluating peripheral AN function and impact of peripheral AN deficits with minimal hearing loss.

neuroscience↗

bioRxiv2022

VPS9D1-AS1 overexpression amplifies intratumoral TGF-β signaling and promotes tumor cell escape from CD8+ T cell killing in colorectal cancer

Efficacy of immunotherapy is limited in patients with colorectal cancer (CRC) because high expression of tumor-derived transforming growth factor (TGF)-{beta} pathway molecules and interferon (IFN)-stimulated genes (ISGs) promotes tumor immune evasion. Here, we identified a long noncoding RNA (lncRNA), VPS9D1-AS1, which was located in ribosomes and amplified TGF-{beta} signaling and ISG expression. We show that high expression of VPS9D1-AS1 was negatively associated with T lymphocyte infiltration in two independent cohorts of CRC. VPS9D1-AS1 served as a scaffolding lncRNA by binding with ribosome protein S3 (RPS3) and a competing endogenous RNA (ceRNA) to sponge miR-22-5p/514a-3p to increase the translation of TGF-{beta}, TGFBR1, and SMAD1/5/9. VPS9D1-AS1 knockout downregulated OAS1, an ISG gene, which further reduced IFNAR1 levels in tumor cells. Conversely, tumor cells overexpressing VPS9D1-AS1 were resistant to CD8+ T cell killing and lowered IFNAR1 expression in CD8+ T cells. In a conditional overexpression mouse model, VPS9D1-AS1 enhanced tumorigenesis and suppressed the infiltration of CD8+ T cells. Treating tumor-bearing mice with antisense oligonucleotide drugs targeting VPS9D1-AS1 significantly suppressed tumor growth. Our findings indicate that the tumor-derived VPS9D1-AS1/TGF-{beta}/ISG signaling cascade promotes tumor growth and enhances immune evasion and may thus serve as a potential therapeutic target for CRC.

cancer biology↗

bioRxiv2022

Highly dense and scalable protein arrays for single-molecule studies

Single-molecule proteomic studies are critically important for understanding the molecular origins of cellular phenotypes. However, no currently available technology can achieve both the single-molecule sensitivity and high dynamic range required to comprehensively analyze the complex mixtures of proteins in biological samples. One approach to achieve high sensitivity across a wide dynamic range would be to create a protein array that arranges billions of single molecules with regular spacing on a patterned surface. However, creating such a protein array has remained an unsolved challenge for the field. Here, we present a highly scalable method for fabricating dense single-molecule protein arrays using a specially designed DNA origami structure, protein click-conjugation, photolithography and surface functionalization. The origami-structure is enhanced via terminal deoxynucleotidyl transferase-extension, which generates brush-like projections, increasing the effective size of the origami from 88 nm to greater than 200 nm. These particles are large enough to enable super-Poisson deposition of individual protein molecules on a nano-patterned chip (>98% occupancy with only 1% of sites occupied with multiple protein molecules). This approach allowed for single-molecule protein display of 600 million protein molecules per microscope slide-sized chip with the potential to scale further with denser feature spacing. We hypothesize that this technology will ultimately enable the development of highly scalable proteomic analysis platforms that address the currently unmet need for protein measurements at single-molecule sensitivity across an exceptionally wide dynamic range of protein concentrations.

bioengineering↗

bioRxiv2022

Sugar transporter Slc37a2 regulates bone metabolism via a dynamic tubular lysosomal network in osteoclasts

Osteoclasts are giant bone-digesting cells that harbour specialized lysosome-related organelles termed secretory lysosomes (SLs). SLs store cathepsin K and serve as a membrane precursor to the ruffled border, the osteoclasts resorptive apparatus. Yet, the molecular composition and spatiotemporal organization of SLs remains incompletely understood. Here, using organelle-resolution proteomics, we identify member a2 of the solute carrier 37 family (Slc37a2) as a SL sugar transporter. We demonstrate that Slc37a2 localizes to the SL limiting membrane and that these organelles adopt a hitherto unnoticed but dynamic tubular network in living osteoclasts that is required for bone digestion. Accordingly, mice lacking Slc37a2 accrue high bone mass owing to uncoupled bone metabolism and disturbances in SL export of monosaccharide sugars, a prerequisite for SL delivery to the ruffled border. Thus, Slc37a2 is a physiological component of the osteoclasts unique secretory organelle and a potential therapeutic target for metabolic bone diseases.

cell biology↗

bioRxiv2022

Broadly neutralizing antibodies target the coronavirus fusion peptide

The potential for future coronavirus outbreaks highlights the need to develop strategies and tools to broadly target this group of pathogens. Here, using an epitope-agnostic approach, we identified six monoclonal antibodies that bound to spike proteins from all seven human-infecting coronaviruses. Epitope mapping revealed that all six antibodies target the conserved fusion peptide region adjacent to the S2 cleavage site. Two antibodies, COV44-62 and COV44-79, broadly neutralize a range of alpha and beta coronaviruses, including SARS-CoV-2 Omicron subvariants BA.1 and BA.2, albeit with lower potency than RBD-specific antibodies. In crystal structures of Fabs COV44-62 and COV44-79 with the SARS-CoV-2 fusion peptide, the fusion peptide epitope adopts a helical structure and includes the arginine at the S2 cleavage site. Importantly, COV44-79 limited disease caused by SARS-CoV-2 in a Syrian hamster model. These findings identify the fusion peptide as the target of the broadest neutralizing antibodies in an epitope-agnostic screen, highlighting this site as a candidate for next-generation coronavirus vaccine development. One-Sentence SummaryRare monoclonal antibodies from COVID-19 convalescent individuals broadly neutralize coronaviruses by targeting the fusion peptide.

immunology↗

bioRxiv2022

Modulation of the gut microbiome by novel synthetic glycans for the production of propionate and the reduction of cardiometabolic risk factors

BackgroundIncreasing evidence indicates that an altered gut microbiome participates in the development of cardiometabolic syndrome and associated risk factors, such as insulin resistance, dyslipidemia, and obesity, and that targeting the gut microbiome is a promising strategy to lower the risk for cardiometabolic diseases. Part of this reduction is mediated by specific metabolites generated by the gut microbiome. Propionate, a short-chain fatty acid (SCFA) produced from dietary glycans by certain gut microbes is known to exert multiple beneficial metabolic effects. Here, we identify KB39, a novel gut microbiome-targeting synthetic glycan selected for its strong propionate-producing capacity, and demonstrate its effects in vivo to reduce cardiometabolic disease using western diet-fed LDL receptor knock-out mice. MethodsEx vivo fermentation screening of a large library of synthetic glycan ensembles was performed using gut microbiome communities from healthy subjects and overweight patients with type 2 diabetes. A synthetic glycan identified for its high propionate-producing capacity (KB39) was then tested in vivo for effects on systemic, blood and cecal metabolic parameters in Ldlr-/- mice fed a western diet. ResultsEx vivo screening of ~600 synthetic glycans using human gut microbiota from healthy subjects and patients with type 2 diabetes identified a novel glycan (KB39) with high propionate-producing capacity that increased propionate contribution to total SCFA and propionate-producing bacterial taxa compared to negative control. In western diet-fed Ldlr-/- mice, KB39 treatment resulted in an enrichment in propiogenic bacteria and propionate biosynthetic genes in vivo and an increase in absolute and relative amounts of propionate in the cecum. This also resulted in significant decreases in serum total cholesterol, LDL-cholesterol, and insulin levels, as well as reduced hepatic triglycerides and cholesterol content compared to non-treated animals. Importantly, KB39 treatment significantly reduced atherosclerosis, liver steatosis and inflammation, upregulated hepatic expression of genes involved in fatty acid oxidation and downregulated transcriptional markers of inflammation, fibrosis and insulin resistance with only a mild lowering of body weight gain. ConclusionsOur data show that KB39, a novel synthetic glycan supporting a high propionate-producing microbiome, can reduce cardiometabolic risk factors and disease in mice and suggest this approach could be of benefit for the prevention or treatment of cardiometabolic diseases in humans. CLINICAL PERSPECTIVEWhat is new? O_LIA novel synthetic glycan, KB39, was selected from a library of compounds for its high propionate-producing capacity and beneficial effects on the human gut microbiome composition C_LIO_LIKB39 modulates the gut microbiome for high propionate production and significantly reduces cardiometabolic risk factors and disease in a murine model of cardiometabolic diseases C_LI What are the clinical implications? O_LIKB39, delivered orally, could be of benefit for the prevention or treatment of cardiometabolic diseases in humans C_LIO_LIThe efficacy of KB39 in mice compared to the clinical drug fenofibrate justifies further study in humans C_LI

microbiology↗

bioRxiv2022

Safety assessment of insecticidal proteins: A case study utilizing His-tagged protein to determine the safety of Mpp75Aa1.1, a new ETX_MTX2 protein that controls western corn rootworm

The recently discovered insecticidal protein Mpp75Aa1.1 from Brevibacillus laterosporus is one member of the ETX_MTX family of beta-pore forming proteins ({beta}-PFPs) expressed in genetically modified (GM) maize to control western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte). In this paper, bioinformatic analysis establishes that although Mpp75Aa1.1 shares varying degrees of similarity to members of the ETX_MTX2 protein family, it is unlikely to contribute to any allergenic, toxic, or otherwise adverse biological effects. The safety of Mpp75Aa1.1 is further supported by a weight of evidence including evaluation of history of safe use (HOSU) of ETX_MTX2 proteins. Assessments using either purified Mpp75Aa1.1 protein or a poly-histidine-tagged (His-tagged) variant of the Mpp75Aa1.1 protein demonstrate that both forms of the protein are heat labile at temperatures at or above 55 {degrees}C, degraded by gastrointestinal proteases within 0.5 min, and have no adverse effects in acute mouse oral toxicity studies at a dose level of 1920 or 2120 mg/kg body weight. Results also indicate that the domain-based protein characterization should be considered as part of the weight of evidence for the safe consumption of food or feed. Furthermore, these results support the use of His-tagged proteins as suitable surrogates for assessing the safety of their non-tagged parent proteins.

pharmacology and toxicology↗