[This corrects the article DOI: 10.3389/fcimb.2022.1015655.].

The global pandemic of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has become a severe global health problem because of its rapid spread. Both Ace2 and NRP1 provide initial viral binding sites for SARS-CoV-2. Here, we show that cysteine residues located in the vestigial plasminogen-apple-nematode (PAN) domain of NRP1 are necessary for SARS-CoV-2 spike protein internalization. Mutating novel cysteine residues in the PAN altered NRP1 stability and downstream activation of extracellular signal-regulated kinase (ERK) signaling pathway and impaired its interaction with the spike protein. This resulted in a significant reduction in spike protein abundance in Vero-E6 cells for the original, alpha, and delta SARS-CoV-2 variants even in the presence of the Ace2. Moreover, mutating these cysteine residues in NRP1 significantly lowered its association with Plexin-A1. As the spike protein is a critical component for targeted therapy, our biochemical study may represent a distinct mechanism to develop a path for future therapeutic discovery.

The trend of using natural fiber composites is increasing rapidly due to the growing environmental concerns and increased awareness on sustainability. However, due to the lower strength of natural fibers (95- 1600MPa) compared to synthetic fibers (2000-4000 MPa), high moisture absorption rate, variation in the fiber properties, and lower processing temperature range limit its applications. This study advances the concept of overmolding of bamboo fiber-polypropylene (BF-PP) composites with unidirectional and 0/90 textile grade carbon fiber (TCF) tape. BF-PP composites were processed using extrusion compression molding (ECM) technique. TCF tape was produced on a thermoplastic polymer impregnation line. Mechanical and morphological properties of overmolded hybrid composites were studied. These studies attempted to evaluate the interface between the BF-PP and the TCF thermoplastic tape. Flexural strength and flexural modulus of BF-PP composites increased by -152% and -164% respectively by overmolding BF-PP with unidirectional TCF tape; and by -53% and -54% respectively on overmolding 0/90 TCF thermoplastic tape. Scanning electron microscopic (SEM) images of the TCF tape overmolded BF-PP composites exhibited good interfacial bonding.

Agrobacterium -mediated plant transformation (AMT) is the basis of modern-day plant biotechnology. One major drawback of this technology is the recalcitrance of many plant species/varieties to Agrobacterium infection, most likely caused by elicitation of plant defense responses. Here, we develop a strategy to increase AMT by engineering Agrobacterium tumefaciens to express a type III secretion system (T3SS) from Pseudomonas syringae and individually deliver the P. syringae effectors AvrPto, AvrPtoB, or HopAO1 to suppress host defense responses. Using the engineered Agrobacterium , we demonstrate increase in AMT of wheat, alfalfa and switchgrass by ~250%–400%. We also show that engineered A. tumefaciens expressing a T3SS can deliver a plant protein, histone H2A-1, to enhance AMT. This strategy is of great significance to both basic research and agricultural biotechnology for transient and stable transformation of recalcitrant plant species/varieties and to deliver proteins into plant cells in a non-transgenic manner.

Staphylococcus aureus (SA) is a significant and well-recognized causative organism of bacterial osteomyelitis. Osteomyelitis is an inflammatory bone disease characterized by progressive bone destruction and loss. This disease causes significant morbidity and mortality to the patient and poses therapeutic challenges for clinicians. To improve the efficacy of therapeutic strategies to combat bacterial osteomyelitis, there is a need to define the molecular epidemiology of bacterial organisms more clearly and further the understanding of the pathogenesis of SA osteomyelitis. We conducted in vitro characterization of the pathogenic capabilities of an isolate of SA ST398 derived from a clinical case of osteomyelitis in a goat. We also report a rodent mandibular defect model to determine the ability of ST398 to cause reproducible osteomyelitis. Our results indicate that ST398 can invade and distort pre-osteoblastic cells in culture, induce significant inflammation and alter expression of osteoregulatory cytokines. We also demonstrate the ability of ST398 to induce osteomyelitis in a rat mandibular model. When compiled, these data support ST398 as a competent osteomyelitis pathogen.

Alfalfa (Medicago sativaL.) is one of the most important forage crops throughout the world. Maximizing leaf retention during the haymaking process is critical for achieving superior hay quality and maintaining biomass yield. Leaf abscission process affects leaf retention. Previous studies have largely focused on the molecular mechanisms of floral organ, pedicel and seed abscission but scarcely touched on leaf and petiole abscission. This study focuses on leaf and petiole abscission in the model legumeMedicago truncatulaand its closely related commercial species alfalfa. By analysing thepetiolule-like pulvinus(plp) mutant inM. truncatulaat phenotypic level (breakstrength and shaking assays), microscopic level (scanning electron microscopy and cross-sectional analyses) and molecular level (expression level and expression pattern analyses), we discovered that the loss of function ofPLPleads to an absence of abscission zone (AZ) formation andPLPplays an important role in leaflet and petiole AZ differentiation. Microarray analysis indicated thatPLPaffects abscission process through modulating genes involved in hormonal homeostasis, cell wall remodelling and degradation. Detailed analyses led us to propose a functional model ofPLPin regulating leaflet and petiole abscission. Furthermore, we cloned thePLPgene (MsPLP) from alfalfa and produced RNAi transgenic alfalfa plants to down-regulate the endogenousMsPLP. Down-regulation ofMsPLPresults in altered pulvinus structure with increased leaflet breakstrength, thus offering a new approach to decrease leaf loss during alfalfa haymaking process.

SummaryAlfalfa (Medicago sativa L.) is one of the most important forage crops throughout the world. Maximizing leaf retention during the haymaking process is critical for achieving superior hay quality and maintaining biomass yield. Leaf abscission process affects leaf retention. Previous studies have largely focused on the molecular mechanisms of floral organ, pedicel and seed abscission but scarcely touched on leaf and petiole abscission. This study focuses on leaf and petiole abscission in the model legume Medicago truncatula and its closely related commercial species alfalfa. By analysing the petiolule‐like pulvinus (plp) mutant in M. truncatula at phenotypic level (breakstrength and shaking assays), microscopic level (scanning electron microscopy and cross‐sectional analyses) and molecular level (expression level and expression pattern analyses), we discovered that the loss of function of PLP leads to an absence of abscission zone (AZ) formation and PLP plays an important role in leaflet and petiole AZ differentiation. Microarray analysis indicated that PLP affects abscission process through modulating genes involved in hormonal homeostasis, cell wall remodelling and degradation. Detailed analyses led us to propose a functional model of PLP in regulating leaflet and petiole abscission. Furthermore, we cloned the PLP gene (MsPLP) from alfalfa and produced RNAi transgenic alfalfa plants to down‐regulate the endogenous MsPLP. Down‐regulation of MsPLP results in altered pulvinus structure with increased leaflet breakstrength, thus offering a new approach to decrease leaf loss during alfalfa haymaking process.

Despite the close association between Kaposi's sarcoma (KS) and immune dysfunction, it remains unclear whether tumor infiltrating immune cells (TIIC), by their absence, presence, or dysfunction, are mechanistically correlated with KS pathogenesis.Therefore, their potential capacity to serve as prognostic biomarkers of KS disease progression or control is unclear.Because epidemic-KS (EpKS) occurs with HIV-1 co-infection, it is particularly important to compare TIIC between EpKS and HIV-negative African endemic-KS (EnKS) to dissect the roles of HIV-1 and Kaposi Sarcoma-associated herpesvirus (KSHV) in KS pathogenesis.This cross-sectional study of 13 advanced KS (4 EnKS, 9 EpKS) patients and 3 healthy controls utilized single-color immunohistochemistry and dual-color immunofluorescence assays to characterize and quantify KSHV infected cells in relation to various TIIC in KS biopsies.Analysis of variance (ANOVA) and Mann-Whitney tests were used to assess differences between groups where P-values < 0.05 were considered significant.The abundance of KSHV infected cells was heterogeneous in KS biopsies.Despite the presence of T-cell chemoattractant chemokine CxCL-9 in biopsies, CD8 + T-cells were sparsely distributed in regions with evident KSHV infected cells but were readily detectable in regions devoid of KSHV infected cells (P < 0.0001).CD68 + (M1) macrophages were evenly and diffusely distributed in KS biopsies, whereas, the majority of CD163 + (M2) macrophages were localized in regions devoid of KSHV infected cells (P < 0.0001).Overall, the poor immune cell infiltration or co-localization in KS biopsies independent of HIV-1 co-infection suggests a fundamental tumor immune evasion mechanism that warrants further investigation.

Introduction: Long noncoding RNAs (lncRNAs) contribute to the pathogenesis of obesity, a risk factor for cardiovascular disease. The underlying mechanisms are not completely understood, in part, due to that the functions of the majority of them remain unknown in many processes such as mitochondrial homeostasis and cellular senescence. Here, we set out to test the hypothesis that lncRNAs play key roles in obesity by regulating mitochondrial function and cellular senescence in the endothelium. Methods and Results: In this study, transcriptome analysis revealed that lncRNA maternally expressed gene 3 (Meg3) is one of the top induced lncRNAs in the endothelium from adipose tissue in diet-induced obese mice. Meg3 knockdown potentiated obesity-induced insulin resistance revealed by intraperitoneal glucose and insulin tolerance tests and an increase in fasting plasma insulin levels (1.67-fold increase; p<0.05); diminished insulin signaling revealed by 43% reduction (p=0.038) in Akt phosphorylation on serine 473 in liver and, to a lesser extent, in skeletal muscle (32%; p<0.05), but not in visceral fat; and increased hepatic endothelial senescence in obese mice (e.g., 2.74- and 3.40-fold increase in p21 and p16 expression, respectively; p<0.001). Endothelial cell-specific p53 knockout partially attenuated Meg3 knockdown-induced cellular senescence and completely restored hepatic insulin signaling in obese mice. Meg3 knockdown inhibited mitochondrial bioenergetics, increased mitochondrial superoxide production, and caused fragmentation of mitochondrial network; also impaired autophagy, induced a type 1 interferon response, and triggered cellular senescence in HUVECs. Finally, the expression of Meg3 is induced in fatty livers of obese patients and strongly correlates with the cellular senescence marker p16 (r=0.50; p=0.0007). Conclusions: Deficiency of lncRNA Meg3 contributes to mitochondrial dysfunction, hepatic endothelial senescence, and accelerated obesity-induced insulin resistance. Meg3 induction is important in limiting obesity-induced endothelial senescence and insulin resistance, suggesting that manipulation of Meg3 expression may represent a novel approach to manage obesity-associated cardiometabolic disease.

When positioned horizontally, roots grow down toward the direction of gravity. This phenomenon, called gravitropism, is influenced by most of the major plant hormones including brassinosteroids. Epi-brassinolide (eBL) was previously shown to enhance root gravitropism, a phenomenon similar to the response of roots exposed to the actin inhibitor, latrunculin B (LatB). This led us to hypothesize that eBL might enhance root gravitropism through its effects on filamentous-actin (F-actin). This hypothesis was tested by comparing gravitropic responses of maize (Zea mays) roots treated with eBL or LatB. LatB- and eBL-treated roots displayed similar enhanced downward growth compared with controls when vertical roots were oriented horizontally. Moreover, the effects of the two compounds on root growth directionality were more striking on a slowly-rotating two-dimensional clinostat. Both compounds inhibited autotropism, a process in which the root straightened after the initial gravistimulus was withdrawn by clinorotation. Although eBL reduced F-actin density in chemically-fixed Z. mays roots, the impact was not as strong as that of LatB. Modification of F-actin organization after treatment with both compounds was also observed in living roots of barrel medic (Medicago truncatula) seedlings expressing genetically encoded F-actin reporters. Like in fixed Z. mays roots, eBL effects on F-actin in living M. truncatula roots were modest compared with those of LatB. Furthermore, live cell imaging revealed a decrease in global F-actin dynamics in hypocotyls of etiolated M. truncatula seedlings treated with eBL compared to controls. Collectively, our data indicate that eBL-and LatB-induced enhancement of root gravitropism can be explained by inhibited autotropic root straightening, and that eBL affects this process, in part, by modifying F-actin organization and dynamics.

Serendipita vermifera (=Sebacina vermifera; isolate MAFF305830) is a mycorrhizal fungus originally isolated from the roots of an Australian orchid that we have previously shown to be beneficial in enhancing biomass yield and drought tolerance in switchgrass, an important bioenergy crop for cellulosic ethanol production in the United States. However, almost nothing is known about how this root-associated fungus proliferates and grows through the soil matrix. Such information is critical to evaluate the possibility of non-target effects, such as unintended spread to weedy plants growing near a colonized switchgrass plant in a field environment. A microcosm experiment was conducted to study movement of vegetative mycelia of S. vermifera between intentionally inoculated switchgrass (Panicum virgatum L.) and nearby weeds. We constructed size-exclusion microcosms to test three different common weeds, large crabgrass (Digitaria sanguinalis L.), Texas panicum (Panicum texanum L.), and Broadleaf signalgrass (Brachiaria platyphylla L.), all species that typically co-occur in Southern Oklahoma and potentially compete with switchgrass. We report that such colonization of non-target plants by S. vermifera can indeed occur, seemingly via co-mingled root systems. As a consequence of colonization, significant enhancement of growth was noted in signalgrass, while a mild increase (albeit not significant) was evident in crabgrass. Migration of the fungus seems unlikely in root-free bulk soil, as we failed to see transmission when the roots were kept separate. This research is the first documentation of non-targeted colonization of this unique root symbiotic fungus and highlights the need for such assessments prior to deployment of biological organisms in the field.