Epidermal Infection Research Articles

Diterpenoids of Caryopteris trichosphaera W. W. Sm. inhibiting MRSA and VRE in vitro and in vivo

Ethnopharmacological relevanceCaryopteris trichosphaera W. W. Sm., a traditional ethnic medicine, was recorded in the Compendium of Materia Medica for treating wound infection by pathogenic infection. However, its antibacterial potential and bioactive compositions against drug-resistant bacteria need to be validated. Aim of the studyTo investigate the chemical constituents of C. trichosphaera and explore its anti-MRSA component in vitro and in vivo, together with the antibacterial mechanism. Materials and methodsBioactive constituents investigation was carried out by phytochemical method and antibacterial screening. The antibacterial mechanism was predicted by network pharmacology, which was further validated by time-kill analysis, membrane function tests, multigenerational resistance induction assay and biofilm test, and metabolomics analysis in vitro. In addition, MRSA-induced epidermal infection in mice was selected to evaluate its pharmacological effect in vivo. ResultsSix antibacterial diterpenoids against MRSA and VRE with MIC values 4–32 μg/mL from C. trichosphaera were reported for the first time, in which the major compound cativic acid (1) disrupted MRSA cell membranes by modulating permeability, depolarization, and fluidity while increasing reactive oxygen species (ROS) and malondialdehyde (MDA) levels. It also displayed remarkable anti-biofilm activity without inducing bacterial resistance or cytotoxicity. Moreover, cativic acid affected MRSA biosynthesis of cofactors, amino acid biosynthesis, nucleotide metabolism by metabolomics analysis. Furthermore, cativic acid accelerated wound healing in MRSA-infected mouse skin wounds, even better than vancomycin. ConclusionsThe results supported the traditional use of C. trichosphaera, and presented unreported anti-MRSA agent, cativic acid, as a plant-derived bactericide in vitro and in vivo for the first time.

Adaptive interventions for advancing in situ wildlife disease management.

There is a critical need for advancements in disease management strategies for wildlife, but free-living animals pose numerous challenges that can hinder progress. Most disease management attempts involve fixed interventions accompanied by post hoc outcome assessments focused on success or failure. Though these approaches have led to valuable management advances, there are limitations to both the rate of advancement and amount of information that can be gained. As such, strategies that support more rapid progress are required. Sarcoptic mange, caused by epidermal infection with Sarcoptes scabiei mites, is a globally emerging and re-emerging panzootic that exemplifies this problem. The bare-nosed wombat (Vombatus ursinus), a marsupial endemic to southeastern Australia, is impacted by sarcoptic mange throughout its geographic range and enhanced disease management capabilities are needed to improve upon existing in situ methods. We sought to advance in situ wildlife disease management for sarcoptic mange in free-living bare-nosed wombats, implementing an adaptive approach using fluralaner (Bravecto, MSD Animal Health) and a structured process of learning and method-optimisation. By using surveillance of treated wombats to inform real-time management changes, we have demonstrated the efficacy of topically administered fluralaner at 45 and 85 mg/kg against sarcoptic mange. Importantly, we observed variation in the effects of 45 mg/kg doses, but through our adaptive approach found that 85 mg/kg doses consistently reduced mange severity. Through modifying our surveillance program, we also identified individual-level variation in wombat observability and used this to quantify the level of surveillance needed to assess long-term management success. Our adaptive intervention represents the first report of sarcoptic mange management with fluralaner in free-living wildlife and evaluation of its efficacy in situ. This study illustrates how adapting interventions in real time can advance wildlife disease management and may be applicable to accelerating in situ improvements for other host-pathogen systems.

Non-specific markers of inflammation in bare-nosed wombats (Vombatus ursinus) with sarcoptic mange.

Sarcoptic mange, caused by epidermal infection with Sarcoptes scabiei, negatively impacts the health, welfare, and local abundance of bare-nosed wombats (Vombatus ursinus) in Australia. Improved understanding of the host immune response to disease and its contribution to pathophysiology could be used to inform management actions for this species in and ex situ. To evaluate the immune response of bare-nosed wombats to sarcoptic mange, we validated three assays (haptoglobin, agarose gel electrophoresis, and micro-erythrocyte sedimentation rate) measuring non-specific markers of inflammation using serum samples from free-living wombats from Tasmania (n = 33). We then analysed correlations between the assay results for each non-specific marker of inflammation and wombat's sarcoptic mange scores, and performed histopathological examinations to investigate association of the acute phase response with systemic amyloidosis. We present evidence that haptoglobin and erythrocyte sedimentation rate increased, and albumin decreased, in association with sarcoptic mange scores. This research demonstrates links between the acute phase response and sarcoptic mange severity in bare-nosed wombats, highlighting the utility of non-specific markers of inflammation for aiding assessment of the systemic effects of mange. Showing the value of agarose gel electrophoresis, we also identified specific acute phase proteins warranting future evaluation and found evidence of an immunoglobulin response in mange-affected wombats, revealed by increasing γ-globulins in association with apparent disease severity. Meanwhile, owing to its relatively low resource requirements and rapidity, the erythrocyte sedimentation rate assay may be useful as a point-of-care test to support therapeutic decisions in the field. Our methods and findings are likely to be applicable to a range of other clinical and population health scenarios in captive and free-living wombats, and species impacted by sarcoptic mange globally.

Ca-doping interfacial engineering and glycolysis enable rapid charge separation for efficient phototherapy of MRSA-infected wounds

Methicillin-resistant Staphylococcus aureus (MRSA) is the primary pathogenic agent responsible for epidermal wound infection and suppuration, seriously threatening the life and health of human beings. To address this fundamental challenge, we propose a heterojunction nanocomposite (Ca-CN/MnS) comprised of Ca-doped g-C3N4 and MnS for the therapy of MRSA-accompanied wounds. The Ca doping leads to a reduction in both the bandgap and the singlet state S1–triplet state T2 energy gap (ΔEST). The Ca doping also facilitates the two-photon excitation, thus remarkably promoting the separation and transfer of 808 nm near-infrared (NIR) light–triggered electron–hole pairs together with the built-in electric field. Thereby, the production of reactive oxygen species and heat are substantially augmented nearby the nanocomposite under 808 nm NIR light irradiation. Consequently, an impressive photocatalytic MRSA bactericidal efficiency of 99.98 ± 0.02 % is achieved following exposure to NIR light for 20 min. The introduction of biologically functional elements (Ca and Mn) can up-regulate proteins such as pyruvate kinase (PKM), L-lactate dehydrogenase (LDHA), and calcium/calmodulin-dependent protein kinase (CAMKII), trigger the glycolysis and calcium signaling pathway, promote cell proliferation, cellular metabolism, and angiogenesis, thereby expediting the wound-healing process. This heterojunction nanocomposite, with its precise charge-transfer pathway, represents a highly effective bactericidal and bioactive system for treating multidrug-resistant bacterial infections and accelerating tissue repair. Statement of significanceDue to the bacterial resistance, developing an antibiotic-free and highly effective bactericidal strategy to treat bacteria-infected wounds is critical. We have designed a heterojunction consisting of calcium doped g-C3N4 and MnS (Ca-CN/MnS) that can rapidly kill methicillin-resistant Staphylococcus aureus (MRSA) without damaging normal tissue through a synergistic effect of two-photon stimulated photothermal and photodynamic therapy. In addition, the release of trace amounts of biofunctional elements Mn and Ca triggers glycolysis and calcium signaling pathways that promote cellular metabolism and cell proliferation, contributing to tissue repair and wound healing.

Isolation, Identification, and Antimicrobial Evaluation of Secondary Metabolite from Serratia marcescens via an In Vivo Epicutaneous Infection Model.

Microbial secondary metabolites, which play a pivotal role in struggling with infectious diseases, are the new source for controlling bacterial contaminations and possess a strong antimicrobial potential. The present study is designed to evaluate the in vitro and in vivo bactericidal activities of prodigiosin against Staphylococcus aureus. For this purpose, Serratia marcescens was used to produce prodigiosin. Characterization of the prodigiosin was carried out using NMR. In addition, bioautographic detection of prodigiosin was detected by TLC. Antibacterial assays, in vivo epicutaneous infection tests, swap analyses, and histopathological examinations were determined. The results revealed that prodigiosin was detected by NMR and TLC. According to antimicrobial susceptibility tests, prodigiosin is an efficient bactericidal compound that demonstrated strong antibacterial activity toward S. aureus. In vivo, animal studies determined that the strong inhibition of S. aureus-caused epidermal infection occurs by prodigiosin at 48 h. Histopathological results showed that S. aureus + prodigiosin skin sections consist of improved and healthy tissues without any infection area compared with the S. aureus and control groups. The in vivo study verified the antibacterial results with swap analyses, and histopathological findings showed that prodigiosin is a promising microbial metabolite effective against S. aureus infection. This study proved that prodigiosin with excellent bioactivity exhibited antibacterial properties, which might possess massive potential for new therapeutic approaches using micro-organisms.

Hybrid-Aligned Fibers of Electrospun Gelatin with Antibiotic and Polycaprolactone Composite Membranes as an In Vitro Drug Delivery System to Assess the Potential Repair Capacity of Damaged Cornea.

The cornea lacks the ability to repair itself and must rely on transplantation to repair damaged tissue. Therefore, creating alternative therapies using dressing membranes based on tissue engineering concepts to repair corneal damage before failure has become a major research goal. Themost outstanding features that are important in reconstructing a damaged cornea are the mechanical strength and transparency of the membrane, which are the most important standard considerations. In addition, preventing infection is an important issue, especially in corneal endothelial healing processes. The purpose of this study was to produce aligned fibers via electrospinning technology using gelatin (Gel) composite polycaprolactone (PCL) as an optimal transport and antibiotic release membrane. The aim of the composite membrane is to achieve good tenacity, transparency, antibacterial properties, and in vitro biocompatibility. Results showed that the Gel and PCL composite membranes with the same electrospinning flow rate had the best transparency. The Gel impregnated with gentamicin antibiotic in composite membranes subsequently exhibited transparency and enhanced mechanical properties provided by PCL and could sustainably release the antibiotic for 48 h, achieving good antibacterial effects without causing cytotoxicity. This newly developed membrane has the advantage of preventing epidermal tissue infection during clinical operations and is expected to be used in the reconstruction of damaged cornea in the future.

Epidermophyton floccosum kao uzročnik Tinea pedis - prikaz slučaja

Tinea pedis or athlete's foot is a surface fungal epidermal infection caused by dermatophytic fungi of the species Trichophyton (T.) rubrum, T. mentagrophytes var. interdigitale, Epidermophyton floccosum or T. tonsurans. It occurs most often in adult men, rarely in women and children. It is estimated that at least 70% of all people have a fungal foot infection at least once in their lifetime. Case report: a 43-year-old male with a clinical picture of Tinea pedis was referred to the Institute of Public Health of Serbia "Dr Milan Jovanović Batut" for laboratory diagnostics of the fungal infection of the right foot. In terms of patient history, he reported having dry, flaky changes to the skin of his right foot for two years, as well as erosion in the III and IV interdigital spaces of the foot. Due to itching, burning, and flaking of the skin on his feet, he reported to the attending physician who put him on betamethasone/gentamicin cream. The itching decreased, but the changes did not recede. Right foot toenails were not showing visible signs of infection. Direct microscopic examination of the right foot scrapings found micellar fibres and arthrospores, while culturing on dermatophyte-appropriate media allowed for the isolation of Epidermophyton floccosum. The isolate was identified based on microscopic morphology of the cultured organism, macroscopic appearance of the culture on dermatophyte isolation media, as well as using MALDI-TOF mass spectrometric diagnostics. Mycological confirmation of foot infection with the Epidermophyton floccosum fungus, with adequate treatment, reduces the risk of developing an onychomycosis, which is harder to treat.

Dengue Virus Infects Human Skin Langerhans Cells through Langerin for Dissemination to Dendritic Cells

Dengue virus (DENV) is the most disease-causative flavivirus worldwide. DENV as a mosquito-borne virus infects human hosts through the skin; however, the initial target cells in the skin remain unclear. In this study, we have investigated whether epidermal Langerhans cells (LCs) play a role in DENV acquisition and dissemination. We have used a human epidermal exvivo infection model as well as isolated LCs to investigate infection by DENV. Notably, both immature and mature LCs were permissive to DENV infection invitro and exvivo, and infection was dependent on C-type lectin receptor langerin because blocking antibodies against langerin significantly reduced DENV infection invitro and exvivo. DENV-infected LCs efficiently transmitted DENV to target cells such as dendritic cells. Moreover, DENV exposure increased the migration of LCs from epidermal explants. These results strongly suggest that DENV targets epidermal LCs for infection and dissemination in the human host. These findings could provide potential drug targets to combat the early stage of DENV infection.

Single-cell analysis identifies genes facilitating rhizobium infection in Lotus japonicus

Legume-rhizobium signaling during establishment of symbiotic nitrogen fixation restricts rhizobium colonization to specific cells. A limited number of root hair cells allow infection threads to form, and only a fraction of the epidermal infection threads progress to cortical layers to establish functional nodules. Here we use single-cell analysis to define the epidermal and cortical cell populations that respond to and facilitate rhizobium infection. We then identify high-confidence nodulation gene candidates based on their specific expression in these populations, pinpointing genes stably associated with infection across genotypes and time points. We show that one of these, which we name SYMRKL1, encodes a protein with an ectodomain predicted to be nearly identical to that of SYMRK and is required for normal infection thread formation. Our work disentangles cellular processes and transcriptional modules that were previously confounded due to lack of cellular resolution, providing a more detailed understanding of symbiotic interactions.

P101: Feasibility Study of the Percutaneous Access Device for Long-Term LVAS Application

Background: Driveline infection (DLI) is a major chronic adverse event requiring re-hospitalization after durable left ventricular assist system (LVAS) implantation. The risk of DLI continues to rise over time and is associated with long-term mortality. Percutaneous access device (PAD) may be a potential technology to prevent DLI by the mechanical barrier interfaced with epidermal tissue. Methods: A prototype PAD was fabricated for the LVAS driveline and evaluated with two mini pigs for up to 69 days at the GLP facility. Test articles were implanted at the subcutaneous position on the left and right abdominal walls. After implant surgery, antibiotics were administered intravenously for three days for prophylactic purposes and discontinued unless there was any sign of infection. Skin and implanted PAD are showered weekly with warm water without any other disinfectant agent. Animals received humane care without restraints in the cage and were checked for general physical condition daily. The blood sample was collected at baseline, POD 7, 14, 28, and 69. Test Animals were euthanized, and articles and surrounding tissue samples were explanted en bloc for histopathology assessment. Results: Postoperative recovery was uneventful, and no remarkable organ dysfunction and no sign of infection were identified. A normal inflammatory response was observed on the skin a few days post-op but normalized within a week. Good tissue integrity was confirmed (no visible gap) around the interface between the test article and the skin without evidence of epidermal down growth and infection. Rich fibromatous tissue with keratin formation was confirmed. Conclusion: Initial feasibility of PAD for LVAS driveline was verified. Further design optimization will be required to finalize the clinical prototype before the pre-clinical GLP study.Figure 1. Upper left: Percutaneous access device tested (implanted to the test animal) Upper right: Close-up view of the skin interface Lower center: Histopathology of test article at subcutaneous tissue

Pellino1 promotes immunity in the skin during infection with herpes simplex virus (HSV)

Abstract Pellino1 (Peli1) is a ubiquitin ligase involved in IL-1 and Toll-like receptor signaling; however, the role of Pellino1 in skin immunity against HSV is unknown. Here, using the mouse flank HSV-1 skin infection model, we demonstrate that Pellino1 has several critical functions during active viral replication. Analyses of single cell genome wide gene expression data (RNA-seq) revealed expression of Peli1mRNA throughout the skin including in epithelial, fibroblast and immune cells. Both histology and RNA-seq demonstrated normal development of the epidermis and dermis in Pellino1 knockout (KO) mice. The median survival of Pellino1 KO mice was 12 days compared to greater than 16 days in wild type mice. Pellino1 deficient mice also developed larger zosteriform skin lesions along affected dermatomes. During infection HSV-1 did not replicate in the dermis. Immunohistochemistry revealed delayed recruitment of myeloid and T cells to early infected epidermis in Pellino1 deficient mice. This correlated with lower expression of the inflammatory IL-1 and IL-36 cytokines and the poorly understood chemokine Grp15l. In Pellino1 KO mice, the virus spread extensively through the epidermis, follicular infundibulum into sebaceous glands where sebocytes were found positive for the virus. Histological analyses for HSV-1 and neuronal axons revealed nerve endings throughout the epidermis and axons wrapped around the hair follicles. Dissemination of HSV-1 into the sebaceous glands did not appear to involve a shift in how the virus migrated through these nerve axons as early lesions were only found in the interfollicular epidermis. In conclusion, Pellino1 plays important roles in restricting viral dissemination. Supported by grant from NIH (R01 AI125111)

Intracellular reactive oxygen species (intraROS)-aided localized cell death contributing to immune responses against wheat powdery mildew pathogen.

Reactive oxygen species (ROS) and hypersensitive response (HR) mediated cell death have long been known to play critical roles in plant immunity to pathogens. Wheat powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt) is a destructive wheat pathogen. Here, we report a quantitative analysis of the proportion of infected cells with local apoplastic ROS (apoROS) versus intracellular ROS (intraROS) accumulation in various wheat accessions that carry different disease resistance genes (R genes), at a series of time points post-infection. The proportion of apoROS accumulation was 70-80% of the infected wheat cells detected in both compatible and incompatible host-pathogen interactions. However, intensive intraROS accumulation followed by localized cell death responses were detected in 11-15% of the infected wheat cells, mainly in wheat lines that carried nucleotide-binding leucine-rich repeat (NLR) R genes (e.g. Pm3F, Pm41, TdPm60, MIIW72, Pm69). The lines that carry unconventional R genes, Pm24 (Wheat Tandem Kinase 3) and pm42 (a recessive R gene), showed very less intraROS responses, while 11% of Pm24 line infected epidermis cells still showed HR cell death, suggesting that different resistance pathways are activated there. Here, we also demonstrated that ROS could not act as a strong systemic signal for inducing high resistance to Bgt in wheat, although it induced the expression of pathogenesis-related (PR) genes. These results provide new insights on the contribution of intraROS and localized cell death to immune responses against wheat powdery mildew.

Role of Iron in Epidermal Healing and Infection

In recent years, the field of iron studies has expanded into sub-domains that investigate the regulation of this metal in various tissues including the heart, mucosal surfaces, tumours, and the skin. Iron homeostasis in the skin and the role of other non-hepatic cells in the regulation of iron are currently incompletely understood. This paper summarizes the role of iron in wound healing, highlights the importance of maintaining iron concentrations within an intermediate range to avoid toxicity or defects; and integrates the antimicrobial role, interactions, and regulation of various cell types. Notably, the autoregulation of hepcidin secretion by keratinocytes and recruited myeloid cells is described. Additionally, the potential therapeutic role of iron chelators in infection control and their mechanisms of action are explored. This paper aims to elucidate the relevance of local iron control in epidermal infections. Although some of the molecular details underlying this condition remain unclear, published data suggest that iron-regulating therapies are a promising treatment for the eradication of skin infections due to their wound-healing and immune-modulating potential.

Site-specific analysis reveals candidate cross-kingdom small RNAs, tRNA and rRNA fragments, and signs of fungal RNA phasing in the barley-powdery mildew interaction.

The establishment of host-microbe interactions requires molecular communication between both partners, which may involve the mutual transfer of noncoding small RNAs. Previous evidence suggests that this is also true for powdery mildew disease in barley, which is caused by the fungal pathogen Blumeria hordei. However, previous studies lacked spatial resolution regarding the accumulation of small RNAs upon host infection by B. hordei. Here, we analysed site-specific small RNA repertoires in the context of the barley-B. hordei interaction. To this end, we dissected infected leaves into separate fractions representing different sites that are key to the pathogenic process: epiphytic fungal mycelium, infected plant epidermis, isolated haustoria, a vesicle-enriched fraction from infected epidermis, and extracellular vesicles. Unexpectedly, we discovered enrichment of specific 31-33-base 5'-terminal fragments of barley 5.8S ribosomal RNA in extracellular vesicles and infected epidermis, as well as particular B. hordei transfer RNA fragments in haustoria. We describe canonical small RNAs from both the plant host and the fungal pathogen that may confer cross-kingdom RNA interference activity. Interestingly, we found first evidence of phased small interfering RNAs in B. hordei, a feature usually attributed to plants, which may be associated with the posttranscriptional control of fungal coding genes, pseudogenes, and transposable elements. Our data suggest a key and possibly site-specific role for cross-kingdom RNA interference and noncoding RNA fragments in the host-pathogen communication between B. hordei and its host barley.

High-throughput phenotyping of infection by diverse microsporidia species reveals a wild C. elegans strain with opposing resistance and susceptibility traits.

Animals are under constant selective pressure from a myriad of diverse pathogens. Microsporidia are ubiquitous animal parasites, but the influence they exert on shaping animal genomes is mostly unknown. Using multiplexed competition assays, we measured the impact of four different species of microsporidia on 22 wild isolates of Caenorhabditis elegans. This resulted in the identification and confirmation of 13 strains with significantly altered population fitness profiles under infection conditions. One of these identified strains, JU1400, is sensitive to an epidermal-infecting species by lacking tolerance to infection. JU1400 is also resistant to an intestinal-infecting species and can specifically recognize and destroy this pathogen. Genetic mapping of JU1400 demonstrates that these two opposing phenotypes are caused by separate loci. Transcriptional analysis reveals the JU1400 sensitivity to epidermal microsporidia infection results in a response pattern that shares similarity to toxin-induced responses. In contrast, we do not observe JU1400 intestinal resistance being regulated at the transcriptional level. The transcriptional response to these four microsporidia species is conserved, with C. elegans strain-specific differences in potential immune genes. Together, our results show that phenotypic differences to microsporidia infection amongst C. elegans are common and that animals can evolve species-specific genetic interactions.

A Novel Rhizobium sp. Chiba-1 Strain Exhibits a Host Range for Nodule Symbiosis in Lotus Species.

Rhizobia are soil bacteria that induce the formation of nodules in the roots of leguminous plants for mutualistic establishment. Although the symbiotic mechanism between Lotus japonicus and its major symbiotic rhizobia, Mesorhizobium loti, has been extensively characterized, our understanding of symbiotic mechanisms, such as host specificity and host ranges, remains limited. In the present study, we isolated a novel Rhizobium strain capable of forming nodules on L. burttii from agricultural soil at Iwate prefecture in Japan. We conducted genomic and host range ana-lyses of various Lotus species. The results obtained revealed that the novel isolated Rhizobium sp. Chiba-1 was closely related to R. leguminosarum and had a wide host range that induced nodule development, including L. burttii and several L. japonicus wild-type accessions. However, L. japonicus Gifu exhibited an incompatible nodule phenotype. We also identified the formation of an epidermal infection threads that was dependent on the Lotus species and independent of nodule organ development. In conclusion, this newly isolated Rhizobium strain displays a distinct nodulation phenotype from Lotus species, and the results obtained herein provide novel insights into the functional mechanisms underlying host specificity and host ranges.

Pellino1 Restricts Herpes Simplex Virus Infections in the Epidermis and Dissemination to Sebaceous Glands

Nearly all adults are infected with one or more herpes viruses. The most common are herpes simplex virus (HSV)-1 and HSV-2, which upon reactivation can cause painful skin and mucosal erosions. Patients who are immune compromised often experience frequent, atypical, or chronic lesions and thus a greatly diminished QOL. Pellino1 is a ubiquitin ligase involved in IL-1 and toll-like receptor signaling; however, the role of Pellino1 in skin immunity against HSV is unknown. In this study, using the mouse-flank HSV-1 skin infection model, we show that Pellino1 has several critical functions during active viral replication. Peli1‒/‒ mice succumb more than wild-type mice to systemic disease and develop larger zosteriform skin lesions along affected dermatomes. In Pellino1-deficient mice, the virus spread extensively through the epidermis and follicular infundibulum into sebaceous glands where sebocytes were found positive for the virus. The latter did not appear to involve a shift in how the virus migrated through the nervous system. Immunohistochemistry revealed delayed recruitment of myeloid and T cells to the infected epidermis in Peli1‒/‒ mice. This was associated with decreased expression of the cytokine mRNAs Il1a, Il36b and 2610528A11Rik; the latter also known as Gpr15l. In conclusion, Pellino1 plays important roles in restricting viral dissemination, and the involved pathways may represent novel therapeutic targets in patients with frequent or chronic HSV infections.

Nodule INception-independent epidermal events lead to bacterial entry during nodule development in peanut (Arachis hypogaea).

Legumes can host nitrogen-fixing rhizobia inside root nodules. In model legumes, rhizobia enter via infection threads (ITs) and develop nodules in which the infection zone contains a mixture of infected and uninfected cells. Peanut (Arachis hypogaea) diversified from model legumes c. 50-55 million years ago. Rhizobia enter through 'cracks' to form nodules in peanut roots where cells of the infection zone are uniformly infected. Phylogenomic studies have indicated symbiosis as a labile trait in peanut. These atypical features prompted us to investigate the molecular mechanism of peanut nodule development. Combining cell biology, genetics and genomic tools, we visualized the status of hormonal signaling in peanut nodule primordia. Moreover, we dissected the signaling modules of Nodule INception (NIN), a master regulator of both epidermal infection and cortical organogenesis. Cytokinin signaling operates in a broad zone, from the epidermis to the pericycle inside nodule primordia, while auxin signaling is narrower and focused. Nodule INception is involved in nodule organogenesis, but not in crack entry. Nodulation Pectate Lyase, which remodels cell walls during IT formation, is not required. By contrast, Nodule enhanced Glycosyl Hydrolases (AhNGHs) are recruited for cell wall modification during crack entry. While hormonal regulation is conserved, the function of the NIN signaling modules is diversified in peanut.

Synergism between the Synthetic Antibacterial and Antibiofilm Peptide (SAAP)-148 and Halicin.

Recently, using a deep learning approach, the novel antibiotic halicin was discovered. We compared the antibacterial activities of two novel bactericidal antimicrobial agents, i.e., the synthetic antibacterial and antibiofilm peptide (SAAP)-148 with this antibiotic halicin. Results revealed that SAAP-148 was more effective than halicin in killing planktonic bacteria of antimicrobial-resistant (AMR) Escherichia coli, Acinetobacter baumannii and Staphylococcus aureus, especially in biologically relevant media, such as plasma and urine, and in 3D human infection models. Surprisingly, SAAP-148 and halicin were equally effective against these bacteria residing in immature and mature biofilms. As their modes of action differ, potential favorable interactions between SAAP-148 and halicin were investigated. For some specific strains of AMR E. coli and S. aureus synergism between these agents was observed, whereas for other strains, additive interactions were noted. These favorable interactions were confirmed for AMR E. coli in a 3D human bladder infection model and AMR S. aureus in a 3D human epidermal infection model. Together, combinations of these two novel antimicrobial agents hold promise as an innovative treatment for infections not effectively treatable with current antibiotics.

Auxin methylation by IAMT1, duplicated in the legume lineage, promotes root nodule development in Lotus japonicus

Legumes attract symbiotic bacteria and create de novo root organs called nodules. Nodule development consists of bacterial infection of root epidermis and subsequent primordium formation in root cortex, steps that need to be spatiotemporally coordinated. The Lotus japonicus mutant “daphne ” has uncoupled symbiotic events in epidermis and cortex, in that it promotes excessive bacterial infection in epidermis but does not produce nodule primordia in cortex. Therefore, daphne should be useful for exploring unknown signals that coordinate these events across tissues. Here, we conducted time-course RNA sequencing using daphne after rhizobial infection. We noticed that IAA carboxyl methyltransferase 1 (IAMT1) , which encodes the enzyme that converts auxin (IAA) into its methyl ester (MeIAA), is transiently induced in wild-type roots at early stages of infection but shows different expression dynamics in daphne. IAMT1 serves an important function in shoot development of Arabidopsis, a nonsymbiotic plant, but the function of IAMT1 in roots has not been reported. Phylogenetic tree analysis suggests a gene duplication of IAMT1 in the legume lineage, and we found that one of the two IAMT1s (named IAMT1a) was induced in roots by epidermal infection. IAMT1a knockdown inhibited nodule development in cortex; however, it had no effect on epidermal infection. The amount of root MeIAA increased with rhizobial infection. Application of MeIAA, but not IAA , significantly induced expression of the symbiotic gene NIN in the absence of rhizobial infection. Our results provide evidence for the role of auxin methylation in an early stage of root nodule development.