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Course-based undergraduate research experiences (CUREs) provide a promising avenue to attract a larger and more diverse group of students into research careers. CUREs are thought to be distinctive in offering students opportunities to make discoveries, collaborate, engage in iterative work, and develop a sense of ownership of their lab course work. Yet how these elements affect students' intentions to pursue research-related careers remain unexplored. To address this knowledge gap, we collected data on three design features thought to be distinctive of CUREs (discovery, iteration, collaboration) and on students' levels of ownership and career intentions from ~800 undergraduates who had completed CURE or inquiry courses, including courses from the Freshman Research Initiative (FRI), which has a demonstrated positive effect on student retention in college and in science, technology, engineering, and mathematics. We used structural equation modeling to test relationships among the design features and student ownership and career intentions. We found that discovery, iteration, and collaboration had small but significant effects on students' intentions; these effects were fully mediated by student ownership. Students in FRI courses reported significantly higher levels of discovery, iteration, and ownership than students in other CUREs. FRI research courses alone had a significant effect on students' career intentions.

In nature, halogenation is a strategy used to increase the biological activity of secondary metabolites, compounds that are often effective as drugs. However, halides are not particularly reactive unless they are activated, typically by oxidation. The pace of discovery of new enzymes for halogenation is increasing, revealing new metalloenzymes, flavoenzymes, S-adenosyl-L-methionine (SAM)-dependent enzymes and others that catalyse halide oxidation using dioxygen, hydrogen peroxide and hydroperoxides, or that promote nucleophilic halide addition reactions., Halogenated natural products have been isolated in abundance from marine eukaryotic organisms, but also increasingly from microorganisms that inhabit marine and terrestrial environments (Fig. 1). These halogenated compounds range from [...]

A bouncer for the bone marrow: P2RY8 is a G protein–coupled receptor (GPCR) that is involved in restraining germinal center (GC) B cell migration and growth. It is unclear how the ligand of P2RY8, S-geranylgeranyl-l-glutathione (GGG), is involved in these processes. Using gain-of-function mouse models and genetically modified human T cells, Gallman et al. showed that expression of gamma-glutamyltransferase-5 (Ggt5) on stromal cells and ATP-binding cassette subfamily C member 1 (Abcc1) on hematopoietic cells was involved in catabolizing and transporting GGG, respectively, and restraining P2RY8+ cells within GCs. GGG and P2RY8 interactions also restrained lymphocyte trafficking to the bone marrow. Thus, GGG and P2RY8 processing and interactions are crucial for the confinement of B cells within GCs and for inhibiting migration of lymphocytes into bone marrow. P2RY8 promotes the confinement and growth regulation of germinal center (GC) B cells, and loss of human P2RY8 is associated with B cell lymphomagenesis. The metabolite S-geranylgeranyl-l-glutathione (GGG) is a P2RY8 ligand. The mechanisms controlling GGG distribution are poorly understood. Here, we show that gamma-glutamyltransferase-5 (Ggt5) expression in stromal cells was required for GGG catabolism and confinement of P2RY8-expressing cells to GCs. We identified the ATP-binding cassette subfamily C member 1 (Abcc1) as a GGG transporter and showed that Abcc1 expression by hematopoietic cells was necessary for P2RY8-mediated GC confinement. Furthermore, we discovered that P2RY8 and GGG negatively regulated trafficking of B and T cells to the bone marrow (BM). P2RY8 loss-of-function human T cells increased their BM homing. By defining how GGG distribution was determined and identifying sites of P2RY8 activity, this work helps establish how disruptions in P2RY8 function contribute to lymphomagenesis and other disease states. [ABSTRACT FROM AUTHOR]

Fungal symbionts are increasingly targeted as tools for crop management, but their use in the field requires an understanding of how fungi interact in a community context. Fungal interactions may result in additive effects on the host plant, which could be predicted simply based on individual fungal behavior. Alternatively, interactions among fungi may result in non-additive synergistic or antagonistic effects on plant performance that are more challenging to predict. Here, we hypothesized that the effects of fungal interactions on the plant host could be predicted from their niche overlap. To test this idea, we used foliar fungal endophytes with a range of niche overlap based on trait dissimilarities to examine the effects of six fungal species pairs compared to the corresponding individual fungal species on switchgrass (Panicum virgatum L.) in water-stressed and well-watered conditions. Mixtures of endophytes had either no effect or predictable, additive effects on plant tiller number, but effects on plant growth rate and wilting were largely nonadditive. Moisture level, fungal stress, and metabolic trait dissimilarity predicted 51 to 92% of the deviation of fungal effects from additive, with less similar fungi likely to have more synergistic effects on the plant host. Furthermore, we identified indicator metabolites for fungal interaction outcomes. However, the effects of endophyte interactions on the plant host were environment dependent making single community applications more challenging. Overall, future development of microbial tools for use in agriculture must consider their interactions to optimize application. [ABSTRACT FROM AUTHOR]

Shipworms are marine bivalve mollusks (Family Teredinidae) that use wood for shelter and food. They harbor a group of closely related, yet phylogenetically distinct, bacterial endosymbionts in bacteriocytes located in the gills. This endosymbiotic community is believed to support the host's nutrition in multiple ways, through the production of cellulolytic enzymes and the fixation of nitrogen. The genome of the shipworm endosymbiont Teredinibacter turnerae T7901 was recently sequenced and in addition to the potential for cellulolytic enzymes and diazotrophy, the genome also revealed a rich potential for secondary metabolites. With nine distinct biosynthetic gene clusters, nearly 7% of the genome is dedicated to secondary metabolites. Bioinformatic analyses predict that one of the gene clusters is responsible for the production of a catecholate siderophore. Here we describe this gene cluster in detail and present the siderophore product from this cluster. Genes similar to the entCEBA genes of enterobactin biosynthesis involved in the production and activation of dihydroxybenzoic acid (DHB) are present in this cluster, as well as a two-module non-ribosomal peptide synthetase (NRPS). A novel triscatecholate siderophore, turnerbactin, was isolated from the supernatant of iron-limited T. turnerae T7901 cultures. Turnerbactin is a trimer of N-(2,3-DHB)-L-Orn-L-Ser with the three monomeric units linked by Ser ester linkages. A monomer, dimer, dehydrated dimer, and dehydrated trimer of 2,3-DHB-L-Orn-L-Ser were also found in the supernatant. A link between the gene cluster and siderophore product was made by constructing a NRPS mutant, TtAH03. Siderophores could not be detected in cultures of TtAH03 by HPLC analysis and Fe-binding activity of culture supernatant was significantly reduced. Regulation of the pathway by iron is supported by identification of putative Fur box sequences and observation of increased Fe-binding activity under iron restriction. Evidence of a turnerbactin fragment was found in shipworm extracts, suggesting the production of turnerbactin in the symbiosis. [ABSTRACT FROM AUTHOR]

Bacterial activation of T helper 17 (Th17) cells exacerbates mouse models of autoimmunity, but how human-associated bacteria impact Th17-driven disease remains elusive. We show that human gut Actinobacterium Eggerthella lenta induces intestinal Th17 activation by lifting inhibition of the Th17 transcription factor Rorγt through cell- and antigen-independent mechanisms. E. lenta is enriched in inflammatory bowel disease (IBD) patients and worsens colitis in a Rorc- dependent manner in mice. Th17 activation varies across E. lenta strains, which is attributable to the cardiac glycoside reductase 2 (Cgr2) enzyme. Cgr2 is sufficient to induce interleukin (IL)-17a, a major Th17 cytokine. cgr2+ E. lenta deplete putative steroidal glycosides in pure culture; related compounds are negatively associated with human IBD severity. Finally, leveraging the sensitivity of Cgr2 to dietary arginine, we prevented E. lenta -induced intestinal inflammation in mice. Together, these results support a role for human gut bacterial metabolism in driving Th17-dependent autoimmunity. [Display omitted] • The prevalent gut Actinobacterium Eggerthella lenta activates Th17 cells • E. lenta is associated with human disease and exacerbates colitis in mice • A strain-specific enzyme Cgr2 induces IL-17a via the metabolism of Rorγt inhibitors • Dietary arginine blocks E. lenta -induced intestinal inflammation Alexander et al. show an autoimmune-associated microbe, Eggerthella lenta , activates Th17 cells and worsens mouse models of colitis. Using strain-level variation, comparative genomics, and bacterial genetics they demonstrate that the cardiac glycoside reductase 2 (Cgr2) enzyme is sufficient for Th17 activation and that elevated dietary arginine blocks E. lenta- induced colitis. [ABSTRACT FROM AUTHOR]

The in vivoand in vitrocharacterization of AntB, a dedicated acyltransferase encoded in the antimycin biosynthetic gene cluster, which catalyzes the C-8 acyloxy formation is reported. It is demonstrated that AntB has broad substrate specificity toward both the acyl substrate and the acyl carrier and produces more antimycin analogues with varying C-8 acyloxy moieties. [ABSTRACT FROM AUTHOR]

Vanadium bromoperoxidase was isolated and cloned from the marine red alga Delisea pulchra. This enzyme catalyzes the bromolactonization of 4-pentynoic acid forming 5E-bromo-methylidenetetrahydro-2-furanone, a compound which is shown herein to inhibit quorum sensing in the engineered reporter strain, Agrobacterium tumefaciensNTL4. [ABSTRACT FROM AUTHOR]

B cell self-tolerance is maintained through multiple checkpoints, including restraints on intracellular signaling and cell trafficking. P2RY8 is a receptor with established roles in germinal center (GC) B cell migration inhibition and growth regulation. Somatic P2RY8 variants are common in GC-derived B cell lymphomas. Here, we identify germline novel or rare P2RY8 missense variants in lupus kindreds or the related antiphospholipid syndrome, including a "de novo" variant in a child with severe nephritis. All variants decreased protein expression, F-actin abundance, and GPCR-RhoA signaling, and those with stronger effects increased AKT and ERK activity and cell migration. Remarkably, P2RY8 was reduced in B cell subsets from some SLE patients lacking P2RY8 gene variants. Low P2RY8 correlated with lupus nephritis and increased age-associated B cells and plasma cells. By contrast, P2RY8 overexpression in cells and mice restrained plasma cell development and reinforced negative selection of DNA-reactive developing B cells. These findings uncover a role of P2RY8 in immunological tolerance and lupus pathogenesis., Competing Interests: Disclosures:  J.G. Cyster reported "other" from Be BioPharma and MiroBio outside the submitted work. No other disclosures were reported., (© 2021 He et al.)

Course-based undergraduate research experiences (CUREs) provide a promising avenue to attract a larger and more diverse group of students into research careers. CUREs are thought to be distinctive in offering students opportunities to make discoveries, collaborate, engage in iterative work, and develop a sense of ownership of their lab course work. Yet how these elements affect students' intentions to pursue research-related careers remain unexplored. To address this knowledge gap, we collected data on three design features thought to be distinctive of CUREs (discovery, iteration, collaboration) and on students' levels of ownership and career intentions from ∼800 undergraduates who had completed CURE or inquiry courses, including courses from the Freshman Research Initiative (FRI), which has a demonstrated positive effect on student retention in college and in science, technology, engineering, and mathematics. We used structural equation modeling to test relationships among the design features and student ownership and career intentions. We found that discovery, iteration, and collaboration had small but significant effects on students' intentions; these effects were fully mediated by student ownership. Students in FRI courses reported significantly higher levels of discovery, iteration, and ownership than students in other CUREs. FRI research courses alone had a significant effect on students' career intentions.

Antimycins are a family of natural products possessing outstanding biological activities and unique structures, which have intrigued chemists for over a half century. The antimycin structural skeleton is built on a nine-membered dilactone ring containing one alkyl, one acyloxy, two methyl moieties, and an amide linkage connecting to a 3-formamidosalicylic acid. Although a biosynthetic gene cluster for antimycins was recently identified, the enzymatic logic that governs the synthesis of antimycins has not yet been revealed. In this work, the biosynthetic pathway for antimycins was dissected by both genetic and enzymatic studies for the first time. A minimum set of enzymes needed for generation of the antimycin dilactone scaffold were identified, featuring a hybrid nonribosomal peptide synthetase (NRPS)-polyketide synthase (PKS) assembly line containing both cis- and trans-acting components. Several antimycin analogues were further produced using in vitro enzymatic total synthesis based on the substrate promiscuity of this NRPS-PKS machinery.

The plant pathogen Dickeya chrysanthemi EC16 (formerly known as Petrobacterium chrysanthemi EC16 and Erwinia chrysanthemi EC16) was found to produce a new triscatecholamide siderophore, cyclic trichrysobactin, the related catecholamide compounds, linear trichrysobactin and dichrysobactin, and the previously reported monomeric siderophore unit, chrysobactin. Chrysobactin is comprised of L-serine, D-lysine, and 2,3-dihydroxybenzoic acid (DHBA). Trichrysobactin is a cyclic trimer of chrysobactin joined by a triserine lactone backbone. The chirality of the ferric complex of cyclic trichrysobactin is found to be in the Λ configuration, similar to Fe(III)-bacillibactin, which contains a glycine spacer between the DHBA and L-threonine components and is opposite that of Fe(III)-enterobactin, which contains DHBA ligated directly to L-serine.

The marine bacterium Vibrio sp. DS40M4 has been found to produce a new triscatechol amide siderophore, trivanchrobactin (1), a related new biscatecholamide compound, divanchrobactin (2), and the previously reported siderophores vanchrobactin (3) and anguibactin (4). Vanchrobactin is comprised of l-serine, d-arginine, and 2,3-dihydroxybenzoic acid, while trivanchrobactin is a linear trimer of vanchrobactin joined by two serine ester linkages. The cyclic trivanchrobactin product was not detected. In addition to siderophore production, extracts of Vibrio sp. DS40M4 were screened for biologically active molecules; anguibactin was found to be cytotoxic against the P388 murine leukemia cell line (IC(50) < 15 microM).

A suite of amphiphilic siderophores, loihichelins A-F, were isolated from cultures of the marine bacterium Halomonas sp. LOB-5. This heterotrophic Mn(II)-oxidizing bacterium was recently isolated from the partially weathered surfaces of submarine glassy pillow basalts and associated hydrothermal flocs of iron oxides collected from the southern rift zone of Loihi Seamount east of Hawai'i. The loihichelins contain a hydrophilic headgroup consisting of an octapeptide comprised of D-threo-beta-hydroxyaspartic acid, D-serine, L-glutamine, L-serine, L-N(delta)-acetyl-N(delta)-hydroxyornithine, dehydroamino-2-butyric acid, D-serine, and cyclic N(delta)-hydroxy-D-ornithine, appended by one of a series of fatty acids ranging from decanoic acid to tetradecanoic acid. The structure of loihichelin C was determined by a combination of amino acid and fatty acid analyses, tandem mass spectrometry, and NMR spectroscopy. The structures of the other loihichelins were inferred from the amino acid and fatty acid analyses and tandem mass spectrometry. The role of these siderophores in sequestering Fe(III) released during basaltic rock weathering, as well as their potential role in the promotion of Mn(II) and Fe(II) oxidation, is of considerable interest.