Getting to the root of root-microbe interactions.

Microbial relationships with roots influence many ecosystem functions and nutrient fluxes, including their sometimes-profound effects on plant health and productivity. Fine roots were often classified with a diameter less than 2 mm, but fine roots under that size perform distinct functional roles in the environment. Importantly, two broad functional categories of fine roots are absorptive and transportive, with absorptive fine roots acting as metabolic hotspots for root activity. In two of our recent studies, we have shown that several microbial community characteristics differ between absorptive and transportive fine roots, including composition, abundance, and function, as well as the root metabolome. This highlights a growing recognition within microbial ecology that we must consider fine-scale environmental variability, such as root physiology and morphology, when interpreting microbial patterns. In this commentary, we summarize the findings of our latest article, further speculate on some of these patterns, and suggest future studies for examining decomposition and applying cutting-edge single-cell sequencing techniques.

Strategies and Tactics for Site Specific Deuterium Incorporation at Each Available Carbon Atom of α-Pinene.

The development of several unique strategies and tactics for the synthesis of α-pinene isotopologues that has culminated in access to all eight possible isomers with deuterium incorporated selectively at each available carbon atom is described. Access to this library of isotopologues provides new tools to more fully investigate the atmospheric autoxidation of α-pinene, a complex process that plays a major role in the formation of secondary organic aerosol in the Earth's atmosphere.

Tandem Condensation-Cycloaddition of Propargylic Amines with α-Azido Ketones and ß-Alkoxy-γ-Azido Enones.

α-Azido ketones and their vinylogous relatives ß-alkoxy-γ-azido enones are versatile building blocks for constructing diverse heterocyclic products, but are prone to azide decomposition. Here, we report their condensation with propargylic amines and investigate the fate of the intermediate azido-enamine condensation products, both experimentally and theoretically. Efficient intramolecular cycloaddition was observed for electron-poor azide substrates, and a range of diversely substituted [1,2,3]triazolo[1,5-a]pyrazine products is reported. For electron-rich substrates, azide decomposition predominated. Computational modeling of possible pathways from the azido-enamine intermediates revealed two alternative mechanisms for azide decomposition, which were consistent with observed side products.

Heavy Atom Quantum Mechanical Tunneling in Total Synthesis.

Contributions from quantum mechanical tunneling to the rates of several radical coupling reactions between carbon sp2 centers used as key steps in natural product total syntheses were computed using density functional theory. Contributions ranging from ∼15-52% from tunneling were predicted at room temperature, thereby indicating that tunneling plays an important role in the rates of these reactions and should perhaps be considered when designing complex synthetic schemes.

Preclinical evaluation of therapeutic vaccines for chronic hepatitis B that stimulate antiviral activities of T cells and NKT cells.

Background & Aims: Liver diseases resulting from chronic HBV infection are a significant cause of morbidity and mortality. Vaccines that elicit T-cell responses capable of controlling the virus represent a treatment strategy with potential for long-term effects. Here, we evaluated vaccines that induce the activity of type I natural killer T (NKT) cells to limit viral replication and license stimulation of conventional antiviral T-cells. Methods: Vaccines were prepared by conjugating peptide epitopes to an NKT-cell agonist to promote co-delivery to antigen-presenting cells, encouraging NKT-cell licensing and stimulation of T cells. Activity of the conjugate vaccines was assessed in transgenic mice expressing the complete HBV genome, administered intravenously to maximise access to NKT cell-rich tissues. Results: The vaccines induced only limited antiviral activity in unmanipulated transgenic hosts, likely attributable to NKT-cell activation as T-cell tolerance to viral antigens is strong. However, in a model of chronic hepatitis B involving transfer of naive HBcAg-specific CD8+ T cells into the transgenic mice, which typically results in specific T-cell dysfunction without virus control, vaccines containing the targeted HBcAg epitope induced prolonged antiviral activity because of qualitatively improved T-cell stimulation. In a step towards a clinical product, vaccines were prepared using synthetic long peptides covering clusters of known HLA-binding epitopes and shown to be immunogenic in HLA transgenic mice. Predictions based on HLA distribution suggest a product containing three selected SLP-based vaccines could give >90 % worldwide coverage, with an average of 3.38 epitopes targeted per individual. Conclusions: The novel vaccines described show promise for further clinical development as a treatment for chronic hepatitis B. Impact and Implications: Although there are effective prophylactic vaccines for HBV infection, it is estimated that 350-400 million people worldwide have chronic hepatitis B, putting these individuals at significant risk of life-threatening liver diseases. Therapeutic vaccination aimed at activating or boosting HBV-specific T-cell responses holds potential as a strategy for treating chronic infection, but has so far met with limited success. Here, we show that a glycolipid-peptide conjugate vaccine designed to coordinate activity of type I NKT cells alongside conventional antiviral T cells has antiviral activity in a mouse model of chronic infection. It is anticipated that a product based on a combination of three such conjugates, each prepared using long peptides covering clusters of known HLA-binding epitopes, could be developed further as a treatment for chronic hepatitis B with broad global HLA coverage.

An expanded transcriptome atlas for Bacteroides thetaiotaomicron reveals a small RNA that modulates tetracycline sensitivity.

Plasticity in gene expression allows bacteria to adapt to diverse environments. This is particularly relevant in the dynamic niche of the human intestinal tract; however, transcriptional networks remain largely unknown for gut-resident bacteria. Here we apply differential RNA sequencing (RNA-seq) and conventional RNA-seq to the model gut bacterium Bacteroides thetaiotaomicron to map transcriptional units and profile their expression levels across 15 in vivo-relevant growth conditions. We infer stress- and carbon source-specific transcriptional regulons and expand the annotation of small RNAs (sRNAs). Integrating this expression atlas with published transposon mutant fitness data, we predict conditionally important sRNAs. These include MasB, which downregulates tetracycline tolerance. Using MS2 affinity purification and RNA-seq, we identify a putative MasB target and assess its role in the context of the MasB-associated phenotype. These data-publicly available through the Theta-Base web browser ( http://micromix.helmholtz-hiri.de/bacteroides/ )-constitute a valuable resource for the microbiome community.

Evidence for a selective link between cooperation and individual recognition.

The ability to recognize others is a frequent assumption of models of the evolution of cooperation. At the same time, cooperative behavior has been proposed as a selective agent favoring the evolution of individual recognition abilities. Although theory predicts that recognition and cooperation may co-evolve, data linking recognition abilities and cooperative behavior with evidence of selection are elusive. Here, we provide evidence of a selective link between individual recognition and cooperation in the paper wasp Polistes fuscatus through a combination of clinal, common garden, and population genomics analyses. We identified latitudinal clines in both rates of cooperative nesting and color pattern diversity, consistent with a selective link between recognition and cooperation. In behavioral experiments, we replicated previous results demonstrating individual recognition in cooperative and phenotypically diverse P. fuscatus from New York. In contrast, wasps from a less cooperative and phenotypically uniform Louisiana population showed no evidence of individual recognition. In a common garden experiment, groups of wasps from northern populations formed more stable and individually biased associations, indicating that recognition facilitates group stability. The strength of recent positive selection on cognition-associated loci likely to mediate individual recognition is substantially greater in northern compared with southern P. fuscatus populations. Collectively, these data suggest that individual recognition and cooperative nesting behavior have co-evolved in P. fuscatus because recognition helps stabilize social groups. This work provides evidence of a specific cognitive phenotype under selection because of social interactions, supporting the idea that social behavior can be a key driver of cognitive evolution.

Correction: Ring-opening yields and auto-oxidation rates of the resulting peroxy radicals from OH-oxidation of α-pinene and ß-pinene.

[This corrects the article DOI: 10.1039/D2EA00133K.].

Assisted reproductive technology outcomes and management considerations for people with epilepsy.

PURPOSE OF REVIEW: Epilepsy is a common neurologic condition amongst people with reproductive capacity, and assisted reproductive technology (ART) is being increasingly utilized. A recent population-based study described favorable outcomes of ART in this population, but other work shows how fluctuating sex hormones may influence medication concentrations and seizures. RECENT FINDINGS: This review discusses hormonal influences on epilepsy and catamenial epilepsy, considerations regarding fertility in women with epilepsy, emerging ART outcomes, and management considerations for people with epilepsy undergoing ART. SUMMARY: Utilizing ART is an effective treatment for people with epilepsy desiring pregnancy, but closer monitoring and antiseizure medication adjustments may be needed to ensure the best outcomes. More research is needed to better guide epilepsy care during ART.

Influence of ß-casein genotype on physicochemical properties and functionality of bovine milk.

Several studies have been focused on the effect of milk protein genetic variants on milk physicochemical properties and functionality in recent years. ß-casein, an important protein related to milk processibility, has been reported to have 2 main genetic variants A1 and A2, for which cows may be homozygous or heterozygous. In this study, several physicochemical properties of milk with ß-casein variants A1A1, A1A2, and A2A2 from 3 collection occasions were analyzed. Higher manganese content and lower pH were found to be associated with the A1A1 variant compared with the other 2 genotypes. Better rennet and acid coagulation were found in A1A1 milk compared with A1A2 and A2A2 milk (although P > 0.05), whereas A2A2 milk was more stable to creaming compared with the other 2 genotypes, which may be linked to its smaller fat globule size. Thus, milk from cows with A1A1 genotype could be preferable for cheese making, while that with A2A2 variant can be used in formulations requiring good stability against creaming, and for example, yogurt making, where the softer yogurt texture may be easier to digest.