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At least 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Conservative Binary Dynamics at Order 𝛼 5 in Electrodynamics

We compute the potential-photon contributions to the classical relativistic scattering angle of two charged nonspinning bodies in electrodynamics through fifth order in the coupling. We use the scattering amplitudes framework, effective field theory, and multiloop integration techniques based on integration by parts and differential equations. At fifth order, the result is expressed in terms of cyclotomic polylogarithms. Our calculation demonstrates the feasibility of the corresponding calculations in general relativity, including the evaluation of the encountered four-loop integrals.

classical electromagnetism↗
DOE OSTI2025

Soft-hard framework with exact four-momentum conservation for small systems

A new framework, called x-scape, for the combined study of both hard and soft transverse momentum sectors in high-energy proton-proton (𝑝−𝑝) and proton-nucleus (𝑝−𝐴) collisions is set up. A dynamical initial state is set up using the 3d-Glauber model with transverse locations of hotspots within each incoming nucleon. A hard scattering that emanates from two colliding hotspots is carried out using the Pythia generator. Initial state radiation from the incoming hard partons is carried out in a new module called I-matter, which includes the longitudinal location of initial splits. The energy-momentum of both the initial hard partons and their associated beam remnants is removed from the hot spots, depleting the energy-momentum available for the formation of the bulk medium. Outgoing showers are simulated using the matter generator, and results are presented for both cases, allowing for and not allowing for energy loss. First comparisons between this hard-soft model and single inclusive hadron and jet data from 𝑝−𝑝 and minimum bias 𝑝−Pb collisions are presented. Single hadron spectra in 𝑝−𝑝 are used to carry out a limited (in number of parameters) Bayesian calibration of the model. Fair comparisons with data are indicative of the utility of this new framework. Theoretical studies of the correlation between jet 𝑝 𝑇 and event activity at mid and forward rapidity are carried out.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Hemiptera phylogenomic resources: Tree‐based orthology prediction and conserved exon identification

Abstract High‐throughput sequencing of transcriptomes and targeted genomic regions are advancing our knowledge of The Tree of Life. Building phylogenies with regions of the genome requires 1‐to‐1 orthologue resources of genes and noncoding loci. One organismal group that has received little attention in this area is the Hemiptera, the fifth largest insect order represented by ~103,590 named species. Here, we present a set of 3,872 Hemiptera 1‐to‐1 orthogroups based on tree‐based orthology inference of eight Hemiptera species with publicly available genome sequences. We also estimate a set of 406 orthologous exons with similar mRNA splice sites that can be used for Sanger sequencing and develop enrichment probes for targeted genome sequencing for phylogenomic inference. We show this novel set of orthologues is informative at the protein, coding sequence and exon molecular levels and provides robust branch support in both gene tree–species tree methods and concatenated sequence phylogenies. In addition, we demonstrate the utility of these loci to resolve relationships in whiteflies, Bemisia tabaci , a large species complex with few phylogenomic resources. Last, we compare our Hemiptera phylogeny with previously published phylogenies and other orthologue databases, while providing suggestions on further improvement to this phylogenomic resource.

Owen, Christopher L.↗
DOE OSTI2023

A conserved gene regulatory network controls root epidermal cell patterning in superrosid species

Summary In superrosid species, root epidermal cells differentiate into root hair cells and nonhair cells. In some superrosids, the root hair cells and nonhair cells are distributed randomly (Type I pattern), and in others, they are arranged in a position‐dependent manner (Type III pattern). The model plant Arabidopsis ( Arabidopsis thaliana ) adopts the Type III pattern, and the gene regulatory network (GRN) that controls this pattern has been defined. However, it is unclear whether the Type III pattern in other species is controlled by a similar GRN as in Arabidopsis, and it is not known how the different patterns evolved. In this study, we analyzed superrosid species Rhodiola rosea , Boehmeria nivea , and Cucumis sativus for their root epidermal cell patterns. Combining phylogenetics, transcriptomics, and cross‐species complementation, we analyzed homologs of the Arabidopsis patterning genes from these species. We identified R. rosea and B. nivea as Type III species and C. sativus as Type I species. We discovered substantial similarities in structure, expression, and function of Arabidopsis patterning gene homologs in R. rosea and B. nivea , and major changes in C. sativus . We propose that in superrosids, diverse Type III species inherited the patterning GRN from a common ancestor, whereas Type I species arose by mutations in multiple lineages.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Conservation of beneficial microbes between the rhizosphere and the cyanosphere

Summary Biocrusts are phototroph‐driven communities inhabiting arid soil surfaces. Like plants, most photoautotrophs (largely cyanobacteria) in biocrusts are thought to exchange fixed carbon for essential nutrients like nitrogen with cyanosphere bacteria. Here, we aim to compare beneficial interactions in rhizosphere and cyanosphere environments, including finding growth‐promoting strains for hosts from both environments. To examine this, we performed a retrospective analysis of 16S rRNA gene sequencing datasets, host–microbe co‐culture experiments between biocrust communities/biocrust isolates and a model grass ( Brachypodium distachyon ) or a dominant biocrust cyanobacterium ( Microcoleus vaginatus ), and metabolomic analysis. All 18 microbial phyla in the cyanosphere were also present in the rhizosphere, with additional 17 phyla uniquely found in the rhizosphere. The biocrust microbes promoted the growth of the model grass, and three biocrust isolates ( Bosea sp._L1B56, Pseudarthrobacter sp. _ L1D14 and Pseudarthrobacter picheli_ L1D33) significantly promoted the growth of both hosts. Moreover, pantothenic acid was produced by Pseudarthrobacter sp._L1D14 when grown on B . distachyon exudates, and supplementation of plant growth medium with this metabolite increased B . distachyon biomass by over 60%. These findings suggest that cyanobacteria and other diverse photoautotrophic hosts can be a source for new plant growth‐promoting microbes and metabolites.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Nonphotochemical quenching kinetics GWAS in sorghum identifies genes that may play conserved roles in maize and Arabidopsis thaliana photoprotection

SUMMARY Photosynthetic organisms must cope with rapid fluctuations in light intensity. Nonphotochemical quenching (NPQ) enables the dissipation of excess light energy as heat under high light conditions, whereas its relaxation under low light maximizes photosynthetic productivity. We quantified variation in NPQ kinetics across a large sorghum ( Sorghum bicolor ) association panel in four environments, uncovering significant genetic control for NPQ. A genome‐wide association study (GWAS) confidently identified three unique regions in the sorghum genome associated with NPQ and suggestive associations in an additional 61 regions. We detected strong signals from the sorghum ortholog of Arabidopsis thaliana Suppressor Of Variegation 3 ( SVR3 ) involved in plastid–nucleus signaling. By integrating GWAS results for NPQ across maize ( Zea mays ) and sorghum‐association panels, we identified a second gene, Non‐yellowing 1 ( NYE1 ), originally studied by Gregor Mendel in pea ( Pisum sativum ) and involved in the degradation of photosynthetic pigments in light‐harvesting complexes. Analysis of nye1 insertion alleles in A. thaliana confirmed the effect of this gene on NPQ kinetics in eudicots. We extended our comparative genomics GWAS framework across the entire maize and sorghum genomes, identifying four additional loci involved in NPQ kinetics. These results provide a baseline for increasing the accuracy and speed of candidate gene identification for GWAS in species with high linkage disequilibrium.

Plant Sciences↗
DOE OSTI2026

A conserved glycan motif induces broadly reactive functional antibodies against the zoonotic pathogen Streptococcus suis

Streptococcus suis is a largely neglected but emerging bacterial zoonotic pathogen of global concern for animal welfare, antibiotic resistance development, and human health. No effective vaccines are now available. Here, we identified and characterized the function and structure of two cell wall polysaccharide variants in pathogenic S. suis strains using genetic deletion and (heterologous) complementation, lectin staining, glycan composition analysis, and specialized NMR spectroscopy. Both glycan variants were anionic polymers that differed in the presence of glucose in the side chain as a result of allelic variation in a glycosyltransferase gene. Deletion of this variable glycosyltransferase revealed an identical glycan “core” and affected S. suis morphology and lysozyme resistance. Immunization of pigs with this core domain elicited antibodies that recognized antigenically diverse pathogenic S. suis strains and induced complement deposition on encapsulated pathogenic S. suis strains. This study provides valuable insights for developing next-generation glycoconjugate vaccines, whereby a single-glycan target could protect against the emerging zoonotic pathogen S. suis.

60 APPLIED LIFE SCIENCES↗