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The stability of the aptamer domain of the pbuE riboswitch is examined and the thermodynamic and kinetic properties of adenine, 2-aminopurine and 2,6-diaminopurine ligand binding are determined. The findings support the hypothesis that many riboswitches rely on the kinetics of ligand binding and the speed of RNA transcription to establish the concentration of metabolite needed to trigger riboswitch function.

Research has been conducted on Bacillus subtilis gene. The authors have demonstrated that this gene carries a conserved RNA element which is a lysine-responsive riboswitch.

Camouflage is a widespread phenomenon throughout nature and an important antipredator tactic in natural selection. Many visual predators have keen color perception, and thus camouflage patterns should provide some degree of color matching in addition to other visual factors such as pattern, contrast, and texture. Quantifying camouflage effectiveness in the eyes of the predator is a challenge from the perspectives of both biology and optical imaging technology. Here we take advantage of hyperspectral imaging (HSI), which records full-spectrum light data, to simultaneously visualize color match and pattern match in the spectral and the spatial domains, respectively. Cuttlefish can dynamically camouflage themselves on any natural substrate and, despite their colorblindness, produce body patterns that appear to have high-fidelity color matches to the substrate when viewed directly by humans or with RGB images. Live camouflaged cuttlefish on natural backgrounds were imaged using HSI, and subsequent spectral analysis revealed that most reflectance spectra of individual cuttlefish and substrates were similar, rendering the color match possible. Modeling color vision of potential di- and trichromatic fish predators of cuttlefish corroborated the spectral match analysis and demonstrated that camouflaged cuttlefish show good color match as well as pattern match in the eyes of fish predators. These findings (i) indicate the strong potential of HSI technology to enhance studies of biological coloration and (ii) provide supporting evidence that cuttlefish can produce color-coordinated camouflage on natural substrates despite lacking color vision. [ABSTRACT FROM AUTHOR]

Nobel metal composite aerogel fibers made from flexible and porous biopolymers offer a wide range of applications, such as in catalysis and sensing, by functionalizing the nanostructure. However, producing these composite aerogels in a defined shape is challenging for many protein-based biopolymers, especially ones that are not fibrous proteins. Here, we present the synthesis of silk fibroin composite aerogel fibers up to 2 cm in length and a diameter of ~300 μm decorated with noble metal nanoparticles. Lyophilized silk fibroin dissolved in hexafluoro-2-propanol (HFIP) was cast in silicon tubes and physically crosslinked with ethanol to produce porous silk gels. Composite silk aerogel fibers with noble metals were created by equilibrating the gels in noble metal salt solutions reduced with sodium borohydride, followed by supercritical drying. These porous aerogel fibers provide a platform for incorporating noble metals into silk fibroin materials, while also providing a new method to produce porous silk fibers. Noble metal silk aerogel fibers can be used for biological sensing and energy storage applications. [ABSTRACT FROM AUTHOR]

Noble metal aerogels offer a wide range of catalytic applications due to their high surface area and tunable porosity. Control over monolith shape, pore size, and nanofiber diameter is desired in order to optimize electronic conductivity and mechanical integrity for device applications. However, common aerogel synthesis techniques such as solvent mediated aggregation, linker molecules, sol–gel, hydrothermal, and carbothermal reduction are limited when using noble metal salts. Here, we present the synthesis of palladium aerogels using carboxymethyl cellulose nanofiber (CNF) biotemplates that provide control over aerogel shape, pore size, and conductivity. Biotemplate hydrogels were formed via covalent cross linking using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) with a diamine linker between carboxymethylated cellulose nanofibers. Biotemplate CNF hydrogels were equilibrated in precursor palladium salt solutions, reduced with sodium borohydride, and rinsed with water followed by ethanol dehydration, and supercritical drying to produce freestanding aerogels. Scanning electron microscopy indicated three-dimensional nanowire structures, and X-ray diffractometry confirmed palladium and palladium hydride phases. Gas adsorption, impedance spectroscopy, and cyclic voltammetry were correlated to determine aerogel surface area. These self-supporting CNF-palladium aerogels demonstrate a simple synthesis scheme to control porosity, electrical conductivity, and mechanical robustness for catalytic, sensing, and energy applications. [ABSTRACT FROM AUTHOR]

Introduction: Wastewater surveillance is an important technique to monitor public health and is being studied extensively for pandemic prevention, force health protection and readiness, and as a potential early warning system for chem-bio defense. Wastewater surveillance has traditionally relied on techniques such as quantitative PCR or targeted sequencing, both of which are microbe- or disease-specific tools. Newer pan-viral metagenomics strategies may provide higher specificity for pathogens of interest, resulting in a lower false negative rate and reduced sequencing of undesired background nucleic acids. One such system, VirCapSeq-VERT, has been developed to target all vertebrate virus pathogens; until recently, its application has been limited to clinical samples. The objective of this study was to use VirCapSeq-VERT to interrogate wastewater samples from the U.S. Air Force Academy (USAFA), Colorado Springs, Colorado, to determine its utility in assessing complex samples and its potential application in public health surveillance., Materials and Methods: Biweekly samples were analyzed from February 2022 through May 2023. Samples were collected from the wastewater treatment facility at USAFA before treatment and stored at -20 °C until total nucleic acid (tNA: DNA and RNA) extraction. tNA was then subject to the probe-based capture system, VirCapSeq, and run through a collection of public bioinformatics pipelines to identify captured viral pathogens and perform phylogenetic analysis. It was determined by the USAFA IRB that the study was non-human subject research and was deemed exempt., Results: In total, 68 families of viruses were identified, comprising thousands of individual strains. This study focused on viruses responsible for gastrointestinal dysfunction as a test of the use of the VirCapSeq-VERT to identify human pathogenic viruses within a complex and highly enriched biological sample. Four enteric viruses dominated the wastewater samples, with Adenoviridae most prevalent before the cadet winter recess (December 17, 2022-January 4, 2023) and Astroviridae most abundant thereafter., Conclusion: Although gastroenteritis outbreaks at USAFA are commonly attributed to norovirus because of clinical presentation and the acute nature of the illness-often diagnosed and treated without confirmatory stool testing-this virus was not found in high prevalence in these wastewater samples. Among adenoviruses, F serotype 41 predominated, suggesting a role in gastrointestinal infections among the cadet population. Phylogenetic investigation of adenovirus and norovirus exposed common variants with seasonal distributions. These findings may prompt correlational studies to assess the clinical predictive capability of VirCapSeq-VERT and to determine the utility of wastewater monitoring as an outbreak early warning system., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2024. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Riboswitches encompass messenger ribonucleic acid transcripts that sense the concentration of small molecule metabolites through binding the target compound and then control the expression of metabolite-related genes in response to the metabolite concentration. While much of the riboswitch-related research has focused on the remarkable ability of different aptamer domains to adopt the intricate structures required to bind a spectrum of biological metabolites with high affinity and specificity, less attention has been paid to the mechanism of riboswitch action. Specifically, the genetic control element of the riboswitch, known as the expression platform, must function cotranscriptionally in the case of transcription termination-controlled riboswitches. By correlating the transcriptional kinetics of the entire switch and the kinetics and thermodynamics of metabolite binding of the aptamer domain, it was found that the FMN-binding riboswitch in the 5' UTR of the Bacillus subtilis ribGBAHT operon functions as a kinetically controlled genetic switch chiefly dependent upon transcriptional pausing and the concentration of the target metabolite. This study has emphasized the importance of studying the switch in its entirety and in the context of an actively transcribing RNA polymerase. Herein I will describe the study of the kinetics of riboswitch transcription and the proposed mechanism for the transcription termination-associated riboswitch control of riboflavin-related genes.