Biology subjects

Shannon, S.

Publications and source records attributed to Shannon, S..

4 recordsLinked to original sources

bioRxiv2025

Non-Thermal Plasma Activated Water is an Effective Nitrogen Fertilizer Alternative for Arabidopsis thaliana

Nitrogen (N) fixation with non-thermal plasmas has been proposed as a sustainable alternative to meet growing N fertilizer demands for agriculture. This technology generates Plasma Activated Water (PAW) with a range of chemical compositions, including different concentrations of nitrate (NO-) and hydrogen peroxide (H2O2), among other compounds. Potential use of PAW as an effective crop fertilizer necessitates a robust understanding of the underlying biology of the plant, which is not yet available. The lack of a unified standard in PAW production and the varying chemical make-up that results from different devices and protocols hampers comparative studies and adoption of this technology. The objective of this study was to compare the efficacy of two PAW solutions with differing concentrations of H2O2 produced from a Radio Frequency (RF) glow discharge plasma source. The effect of these solutions on plant growth, ROS accumulation, gene expression and heat stress response were compared to N-equivalent controls in the model plant Arabidopsis to assess their potential as an alternative N fertilizer. While PAW solutions lacking detectable H2O2 enhanced seedling growth, those containing approximately 0.3 {micro}M of H2O2 did not. ROS accumulation in root tissues was similar between PAW and chemically equivalent solutions, suggesting H2O2 is the primary ROS present in the PAW at the time of treatment. Gene expression studies showed induction of genes involved in N uptake and assimilation in PAW-treated seedlings. Pre- treatment of seedlings with PAW solutions containing H2O2 improved root growth under heat stress which indicates that this treatment may induce plant stress response pathways. Finally, mature plants showed similar growth when fertilized with PAW lacking H2O2 or NO3- control regimes for over 5 weeks indicating equivalency in chemical composition, plant nutrient uptake and utilization. Overall, these results demonstrate that PAW is an effective alternative to NO3- fertilizers for plant cultivation but the levels of H2O2 need to be carefully controlled.

plant biology↗

bioRxiv2023

Constructed languages are processed by the same brain mechanisms as natural languages

What constitutes a language? Natural languages share features with other domains: from math, to music, to gesture. However, the brain mechanisms that process linguistic input are highly specialized, showing little response to diverse non-linguistic tasks. Here, we examine constructed languages (conlangs) to ask whether they draw on the same neural mechanisms as natural languages, or whether they instead pattern with domains like math and programming languages. Using individual-subject fMRI analyses, we show that understanding conlangs recruits the same brain areas as natural language comprehension. This result holds for Esperanto (n=19 speakers) and four fictional conlangs (Klingon (n=10), Navi (n=9), High Valyrian (n=3), and Dothraki (n=3)). These findings suggest that conlangs and natural languages share critical features that allow them to draw on the same representations and computations, implemented in the left-lateralized network of brain areas. The features of conlangs that differentiate them from natural languages--including recent creation by a single individual, often for an esoteric purpose, the small number of speakers, and the fact that these languages are typically learned in adulthood-- appear to not be consequential for the reliance on the same cognitive and neural mechanisms. We argue that the critical shared feature of conlangs and natural languages is that they are symbolic systems capable of expressing an open-ended range of meanings about our outer and inner worlds. Significance StatementWhat constitutes a language has been of interest to diverse disciplines - from philosophy and linguistics to psychology, anthropology, and sociology. An empirical approach is to test whether the system in question recruits the brain system that processes natural languages. In spite of their similarity to natural languages, math and programming languages recruit a distinct brain system. Using fMRI, we test brain responses to stimuli not previously investigated--constructed languages (conlangs)--and find that they are processed by the same brain network as natural languages. Thus, an ability for a symbolic system to express diverse meanings about the world-- but not the recency, manner, and purpose of its creation, or a large user base--is a defining characteristic of a language.

neuroscience↗

bioRxiv2022

LanA (Language Atlas): A probabilistic atlas for the language network based on fMRI data from >800 individuals

Two analytic traditions characterize fMRI language research. One relies on averaging activations voxel-wise across individuals. This approach has limitations: because of inter-individual variability in the locations of language areas, a location in a common brain space cannot be meaningfully linked to function. An alternative approach relies on identifying language areas in each individual using a functional localizer. Because of its greater sensitivity, functional resolution, and interpretability, functional localization is gaining popularity, but it is not always feasible, and cannot be applied retroactively to past studies. We provide a solution for bridging these currently disjoint approaches in the form of a probabilistic functional atlas created from fMRI data for an extensively validated language localizer in 806 individuals. This atlas enables estimating the probability that any given location in a common brain space belongs to the language network, and thus can help interpret group-level peaks and meta-analyses of such peaks, and lesion locations in patient investigations. More meaningful comparisons of findings across studies should increase robustness and replicability in language research.

neuroscience↗

bioRxiv2019

Genetic heterogeneity of the Spy1336/R28 - Spy1337 Virulence Axis in Streptococcus pyogenes and Effect on Gene Transcript Levels and Pathogenesis

Streptococcus pyogenes is a strict human pathogen responsible for more than 700 million infections annually worldwide. Strains of serotype M28 S. pyogenes are typically among the five more abundant types causing invasive infections and pharyngitis in adults and children. Type M28 strains also have an unusual propensity to cause puerperal sepsis and neonatal disease. We recently discovered that a one-nucleotide indel in an intergenic homopolymeric tract located between genes Spy1336/R28 and Spy1337 altered virulence in a mouse model of infection. In the present study, we analyzed size variation in this homopolymeric tract and determined the extent of heterogeneity in the number of tandemly-repeated 79-amino acid domains in the coding region of Spy1336/R28 in large samples of strains recovered from humans with invasive infections. Both repeat sequence elements are highly polymorphic in natural populations of M28 strains. Variation in the homopolymeric tract results in (i) changes in transcript levels of Spy1336/R28 and Spy1337 in vitro, (ii) differences in virulence in a mouse model of necrotizing myositis, and (iii) global transcriptome changes as shown by RNAseq analysis of isogenic mutant strains. Variation in the number of tandem repeats in the coding sequence of Spy1336/R28 is responsible for size variation of R28 protein in natural populations. Isogenic mutant strains in which genes encoding R28 or transcriptional regulator Spy1337 are inactivated are significantly less virulent in a nonhuman primate model of necrotizing myositis. Our findings provide impetus for additional studies addressing the role of R28 and Spy1337 variation in pathogen-host interactions.

microbiology↗