81 research outputs found
Analysis of G-quadruplexes as environmental sensors: Novel statistical models and computational algorithms enable interpretation of complex gene expression patterns for maize under salt stress conditions
The occurrence of G-quadruplex (G4) structures in both genic and non-genic sequences have been well-documented. However, even in genic regions the biological functions of these motifs remains poorly understood, though their potential to act in a regulatory fashion has been hypothesized. With the recent development of next-generation sequencing technology, we have accumulated genomic and transcriptomic sequences from various species and tissues. Coupled with pattern recognition software that can identify putative G4 sequences, the time is right for tackling the question of whether and how G4âs are involved in regulating gene expression. Previous studies suggested that G4 conformation can be dependent on cation type and concentration, along with G4 motif patterns differences (e.g., number of consecutive guanines). It also has been shown that G4 function may be associated with the location relative to a given geneâs structural elements (transcription start site [TSS], exon/intron boundaries, etc.).
My project focused on the expression of G4-containing genes from maize tissues under various abiotic stress conditions, including salt stress, which would be likely to change physiological cation concentrations. I quantified, compared, and visualized expression of G4-containing gene groups by developing and applying novel computational algorithms and statistical models. These methods were packaged into a software program I released on a web server called C-REx (http://c-rex.dill-picl.org/). I found that under salt stress conditions, transcription factors (TFs) with a G4 on the anti-sense strand upstream of the TSS are 455% more likely to be up-regulated than non-G4 genes. Likewise, transcription factors with a G4 on the anti-sense strand just downstream of the TSS are 259% more likely to be up-regulated. In addition, among G4 transcription factors that are up-regulated, heat shock factors are significantly enriched. On the other hand, under salt stress conditions non-TF genes with a G4 on anti-sense strand upstream of the TSS are 157% more likely to be down-regulated, and those with the G4 on the anti-sense strand downstream of the TSS are 124% more likely to be down-regulated. Through G4 sequence feature analysis, we found that the length of G-runs was significantly associated with whether genes were switched âonâ or âoffâ in salt stress conditions. The shortest G-runs were associated with G4 motifs in TF genes that were switched âonâ and longest G-runs were associated with G4s in non-TF genes that were switched âoffâ. These findings suggest that salt stress resilience could potentially be improved in maize by selecting for natural gene variants with specific G4 constitutions or by introducing specific G4 motifs of varying lengths into TF and non-TF genes involved in response to salt stress
Single-peak and narrow-band mid-infrared thermal emitters driven by mirror-coupled plasmonic quasi-BIC metasurfaces
Wavelength-selective thermal emitters (WS-EMs) hold considerable appeal due
to the scarcity of cost-effective, narrow-band sources in the mid-to-long-wave
infrared spectrum. WS-EMs achieved via dielectric materials typically exhibit
thermal emission peaks with high quality factors (Q factors), but their optical
responses are prone to temperature fluctuations. Metallic EMs, on the other
hand, show negligible drifts with temperature changes, but their Q factors
usually hover around 10. In this study, we introduce and experimentally verify
a novel EM grounded in plasmonic quasi-bound states in the continuum (BICs)
within a mirror-coupled system. Our design numerically delivers an
ultra-narrowband single peak with a Q factor of approximately 64, and
near-unity absorptance that can be freely tuned within an expansive band of
more than 10 {\mu}m. By introducing air slots symmetrically, the Q factor can
be further augmented to around 100. Multipolar analysis and phase diagrams are
presented to elucidate the operational principle. Importantly, our infrared
spectral measurements affirm the remarkable resilience of our designs'
resonance frequency in the face of temperature fluctuations over 300 degrees
Celsius. Additionally, we develop an effective impedance model based on the
optical nanoantenna theory to understand how further tuning of the emission
properties is achieved through precise engineering of the slot. This research
thus heralds the potential of applying plasmonic quasi-BICs in designing
ultra-narrowband, temperature-stable thermal emitters in mid-infrared.
Moreover, such a concept may be adaptable to other frequency ranges, such as
near-infrared, Terahertz, and Gigahertz.Comment: 39 pages, 12 figure
Image polaritons in boron nitride for extreme polariton confinement with low losses
Polaritons in two-dimensional materials provide extreme light confinement
that is difficult to achieve with metal plasmonics. However, such tight
confinement inevitably increases optical losses through various damping
channels. Here we demonstrate that hyperbolic phonon polaritons in hexagonal
boron nitride can overcome this fundamental trade-off. Among two observed
polariton modes, featuring a symmetric and antisymmetric charge distribution,
the latter exhibits lower optical losses and tighter polariton confinement.
Far-field excitation and detection of this high-momenta mode becomes possible
with our resonator design that can boost the coupling efficiency via virtual
polariton modes with image charges that we dub image polaritons. Using these
image polaritons, we experimentally observe a record-high effective index of up
to 132 and quality factors as high as 501. Further, our phenomenological theory
suggests an important role of hyperbolic surface scattering in the damping
process of hyperbolic phonon polaritons
Response to Persistent ER Stress in Plants: a Multiphasic Process that Transitions Cells from Prosurvival Activities to Cell Death
The unfolded protein response (UPR) is a highly conserved response that protects plants from adverse environmental conditions. The UPR is elicited by endoplasmic reticulum (ER) stress, in which unfolded and misfolded proteins accumulate within the ER. Here, we induced the UPR in maize (Zea mays) seedlings to characterize the molecular events that occur over time during persistent ER stress. We found that a multiphasic program of gene expression was interwoven among other cellular events, including the induction of autophagy. One of the earliest phases involved the degradation by regulated IRE1-dependent RNA degradation (RIDD) of RNA transcripts derived from a family of peroxidase genes. RIDD resulted from the activation of the promiscuous ribonuclease activity of ZmIRE1 that attacks the mRNAs of secreted proteins. This was followed by an upsurge in expression of the canonical UPR genes indirectly driven by ZmIRE1 due to its splicing of Zmbzip60 mRNA to make an active transcription factor that directly upregulates many of the UPR genes. At the peak of UPR gene expression, a global wave of RNA processing led to the production of many aberrant UPR gene transcripts, likely tempering the ER stress response. During later stages of ER stress, ZmIRE1\u27s activity declined as did the expression of survival modulating genes, Bax inhibitor1 and Bcl-2-associated athanogene7, amidst a rising tide of cell death. Thus, in response to persistent ER stress, maize seedlings embark on a course of gene expression and cellular events progressing from adaptive responses to cell death
Research progress on deep learning in magnetic resonance imagingâbased diagnosis and treatment of prostate cancer: a review on the current status and perspectives
Multiparametric magnetic resonance imaging (mpMRI) has emerged as a first-line screening and diagnostic tool for prostate cancer, aiding in treatment selection and noninvasive radiotherapy guidance. However, the manual interpretation of MRI data is challenging and time-consuming, which may impact sensitivity and specificity. With recent technological advances, artificial intelligence (AI) in the form of computer-aided diagnosis (CAD) based on MRI data has been applied to prostate cancer diagnosis and treatment. Among AI techniques, deep learning involving convolutional neural networks contributes to detection, segmentation, scoring, grading, and prognostic evaluation of prostate cancer. CAD systems have automatic operation, rapid processing, and accuracy, incorporating multiple sequences of multiparametric MRI data of the prostate gland into the deep learning model. Thus, they have become a research direction of great interest, especially in smart healthcare. This review highlights the current progress of deep learning technology in MRI-based diagnosis and treatment of prostate cancer. The key elements of deep learning-based MRI image processing in CAD systems and radiotherapy of prostate cancer are briefly described, making it understandable not only for radiologists but also for general physicians without specialized imaging interpretation training. Deep learning technology enables lesion identification, detection, and segmentation, grading and scoring of prostate cancer, and prediction of postoperative recurrence and prognostic outcomes. The diagnostic accuracy of deep learning can be improved by optimizing models and algorithms, expanding medical database resources, and combining multi-omics data and comprehensive analysis of various morphological data. Deep learning has the potential to become the key diagnostic method in prostate cancer diagnosis and treatment in the future
Infrared permittivity of the biaxial van der Waals semiconductor -MoO from near- and far-field correlative studies
The biaxial van der Waals semiconductor -phase molybdenum trioxide
(-MoO) has recently received significant attention due to its
ability to support highly anisotropic phonon polaritons (PhPs) -infrared (IR)
light coupled to lattice vibrations in polar materials-, offering an
unprecedented platform for controlling the flow of energy at the nanoscale.
However, to fully exploit the extraordinary IR response of this material, an
accurate dielectric function is required. Here, we report the accurate IR
dielectric function of -MoO by modelling far-field, polarized IR
reflectance spectra acquired on a single thick flake of this material. Unique
to our work, the far-field model is refined by contrasting the experimental
dispersion and damping of PhPs, revealed by polariton interferometry using
scattering-type scanning near-field optical microscopy (s-SNOM) on thin flakes
of -MoO, with analytical and transfer-matrix calculations, as well
as full-wave simulations. Through these correlative efforts, exceptional
quantitative agreement is attained to both far- and near-field properties for
multiple flakes, thus providing strong verification of the accuracy of our
model, while offering a novel approach to extracting dielectric functions of
nanomaterials, usually too small or inhomogeneous for establishing accurate
models only from standard far-field methods. In addition, by employing density
functional theory (DFT), we provide insights into the various vibrational
states dictating our dielectric function model and the intriguing optical
properties of -MoO
Chinese Cerebrovascular Neurosurgery Society and Chinese Interventional & Hybrid Operation Society, of Chinese Stroke Association Clinical Practice Guidelines for Management of Brain Arteriovenous Malformations in Eloquent Areas
Aim: The aim of this guideline is to present current and comprehensive recommendations for the management of brain arteriovenous malformations (bAVMs) located in eloquent areas.Methods: An extended literature search on MEDLINE was performed between Jan 1970 and May 2020. Eloquence-related literature was further screened and interpreted in different subcategories of this guideline. The writing group discussed narrative text and recommendations through group meetings and online video conferences. Recommendations followed the Applying Classification of Recommendations and Level of Evidence proposed by the American Heart Association/American Stroke Association. Prerelease review of the draft guideline was performed by four expert peer reviewers and by the members of Chinese Stroke Association.Results: In total, 809 out of 2,493 publications were identified to be related to eloquent structure or neurological functions of bAVMs. Three-hundred and forty-one publications were comprehensively interpreted and cited by this guideline. Evidence-based guidelines were presented for the clinical evaluation and treatment of bAVMs with eloquence involved. Topics focused on neuroanatomy of activated eloquent structure, functional neuroimaging, neurological assessment, indication, and recommendations of different therapeutic managements. Fifty-nine recommendations were summarized, including 20 in Class I, 30 in Class IIa, 9 in Class IIb, and 2 in Class III.Conclusions: The management of eloquent bAVMs remains challenging. With the evolutionary understanding of eloquent areas, the guideline highlights the assessment of eloquent bAVMs, and a strategy for decision-making in the management of eloquent bAVMs
An ontology approach to comparative phenomics in plants
BACKGROUND: Plant phenotype datasets include many different types of data, formats, and terms from specialized vocabularies. Because these datasets were designed for different audiences, they frequently contain language and details tailored to investigators with different research objectives and backgrounds. Although phenotype comparisons across datasets have long been possible on a small scale, comprehensive queries and analyses that span a broad set of reference species, research disciplines, and knowledge domains continue to be severely limited by the absence of a common semantic framework. RESULTS: We developed a workflow to curate and standardize existing phenotype datasets for six plant species, encompassing both model species and crop plants with established genetic resources. Our effort focused on mutant phenotypes associated with genes of known sequence in Arabidopsis thaliana (L.) Heynh. (Arabidopsis), Zea mays L. subsp. mays (maize), Medicago truncatula Gaertn. (barrel medic or Medicago), Oryza sativa L. (rice), Glycine max (L.) Merr. (soybean), and Solanum lycopersicum L. (tomato). We applied the same ontologies, annotation standards, formats, and best practices across all six species, thereby ensuring that the shared dataset could be used for cross-species querying and semantic similarity analyses. Curated phenotypes were first converted into a common format using taxonomically broad ontologies such as the Plant Ontology, Gene Ontology, and Phenotype and Trait Ontology. We then compared ontology-based phenotypic descriptions with an existing classification system for plant phenotypes and evaluated our semantic similarity dataset for its ability to enhance predictions of gene families, protein functions, and shared metabolic pathways that underlie informative plant phenotypes. CONCLUSIONS: The use of ontologies, annotation standards, shared formats, and best practices for cross-taxon phenotype data analyses represents a novel approach to plant phenomics that enhances the utility of model genetic organisms and can be readily applied to species with fewer genetic resources and less well-characterized genomes. In addition, these tools should enhance future efforts to explore the relationships among phenotypic similarity, gene function, and sequence similarity in plants, and to make genotype-to-phenotype predictions relevant to plant biology, crop improvement, and potentially even human health.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]
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