检索结果-内蒙古大学图书馆

An Artificial Yeast Genetic Circuit Enables Deep Mutational Scanning of an Antimicrobial Resistance Protein

ACS SYNTHETIC BIOLOGY 2018年第8期7卷 1907-1917页

作者： Scott, Louis H. Mathews, James C. Flematti, Gavin R. Filipovska, Aleksandra Rackham, Oliver Univ Western Australia Harry Perkins Inst Med Res Nedlands WA 6009 Australia Univ Western Australia Ctr Med Res Nedlands WA 6009 Australia Univ Western Australia Sch Mol Sci Crawley 6009 Australia

Understanding the molecular mechanisms underlying antibiotic resistance requires concerted efforts in enzymology and medicinal chemistry. Here we describe a new synthetic biology approach to antibiotic development, where the presence of tetracycline antibiotics is linked to a life death selection in Saccharomyces cerevisiae. This artificial,genetic circuit allowed the deep mutational scanning of the tetracycline inactivating enzyme TetX, revealing key functional residues. We used both positive and negative selections to confirm the importance of different residues for TetX activity, and profiled activity hotspots for different tetracyclines to reveal substrate specific activity determinants. We found that precise positioning of FAD and hydrophobic shielding of the tetracycline are critical for enzymatic inactivation of doxycycline. However, positioning of FAD is suboptimal in the case of anhydrotetracycline, potentially explaining its comparatively poor degradation and potential as an inhibitor for this family of enzymes. By combining artificial genetic circuits whose function can be modulated by antimicrobial resistance determinants, we establish a framework to select for the next generation of antibiotics.

关键词： synthetic biology tetracycline structure-function relationships TetX antibiotic resistance genetic selection deep mutational scanning

来源：评论

学校读者我要写书评

暂无评论

A Metacognitive Approach to the Next Generation Science and Engineering Practices

引用

Science Scope 2019年第1期43卷 51-55页

作者： Bobbi Lynn Monroe Eric Brunsell

Despite implementing the Next Generation Science Standards (NGSS) in my middle school classroom for the past five years, completing biannual professional development, and fully embracing all that three-dimensional learning has to offer, I still wasn’t seeing my students fully grasp and embrace the science and engineering practices. [...]during the kick-off lesson, we came up with: "We examined the structure and function of flower parts by observing them in nature and developed a model that explained how those structures help the pollination of the flower." Examining the understanding of the growth with the practices through assessments, it was statistically clear (based on a student ř-test) that students showed considerable and significant gains through comparison of different grading quarters when there was no treatment to when students participated in the regular metacognitive tracking of the science practice(s) during the class. Ultimately, this reinforced what I believe is at the heart of teaching middle school science.

关键词： Pollination Teaching Engineering Students Classrooms Science education Metacognition structure-function relationships Learning Skills Plant reproduction

来源：评论

学校读者我要写书评

暂无评论

Front Cover: Photochemical CO2Reduction Using Rhenium(I) Tricarbonyl Complexes with Bipyridyl-Type Ligands with and without Second Coordination Sphere Effects (ChemPhotoChem 6/2021)

引用

ChemPhotoChem 2021年第6期5卷

作者： Laura Rotundo David C. Grills Roberto Gobetto Emanuele Priola Carlo Nervi Dmitry E. Polyansky Etsuko Fujita Chemistry Department University of Torino Via P. Giuria 7 10125 Torino Italy CIRCC Via Celso Ulpiani 27 70126 Bari Italy Chemistry Division Brookhaven National Laboratory Upton NY 11973–5000 USA

来源：评论

学校读者我要写书评

暂无评论

Cultivating Curiosity About Creatures

引用

Science and Children 2019年第8期56卷 54-62页

作者： Leslie Bradbury Rachel Wilson

Bradbury and Wilson share how their fourth-grade students investigate the physical and behavioral adaptations of crayfish. Because crayfish are native to our area and many students have experience observing them in our local streams, we decided to use these organisms to explore the relationship between the structure of their various body parts and how those structures help the crayfish survive. We worked with the fourth-grade students over two days using a variety of modalities to support students’ understanding of the connections between structure and function for the crayfish. Each of our lessons lasted approximately one hour and fifteen minutes but could have easily been broken into shorter segments over a larger number of days.

关键词： Crustaceans Science education Teaching methods Adaptations structure-function relationships Students Body parts Crayfish

来源：评论

学校读者我要写书评

暂无评论

A lesion and connectivity-based hierarchical model of chronic aphasia recovery dissociates patients and healthy controls

引用

NEUROIMAGE-CLINICAL 2019年 23卷 101919-000页

作者： Meier, Erin L. Johnson, Jeffrey P. Pan, Yue Kiran, Swathi Boston Univ Dept Speech Language & Hearing Sci Sargent Coll Hlth & Rehabil Sci 635 Commonwealth AveRoom 326 Boston MA 02215 USA

Traditional models of left hemisphere stroke recovery propose that reactivation of remaining ipsilesional tissue is optimal for language processing whereas reliance on contralesional right hemisphere homologues is less beneficial or possibly maladaptive in the chronic recovery stage. However, neuroimaging evidence for this proposal is mixed. This study aimed to elucidate patterns of effective connectivity in patients with chronic aphasia in light of healthy control connectivity patterns and in relation to damaged tissue within left hemisphere regions of interest and according to performance on a semantic decision task. Using fMRI and dynamic causal modeling, biologically-plausible models within four model families were created to correspond to potential neural recovery patterns, including Family A: Left-lateralized connectivity (i.e., no/minimal damage), Family B: Bilateral anterior-weighted connectivity (i.e., posterior damage), Family C: Bilateral posterior-weighted connectivity (i.e., anterior damage) and Family D: Right-lateralized connectivity (i.e., extensive damage). Controls exhibited a strong preference for left-lateralized network models (Family A) whereas patients demonstrated a split preference for Families A and C. At the level of connections, controls exhibited stronger left intrahemispheric task-modulated connections than did patients. Within the patient group, damage to left superior frontal structures resulted in greater right intrahemispheric connectivity whereas damage to left ventral structures resulted in heightened modulation of left frontal regions. Lesion metrics best predicted accuracy on the fMRI task and aphasia severity whereas left intrahemispheric connectivity predicted fMRI task reaction times. These results are discussed within the context of the hierarchical recovery model of chronic aphasia.

关键词： Aphasia Stroke Lexical-semantics Effective connectivity structure-function relationships

来源：评论

学校读者我要写书评

暂无评论

Warming alters energetic structure and function but not resilience of soil food webs

引用

NATURE CLIMATE CHANGE 2017年第12期7卷 895-+页

作者： Schwarz, Benjamin Barnes, Andrew D. Thakur, Madhav P. Brose, Ulrich Ciobanu, Marcel Reich, Peter B. Rich, Roy L. Rosenbaum, Benjamin Stefanski, Artur Eisenhauer, Nico Friedrich Schiller Univ Jena Inst Ecol Jena Germany Albert Ludwigs Univ Freiburg Biometry & Environm Syst Anal Freiburg Germany German Ctr Integrat Biodivers Res iDiv Leipzig Germany Univ Leipzig Inst Biol Leipzig Germany Univ Munster Inst Landscape Ecol Munster Germany Branch Natl Inst Res & Dev Biol Sci Inst Biol Res Cluj Napoca Romania Univ Minnesota Dept Forest Resources Minneapolis MN USA Western Sydney Univ Hawkesbury Inst Environm Penrith NSW Australia Smithsonian Environm Res Ctr POB 28 Edgewater MD 21037 USA

Climate warming is predicted to alter the structure, stability, and functioning of food webs(1-5). Yet, despite the importance of soil food webs for energy and nutrient turnover in terrestrial ecosystems, the effects of warming on these food webs-particularly in combination with other global change drivers-are largely unknown. Here, we present results from two complementary field experiments that test the interactive effects of warming with forest canopy disturbance and drought on energy flux in boreal-temperate ecotonal forest soil food webs. The first experiment applied a simultaneous above-and belowground warming treatment (ambient, +1.7 degrees C, +3.4 degrees C) to closed-canopy and recently clear-cut forest, simulating common forest disturbance(6). The second experiment crossed warming with a summer drought treatment (-40% rainfall) in the clear-cut habitats. We show that warming reduces energy flux to microbes, while forest canopy disturbance and drought facilitates warming-induced increases in energy flux to higher trophic levels and exacerbates the reduction in energy flux to microbes, respectively. Contrary to expectations, we find no change in whole-network resilience to perturbations, but significant losses in ecosystem functioning. Warming thus interacts with forest disturbance and drought, shaping the energetic structure of soil food webs and threatening the provisioning of multiple ecosystem functions in boreal-temperate ecotonal forests.

关键词： Soil stability Forest management Global warming Food webs Ecosystems Disturbance Drought Trophic levels Forest soils Field tests Energy Forest ecosystems Forests Reduction Soil structure Stability Canopies Terrestrial ecosystems Flux Forest canopy Soils Vegetation cover Ecosystem assessment Rainfall Ecosystem disturbance Climate warming Environmental changes Climate change Clear cutting Fluctuations Terrestrial environments Energy transfer Droughts Resilience Provisioning Energy flux Food chain Nutrients (mineral) Food chains structure-function relationships Rain Structural stability

来源：评论

学校读者我要写书评

暂无评论

Tall Amazonian forests are less sensitive to precipitation variability

引用

NATURE GEOSCIENCE 2018年第6期11卷 405-+页

作者： Giardina, Francesco Konings, Alexandra G. Kennedy, Daniel Alemohammad, Seyed Hamed Oliveira, Rafael S. Uriarte, Maria Gentine, Pierre Columbia Univ Dept Earth & Environm Engn New York NY USA Ecole Polytech Fed Lausanne Lausanne Switzerland Stanford Univ Dept Earth Syst Sci Stanford CA 94305 USA Columbia Univ Dept Earth & Environm Engn New York NY 10027 USA Univ Estadual Campinas Dept Biol Vegetal Campinas SP Brazil Univ Western Australia Sch Plant Biol Perth WA Australia Columbia Univ Dept Ecol Evolut & Environm Biol New York NY USA Columbia Univ Earth Inst New York NY 10027 USA

Climate change is altering the dynamics, structure and function of the Amazon, a biome deeply connected to the Earth's carbon cycle. Climate factors that control the spatial and temporal variations in forest photosynthesis have been well studied, but the influence of forest height and age on this controlling effect has rarely been considered. Here, we present remote sensing observations of solar-induced fluorescence (a proxy for photosynthesis), precipitation, vapour-pressure deficit and canopy height, together with estimates of forest age and aboveground biomass. We show that photosynthesis in tall Amazonian forests, that is, forests above 30 m, is three times less sensitive to precipitation variability than in shorter (less than 20 m) forests. Taller Amazonian forests are also found to be older, have more biomass and deeper rooting systems(1), which enable them to access deeper soil moisture and make them more resilient to drought. We suggest that forest height and age are an important control of photosynthesis in response to interannual precipitation fluctuations. Although older and taller trees show less sensitivity to precipitation variations, they are more susceptible to fluctuations in vapour-pressure deficit. Our findings illuminate the response of Amazonian forests to water stress, droughts and climate change.

关键词： Carbon cycle Soil moisture Biomass Variations Precipitation Remote sensing Drought Photosynthesis Age Variability Climate change Energy flow Precipitation variability Fluorescence Forests Pressure Temporal variations Soils Vegetation cover Water stress Climatic variability Spatial discrimination Fluctuations Droughts Dynamics Rainfall Rooting Earth Precipitation variations structure-function relationships Height Climatic changes

来源：评论

学校读者我要写书评

暂无评论

It's Not a Bug, It's a Feature: functional Materials in Insects

引用

ADVANCED MATERIALS 2018年第19期30卷 1705322-1705322页

作者： Schroeder, Thomas B. H. Houghtaling, Jared Wilts, Bodo D. Mayer, Michael Univ Michigan Dept Chem Engn 2300 Hayward St Ann Arbor MI 48109 USA Univ Fribourg Adolphe Merkle Inst Chemin Verdiers 4 CH-1700 Fribourg Switzerland Univ Michigan Dept Biomed Engn 2200 Bonisteel Blvd Ann Arbor MI 48109 USA

Over the course of their wildly successful proliferation across the earth, the insects as a taxon have evolved enviable adaptations to their diverse habitats, which include adhesives, locomotor systems, hydrophobic surfaces, and sensors and actuators that transduce mechanical, acoustic, optical, thermal, and chemical signals. Insect-inspired designs currently appear in a range of contexts, including antireflective coatings, optical displays, and computing algorithms. However, as over one million distinct and highly specialized species of insects have colonized nearly all habitable regions on the planet, they still provide a largely untapped pool of unique problem-solving strategies. With the intent of providing materials scientists and engineers with a muse for the next generation of bioinspired materials, here, a selection of some of the most spectacular adaptations that insects have evolved is assembled and organized by function. The insects presented display dazzling optical properties as a result of natural photonic crystals, precise hierarchical patterns that span length scales from nanometers to millimeters, and formidable defense mechanisms that deploy an arsenal of chemical weaponry. Successful mimicry of these adaptations may facilitate technological solutions to as wide a range of problems as they solve in the insects that originated them.

关键词： biomaterials entomology hierarchical materials nanomaterials structure-function relationships

来源：评论

学校读者我要写书评

暂无评论

A review about brown algal cell walls and fucose-containing sulfated polysaccharides: Cell wall context, biomedical properties and key research challenges

引用

CARBOHYDRATE POLYMERS 2017年 175卷 395-408页

作者： Deniaud-Bouet, Estelle Hardouin, Kevin Potin, Philippe Kloareg, Bernard Herve, Cecile UPMC Univ Paris 06 Sorbonne Univ UMR 8227 Integrat Biol Marine ModelsStn Biol Roscoff CS 90074 Roscoff France CNRS UMR 8227 Integrat Biol Marine Models Stn Biol Roscoff CS 90074 Roscoff France

Studies on brown algal cell walls have entered a new phase with the concomitant discovery of novel polysaccharides present in cell walls and the establishment of a comprehensive generic model for cell wall architecture. Brown algal cell walls are composites of structurally complex polysaccharides. In this review we discuss the most recent progress in the structural composition of brown algal cell walls, emphasizing the significance of extraction and screening techniques, and the biological activities of the corresponding polysaccharides, with a specific focus on the fucose-containing sulfated polysaccharides. They include valuable marine molecules that exert a broad range of pharmacological properties such as antioxidant and anti-inflammatory activities, functions in the regulation of immune responses and of haemostasis, anti-infectious and anticancer actions. We identify the key remaining challenges in this research field. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Brown algae Fucose-containing sulfated polysaccharides Sulfated fucans Fucoidans Biomedical activity structure-function relationships

来源：评论

学校读者我要写书评

暂无评论

Cardiotoxins: functional Role of Local Conformational Changes

引用

JOURNAL OF CHEMICAL INFORMATION AND MODELING 2017年第11期57卷 2799-2810页

作者： Konshina, Anastasia G. Krylov, Nikolay A. Efremov, Roman G. Russian Acad Sci Shemyakin Ovchinnikov Inst Bioorgan Chem 16-10 Mildukho Maklaya StrV-437 Moscow 117997 Russia Russian Acad Sci Joint Supercomp Ctr Leninsky Prospect 32a Moscow 119991 Russia

Cardiotoxins (CTs) from snake venoms are a family of homologous highly basic proteins that have extended hydrophobic patterns on their molecular surfaces. CTs are folded into three beta-structured loops stabilized by four disulfide bridges. Being well-structured in aqueous solution, most of these proteins are membrane-active, although the exact molecular mechanisms of CT-induced cell damage are still I poorly understood. To elucidate the structure function relationships in CTs, a detailed knowledge of their spatial organization and local conformational dynamics is required. Protein domain motions can be either derived from a set of experimental structures or generated via molecular dynamics (MD). At the same time, traditional clustering algorithms in the Cartesian coordinate space often fail to properly take into account the local large-scale dihedral angle transitions that occur in MD simulations. This is because such perturbations are usually offset by changes in the neighboring dihedrals, thus preserving the overall protein fold. States with a "locally perturbed" backbone were found in experimental 3D models of some globular proteins and have been shown to be functionally meaningful. In this work, the possibility of large-scale dihedral angle transitions in the course of long-term MD in explicit water was explored for three. CTs with different membrane activities: CT 1, 2 (Naja oxiana) and CT A3 (Naja atra). Analysis of the MD-derived distributions of backbone torsion angles revealed several important common and specific features in the structural/dynamic behavior of these proteins. First, large-amplitude transitions were detected in some residues located in the functionally important loop I region. The K5/L6 pair of residues was found to induce a perturbation of the hydrophobic patterns on the molecular surface of CTs reversible breaking of a large nonpolar zone ("bottom") into two smaller ones and their subsequent association. Second, the characteristic sizes o

关键词： perturbation cell injury Cardiotoxins Proteins Protein Folding Molecular surface structure-function relationships Spine Dihedral angle Clustering algorithms Residues Disulfides Cartesian coordinate system Spatial Organization Snake Venoms

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：