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Arabidopsis thaliana T-DNA Mutants Implicate GAUT Genes in the Biosynthesis of Pectin and Xylan in Cell Walls and Seed Testa

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Molecular Plant 2009年第5期2卷 1000-1014页

作者： Kerry H. Caffall Sivakumar Pattathil Sarah E. Phillips michael G. hahn Debra Mohnen Department of Biochemistry and Molecular Biology University of Georgia Athens GA 30602 USA Complex Carbohydrate Research Center BioEnergy Science Center 315 Riverbend Road University of Georgia Athens GA 30602 USA Department of Plant Biology University of Georgia Athens GA 30602 USA

Galacturonosyltransferase 1 （GAUT1） is an α1,4-D-galacturonosyltransferase that transfers galacturonic acid from uridine 5＇-diphosphogalacturonic acid onto the pectic polysaccharide homogalacturonan （Sterling et al., 2006）. The 25-member Arabidopsis thaliana GAUT1-related gene family encodes 15 GAUT and 10 GAUT-like （GATL） proteins with, respectively, 56-84 and 42-53% amino acid sequence similarity to GAUT1. Previous phylogenetic analyses of AtGAUTs indicated three clades： A through C. A comparative phylogenetic analysis of the Arabidopsis, poplar and rice GAUT families has sub-classified the GAUTs into seven clades： clade A-1 （GAUTs 1 to 3）; A-2 （GAUT4）; A-3 （GAUTs 5 and 6）; A-4 （GAUT7）; B-1 （GAUTs 8 and 9）; B-2 （GAUTs 10 and 11）; and clade C （GAUTs 12 to 15）. The Arabidopsis GAUTs have a distribution comparable to the poplar orthologs, with the exception of GAUT2, which is absent in poplar. Rice, however, has no orthologs of GAUTs 2 and 12 and has multiple apparent orthologs of GAUTs 1, 4, and 7 compared with eitherArabidopsis or poplar. The cell wall glycosyl residue compositions of 26 homozygous T-DNA insertion mutants for 13 of 15 Arabidopsis GAUTgenes reveal significantly and reproducibly different cell walls in specific tissues of gaut mutants 6, 8, 9, 10, 11, 12, 13, and 14 from that of wild-type Arabidopsis walls. Pectin and xylan polysaccharides are affected by the loss of GAUT function, as demonstrated by the altered galacturonic acid, xylose, rhamnose, galactose, and arabinose composition of distinct gaut mutant walls. The wall glycosyl residue compositional phenotypes observed among the gaut mutants suggest that at least six different biosynthetic linkages in pectins and/or xylans are affected by the lesions in these GAUTgenes. Evidence is also presented to support a role for GAUT11 in seed mucilage expansion and in seed wall and mucilage composition.

关键词： Carbohydrate metabolism cell walls Arabidopsis biosynthesis mutant pectin mucilage

Two Poplar Glycosyltransferase Genes, PdGATL 1.1 and PdGATL1.2, Are Functional Orthologs to PARVUS/AtGATL 1 in Arabidopsis

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Molecular Plant 2009年第5期2卷 1040-1050页

作者： Yingzhen Kong Gongke Zhou Utku Avci Xiaogang Gu Chelsea Jones Yanbin Yin Ying Xu michael G. hahn Complex Carbohydrate Research Center The University of Georgia 315 Riverbend Road Athens GA 30602 USA BioEnergy Science Center The University of Georgia 315 Riverbend Road Athens GA 30602 USA Computational System Biology Lab Dept. of Biochemistry and Molecular Biology and Institute of Bioinformatics The University of Georgia Athens GA 30602 USA

Several genes in Arabidopsis, including PARVUS/AtGATL1, have been implicated in xylan synthesis. However, the biosynthesis of xylan in woody plants, where this polysaccharide is a major component of wood, is poorly understood. Here, we characterize two Populus genes, PdGATL 1.1 and PdGATL 1.2, the closest orthologs to the Arabidopsis PARVUS/GATL1 gene, with respect to their gene expression in poplar, their sub-cellular localization, and their ability to complement the parvus mutation in Arabidopsis. Overexpression of the two poplar genes in the parvus mutant rescued most of the defects caused by the parvus mutation, including morphological changes, collapsed xylem, and altered cell wall monosaccharide composition. Quantitative RT-PCR showed that PdGATL1.1 is expressed most strongly in developing xylem of poplar. In contrast, PdGATL1.2 is expressed much more uniformly in leaf, shoot tip, cortex, phloem, and xylem, and the transcript level of PdGATL1.2 is much lower than that of PdGATL 1.1 in all tissues examined. Sub-cellular localization experiments showed that these two proteins are localized to both ER and Golgi in comparison with marker proteins resident to these sub-cellular compartments. Our data indicate that PdGATLI.1 and PdGATL1.2 are functional orthologs of PARVUS/ GATL1 and can play a role in xylan synthesis, but may also have role（s） in the synthesis of other wall polymers.

关键词： Arabidopsis thaliana poplar xylan glycosyltransferase.

Virus-Induced Gene Silencing Offers a Functional Genomics Platform for Studying Plant Cell Wall Formation

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Molecular Plant 2010年第5期3卷 818-833页

作者： Xiaohong Zhu Sivakumar Pattathil Koushik Mazumder Amanda Brehm michael G. hahn S.P. Dinesh-Kumar Chandrashekhar P. Joshi Biotechnology Research Center School of Forest Resources and Environmental Science Michigan Technological University Houghton MI 49931 USA BioEnergy Science Center Complex Carbohydrate Research Center University of Georgia 315 Riverbend Road Athens GA 30602 USA Department of Plant Biology University of Georgia Athens GA 30602 USA Section of Plant Biology and Genome Center University of California Davis CA 95616 USA Department of Bioenergy Science and Technology Chonnam National University Gwangju 500-757 Korea

Virus-induced gene silencing （VIGS） is a powerful genetic tool for rapid assessment of plant gene functions in the post-genomic era. Here, we successfully implemented a Tobacco Rattle Virus （TRV）-based VlGS system to study functions of genes involved in either primary or secondary cell wall formation in Nicotiana benthamiana plants. A 3-week post- VIGS time frame is sufficient to observe phenotypic alterations in the anatomical structure of stems and chemical composition of the primary and secondary cell walls. We used cell wall glycan-directed monoclonal antibodies to demonstrate that alteration of cell wall polymer synthesis during the secondary growth phase of VIGS plants has profound effects on the extractability of components from woody stem cell walls. Therefore, TRV-based VlGS together with cell wall component profiling methods provide a high-throughput gene discovery platform for studying plant cell wall formation from a bioenergy perspective.

关键词： Plant cell wall VIGS cellulose xylan lignin Nicotiana.

Application of Remote Sensing in Coral Reef Mapping and Assessment of Climatic and Environmental Conditions

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Journal of Geoscience and Environment Protection 2024年第11期12卷 284-306页

作者： Amina Said Mark Boitt michael hahn Faculty of Geomatics Computer Science and Mathematics Hochschule fuer Technik Stuttgart Stuttgart Germany Institute of Geomatics GIS and Remote Sensing Dedan Kimathi University of Technology Nyeri Kenya

Coral reefs have tremendous benefits to both humans and marine biodiversity but are globally endangered. Traditionally, data collection of coral reefs was fieldwork based, which is time-consuming, costly and lacking in full coverage. This study shows that optical imageries can be utilised to map coral reefs, by fusing visible bands and depth invariant index (DII) to classify benthic features. Overall accuracy of at least 68 percent is achieved. However, to overcome the challenge of cloud cover, which is common in coastal areas, microwave imagery is used to map the emergent coral reefs. Again, remote sensing proves to be reliable in estimation of sea surface temperature (SST) and extraction of water quality parameters through Case-2 Region CoastColour (C2RCC) processor. Thereafter, regression analysis is performed to evaluate the correlation of SST and water quality. It is concluded that higher spatial resolution can improve coral mapping and that there is a need for more research on correlation to its environment.

关键词： Coral Reef DII SST C2RCC Water Quality

Kynurenine is an endothelium-derived relaxing factor produced during inflammation

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Kynurenine is an endothelium-derived relaxing factor produce...

Helicobacter pylori upregulates prion protein expression in gastric mucosa: A possible link to prion disease

中国生理学会第23届全国会员代表大会暨生理学学术大会

作者： Gavin McKenzie Paul K Witting Johannes-Peter Stasch michael hahn Dechaboon Changsirivathanathamrong Helen J Ball Shane R Thomas Vimal Kapoor David S Celermajer Andrew L Mellor John F Keaney,Jr Nicholas H Hunt Roland Stocker School of Medical Sciences University of New South WalesNSW 2052Australia School of Medical Sciences(Pathology)and Bosch Institute Faculty of MedicineUniversity of SydneyNSW 2006Australia Cardiovascular Research Bayer HealthCare WuppertalGermany Medicinal Chemistry Bayer HealthCareWuppertalGermany Centre for Vascular Research School of Medical Sciences(Pathology)and Bosch InstituteFaculty of MedicineUniversity of SydneyNSW 2006Australia Centre for Vascular Research University of New South WalesNSW 2052Australia School of Medicine and Pharmacology University of Western AustraliaPerth WA 6009Australia Royal Prince Alfred Hospital University of SydneyNSW 2006Australia Immunotherapy Center Medical College of GeorgiaAugusta GA 30912U.S.A

＜正＞Control of blood vessel tone is central to vascular *** we show that metabolism of tryptophan to kynurenine by indoleamine 2,3-dioxygenase（Ido） expressed in endothelial cells contributes to arterial vessel relaxation and the control of blood *** of mice with malarial parasites（Plasmodium berghei） or induction of endotoxemia in mice led to endothelial expression of Ido,decreased plasma tryptophan concentration, increased kynurenine concentration and *** inhibition of Ido increased blood pressure in systemically inflamed mice but not in mice deficient in Ido or interferon-γ,which is required for Ido *** tryptophan and kynurenine dilated preconstricted porcine coronary arteries;the dilating effect of tryptophan required the presence of active Ido and an intact endothelium,whereas the effect of kynurenine was endothelium *** arterial relaxation induced by kynurenine was mediated by activation of the adenylate and soluble guanylate cyclase *** administration decreased blood pressure in a dose-dependent manner in spontaneously hypertensive *** results identify tryptophan metabolism by Ido as a new pathway contributing to the regulation of vascular tone.

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World Journal of Gastroenterology 2005年第48期11卷 7651-7656页

作者： Peter C Konturek Karolina Bazela Vitally Kukharskyy michael Bauer Eckhart G hahn Detlef Schuppan Department of Medicine

AIM： Pathological prion protein （PrP^sc） is responsible for the development of transmissible spongiform encephalopathies （TSE）. While PrPc enters the organism via the oral route, less data is available to know about its uptake and the role of gastrointestinal inflammation on the expression of priori precursor PrPc, which is constitutively expressed in the gastric ***： We studied PrPc expression in the gastric mucosa of 10 Helicobacter pylori-positive patients before and after successful H pylori eradication compared to non-infected controls using RT-PCR and Western blotting. The effect of central mediators of gastric inflammation, i.e., gastrin, prostaglandin E2 （PGE2）, tumor necrosis factor alpha （TNF-α） and interleukin 1 beta （IL-1β） on PrPc expression was analyzed in gastric cell ***： PrPc expression was increased in H pyloriinfection compared with non-infected controls and decreased to normal after successful eradication. Gastrin, PGE2, and IL-1β dose-dependently upregulated PrPc in gastric cells, while TNF-α had no ***： H pylori infection leads to the upregulation of gastric PrPc expression. This can be linked to H pylori induced hypergastrinemia and increased mucosal PGE2 and IL-1β synthesis. H pylori creates a milieu for enhanced propagation of prions in the gastrointestinal tract.

关键词： Prions Helicobacter pylori, Gastrin Proinflammatory cytokines

Stretching the limits of maximal voluntary eccentric force production in vivo

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Journal of Sport and Health Science 2018年第3期7卷 275-281页

作者： Daniel hahn Human Movement Science Faculty of Sport Science Ruhr-University Bochum School of Human Movement and Nutrition Sciences University of Queensland

During eccentric contractions,muscular force production capacity is enhanced compared to isometric *** this is well accepted in terms of muscle mechanics,maximal voluntary eccentric contractions are associated with neural inhibition that prevents increased force production of in vivo human ***,because it was shown that maximal voluntary eccentric forces can exceed maximum isometric forces by a factor of 1.2-1.4,this review focuses on the question of whether the absent eccentric force enhancement,as observed in many studies,can unambiguously be attributed to an inherent neural ***,we demonstrate that participant familiarization,preload,and fascicle behavior are crucial factors influencing maximal voluntary eccentric force ***,we show that muscle mechanics such as muscle length,lengthening velocity,and stretch amplitude interact when it comes to maximal voluntary eccentric force ***,we discuss the diverging findings on neural inhibition during maximal voluntary eccentric *** there was no inhibition of the major motor pathways in the presence of enhanced maximal voluntary eccentric forces,further research is needed to test the concept of neural inhibition and to understand why maximal voluntary force production is reduced compared to the force capacity of isolated muscle preparations.

关键词： Active lengthening Eccentric contraction Inhibition Muscle Neural control

NONLINEAR DYNAMICS OF A CRACKED ROTOR IN A MANEUVERING AIRCRAFT

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Applied Mathematics and Mechanics(English Edition) 2004年第10期25卷 1139-1150页

作者：林富生孟光 Eric hahn State Key Laboratory of Vibration Shock and Noise Shanghai Jiaotong University School of Mechanical and Manufacturing Engineering The University of New South Wales

The nonlinear dynamics of a cracked rotor system in an aircraft maneuvering with constant velocity or acceleration was investigated. The influence of the aircraft climbing angle on the cracked rotor system response is of particular interest and the results show that the climbing angle can markedly affect the parameter range for bifurcation, for quasi-periodic response and for chaotic response as well as for system stability. Aircraft acceleration is also shown to significantly affect the nonlinear behavior of the cracked rotor system, illustrating the possibility for on-line rotor crack fault diagnosis.

关键词： cracked rotor maneuvering aircraft nonlinear response fault diagnosis

Multifaceted progress in high-field superconducting magnet mechanics

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Acta Mechanica Sinica 2024年第4期40卷 1-3页

作者： Xingzhe Wang Seungyong hahn Key Laboratory of Mechanics on Western Disaster and Environment Ministry of EducationCollege of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China Department of Electrical and Computer Engineering Seoul National UniversitySeoul 08826Republic of Korea

High-field superconducting magnets are poised to revolutionize technologies,including particle accelerators,magnetic resonance imaging(MRI)machines,and fusion *** stand at the frontier of superconductor ***_(3)Sn wires,which operate at cold temperatures,along with rare-earth barium copper oxide(REBCO)coated conductors that include rare earth elements like Y,Gd,and Dy,are gaining *** high electrical efficiency in strong magnetic fields makes them particularly attractive for such advanced applications.

关键词： Nb_(3)Sn field earth