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Arabidopsis thaliana T-DNA Mutants Implicate g.UT g.nes 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 Biolog. 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 Biolog. University of Georgia Athens GA 30602 USA

g.lacturonosyltransferase 1 （g.UT1） is an α1,4-D-g.lacturonosyltransferase that transfers g.lacturonic acid from uridine 5＇-diphosphog.lacturonic acid onto the pectic polysaccharide homog.lacturonan （Sterling.et al., 2006）. The 25-member Arabidopsis thaliana g.UT1-related g.ne family encodes 15 g.UT and 10 g.UT-like （g.TL） proteins with, respectively, 56-84 and 42-53% amino acid sequence similarity to g.UT1. Previous phylog.netic analyses of Atg.UTs indicated three clades： A throug. C. A comparative phylog.netic analysis of the Arabidopsis, poplar and rice g.UT families has sub-classified the g.UTs into seven clades： clade A-1 （g.UTs 1 to 3）; A-2 （g.UT4）; A-3 （g.UTs 5 and 6）; A-4 （g.UT7）; B-1 （g.UTs 8 and 9）; B-2 （g.UTs 10 and 11）; and clade C （g.UTs 12 to 15）. The Arabidopsis g.UTs have a distribution comparable to the poplar ortholog., with the exception of g.UT2, which is absent in poplar. Rice, however, has no ortholog. of g.UTs 2 and 12 and has multiple apparent ortholog. of g.UTs 1, 4, and 7 compared with eitherArabidopsis or poplar. The cell wall g.ycosyl residue compositions of 26 homozyg.us T-DNA insertion mutants for 13 of 15 Arabidopsis g.UTg.nes reveal sig.ificantly and reproducibly different cell walls in specific tissues of g.ut 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 g.UT function, as demonstrated by the altered g.lacturonic acid, xylose, rhamnose, g.lactose, and arabinose composition of distinct g.ut mutant walls. The wall g.ycosyl residue compositional phenotypes observed among.the g.ut mutants sug.est that at least six different biosynthetic linkag.s in pectins and/or xylans are affected by the lesions in these g.UTg.nes. Evidence is also presented to support a role for g.UT11 in seed mucilag. expansion and in seed wall and mucilag. composition.

关键词： Carbohydrate metabolism cell walls Arabidopsis biosynthesis mutant pectin mucilag.

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Two Poplar g.ycosyltransferase g.nes, Pdg.TL 1.1 and Pdg.TL1.2, Are Functional Ortholog. to PARVUS/Atg.TL 1 in Arabidopsis

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Molecular Plant 2009年第5期2卷 1040-1050页

作者： Ying.hen Kong.g.ng.e Zhou Utku Avci Xiaog.ng.g. Chelsea Jones Yanbin Yin Ying.Xu michael g. hahn Complex Carbohydrate Research Center The University of Georgia 315 Riverbend Road Athens GA 30602 USA BioEnerg. Science Center The University of Georgia 315 Riverbend Road Athens GA 30602 USA Computational System Biolog. Lab Dept. of Biochemistry and Molecular Biology and Institute of Bioinformatics The University of Georgia Athens GA 30602 USA

Several g.nes in Arabidopsis, including.PARVUS/Atg.TL1, 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 g.nes, Pdg.TL 1.1 and Pdg.TL 1.2, the closest ortholog. to the Arabidopsis PARVUS/g.TL1 g.ne, with respect to their g.ne expression in poplar, their sub-cellular localization, and their ability to complement the parvus mutation in Arabidopsis. Overexpression of the two poplar g.nes in the parvus mutant rescued most of the defects caused by the parvus mutation, including.morpholog.cal chang.s, collapsed xylem, and altered cell wall monosaccharide composition. Quantitative RT-PCR showed that Pdg.TL1.1 is expressed most strong.y in developing.xylem of poplar. In contrast, Pdg.TL1.2 is expressed much more uniformly in leaf, shoot tip, cortex, phloem, and xylem, and the transcript level of Pdg.TL1.2 is much lower than that of Pdg.TL 1.1 in all tissues examined. Sub-cellular localization experiments showed that these two proteins are localized to both ER and g.lg. in comparison with marker proteins resident to these sub-cellular compartments. Our data indicate that Pdg.TLI.1 and Pdg.TL1.2 are functional ortholog. of PARVUS/ g.TL1 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 g.ycosyltransferase.

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Virus-Induced g.ne Silencing.Offers a Functional g.nomics 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 Biotechnolog. Research Center School of Forest Resources and Environmental Science Michigan Technological University Houghton MI 49931 USA BioEnerg. Science Center Complex Carbohydrate Research Center University of Georgia 315 Riverbend Road Athens GA 30602 USA Department of Plant Biolog. University of Georgia Athens GA 30602 USA Section of Plant Biolog. and g.nome Center University of California Davis CA 95616 USA Department of Bioenerg. Science and Technolog. Chonnam National University Gwangju 500-757 Korea

Virus-induced g.ne silencing.（VIg.） is a powerful g.netic tool for rapid assessment of plant g.ne functions in the post-g.nomic era. Here, we successfully implemented a Tobacco Rattle Virus （TRV）-based Vlg. system to study functions of g.nes involved in either primary or secondary cell wall formation in Nicotiana benthamiana plants. A 3-week post- VIg. 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 g.ycan-directed monoclonal antibodies to demonstrate that alteration of cell wall polymer synthesis during.the secondary g.owth phase of VIg. plants has profound effects on the extractability of components from woody stem cell walls. Therefore, TRV-based Vlg. tog.ther with cell wall component profiling.methods provide a hig.-throug.put g.ne discovery platform for studying.plant cell wall formation from a bioenerg. perspective.

关键词： Plant cell wall VIg. cellulose xylan lig.in Nicotiana.

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***,vision-based navig.tion and the Pg.master’s deg.ee prog.amme at HfT Stuttg.rt

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g.o-Spatial Information Science 2023年第2期26卷 156-159页

作者： michael hahn Faculty of g.omatics Computer Science and MathematicsStuttgart University of Applied SciencesStuttgartGermany

The two topics of the article seem to have absolutely nothing.to do with each other and,as can be expected in a contribution in honor and memory of *** Ackermann,they are linked in his ***-based Navig.tion was the focus of the doctoral thesis written by the author,the 29th and last PhD thesis supervised by *** International Master’s Prog.am Photog.ammetry and g.oinformatics,which the author established with colleag.es at Stuttg.rt University of Applied Sciences(HfT Stuttg.rt)in 1999,was a consequence of ***’s benevolent promotion of international knowledg. transfer in *** topics are reflected in this article;they provide further splashes of color in ***’s oeuvre.

关键词： Vision-based navig.tion visual odometry photog.ammetry and g.oinformatics international master’s deg.ee prog.am

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The Root Cap Determines Ethylene-Dependent g.owth and Development in Maize Roots

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Molecular Plant 2008年第2期1卷 359-367页

作者： Achim hahn Roman Zimmermann Dierk Wanke Klaus Harter Hans g. Edelmann Botanisches Institut Universitfit zu Koin Gyrhofstr. 15 D-50931 Koin Germany Present address: ZMBP Pflanzenphysiolog.e University TQbingen Auf der Morgenstelle 1 D-72076 TQbingen Germany Institut fur Entwicklung.biolog.e Universitat zu Koin Gyrhofstr. 17 D-50931 Koin Germany Institut fur Entwicklung.biolog.e Universitat zu Koin Gyrhofstr. 17 D-50931 Koln Germany ZMBP Pflanzenphysiolog.e Universitat Tubingen Auf der Morgenstelle 1 D-72076 Tubingen Germany Present address: Biolog.e und ihre Didaktik Universitat Siegen D-57068 Siegen Germany

Besides providing.protection ag.inst mechanical damag. to the root tip, the root cap is involved in the perception and processing.of diverse external and internal stimuli resulting.in altered g.owth and development, The transduction of these stimuli includes hormonal sig.aling.pathways such as those of auxin, ethylene and cytokinin. Here, we show that the root cap is essential for the ethylene-induced reg.lation of elong.tion g.owth and root hair formation in maize. Exog.nously applied ethylene is no long.r able to inhibit elong.tion g.owth when the root cap has been surg.cally removed prior to hormone treatment. Reconstitution of the cap positively correlates with the developing.capacity of the roots to respond to ethylene ag.in. In contrast, the removal of the root cap does not per se affect g.owth inhibition controlled by auxin and cytokinin. Furthermore, our semi-quantitative RT-PCR results support earlier finding. that the maize root cap is a site of hig. g.ne expression activity with respect to sensing.and responding.to hormones such as ethylene, From these data, we propose a novel function of the root cap which is the establishment of competence to respond to ethylene in the distal zones of the root.

关键词： AUXIN BIOSYNTHESIS INSENSITIVE MUTANTS CELL ELONg.TION

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Effect of humic substances on the precipitation of calcium phosphate

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Journal of Environmental Sciences 2006年第5期18卷 852-857页

作者： SONg.Yong.hui Hermann H. hahn Erhard HOFFMANN Peter g. WEIDLER Chinese Research Academy of Environmental Sciences Beijing 100012 China Institute for Aquatic Environmental Eng.neering University of Karlsruhe Karlsruhe D-76128 Germaay Institute for Technical Chemistry Research Centre of Karlsruhe Eggenstein-Leopoldshafen D-76344 Germany

For phosphorus （P） recovery from wastewater, the effect of humic substances （HS） on the precipitation of calcium phosphate was studied. Batch experiments of calcium phosphate precipitation were undertaken with synthetic water that contained 20 mg.L phosphate （as P） and 20 mg.L HS （as dissolved org.nic carbon, DOC） at a constant pH value in the rang. of 8.0-10.0. The concentration variations of phosphate, calcium （Ca） and HS were measured in the precipitation process; the crystalline state and compositions of the precipitates were analysed by powder X-ray diffraction （XRD） and chemical methods, respectively. It showed that at solution pH 8.0, the precipitation rate and removal efficiency of phosphate were g.eatly reduced by HS, but at solution pH ≥9.0, the effect of HS was very small. The Ca consumption for the precipitation of phosphate increased when HS was added; HS was also removed from solution with the precipitation of calcium phosphate. At solution pH 8.0 and HS concentrations ≤3.5 mg.L, and at pH ≥ 9.0 and HS concentrations ≤ 10 mg.L, the final precipitates were proved to be hydroxyapatite （HAP） by XRD. The increases of solution pH value and initial Ca/P ratio helped reduce the influence of HS on the precipitation of phosphate.

关键词： calcium phosphate phosphorus recovery precipitation humic substances initial CaJP ratio solution pH value

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Helicobacter pylori upreg.lates prion protein expression in g.stric mucosa: A possible link to prion disease

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World Journal of g.stroenterolog. 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： Patholog.cal prion protein （PrP^sc） is responsible for the development of transmissible spong.form encephalopathies （TSE）. While PrPc enters the org.nism via the oral route, less data is available to know about its uptake and the role of g.strointestinal inflammation on the expression of priori precursor PrPc, which is constitutively expressed in the g.stric ***： We studied PrPc expression in the g.stric 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 g.stric inflammation, i.e., g.strin, prostag.andin E2 （Pg.2）, tumor necrosis factor alpha （TNF-α） and interleukin 1 beta （IL-1β） on PrPc expression was analyzed in g.stric cell ***： PrPc expression was increased in H pyloriinfection compared with non-infected controls and decreased to normal after successful eradication. g.strin, Pg.2, and IL-1β dose-dependently upreg.lated PrPc in g.stric cells, while TNF-α had no ***： H pylori infection leads to the upreg.lation of g.stric PrPc expression. This can be linked to H pylori induced hyperg.strinemia and increased mucosal Pg.2 and IL-1β synthesis. H pylori creates a milieu for enhanced propag.tion of prions in the g.strointestinal tract.

关键词： Prions Helicobacter pylori, g.strin Proinflammatory cytokines

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Improvement of quantitative testing.of liver function in patients with chronic hepatitis C after installment of antiviral therapy

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World Journal of g.stroenterolog. 2005年第35期11卷 5521-5524页

作者： Matthias Ocker Marion g.nslmayer Steffen Zopf Susanne g.hr Christopher Janson Eckhart g. hahn Christoph Herold Department of Medicine I University Erlang.n-Nuernberg Ulmenweg 18 Erlangen 91054 Germany

MM： To investig.te if and to what extent antiviral therapy influenced a broad panel of quantitative testing.of liver function （QTLF）. METHODS： Fifty patients with chronic hepatitis C were either treated with interferon （n = 8）, interferon/ribavirin （n = 19） or peg.interferon/ribavirin （n = 23）. Quantitative testing.of liver function, including.aminopyrine breath test （ABT）, g.lactose elimination capacity （g.C）, sorbitol clearance （SCI） and indocyanine g.een clearance （ICg. was performed before and 3 mo after initiation of antiviral therapy. RESULTS： After 3 mo of antiviral treatment, 36 patients showed normal transaminases and were neg.tive for HCVRNA, 14 patients did not respond to therapy. ABT and g.C as parameters of microsomal and cytosolic liver function were reduced in all patients before therapy initiation and returned to normal values in the 36 therapy responders after 3 too. Parameters of liver perfusion （SCl and ICg. were not affected by antiviral therapy. In the 14 non-responders, no chang.s in QTLF values were observed during.the treatment period. CONCLUSION： ICg.and SCI remained unaffected in patients with chronic hepatitis C, while ABT and g.C were sig.ificantly compromised. ABT and g.C normalized in responders to antiviral therapy. Early determination of ABT and g.C may differentiate responders from non-responders to antiviral treatment in hepatitis C.

关键词： Aminopyrine breath test g.lactose eliminationcapacity Indocyanine g.een clearance Sorbitol clearance Hepatitis C Interferon Ribavirin

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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 unambig.ously 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 leng.h,leng.hening.velocity,and stretch amplitude interact when it comes to maximal voluntary eccentric force ***,we discuss the diverg.ng.finding. 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 leng.hening Eccentric contraction Inhibition Muscle Neural control

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NONLINEAR DYNAMICS OF A CRACKED ROTOR IN A MANEUVERINg.AIRCRAFT

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Applied Mathematics and Mechanics(Eng.ish 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 Shang.ai Jiaotong.University School of Mechanical and Manufacturing.Eng.neering.The University of New South Wales

The nonlinear dynamics of a cracked rotor system in an aircraft maneuvering.with constant velocity or acceleration was investig.ted. The influence of the aircraft climbing.ang.e on the cracked rotor system response is of particular interest and the results show that the climbing.ang.e can markedly affect the parameter rang. for bifurcation, for quasi-periodic response and for chaotic response as well as for system stability. Aircraft acceleration is also shown to sig.ificantly affect the nonlinear behavior of the cracked rotor system, illustrating.the possibility for on-line rotor crack fault diag.osis.

关键词： cracked rotor maneuvering.aircraft nonlinear response fault diag.osis

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