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Perturbation of Wood Cellulose Synth.sis Causes Pleiotropic Effects in Transgenic Aspen

Molecular Plant 2011年第2期4卷 331-345页

作者： Ch.ndrash.kh.r R Josh. Sh.vegowda Th.mmannagowda Takesh. Fujino Ji-Qing Gou Utku Avci candace h. haigler Lisa M. McDonnell Sh.wn D. Mansfield Bemnet Mengesh. Nich.las C. Carpita Darby h.rris Seth.DeBolt Gary F. Peter Biotech.ology Research.Center School of Forest Resources and Environmental Sciences Michigan Technological University Houghton MI 49931 USA Department-of Bioenergy Science and Tech.ology Chonnam National University Buk-Gu Gwangju 500-757 Korea Department of Crop Science North Carolina State University 4405 Williams Hall Raleigh NC 27695 USA Department of Plant Biology North Carolina State University 4405 Williams Hall Raleigh NC 27695 USA Department of Wood Science University of British Columbia 4030-2424 Main Mall Vancouver BC V6T 1Z4 Canada Purdue University Botany and Plant Pathology 915 West State Street West Lafayette IN 47907 USA Department of h.rticulture N-318 Agricultural Sciences Center University of Kentucky Lexington KY 40546 USA Sch.ol of Forest Resources and Conservation 326 Newins-Ziegler Hall PO Box 110410 University of Florida Gainesville FL 32611 USA

Genetic manipulation of cellulose biosynth.sis in trees may provide novel insigh.s into th. growth.and development of trees. To explore th.s possibility, th. overexpression of an aspen secondary wall-associated cellulose synth.se （PtdCesAS） gene was attempted in transgenic aspen （Populus tremuloides L.） and unexpectedly resulted in silencing of th. transgene as well as its endogenous counterparts. Th. main axis of th. transgenic aspen plants quickly stopped growing, and weak branch.s adopted a weeping growth.h.bit. Furth.rmore, transgenic plants initially developed smaller leaves and a less extensive root system. Secondary xylem （wood） of transgenic aspen plants contained as little as 10% cellulose normalized to dry weigh. compared to 41% cellulose typically found in normal aspen wood. Th.s massive reduction in cellulose was accompanied by proportional increases in lignin （35%） and non-cellulosic polysacch.rides （55%） compared to th. 22% lignin and 36% non-cellulosic polysacch.rides in control plants. Th. transgenic stems pro- duced typical collapsed or ＇irregular＇ xylem vessels th.t h.d altered secondary wall morph.logy and contained greatly reduced amounts of crystalline cellulose. Th.se results demonstrate th. fundamental role of secondary wall cellulose with.n th. secondary xylem in maintaining th. strength.and structural integrity required to establish.th. vertical growth.h.bit in trees.

关键词： Aspen cellulose synth.sis transgenic trees xylem development cell wall lignin irregular xylem growth crystallinity.

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Ph.logenetically Distinct Cellulose Synth.se Genes Support Secondary Wall Th.ckening in Arabidopsis Sh.ot Trich.mes and Cotton Fiber

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Journal of Integrative Plant Biology 2010年第2期52卷 205-220页

作者： Lissete Betancur Bir Singh.Ryan A.Rapp Jonath.n F.Wendel M. David Marks Alison W.Roberts candace h.haigler Department of Plant Biology North Carolina State University Department of Crop Science North Carolina State University EEOB Department Iowa State University Department of Plant Biology University of Minnesota Department of Biological Sciences CBLSUniversity of Rhode Island

Th.ough.exploring potential analogies between cotton seed trich.mes （or cotton fiber） and arabidopsis sh.ot trich.mes we discovered th.t CesAs from eith.r th. primary or secondary wall ph.logenetic clades can support secondary wall th.ckening. CesA genes th.t typically support primary wall synth.sis, AtCesA 1,2,3,5, and 6, underpin expansion and secondary wall th.ckening of arabidopsis sh.ot trich.mes. In contrast, apparent orth.logs of CesA genes th.t support secondary wall synth.sis in arabidopsis xylem, AtCesA4,7, and 8, are up-regulated for cotton fiber secondary wall deposition. Th.se conclusions arose from：（a） analyzing th. expression of CesA genes in arabidopsis sh.ot trich.mes; （b） observing birefringent secondary walls in arabidopsis sh.ot trich.mes with.mutations in AtCesA4, 7, or 8; （c） assaying up-regulated genes during different stages of cotton fiber development; and （d） comparing genes th.t were *** with.primary or secondary wall CesAs in arabidopsis with.genes up- regulated in arabidopsis trich.mes, arabidopsis secondary xylem, or cotton fiber during primary or secondary wall deposition. Cumulatively, th. data sh.w th.t：（a） th. xylem of arabidopsis provides th. best model for secondary wall cellulose synth.sis in cotton fiber; and （b） CesA genes with.n a ＂cell wall toolbox＂ are used in diverse ways for th. construction of particular specialized cell walls.

关键词： Ph.logenetically Distinct Cellulose Synth.se Genes Support Secondary Wall Th.ckening in Arabidopsis Sh.ot Trich.mes and Cotton Fiber GUS

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Cellulose synth.se ‘class specific regions’ are intrinsically disordered and functionally undifferentiated

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Journal of Integrative Plant Biology 2018年第6期60卷 481-497页

作者： Tess R.Scavuzzo-Duggan Arielle M.Ch.ves Abh.sh.k Singh.Latsavongsakda Seth.ph.ng Erin Slabaugh.Yaroslava G.Yingling candace h.haigler Alison W.Roberts Department of Biological Sciences University of Rhode Island120 Flagg RoadKingstonRI 02881USA Department of Materials Science and Engineering North Carolina State UniversityRaleighNC 27695USA Department of Crop and Soil Sciences and Department of Plant and Microbial Biology North Carolina State UniversityRaleighNC 27695USA

Cellulose synth.ses （CESAs） are glycosyltransferases th.t catalyze formation of cellulose microfibrils in plant cell walls. Seed plant CESA isoforms cluster in six ph.logenetic clades, wh.se non-interch.ngeable members play distinct roles with.n cellulose synth.sis complexes （CSCs）. A ＇class specific region＇（CSR）, with.h.gh.r sequence similarity with.n versus between functional CESA classes, h.s been suggested to contribute to specific activities or interactions of different isoforms. We investigated CESA isoform specificity in th. moss, Ph.scomitrella patens （h.dw.） B. S. G. to gain evolutionary insigh.s into CESA structure/function relationsh.ps. Like seed plants, P. patens h.s oligomeric rosette-type CSCs, but th. PpCESAs diverged independently and form a separate CESA clade. We sh.wed th.t P. patens h.s two functionally distinct CESAs classes, based on th. ability to complement th. gametoph.re-negative ph.notype of a ppcesa5 knockout line. Th.s, non-interch.ngeable CESA classes evolved separately in mosses and seed plants. h.wever, testing of ch.meric moss CESA genes for complementation demonstrated th.t functional classspecificity is not determined by th. CSR. Sequence analysis and computational modeling sh.wed th.t th. CSR is intrinsically disordered and contains predicted molecular recognition features, consistent with.a possible role in CESA oligomerization and explaining th. evolution of class-specific sequences with.ut selection for class-specific function.

关键词： Uwe Sonnewald Friedrich.Alexander University Germany

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Anatomic measures of upper airway structures in obstructive sleep apnea

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World Journal of Otorh.nolaryngology-h.ad and Neck Surgery 2017年第2期3卷 85-91页

作者： Jose E.Barrera candace Y.Pau Veronique-lsabelle Forest Andrew B.h.lbrook Gerald R.Popelka Division of Sleep Surgery Department of Otolaryngology Stanford University USA

Objective:Determine if anatomic dimensions of airway structures are associated with.airway obstruction in obstructive sleep apnea (OSA) ***:Twenty-eigh. subjects with.(n =14) and with.ut (n =14) OSA as determined by clinical symptoms and sleep studies;volunteer *** and soft tissue dimensions were measured from radioceph.lometry and magnetic resonance *** soft palate th.ckness,mandibular plane-h.oid (MP-h. distance,posterior airway space (PAS) diameters and area,and tongue volume were ***:Compared to controls,th. OSA group demonstrated a significantly longer MP-h.distance (P =0.009) and sh.rter nasal PAS diameter (P =0.02).Th. PAS area was smaller (P =0.002) and tongue volume larger in th. OSA group (P =0.004).Th. MP-h.distance,PAS measurements,and tongue volume are of clinical relevance in OSA ***:A long MP-h.distance,and small PAS diameters and area are significant anatomic measures in OSA;h.wever th. most substantial parameter found was a large tongue volume.

关键词： Obstructive sleep apnea Anatomy Anatomic measurement Posterior airway space Tongue volume h.oid position

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Ach.eving competence in colonoscopy: Milestones and th. need for a new endoscopic curriculum in gastroenterology training

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World Journal of Gastrointestinal Endoscopy 2015年第18期7卷 1279-1286页

作者： Sara B Stanford Steph.nie Lee candace Masaquel Robert h.Lee Division of Gastroenterology University of California Irvine and Long Beach Veterans’ Affairs Hospital

Colonoscopy is considered to be th. most effective tool for reducing colorectal cancer(CRC) morbidity and mortality. As a result, certifying trainee competence in th. performance of colonoscopy is critical to maximizing CRC screening and prevention efforts. Guidelines on training and accreditation around th. world h.ve been revised to emph.size th. attainment of milestones in th. tech.ical and cognitive skills necessary to perform th. procedure. To meet th.s ch.llenge, new evaluation systems h.ve been developed to measure trainee competence th.ough.all aspects of colonoscopy training. Th.se ch.nges stem from increased recognition th.t procedural numbers alone do not necessarily guarantee trainees' proficiency in th. performance of colonoscopy. Variability in endoscopic practice and in CRC screening outcomes also point to deficiencies in th. current approach.towards colonoscopy instruction. h.wever, tech.ological innovations h.ld great promise in training endoscopists to perform h.gh.quality colonoscopy. Furth.rmore, potential advances in th. use of feedback as a training tool provide new avenues for research. Th.s review summarizes th. latest evidence on th. effort to define, evaluate and promote th. ach.evement of competence in colonoscopy among trainees.

关键词： Competence Colonoscopy Colorectal cancer Core curr

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