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Phylogenetically Distinct Cellulose Synthase Genes Support Secondary Wall Thickening in Arabidopsis Shoot Trichomes 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 Jonathan 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

Through exploring potential analogies between cotton seed trichomes （or cotton fiber） and arabidopsis shoot trichomes we discovered that CesAs from either the primary or secondary wall phylogenetic clades can support secondary wall thickening. CesA genes that typically support primary wall synthesis, AtCesA 1,2,3,5, and 6, underpin expansion and secondary wall thickening of arabidopsis shoot trichomes. In contrast, apparent orthologs of CesA genes that support secondary wall synthesis in arabidopsis xylem, AtCesA4,7, and 8, are up-regulated for cotton fiber secondary wall deposition. These conclusions arose from：（a） analyzing the expression of CesA genes in arabidopsis shoot trichomes; （b） observing birefringent secondary walls in arabidopsis shoot trichomes with mutations in AtCesA4, 7, or 8; （c） assaying up-regulated genes during different stages of cotton fiber development; and （d） comparing genes that were *** with primary or secondary wall CesAs in arabidopsis with genes up- regulated in arabidopsis trichomes, arabidopsis secondary xylem, or cotton fiber during primary or secondary wall deposition. Cumulatively, the data show that：（a） the xylem of arabidopsis provides the best model for secondary wall cellulose synthesis in cotton fiber; and （b） CesA genes within a ＂cell wall toolbox＂ are used in diverse ways for the construction of particular specialized cell walls.

关键词： Phylogenetically Distinct Cellulose Synthase Genes Support Secondary Wall Thickening in Arabidopsis Shoot Trichomes and Cotton Fiber GUS

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Cellulose synthase ‘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.Chaves Abhishek Singh Latsavongsakda Sethaphong 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 synthases （CESAs） are glycosyltransferases that catalyze formation of cellulose microfibrils in plant cell walls. Seed plant CESA isoforms cluster in six phylogenetic clades, whose non-interchangeable members play distinct roles within cellulose synthesis complexes （CSCs）. A ＇class specific region＇（CSR）, with higher sequence similarity within versus between functional CESA classes, has been suggested to contribute to specific activities or interactions of different isoforms. We investigated CESA isoform specificity in the moss, Physcomitrella patens （hedw.） B. S. G. to gain evolutionary insights into CESA structure/function relationships. Like seed plants, P. patens has oligomeric rosette-type CSCs, but the PpCESAs diverged independently and form a separate CESA clade. We showed that P. patens has two functionally distinct CESAs classes, based on the ability to complement the gametophore-negative phenotype of a ppcesa5 knockout line. Thus, non-interchangeable CESA classes evolved separately in mosses and seed plants. however, testing of chimeric moss CESA genes for complementation demonstrated that functional classspecificity is not determined by the CSR. Sequence analysis and computational modeling showed that the CSR is intrinsically disordered and contains predicted molecular recognition features, consistent with a possible role in CESA oligomerization and explaining the evolution of class-specific sequences without selection for class-specific function.

关键词： Uwe Sonnewald Friedrich-Alexander University Germany

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Perturbation of Wood Cellulose Synthesis Causes Pleiotropic Effects in Transgenic Aspen

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Molecular Plant 2011年第2期4卷 331-345页

作者： Chandrashekhar R Joshi Shivegowda Thammannagowda Takeshi Fujino Ji-Qing Gou Utku Avci candace h. haigler Lisa M. McDonnell Shawn D. Mansfield Bemnet Mengesha Nicholas C. Carpita Darby harris Seth DeBolt Gary F. Peter Biotechnology Research Center School of Forest Resources and Environmental Sciences Michigan Technological University Houghton MI 49931 USA Department-of Bioenergy Science and Technology 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 horticulture N-318 Agricultural Sciences Center University of Kentucky Lexington KY 40546 USA School of Forest Resources and Conservation 326 Newins-Ziegler Hall PO Box 110410 University of Florida Gainesville FL 32611 USA

Genetic manipulation of cellulose biosynthesis in trees may provide novel insights into the growth and development of trees. To explore this possibility, the overexpression of an aspen secondary wall-associated cellulose synthase （PtdCesAS） gene was attempted in transgenic aspen （Populus tremuloides L.） and unexpectedly resulted in silencing of the transgene as well as its endogenous counterparts. The main axis of the transgenic aspen plants quickly stopped growing, and weak branches adopted a weeping growth habit. Furthermore, 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 weight compared to 41% cellulose typically found in normal aspen wood. This massive reduction in cellulose was accompanied by proportional increases in lignin （35%） and non-cellulosic polysaccharides （55%） compared to the 22% lignin and 36% non-cellulosic polysaccharides in control plants. The transgenic stems pro- duced typical collapsed or ＇irregular＇ xylem vessels that had altered secondary wall morphology and contained greatly reduced amounts of crystalline cellulose. These results demonstrate the fundamental role of secondary wall cellulose within the secondary xylem in maintaining the strength and structural integrity required to establish the vertical growth habit in trees.

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

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Anatomic measures of upper airway structures in obstructive sleep apnea

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World Journal of Otorhinolaryngology-head 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.holbrook 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-eight subjects with (n =14) and without (n =14) OSA as determined by clinical symptoms and sleep studies;volunteer *** and soft tissue dimensions were measured from radiocephalometry and magnetic resonance *** soft palate thickness,mandibular plane-hyoid (MP-h) distance,posterior airway space (PAS) diameters and area,and tongue volume were ***:Compared to controls,the OSA group demonstrated a significantly longer MP-h distance (P =0.009) and shorter nasal PAS diameter (P =0.02).The PAS area was smaller (P =0.002) and tongue volume larger in the OSA group (P =0.004).The 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;however the most substantial parameter found was a large tongue volume.

关键词： Obstructive sleep apnea Anatomy Anatomic measurement Posterior airway space Tongue volume hyoid position

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Achieving competence in colonoscopy: Milestones and the 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 Stephanie Lee candace Masaquel Robert h Lee Division of Gastroenterology University of California Irvine and Long Beach Veterans’ Affairs Hospital

Colonoscopy is considered to be the most effective tool for reducing colorectal cancer(CRC) morbidity and mortality. As a result, certifying trainee competence in the performance of colonoscopy is critical to maximizing CRC screening and prevention efforts. Guidelines on training and accreditation around the world have been revised to emphasize the attainment of milestones in the technical and cognitive skills necessary to perform the procedure. To meet this challenge, new evaluation systems have been developed to measure trainee competence through all aspects of colonoscopy training. These changes stem from increased recognition that procedural numbers alone do not necessarily guarantee trainees' proficiency in the performance of colonoscopy. Variability in endoscopic practice and in CRC screening outcomes also point to deficiencies in the current approach towards colonoscopy instruction. however, technological innovations hold great promise in training endoscopists to perform high quality colonoscopy. Furthermore, potential advances in the use of feedback as a training tool provide new avenues for research. This review summarizes the latest evidence on the effort to define, evaluate and promote the achievement of competence in colonoscopy among trainees.

关键词： Competence Colonoscopy Colorectal cancer Core curr

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