1,720,956 research outputs found
Pectin - Xyloglucan linkages in type I primary cell walls of plants
No full textEvidence for covalent pectin - xyloglucan linkages in the cell wall of growing cells and maturing tissues has been reported. In-vitro studies using isolated Golgi membranes, and pulse-labelling studies in vivo, indicate that pectin - xyloglucan linkages form in the Golgi apparatus. The structure and biological significance of these complexes are discussed. © 2005 Società Botanica Italiana.Abdel-Massih RM, 2003, PLANTA, V216, P502, DOI 10.1007-s00425-002-0861-y; Brett C.T., 1996, PHYSL BIOCH PLANT CE; BRETT CT, 2004, 10 CELL WALL M 2004, P66; Femenia A, 1999, CARBOHYD POLYM, V39, P151, DOI 10.1016-S0144-8617(99)00003-X; KEEGSTRA K, 1973, PLANT PHYSIOL, V51, P188, DOI 10.1104-pp.51.1.188; MCCANN MC, 1990, J CELL SCI, V96, P323; POPPER ZA, 2004, 10 CELL WALL M 2004, P85; Thompson JE, 2000, PLANTA, V211, P275, DOI 10.1007-s004250000287; Vincken JP, 2003, PLANT PHYSIOL, V132, P1781, DOI 10.1104-pp.103.022350; WALDRON KW, 1992, PHYTOCHEMISTRY, V31, P1931, DOI 10.1016-0031-9422(92)80336-D89
Nascent pectin formed in Golgi apparatus of pea epicotyls by addition of uronic acids has different properties from nascent pectin at the stage of galactan elongation
No full textMicrosomal membranes were prepared from etiolated pea (Pisum sativum L.) epicotyls and used to form nascent [Uronic acid-14C]pectin. The enzyme products were characterized by selective enzymic degradation, gel permeation chromatography and analysis of cellulose binding properties. The product obtained had a molecular weight of around 40 kDa, which was significantly lower than that of nascent [Gal-14C]pectin prepared from the same tissues. It is composed mainly of polygalacturonan and perhaps also rhamnogalacturonan (RG-I). Evidence was obtained for the presence of a protein attached to the nascent [Uronic acid-14C]pectin, but it was unaffected by endoglucanase and did not bind to cellulose. Hence, no xyloglucan appeared to be attached to the nascent [Uronic acid-14C]pectin. A model is proposed in which xyloglucan is attached to nascent pectin after formation of homogalacturonan, but before the pectin leaves the Golgi apparatus. © 2006 Elsevier GmbH. All rights reserved.Abdel-Massih RM, 2003, PLANTA, V216, P502, DOI 10.1007-s00425-002-0861-y; BAYDOUN EAH, 1989, BIOCHEM J, V257, P853; Baydoun EAH, 2001, J PLANT PHYSIOL, V158, P145, DOI 10.1078-0176-1617-00068; Brett C.T., 1996, PHYSL BIOCH PLANT CE; Cumming CM, 2005, PLANTA, V222, P546, DOI 10.1007-s00425-005-1560-2; DUBOIS M, 1956, ANAL CHEM, V28, P350, DOI 10.1021-ac60111a017; Femenia A, 1999, CARBOHYD POLYM, V39, P151, DOI 10.1016-S0144-8617(99)00003-X; FRY SC, 1992, BIOCHEM J, V282, P821; KEEGSTRA K, 1973, PLANT PHYSIOL, V51, P188, DOI 10.1104-pp.51.1.188; LAU JM, 1985, CARBOHYD RES, V137, P111, DOI 10.1016-0008-6215(85)85153-3; Mohnen D., 1992, COMPREHENSIVE NATURA, V3, P497; ONeill MA, 1996, J BIOL CHEM, V271, P22923; RIZK SE, 2000, THESIS U GLASGOW; Rizk SE, 2000, PLANTA, V211, P423, DOI 10.1007-s004250000303; Thompson JE, 2000, PLANTA, V211, P275, DOI 10.1007-s004250000287; Vincken JP, 2003, PLANT PHYSIOL, V132, P1781, DOI 10.1104-pp.103.02235034
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Biosynthesis and cell-wall deposition of a pectin-xyloglucan complex in pea
No full textGolgi-enriched enzyme preparations prepared from etiolated pea epicotyls incorporated [U-14C]galactose from UDP-[U-14C]galactose into the 1,4-β-galactan sidechains of a pectin-xyloglucan complex. This complex could bind to paper and was degraded both by pectin-degrading enzymes and by a xyloglucan-specific endoglucanase. Gel permeation chromatography was used to assess the molecular size of the complex and of enzymically-degraded, galactan-containing fragments of it. Etiolated pea stems were labelled with [U-14C]sucrose for 1 h, and the newly-synthesised cell wall polysaccharides were extracted with EDTA or NaOH and fractionated by ion-exchange chromatography. The NaOH-extracted, acidic radioactive polysaccharides obtained in this way were also degraded both by pectin-degrading enzymes and by xyloglucan-specific endoglucanase. Analysis of the radioactive sugar composition indicated that neutral sugars characteristic of both pectin and xyloglucan were present. Analysis of the total non-radioactive, neutral sugar composition of the NaOH-extracted, acidic cell-wall polysaccharides indicated that pectin-xyloglucan complexes were a general feature of the cell wall in this tissue. © Springer-Verlag 2005.Abdel-Massih RM, 2003, PLANTA, V216, P502, DOI 10.1007-s00425-002-0861-y; Baydoun EAH, 2001, J PLANT PHYSIOL, V158, P145, DOI 10.1078-0176-1617-00068; BOWLES DJ, 1972, BIOCHEM J, V130, P1133; Brett C.T., 1996, PHYSL BIOCH PLANT CE; Darvill AG, 1980, BIOCH PLANTS, V1, P91; DUBOIS M, 1956, ANAL CHEM, V28, P350, DOI 10.1021-ac60111a017; Femenia A, 1999, CARBOHYD POLYM, V39, P151, DOI 10.1016-S0144-8617(99)00003-X; Fleischer A, 1999, PLANT PHYSIOL, V121, P829, DOI 10.1104-pp.121.3.829; Fry S, 1988, GROWING PLANT CELL W; FRY SC, 1992, BIOCHEM J, V282, P821; Goubet F, 2002, ANAL BIOCHEM, V300, P53, DOI 10.1006-abio.2001.5444; Ishii T, 1999, J BIOL CHEM, V274, P13098, DOI 10.1074-jbc.274.19.13098; Jarvis MC, 2003, PLANT CELL ENVIRON, V26, P977, DOI 10.1046-j.1365-3040.2003.01034.x; KEEGSTRA K, 1973, PLANT PHYSIOL, V51, P188, DOI 10.1104-pp.51.1.188; McCartney L, 2000, PLANT J, V22, P105, DOI 10.1046-j.1365-313x.2000.00719.x; Mohnen D., 1992, COMPREHENSIVE NATURA, V3, P497; Pauly M, 1999, GLYCOBIOLOGY, V9, P93, DOI 10.1093-glycob-9.1.93; Thompson JE, 2000, PLANTA, V211, P275, DOI 10.1007-s004250000287; Thompson JE, 1997, J EXP BOT, V48, P297, DOI 10.1093-jxb-48.2.297; Vincken JP, 2003, PLANT PHYSIOL, V132, P1781, DOI 10.1104-pp.103.022350; Willats WGT, 1999, PLANT J, V20, P619, DOI 10.1046-j.1365-313X.1999.00629.x; Youl JJ, 1998, P NATL ACAD SCI USA, V95, P7921, DOI 10.1073-pnas.95.14.792124191
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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