Syringyl Guaiacyl Ratio
Mostrando 1-10 de 10 artigos, teses e dissertações.
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1. Qualidade da madeira de Eucalyptus para a produção de carvão vegetal / Wood quality of Eucalyptus for charcoal production
The present study aimed to determine the properties of wood and charcoal from different clones of Eucalyptus spp. Six clones at 7.5 years old were evaluated and the samples were from a clonal test of a forestry company, located in the city of Lassance, Minas Gerais, Brazil. For wood, basic density, heart/sapwood ratio, morphological analysis of fibers and po
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 13/02/2012
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2. Determinação da relação siringila/guaiacila da lignina em madeiras de eucalipto por pirólise acoplada à cromatografia gasosa e espectrometria de massas (PI CG/EM)
The use of analytical pyrolysis combined with gas chromatography/mass spectrometry (Py-GC/MS) to determine the syringyl/guaiacyl ratio (S/G) in lignins from Eucalyptus spp woods was investigated. Sample of E. grandis and "E. urograndis" wood, with and without extractives, were subjected to pyrolysis from 300 ºC to 600 ºC. The products that results from pyr
Química Nova. Publicado em: 2008
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3. Uso da pirólise acoplada à cromatografia gasosa e à espectrometria de massas na determinação da relação siringil/guaiacil em ligninas de clones de Eucalyptus spp / Use of the pyrolysis coupled with gas chromatography and mass spectrometry in the determination of the syringyl/guaiacyl ratio in Eucalyptus spp. clones lignins
A relação siringil/guaiacil (S/G) foi determinada em madeiras de seis diferentes clones de Eucalyptus cultivados em quatro regiões do estado brasileiro de Minas Gerais. As determinações foram realizadas por pirólise acoplada à cromatografia gasosa e à espectrometria de massas (Pi- CG/EM) e os resultados obtidos foram comparados à valores de referên
Publicado em: 2008
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4. Determinação da relação siringila/guaiacila em ligninas de Eucalyptus spp. por pirólise associada à cromatografia gasosa e à espectrometria de massas / Determination of the syringyl/guaiacyl ratio in lignin of Eucalyptus spp. by pyrolysis associated to both gas chromatography and mass spectrometry
Lignin is one of the main components of the wood together with cellulose and hemicellulose. Its structure is quite complex being built up by p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) units. Some studies show that the lignin structural composition may affect the pulping process. Thus, some analyses of the wood of six species of eucalyptus were done b
Publicado em: 2007
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5. Reduced Lignin Content and Altered Lignin Composition in Transgenic Tobacco Down-Regulated in Expression of L-Phenylalanine Ammonia-Lyase or Cinnamate 4-Hydroxylase.
We analyzed lignin content and composition in transgenic tobacco (Nicotiana tabacum) lines altered in the expression of the early phenylpropanoid biosynthetic enzymes L-phenylalanine ammonia-lyase and cinnamate 4-hydroxylase (C4H). The reduction of C4H activity by antisense expression or sense suppression resulted in reduced levels of Klason lignin, accompan
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6. Combinatorial modification of multiple lignin traits in trees through multigene cotransformation
Lignin quantity and reactivity [which is associated with its syringyl/guaiacyl (S/G) constituent ratio] are two major barriers to wood-pulp production. To verify our contention that these traits are regulated by distinct monolignol biosynthesis genes, encoding 4-coumarate–CoA ligase (4CL) and coniferaldehyde 5-hydroxylase (CAld5H), we used Agrobacterium to
The National Academy of Sciences.
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7. Dual methylation pathways in lignin biosynthesis
Caffeoyl-coenzyme A (CoA) O-methyltransferase (CCoAOMT) has been proposed to be involved in an alternative methylation pathway of lignin biosynthesis. However, no direct evidence has been available to confirm that CCoAOMT is essential for lignin biosynthesis. To understand further the methylation steps in lignin biosynthesis, we used an antisense approach to
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8. Characterization of Palo Podrido, a Natural Process of Delignification in Wood †
Chemical and morphological changes of incipient to advanced stages of palo podrido, an extensively delignified wood, and other types of white rot decay found in the temperate forests of southern Chile were investigated. Palo podrido is a general term for white rot decay that is either selective or nonselective for the removal of lignin, whereas palo blanco d
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9. Antisense suppression of 4-coumarate:coenzyme A ligase activity in Arabidopsis leads to altered lignin subunit composition.
The phenylpropanoid enzyme 4-coumarate:coenzyme A ligase (4CL) is considered necessary to activate the hydroxycinnamic acids for the biosynthesis of the coniferyl and sinapyl alcohols subsequently polymerized into lignin. To clarify the role played by 4CL in the biosynthesis of the guaiacyl (G) and syringyl (S) units characteristic of angiosperm lignin, we g
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10. Molecular Phenotyping of the pal1 and pal2 Mutants of Arabidopsis thaliana Reveals Far-Reaching Consequences on Phenylpropanoid, Amino Acid, and Carbohydrate Metabolism
The first enzyme of the phenylpropanoid pathway, Phe ammonia-lyase (PAL), is encoded by four genes in Arabidopsis thaliana. Whereas PAL function is well established in various plants, an insight into the functional significance of individual gene family members is lacking. We show that in the absence of clear phenotypic alterations in the Arabidopsis pal1 an
American Society of Plant Biologists.