Quantitative assessment of xylan distribution across the secondary cell wall layers of Eucalyptus dissolving pulp fibres

AbstractA quantitative method has been developed for assessment of the distribution of xylan across the secondary cell wall layers ofEucalyptusdissolving pulp fibres by means of a carbohydrate binding module (CBM),CtCBM6, in combination with transmission electron microscopy (TEM). To ensure reproducibility and to minimise non-specific labelling, various parameters were optimised, namely the size of the gold colloid marker,CtCBM6 concentration, and the selection of buffer solutions. The method was replicated on processedEucalyptusfibres containing different xylan contents. Reproducible xylan counts and distributions across the secondary cell wall layers were obtained for unbleached and bleachedEucalyptusfibres. The xylan distribution pattern across the cell wall layers S1, S2 and S3 was similar, but the S1 and S3 layers contained after bleaching more xylan than the S2 layer. The technique has a wide range of applications in basic wood research as well as in the analysis of technological processes.

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Effects of refining on the fibre structure of kraft pulps as revealed by FE-SEM and TEM: Influence of alkaline degradation

Holzforschung ◽

10.1515/hf.2004.035 ◽

2004 ◽

Vol 58 (3) ◽

pp. 226-232 ◽

Cited By ~ 17

Author(s):

U. Molin ◽

G. Daniel

Keyword(s):

Electron Microscopy ◽

Intrinsic Viscosity ◽

Fibre Length ◽

Fibre Surface ◽

Alkali Concentration ◽

Kraft Pulps ◽

Transmission Electron ◽

Pulp Fibres ◽

Pfi Refining ◽

S2 Layer

Abstract The aim of the study was to evaluate the effect of refining on the ultrastructure of spruce pulp fibres. Pulps with different molar masses of cellulose (estimated as intrinsic viscosity) were studied after PFI-refining. The molar masses of the polymers were decreased by increases in alkali concentration during pulping. Fibre surface structures were examined using Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) was used to observe changes in the internal structure of the fibres. Pulps with lower (125 and 329 ml g−1) intrinsic viscosity showed more damaged during refining than pulps with higher (620 and 1120 ml g−1) intrinsic viscosity. Observations showed pulps with lower intrinsic viscosity to have large decreases in fibre length after refining. Fibres with low intrinsic viscosity (i.e., 125 ml g−1) had less primary wall and S1 layer remaining and the external fibrillation and damage of the S2 layer had increased. The S2 wall of fibres with high intrinsic viscosity showed characteristic delamination. Similar delamination was not visible for fibres with low intrinsic viscosity.

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Direct Insights on Flax Fiber Structure by Focused Ion Beam Microscopy

Microscopy and Microanalysis ◽

10.1017/s1431927609991292 ◽

2010 ◽

Vol 16 (2) ◽

pp. 175-182 ◽

Cited By ~ 12

Author(s):

Bernadette Domenges ◽

Karine Charlet

Keyword(s):

Electron Microscopy ◽

Cell Wall ◽

Cross Sections ◽

Secondary Cell Wall ◽

Focused Ion Beam ◽

Ion Beam ◽

Flax Fibers ◽

Transmission Electron ◽

Transition Modes ◽

Beam Currents

AbstractIn this article, it is shown that focused ion beam (FIB) systems can be used to study the inner structure of flax fibers, the use of which as a reinforcing material in polymer composites still draws much interest from multiple disciplines. This technique requires none of the specific preparations necessary for scanning electron microscopy or transmission electron microscopy studies. Irradiation experiments performed on FIB prepared cross sections with very low Ga+ion beam currents revealed the softer material components of fibers. Thus, it confirmed the presence of pectin-rich layers at the interfaces between the fibers of a bundle, but also allowed the precise localization of such layers within the secondary cell wall. Furthermore, it suggested new insights on the transition modes between the sublayers of the secondary cell wall.

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Preparation of diagnostic specimens for transmission electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110684 ◽

1984 ◽

Vol 42 ◽

pp. 62-65

Author(s):

Joseph M. Harb

Keyword(s):

Diagnostic Laboratory ◽

Specimen Handling ◽

Simultaneous Processing ◽

Transmission Electron ◽

Wide Range ◽

Negative Effect ◽

Muscle Nerve ◽

Embedding Medium ◽

Technical Reliability ◽

Selection Of

Several factors influence the selection of preparatory procedures for diagnostic TEM. These include variability of specimens, lack of accessibility to additional specimens, and the need for expeditious turn-around time and technical reliability. Specimens encountered in a diagnostic laboratory may include peripheral blood huffy coats and bone marrows, biopsies of liver, muscle, nerve, skin, kidney, lung and other organs, and a variety of tumors. It would be desirable for optimal preservation to employ a dehydration and embeddment schedule designed specifically for each specimen type, but such a practice in a diagnostic setting would seriously multiply the specimen handling steps and preclude simultaneous processing of different specimen types. Such a practice could also induce errors and increase the technical workload, which could have a negative effect on cost containment. Therefore, generalization of the preparatory schedule and selection of an embedding medium which will adequately preserve ultrastructural details for a wide range of specimens is appropriate.

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Cytochemistry of defense responses in cassava infected by Xanthomonas campestris pv. manihotis

Canadian Journal of Microbiology ◽

10.1139/m96-145 ◽

1996 ◽

Vol 42 (11) ◽

pp. 1131-1143 ◽

Cited By ~ 56

Author(s):

K. Kpémoua ◽

B. Boher ◽

M. Nicole ◽

P. Calatayud ◽

J. P. Geiger

Keyword(s):

Cell Wall ◽

Bacterial Growth ◽

Xanthomonas Campestris ◽

Secondary Cell Wall ◽

Defense Responses ◽

Resistant Variety ◽

Xylem Parenchyma ◽

Callose Deposition ◽

Wide Range ◽

Parenchyma Cells

Stems of susceptible and resistant cassava plants have been cytologically investigated for their defense reactions to an aggressive strain of Xanthomonas campestris pv. manihotis. Histochemistry, in conjunction with gold cytochemistry, revealed that in susceptible and resistant plants, phloem and xylem parenchyma cells displayed a wide range of responses that limited the bacterial growth within the infected plants. Lignification and suberization associated with callose deposition were effective mechanisms that reinforced host barriers in the phloem. In the infected xylem, vessels were plugged by a material of pectic and (or) lignin-like origin. Flavonoids have been seen to be incorporated in secondary cell wall coatings. These reactions occurred at a higher intensity in the resistant plants. The number of phoem and xylem cells producing autofluorescent compounds was higher in infected resistant plants than in susceptible plants. Reactions have been observed in the resistant variety only, such as secretion of phenol-like molecules by tyloses and hyperplasic activity of phloem cells that compartmentalized bacterial lysis pockets, which are potent secondary inoculum sources.Key words: lignin, suberin, callose, phenol, tylose, flavonoid, pectin.

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A Multilayered Secondary Wall in Fibres of Eucalyptus Obliqua L'hérit.

Australian Journal of Biological Sciences ◽

10.1071/bi9670481 ◽

1967 ◽

Vol 20 (2) ◽

pp. 481

Author(s):

DS Skene

Keyword(s):

Cell Wall ◽

Small Angle ◽

Secondary Wall ◽

Secondary Cell Wall ◽

Large Angle ◽

Cell Wall Structure ◽

Fibre Axis ◽

Wall Structure ◽

Polarizing Microscope ◽

S2 Layer

The secondary cell wall structure most commonly found in fibres and tracheids consists of three layers, as first proposed by Bailey and Kerr (1935) and recently reviewed by Wardrop (1964). The thin outermost and innermost layers, the S1 and Sa layers respectively, are characterized by the microfibrils being aligned at a large angle to the fibre axis. Between these two layers there is another, the S2layer, in which the microfibrils are aligned at a small angle to the fibre axis. These layers can be readily distinguished using a polarizing microscope, the S1 and Sa layers appearing bright and the S2 layer dark in transverse sections.

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Apoplastic CBM1-interacting proteins bind conserved carbohydrate binding module 1 motifs in fungal hydrolases to counter pathogen invasion

10.1101/2021.12.31.474618 ◽

2022 ◽

Author(s):

Takumi Takeda ◽

Machiko Takahashi ◽

Motoki Shimizu ◽

Yu Sugihara ◽

Hiromasa Saitoh ◽

...

Keyword(s):

Cell Wall ◽

Cell Walls ◽

Fungal Pathogens ◽

Carbohydrate Binding ◽

Carbohydrate Binding Module ◽

Cell Wall Degrading Enzymes ◽

Fungal Enzymes ◽

General Role ◽

Pathogen Invasion ◽

Wide Range

When infecting plants, fungal pathogens secrete cell wall degrading enzymes (CWDEs) that break down cellulose and hemicellulose, the primary components of plant cell walls. Some fungal CWDEs contain a unique domain, named the carbohydrate binding module (CBM), that facilitates their access to polysaccharides. However, little is known about how plants counteract pathogen degradation of their cell walls. Here, we show that the rice cysteine-rich repeat secretion protein OsCBMIP binds to and inhibits xylanase MoCel10A of the blast fungus pathogen Magnaporthe oryzae, interfering with its access to the rice cell wall and degradation of rice xylan. We found binding of OsCBMIP to various CBM1-containing enzymes, suggesting it has a general role in inhibiting the catalytic activities of fungal enzymes. OsCBMIP is localized to the apoplast, and its expression is strongly induced in leaves infected with M. oryzae. Remarkably, knockdown of OsCBMIP reduced rice defense against M. oryzae, demonstrating that inhibition of CBM1-containing fungal enzymes by OsCBMIP is crucial for rice defense. We also identified additional CBMIP-related proteins from Arabidopsis thaliana and Setaria italica, indicating that a wide range of plants counteract pathogens through this mechanism.

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DELLA-NAC Interactions Mediate GA Signaling to Promote Secondary Cell Wall Formation in Cotton Stem

Frontiers in Plant Science ◽

10.3389/fpls.2021.655127 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yi Wang ◽

Wanting Yu ◽

Lingfang Ran ◽

Zhong Chen ◽

Chuannan Wang ◽

...

Keyword(s):

Cell Wall ◽

Gene Silencing ◽

Secondary Cell Wall ◽

Cell Wall Formation ◽

Virus Induced Gene Silencing ◽

Secondary Cell Wall Formation ◽

Della Proteins ◽

Ga Signaling ◽

Wide Range ◽

New System

Gibberellins (GAs) promote secondary cell wall (SCW) development in plants, but the underlying molecular mechanism is still to be elucidated. Here, we employed a new system, the first internode of cotton, and the virus-induced gene silencing method to address this problem. We found that knocking down major DELLA genes via VIGS phenocopied GA treatment and significantly enhanced SCW formation in the xylem and phloem of cotton stems. Cotton DELLA proteins were found to interact with a wide range of SCW-related NAC proteins, and virus-induced gene silencing of these NAC genes inhibited SCW development with downregulated biosynthesis and deposition of lignin. The findings indicated a framework for the GA regulation of SCW formation; that is, the interactions between DELLA and NAC proteins mediated GA signaling to regulate SCW formation in cotton stems.

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Overexpression of PtrMYB121 Positively Regulates the Formation of Secondary Cell Wall in Arabidopsis thaliana

International Journal of Molecular Sciences ◽

10.3390/ijms21207734 ◽

2020 ◽

Vol 21 (20) ◽

pp. 7734

Author(s):

Ying Liu ◽

Jiayin Man ◽

Yinghao Wang ◽

Chao Yuan ◽

Yuyu Shi ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Cell Wall ◽

Transcription Factors ◽

Secondary Cell Wall ◽

Tissue Expression ◽

Wild Type ◽

Tissue Expression Analysis ◽

Wide Range ◽

Transgenic Lines ◽

Key Enzyme

MYB transcription factors have a wide range of functions in plant growth, hormone signaling, salt, and drought tolerances. In this study, two homologous transcription factors, PtrMYB55 and PtrMYB121, were isolated and their functions were elucidated. Tissue expression analysis revealed that PtrMYB55 and PtrMYB121 had a similar expression pattern, which had the highest expression in stems. Their expression continuously increased with the growth of poplar, and the expression of PtrMYB121 was significantly upregulated in the process. The full length of PtrMYB121 was 1395 bp, and encoded protein contained 464 amino acids including conserved R2 and R3 MYB domains. We overexpressed PtrMYB121 in Arabidopsis thaliana, and the transgenic lines had the wider xylem as compared with wild-type Arabidopsis. The contents of cellulose and lignin were obviously higher than those in wild-type materials, but there was no significant change in hemicellulose. Quantitative real-time PCR demonstrated that the key enzyme genes regulating the synthesis of lignin and cellulose were significantly upregulated in the transgenic lines. Furthermore, the effector-reporter experiment confirmed that PtrMYB121 bound directly to the promoters of genes relating to the synthesis of lignin and cellulose. These results suggest that PtrMYB121 may positively regulate the formation of secondary cell wall by promoting the synthesis of lignin and cellulose.

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The S2 Layer in the Tracheid Walls of Picea abies Wood: Inhomogeneity in Lignin Distribution and Cell Wall Microstructure

Holzforschung ◽

10.1515/hf.2001.062 ◽

2001 ◽

Vol 55 (4) ◽

pp. 373-378 ◽

Cited By ~ 17

Author(s):

Adya P. Singh ◽

Geoffrey Daniel

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Cell Wall ◽

Picea Abies ◽

Lignin Distribution ◽

Transmission Electron ◽

S2 Layer ◽

Tangential Directions ◽

Electron Lucent

Summary Transmission electron microscopy (TEM) of the walls of Picea abies axial tracheids showed the distribution of lignin in the S2 layer to be inhomogenous. At relatively low magnifications, some parts of the outer and inner S2 layer appeared more electron dense than the mid region in the tracheids which were in contact with or in proximity to a ray. At similar magnifications, the presence of radial and tangential features was observed in the S2 layer of the tracheids which were in contact with or close to rays as well as in those which occurred elsewhere. Higher magnification views showed the S2 layer to be differentiated into electron lucent and dense regions in both radial and tangential directions. A comparison of the counts made of lignin particles in these regions suggested that the differentiation of the S2 wall into lucent and dense regions resulted from inhomogenous distribution of lignin observable at a nano level.

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