Structural and chemical changes of cell wall types during stem development: consequences for fibre degradation by rumen microflora

1997 ◽  
Vol 48 (2) ◽  
pp. 165 ◽  
Author(s):  
J. R. Wilson ◽  
R. D. Hatfield
Keyword(s):  
Cell Wall ◽  
Surface Area ◽  
Middle Lamella ◽  
Cell Types ◽  
Anatomical Structure ◽  
Mesophyll Cells ◽  
Rumen Microorganisms ◽  
Chemical Structures ◽  
Stems Cells

Legume and grass stems decrease substantially in digestibility as they mature. This review evaluates how anatomical and chemical factors restrict digestion of cell walls in legume and grass stems. Cells that make up legume stems fall into 2 groups: cells with high (≅ 100%) digestibility (e.g. cortex and pith) and cells that appear indigestible (e.g. xylem). The digestibility of xylem cells is restricted by the highly lignified secondary walls (SW). Although cortex and pith cells may develop SW or thickened primary walls, digestibility is high because these cell types do not undergo lignification. In contrast, as grass stems mature, SW thickening and lignification occur in all main cell types. However, lignified SW in grass is readily digested when accessible to rumen microorganisms. Analysis of tissue and cell architecture in grasses strongly supports the hypothesis that observed poor digestion of lignified SW in vivo is due to limits imposed by anatomical structure. Compositional limitation to wall digestion lies in the lignified, indigestible middle lamella–primary wall. This structure confines SW digestion to inner (lumen) surfaces of cells with an open end. Low sclerenchyma SW degradation in vivo can be explained by limited movement of bacteria into sclerenchyma cells and low surface area on interior walls. For example, the ratio of surface area to total cell wall volume for sclerenchyma cells is 100-fold lower than for mesophyll cells. Apparent relationships of some wall constituents–chemical structures to wall digestibility may be the result of the increasing SW and, therefore, may simply reflect limitations imposed by anatomical structure.

Endothelial adenosine transporter characterization in perfused guinea pig hearts

2000 ◽  
Vol 279 (4) ◽  
pp. H1502-H1511 ◽  
Author(s):  
Lisa M. Schwartz ◽  
Thomas R. Bukowski ◽  
James D. Ploger ◽  
James B. Bassingthwaighte
Keyword(s):  
Guinea Pig ◽  
Surface Area ◽  
Cell Types ◽  
Maximal Velocity ◽  
Passive Transport ◽  
Multiple Indicator Dilution ◽  
Luminal Membrane ◽  
Permeability Surface ◽  
Multiple Indicator

Adenosine (Ado), a smooth muscle vasodilator and modulator of cardiac function, is taken up by many cell types via a saturable transporter, blockable by dipyridamole. To quantitate the influences of endothelial cells in governing the blood-tissue exchange of Ado and its concentration in the interstitial fluid, one must define the permeability-surface area products ( PS) for Ado via passive transport through interendothelial gaps [ PS g(Ado)] and across the endothelial cell luminal membrane ( PS ecl) in their normal in vivo setting. With the use of the multiple-indicator dilution (MID) technique in Krebs-Ringer perfused, isolated guinea pig hearts (preserving endothelial myocyte geometry) and by separating Ado metabolites by HPLC, we found permeability-surface area products for an extracellular solute, sucrose, via passive transport through interendothelial gaps [ PS g(Suc)] to be 1.9 ± 0.6 ml · g−1 · min−1( n = 16 MID curves in 4 hearts) and took PS g(Ado) to be 1.2 times PS g(Suc). MID curves were obtained with background nontracer Ado concentrations up to 800 μm, partially saturating the transporter and reducing its effective PS ecl for Ado. The estimated maximum value for PS ecl in the absence of background adenosine was 1.1 ± 0.1 ml · g−1 · min−1 [maximum rate of transporter conformational change to move the substrate from one side of the membrane to the other (maximal velocity; V max) times surface area of 125 ± 11 nmol · g−1 · min−1], and the Michaelis-Menten constant ( K m) was 114 ± 12 μM, where ± indicates 95% confidence limits. Physiologically, only high Ado release with hypoxia or ischemia will partially saturate the transporter.

scholarly journals Posttranslational Modifications Required for Cell Surface Localization and Function of the Fungal Adhesin Aga1p

2003 ◽  
Vol 2 (5) ◽  
pp. 1099-1114 ◽  
Author(s):  
Guohong Huang ◽  
Mingliang Zhang ◽  
Scott E. Erdman
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Posttranslational Modifications ◽  
Transmembrane Domain ◽  
Signal Sequence ◽  
Cell Types ◽  
Fungal Species ◽  
Surface Proteins ◽  
Functional Requirements

ABSTRACT Adherence of fungal cells to host substrates and each other affects their access to nutrients, sexual conjugation, and survival in hosts. Adhesins are cell surface proteins that mediate these different cell adhesion interactions. In this study, we examine the in vivo functional requirements for specific posttranslational modifications to these proteins, including glycophosphatidylinositol (GPI) anchor addition and O-linked glycosylation. The processing of some fungal GPI anchors, creating links to cell wall β-1,6 glucans, is postulated to facilitate postsecretory traffic of proteins to cell wall domains conducive to their functions. By studying the yeast sexual adhesin subunit Aga1p, we found that deletion of its signal sequence for GPI addition eliminated its activity, while deletions of different internal domains had various effects on function. Substitution of the Aga1p GPI signal domain with those of other GPI-anchored proteins, a single transmembrane domain, or a cysteine capable of forming a disulfide all produced functional adhesins. A portion of the cellular pool of Aga1p was determined to be cell wall resident. Aga1p and the α-agglutinin Agα1p were shown to be under glycosylated in cells lacking the protein mannosyltransferase genes PMT1 and PMT2, with phenotypes manifested only in MATα cells for single mutants but in both cell types when both genes are absent. We conclude that posttranslational modifications to Aga1p are necessary for its biogenesis and activity. Our studies also suggest that in addition to GPI-glucan linkages, other cell surface anchorage mechanisms, such as transmembrane domains or disulfides, may be employed by fungal species to localize adhesins.

scholarly journals Different Cell Wall-Degradation Ability Leads to Tissue-Specificity between Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola

Pathogens ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 187
Author(s):  
Jianbo Cao ◽  
Chuanliang Chu ◽  
Meng Zhang ◽  
Limin He ◽  
Lihong Qin ◽  
...  
Keyword(s):  
Cell Wall ◽  
Tissue Specificity ◽  
Mesophyll Cell ◽  
Xanthomonas Oryzae ◽  
Cell Wall Degradation ◽  
Intercellular Spaces ◽  
Mesophyll Cells ◽  
Degradation Ability

Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) lead to the devastating rice bacterial diseases and have a very close genetic relationship. There are tissue-specificity differences between Xoo and Xoc, i.e., Xoo only proliferating in xylem vessels and Xoc spreading in intercellular space of mesophyll cell. But there is little known about the determinants of tissue-specificity between Xoo and Xoc. Here we show that Xoc can spread in the intercellular spaces of mesophyll cells to form streak lesions. But Xoo is restricted to growth in the intercellular spaces of mesophyll cells on the inoculation sites. In vivo, Xoc largely breaks the surface and inner structures of cell wall in mesophyll cells in comparison with Xoo. In vitro, Xoc strongly damages the cellulose filter paper in comparison with Xoo. These results suggest that the stronger cell wall-degradation ability of Xoc than that of Xoo may be directly determining the tissue-specificity.

The ultrastructure of the Spilocaea state of Venturia inaequalis in vivo

1976 ◽  
Vol 22 (8) ◽  
pp. 1144-1152 ◽  
Author(s):  
Michael Corlett ◽  
James Chong ◽  
E. G. Kokko
Keyword(s):  
Cell Wall ◽  
Epidermal Cell ◽  
Venturia Inaequalis ◽  
Conidiogenous Cell ◽  
Epidermal Cells ◽  
Apical Region ◽  
Mesophyll Cells ◽  
Epidermal Cell Wall ◽  
Primary Conidium

There are indications that the fungus enzymatically degrades the cuticle and epidermal cell wall. The epidermal cells and to a lesser degree the palisade mesophyll cells beneath a sporulating lesion (susceptible reaction) are killed or seriously disrupted. Various stages of conidiogenesis, including development of the primary conidium, were observed. A conidium is delimited by a two-layered transverse septum. Before conidium secession, a new two-layered inner wall is laid down around the entire conidiogenous cell adjacent to the plasmalemma. The apical region of the new inner wall proliferates beyond the annellation scar left by the seceded conidium and eventually produces another conidium.

scholarly journals VARIATIONS IN CELL WALL ULTRASTRUCTURE AND CHEMISTRY IN CELL TYPES OF EARLYWOOD AND LATEWOOD IN ENGLISH OAK (QUERCUS ROBUR)

IAWA Journal ◽  
2016 ◽  
Vol 37 (3) ◽  
pp. 383-401 ◽  
Author(s):  
Jong Sik Kim ◽  
Geoffrey Daniel
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Quercus Robur ◽  
Growth Ring ◽  
Middle Lamella ◽  
Cell Types ◽  
Parenchyma Cells ◽  
Ray Parenchyma ◽  
English Oak ◽  
Ray Parenchyma Cells

Although there is considerable information on anatomy and gross chemistry of oak wood, little is known on the ultrastructure and chemistry at the individual cell wall level. In particular, differences in ultrastructure and chemistry within the same cell type between earlywood (EW) and latewood (LW) are poorly understood. This study investigated the ultrastructure and chemistry of (vasicentric) tracheids, vessels, (libriform) fibers and axial/ray parenchyma cells of English oak xylem (Quercus robur L.) using light-, fluorescence- and transmission electron microscopy combined with histo/cytochemistry and immunohisto/ cytochemistry. EW tracheids showed several differences from LW tracheids including thinner cell walls, wider middle lamella cell corner (MLcc) regions and lesser amounts of mannan epitopes. Fibers showed thicker cell walls and higher amounts of mannan epitopes than tracheids. EW vessels were rich in guaiacyl (G) lignin with a characteristic non-layered cell wall organization (absence of S1–3 layers), whereas LW vessels were rich in syringyl (S) lignin with a three layered cell wall structure (S1–3 layers). Formation of a highly lignified and wide protective layer (PL) inside axial/ray parenchyma cells was detected only in EW. Distribution of mannan epitopes varied greatly between cell types and between EW and LW, whereas distribution of xylan epitopes was almost identical in all cell types within a growth ring. Together, this study demonstrates that there are great variations in ultrastructure and chemistry of cell walls within a single growth ring of English oak xylem.

scholarly journals High-order mutants reveal an essential requirement for peroxidases but not laccases in Casparian strip lignification

2020 ◽  
Author(s):  
Nelson Rojas-Murcia ◽  
Kian Hématy ◽  
Yuree Lee ◽  
Aurélia Emonet ◽  
Robertas Ursache ◽  
...  
Keyword(s):  
Cell Wall ◽  
Lignin Biosynthesis ◽  
Cell Types ◽  
Arabidopsis Genome ◽  
Essential Requirement ◽  
Knock Out ◽  
Homologous Genes ◽  
Casparian Strips ◽  
Different Cell Types

ABSTRACTThe invention of lignin has been at the heart of plants’ capacity to colonize land, allowing them to grow tall, transport water within their bodies and protect themselves against various stresses. Consequently, this polyphenolic polymer, that impregnates the cellulosic plant cell walls, now represents the second most abundant polymer on Earth, after cellulose itself. Yet, despite its great physiological, ecological and economical importance, our knowledge of lignin biosynthesis in vivo, especially the crucial last steps of polymerization within the cell wall, remains vague. Specifically, the respective roles and importance of the two main polymerizing enzymes classes, laccases and peroxidases have remained obscure. One reason for this lies in the very high numbers of laccases and peroxidases encoded by 17 and 73 homologous genes, respectively, in the Arabidopsis genome. Here, we have focused on a specific lignin structure, the ring-like Casparian strips (CS) within the endodermis of Arabidopsis roots. By reducing the number of possible candidate genes using cellular resolution expression and localization data and by boosting the levels of mutants that can be stacked using CRISPR/Cas9, we were able to knock-out more than half of all laccases in the Arabidopsis genome in a nonuple mutant – abolishing the vast majority of laccases with detectable endodermal-expression. Yet, we were unable to detect even slight defects in CS formation. By contrast, we were able to induce a complete absence of CS formation in a quintuple peroxidase mutant. Our findings are in stark contrast to the strong requirement of xylem vessels for laccase action and indicate that lignin in different cell types can be polymerized in very distinct ways. We speculate that cells lignify differently depending on whether they deposit lignin in a localized or ubiquitous fashion, whether they stay alive during and after lignification as well as the composition of the cell wall.

The Massaria disease of plane trees:its wood decay mechanism

IAWA Journal ◽  
2014 ◽  
Vol 35 (4) ◽  
pp. 395-406 ◽  
Author(s):  
Uwe Schmitt ◽  
Benjamin Lüer ◽  
Dirk Dujesiefken ◽  
Gerald Koch
Keyword(s):  
Cell Walls ◽  
Parenchyma Cell ◽  
Middle Lamella ◽  
Wood Decay ◽  
Cell Types ◽  
Cell Corner ◽  
Transmission Electron ◽  
Parenchyma Cells ◽  
Decay Pattern

Branches of Platanus × hispanica with distinct symptoms of the Massaria disease were investigated by light and transmission electron microscopy and cellular UVmicrospectrophotometry. The samples collected in the city of Mannheim, Germany, were infected in vivo with the fungus Splanchnonema platani and showed various degrees of wood decay. The investigations were focused on the decay pattern of cell walls in the different cells, i.e., fibres, vessels as well as ray and axial parenchyma cells. The following results were obtained. Hyphae of the ascomycete fungus Splanchnonema platani penetrated from cell to cell through the pits and not through the cell wall middle lamella, by the formation of thin perforation hyphae. During this process, the 1–5 μm thick hyphae became narrower without attacking the wall around the pit canal. After penetration through a pit, the hyphae again enlarged to their original diameter. This is true for all pit pairs connecting the various cell types. Late decay stages did not show a decay of cell corner regions and middle lamellae of fibres as well as vessel and parenchyma cell walls. Phenolic deposits in parenchyma cells were still present in severely attacked xylem tissue. These features point to a low lignolytic capacity of the fungus. The frequently found microscopic decay pattern with the formation of oval or spherical cavities in the S2 layer of the secondary wall with an often structurally intact S3 layer is a characteristic of softrot decay. This classification is also supported by the remaining cell corner and middle lamella regions in advanced decay stages. As a consequence of this decay type, branches fracture in a brittle mode.

scholarly journals High-order mutants reveal an essential requirement for peroxidases but not laccases in Casparian strip lignification

2020 ◽  
Vol 117 (46) ◽  
pp. 29166-29177
Author(s):  
Nelson Rojas-Murcia ◽  
Kian Hématy ◽  
Yuree Lee ◽  
Aurélia Emonet ◽  
Robertas Ursache ◽  
...  
Keyword(s):  
Cell Wall ◽  
Lignin Biosynthesis ◽  
Cell Types ◽  
Plant Cell Walls ◽  
Essential Requirement ◽  
Homologous Genes ◽  
Casparian Strips ◽  
Different Cell Types ◽  
Root Endodermis

Lignin has enabled plants to colonize land, grow tall, transport water within their bodies, and protect themselves against various stresses. Consequently, this polyphenolic polymer, impregnating cellulosic plant cell walls, is the second most abundant polymer on Earth. Yet, despite its great physiological, ecological, and economical importance, our knowledge of lignin biosynthesis in vivo, especially the polymerization steps within the cell wall, remains vague—specifically, the respective roles of the two polymerizing enzymes classes, laccases and peroxidases. One reason for this lies in the very high numbers of laccases and peroxidases encoded by 17 and 73 homologous genes, respectively, inArabidopsis. Here, we have focused on a specific lignin structure, the ring-like Casparian strips (CSs) within the root endodermis. By reducing candidate numbers using cellular resolution expression and localization data and by boosting stacking of mutants using CRISPR-Cas9, we mutated the majority of laccases inArabidopsisin a nonuple mutant—essentially abolishing laccases with detectable endodermal expression. Yet, we were unable to detect even slight defects in CS formation. By contrast, we were able to induce a complete absence of CS formation in a quintuple peroxidase mutant. Our findings are in stark contrast to the strong requirement of xylem vessels for laccase action and indicate that lignin in different cell types can be polymerized in very distinct ways. We speculate that cells lignify differently depending on whether lignin is localized or ubiquitous and whether cells stay alive during and after lignification, as well as the composition of the cell wall.

scholarly journals Real-time conversion of tissue-scale mechanical forces into an interdigitated growth pattern

2021 ◽  
Author(s):  
Samuel A. Belteton ◽  
Wenlong Li ◽  
Makoto Yanagisawa ◽  
Faezeh A. Hatam ◽  
Madeline I. Quinn ◽  
...  
Keyword(s):  
Cell Wall ◽  
Real Time ◽  
Agronomic Traits ◽  
Spatial Scales ◽  
Middle Lamella ◽  
Cell Types ◽  
Adjacent Cell ◽  
Pavement Cell ◽  
Pavement Cells ◽  
Tensile Forces

Abstract The leaf epidermis is a dynamic biomechanical shell that integrates growth across spatial scales to influence organ morphology. Pavement cells, the fundamental unit of this tissue, morph irreversibly into highly lobed cells that drive planar leaf expansion. Here we define how tissue-scale cell wall tensile forces and the microtubule-cellulose synthase systems pattern interdigitated growth in real-time. A morphologically potent subset of cortical microtubules span the periclinal and anticlinal cell faces to pattern cellulose fibers that generate a patch of anisotropic wall. The result is local polarized growth that is mechanically coupled to the adjacent cell via a pectin-rich middle lamella, and this drives lobe formation. Finite element pavement cell models revealed cell wall tensile stress as an upstream patterning element that links cell- and tissue-scale biomechanical parameters to interdigitated growth. Cell lobing in leaves is evolutionarily conserved, occurs in multiple cell types, and is associated with important agronomic traits. Our general mechanistic models of lobe formation provide a foundation to analyze the cellular basis of leaf morphology and function.

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