Pit Pairs With Tori in the Wood of Osmanthus Americanus (Oleaceae)

IAWA Journal ◽  
1987 ◽  
Vol 8 (3) ◽  
pp. 237-244 ◽  
Author(s):  
Roland R. Dute ◽  
Ann E. Rushing
Keyword(s):  
Middle Lamella ◽  
Radial Component ◽  
Wall Material ◽  
Sodium Chlorite ◽  
Variable Amount ◽  
Tracheary Elements ◽  
Bordered Pit ◽  
Compound Middle Lamella ◽  
Pit Membrane

Bordered pit pairs connecting tracheary elements in the wood of Osmanthus americanus (L.) Benth. ' Hook. ex Gray contained a torus in the pit membrane. This structure is approximately 2.5 μm in diameter, and is located at or near the centre of the pit membrane. The encrusting material of the torus could be removed by treatment with sodium chlorite. Thin seetions through theJorus showed it to consist of a pad of wall material appressed to either side of the compound middle lamella. The membrane surrounding the torus (the margo) consisted of fibrils and a variable amount of enc10sing matrix. The fibrils were generally c1oseIy packed and randomly oriented, although occasionally a radial component was also present. Aspiration of the pit membrane in air-dried material caused the torus to seal off one of the pit apertures. During this process the torus probably prevented rupture of the pit membrane at that site.

Torus-Bearing Pit Membranes in Cercocarpus

IAWA Journal ◽  
2010 ◽  
Vol 31 (1) ◽  
pp. 53-66 ◽  
Author(s):  
Roland Dute ◽  
Jaynesh Patel ◽  
Steven Jansen
Keyword(s):  
Secondary Wall ◽  
Membrane Surface ◽  
Parenchyma Cell ◽  
Protective Layer ◽  
Wall Material ◽  
Tracheary Elements ◽  
Bordered Pit ◽  
Parenchyma Cells ◽  
Conducting Cell ◽  
Cell Ontogeny

Intervascular pit membranes of Cercocarpus possess torus thickenings. The thickenings, or pads, consist of lignified, secondary wall material. Torus pad deposition occurs late in cell ontogeny and is not associated with a microtubule plexus. Half-bordered pit pairs between tracheary elements and parenchyma cells often have a torus pad on the membrane surface facing the conducting cell. In contrast, a thick protective layer fills the pit cavity on the side of the parenchyma cell. Ontogeny of the torus thickenings in Cercocarpus represents a third mode of torus development in eudicots when compared to that occurring in Osmanthus/Daphne and Ulmus/Celtis.

An “Ultrafilter” in the Margo of Mature Bordered Pits?

1972 ◽  
Vol 30 ◽  
pp. 206-207
Author(s):  
I. B. Sachs ◽  
R. E. Kinney
Keyword(s):  
Surface Tension ◽  
Electron Microscope ◽  
Molecular Sieve ◽  
Pinus Strobus ◽  
Postmortem Changes ◽  
Sodium Chlorite ◽  
Bordered Pit ◽  
Pit Membrane ◽  
Bordered Pits ◽  
Surface Tension Forces

The micrographs illustrating this paper were obtained from never-dried springwood bordered pit-pairs of Pinus strobus L. Specimens were treated with acidified sodium chlorite in order to remove incrusting materials from the pit membrane. To prevent or reduce interfacial and surface tension forces and provide a view of bordered pit structure without postmortem changes, the specimens were further treated either by the critical point method of Weatherwax and Caulfield, a version of Anderson's method, or by a low temperature evaporation method using molecular sieve material at -40° C. to gently remove the alcohol, Arenberg, et al. For studying the pit membrane of bordered pit-pairs, neither technique seems to have an advantage, giving similar results.Light and electron microscope studies have established that structurally the bordered pit-pair membrane consists of a torus and a margo.

Cell biology of bordered-pit formation in balsam-fir trees

Botany ◽  
2014 ◽  
Vol 92 (7) ◽  
pp. 495-511 ◽  
Author(s):  
Rodney Arthur Savidge
Keyword(s):  
Cell Biology ◽  
De Novo ◽  
Secondary Xylem ◽  
Abies Balsamea ◽  
Middle Lamella ◽  
Wall Material ◽  
Bordered Pit ◽  
Pit Formation ◽  
A Cell ◽  
Basal Disk

A mature bordered pit in secondary xylem of Pinaceae comprises a circular border of secondary-wall material that protrudes into the tracheid lumen and is punctuated by a centralized aperture through which sap flows. The overarching border encloses a pit chamber within which is a “membrane”, or diaphragm, consisting of a central torus and margo strands. Bordered-pit pairs are abundantly present in all woods, and their membranes serve as swinging-diaphragm check valves regulating sap flow between adjoining tracheary elements, simultaneously trapping emboli and particulates in water as it moves from roots to leaves. The cell biology of bordered-pit formation in cambial derivatives of Abies balsamea (L.) Mill. was investigated by light and scanning electron microscopy during early stages of cellular differentiation of cambial derivatives into secondary xylem tracheids. A bordered-pit template (BPT), a bordered-pit organelle (BPO), a bordered-pit basal disk, and additional novel structures were found to be associated with bordered-pit formation. Evidence was found that the membrane does not comprise residual compound middle lamella; rather, the membrane forms de novo as BPO remnants. A cell-biology model and new terminology are introduced to explain how BPTs, BPOs, and basal disks contribute to successive stages in formation of bordered-pit pairs.

Torus Structure and Development in Species of Daphne

IAWA Journal ◽  
1990 ◽  
Vol 11 (4) ◽  
pp. 401-412 ◽  
Author(s):  
Roland R. Dute ◽  
Ann E. Rushing ◽  
James W. Perry
Keyword(s):  
Tracheary Element ◽  
Tracheary Elements ◽  
Bordered Pit ◽  
Fibrillar Material ◽  
Pit Membrane ◽  
Parenchyma Cells ◽  
Daphne Odora

A torus is present in intervascular pit membranes in the wood of Daphne odora and D. cneorum, but not in D. mezereum. In the two former species, each torus is surrounded by a margo consisting of fibrillar material in a tightly woven pattern. Tori are of greater diameter than pit apertures and completely occlude the apertures during aspiration. Evidence from D. odora indicates that torus deposition is spatially associated with vesicles and a plexus of microtubules, and does not begin until pit border formation is complete. The material deposited during torus synthesis also impregnates the wall of the pre-existing pit membrane. The plasmalemma often is closely appressed to the pit membrane at the site of the developing torus. In half-bordered pit pairs between tracheary elements and parenchyma cells, a torus thickening is deposited only on the side of the tracheary element. As in Osmanthus americanus, it is hypothesised that the presence of tori in species of Daphne prevents rupture of the pit membrane during aspiration.

scholarly journals Bacterial Biodegradation of Extractives and Patterns of Bordered Pit Membrane Attack in Pine Wood

2000 ◽  
Vol 66 (12) ◽  
pp. 5201-5205 ◽  
Author(s):  
Todd A. Burnes ◽  
Robert A. Blanchette ◽  
Roberta L. Farrell
Keyword(s):  
Xanthomonas Campestris ◽  
Treated Wood ◽  
Wood Chips ◽  
Pulp Mills ◽  
Wood Extractives ◽  
Bordered Pit ◽  
Pine Wood ◽  
Pit Membrane ◽  
Pine Wood Chips ◽  
Ray Parenchyma Cells

ABSTRACT Wood extractives, commonly referred to as pitch, cause major problems in the manufacturing of pulp and paper. Treatment of nonsterile southern yellow pine chips for 14 days withPseudomonas fluorescens, Pseudomonas sp.,Xanthomonas campestris, and Serratia marcescens reduced wood extractives by as much as 40%. Control treatments receiving only water lost 11% of extractives due to the growth of naturally occurring microorganisms. Control treatments were visually discolored after the 14-day incubation, whereas bacterium-treated wood chips were free of dark staining. Investigations using P. fluorescens NRRL B21432 showed that all individual resin and fatty acid components of the pine wood extractives were substantially reduced. Micromorphological observations showed that bacteria were able to colonize resin canals, ray parenchyma cells, and tracheids. Tracheid pit membranes within bordered pit chambers were degraded after treatment with P. fluorescensNRRL B21432. P. fluorescens and the other bacteria tested appear to have the potential for biological processing to substantially reduce wood extractives in pine wood chips prior to the paper making process so that problems associated with pitch in pulp mills can be controlled.

Structure and Ultrastructure of the Tracheary Elements of Asplenium (Pteridophyta) from the “Yungas”, Argentina

IAWA Journal ◽  
2010 ◽  
Vol 31 (2) ◽  
pp. 227-240 ◽  
Author(s):  
María Luján Luna ◽  
Gabriela Elena Giudice ◽  
María Alejandra Ganem ◽  
Elías Ramón de la Sota
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Maturation Stage ◽  
Tracheary Elements ◽  
Transmission Electron ◽  
Pit Membrane ◽  
Membrane Hydrolysis ◽  
Structure And Ultrastructure ◽  
Scanning Electron

The structure of root and rhizome tracheary cells of Asplenium spp. (Filicales, Pteridophyta) growing in NW Argentina was studied using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In all cases, tracheary cells consisted of tracheids with various facets, mainly with scalariform pitting. With SEM, intertracheary pit membranes appeared smooth and non porose in most cases. In some instances, porose or web-like to thread-like pit membranes were noticed in rhizome tracheids. Under TEM secondary walls displayed a smooth and uniform appearance. Pit membranes showed a variation in thickness in presumed association with their maturation stage. More mature tracheary cells showed pit membranes with a mesh-like aspect and visible openings or pores. These characteristics are attributed to pit membrane hydrolysis, which facilitates water transport among tracheary cells.

Within-process and seasonal changes during industrial production of high-density fibreboard. Part 1: Influence of wood species composition on polyoses in the products

Holzforschung ◽  
2012 ◽  
Vol 66 (5) ◽  
pp. 667-672 ◽  
Author(s):  
Martin Weigl ◽  
Rupert Wimmer ◽  
Thomas Ters ◽  
Roland Mitter ◽  
Thomas Kuncinger
Keyword(s):  
Wood Species ◽  
Galacturonic Acid ◽  
Middle Lamella ◽  
Strength Loss ◽  
High Density ◽  
Chemical Degradation ◽  
Structural Alterations ◽  
Compound Middle Lamella ◽  
Hemicellulose Degradation ◽  
Composition Changes

Abstract Industrially produced high-density fibreboard fibres are inhomogeneous in structure and chemical composition. Changes in polysaccharide chemistry during processing have an impact on strength loss, fibre separation and structural alterations. In the present study, carbohydrate composition of extracted wood chips and refiner fibres was monitored for a year at an industrial HDF plant. The polysaccharides were analysed via methanolysis and quantification of the monomeric sugars released. Significant reductions of arabinose, xylose, rhamnose and galacturonic acid were observed. The amount of glucose and extractable substances increased. The depletion of galacturonic acid and rhamnose indicates a degradation of pectin located in the compound middle lamella. The diminishing amounts of the other sugars and elevated extractive contents are a result of hemicellulose degradation. A pronounced seasonal variability of the data was observed depending on the processed wood species and degree of chemical degradation.

Ultrastructure des parois de cerises Bigarreau Burlat de textures différentes au cours de la maturation

1996 ◽  
Vol 74 (12) ◽  
pp. 1974-1981 ◽  
Author(s):  
C. Batisse ◽  
P. J. Coulomb ◽  
C. Coulomb ◽  
M. Buret
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Middle Lamella ◽  
Primary Cell ◽  
Wall Material ◽  
Cell Wall Degradation ◽  
Composition And Structure ◽  
Cell Wall Texture ◽  
Synthesis And Degradation ◽  
Soft Fruits

The changes in texture of fruits during ripening are linked to cell wall degradation involving synthesis and degradation of polymers. An increase in pectin solubility leads to cell sliding and an elastic aspect of tissues. The biochemical cell wall process differs between soft and crisp fruits originating from a same cultivar but cultivated under different agroclimatic conditions. Although the proportions of cell wall material are similar, the composition and structure of the two cell walls are very different at maturity. A solubilization of the middle lamella and a restructuration of the primary cell walls arising from the cells separation is observed in crisp fruits. In contrast, the middle lamella of the soft fruits is better preserved and the primary cell walls are thin and show degradation bags delimited by residual membrane formations. In addition, the macroendocytosis process by endosome individualization is more important in soft fruits. In conclusion, the fruit texture depends on the extent of the links between cell wall polymers. Keywords: cherry, cell wall, texture, ultrastructural study.

Torus Structure and Development in the Woods of Ulmus Alata Michx., Celtis Laevigata Willd., and Celtis Occidentalis L.

IAWA Journal ◽  
1990 ◽  
Vol 11 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Roland R. Dute ◽  
Ann E. Rushing
Keyword(s):  
Secondary Wall ◽  
Small Diameter ◽  
Three Dimensions ◽  
Central Layer ◽  
Tracheary Elements ◽  
Pit Membrane ◽  
Celtis Occidentalis ◽  
Celtis Laevigata ◽  
Ulmus Alata ◽  
Grooved Wheel

Pit membranes between tracheary elements of Ulmus alata, Celtis laevigata, and Celtis occidentalis often contained tori. The degree of development of tori varied and was greatest in those membranes connecting elements of small diameter. Complete tori consisted of two wall thickenings adjoined by a central layer. In three dimensions the shape of the torus often approximated a grooved wheel. Initiation of thickening in the pit membrane occurred first on the side of the older cell and was well underway prior to the beginning of secondary wall synthesis. Torus formation resulted from the thickening of the primary walls of the pit membrane. Development of the torus was associated with membranous vesicles and cisternae but not with microtubule complexes as was reported in Osmanthus. The pit membranes in this study are capable of aspiration, and the tori may prevent rupture of the pit membrane during this process.

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