Torus of the Bordered-pit Membrane in Conifers

Nature ◽  
1963 ◽  
Vol 198 (4883) ◽  
pp. 906-907 ◽  
Author(s):  
IRVING B. SACHS
Keyword(s):  
Bordered Pit ◽  
Pit Membrane

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.

PIT MEMBRANES OF EPHEDRA RESEMBLE GYMNOSPERMS MORE THAN ANGIOSPERMS

IAWA Journal ◽  
2014 ◽  
Vol 35 (3) ◽  
pp. 217-235 ◽  
Author(s):  
Roland R. Dute ◽  
Lauren A. Bowen ◽  
Sarah Schier ◽  
Alexa G. Vevon ◽  
Troy L. Best ◽  
...  
Keyword(s):  
Bordered Pit ◽  
Pit Membrane ◽  
Torus Surface ◽  
Different Types ◽  
Secondary Plasmodesmata ◽  
Ultrathin Sections

Bordered pit pairs of Ephedra species were characterized using different types of microscopy. Pit membranes contained tori that did not stain for lignin. SEM and AFM views of the torus surface showed no plasmodesmatal openings, but branched, secondary plasmodesmata were occasionally noted using TEM in conjunction with ultrathin sections. The margo consisted of radial microfibrils as well as finer diameter tangential fibrils. The former formed fascicles of fibrils that merged into even thicker buttresses during the act of pit membrane aspiration. AFM showed a discontinuous layer of non-microfibrillar material on the surface of both torus and margo. It is hypothesized that this material is responsible for adhesion of the pit membrane to the surface of the pit border during the process of aspiration. Taken as a whole, intervascular pit membranes of Ephedra more closely resemble those of conifers than those of torus-bearing pit membranes of angiosperms.

Ultrastructural observations on pit membrane alterations and associated effects in elm xylem tissues infected by Ceratocystis ulmi

1978 ◽  
Vol 56 (20) ◽  
pp. 2567-2588 ◽  
Author(s):  
G. B. Ouellette
Keyword(s):  
Protective Layer ◽  
Cavity Formation ◽  
Bordered Pit ◽  
Fibrillar Material ◽  
Host Cytoplasm ◽  
Pit Membrane ◽  
Bordered Pits ◽  
Parenchyma Cells

Gradations in the degree of pit membrane alteration in tissues infected by Ceratocystis ulmi (Buism.) C. Moreau and collected at various intervals after inoculation are described. Membranes of bordered pit pairs are coated and apparently impregnated with bands or masses of osmiophilic material; this coating may be thick and stratified and the pit cavities completely occluded. Similar osmiophilic material also occurs in decreasing amounts over and within membranes of simple or half-bordered pits and within the adjacent protective layer. Various degrees of distention and cavity formation in these pit membranes are associated with the osmiophilic material. Products released into vessels from disintegrating pit membranes seem to be sparse. Host cytoplasm in contiguous parenchyma cells can have diverse reactions.Examination of specimens at various angles established the interrelationship between osmiophilic material and remnants of pit membranes. Variously oriented lamellar-like structures and a fibrillar material intermixed with a more amorphous one characterize the osmiophilic material. The significance of these observations is discussed.

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.

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.

scholarly journals Investigating Effects of Bordered Pit Membrane Morphology and Properties on Plant Xylem Hydraulic Functions—A Case Study from 3D Reconstruction and Microflow Modelling of Pit Membranes in Angiosperm Xylem

Plants ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 231 ◽  
Author(s):  
Shan Li ◽  
Jie Wang ◽  
Yafang Yin ◽  
Xin Li ◽  
Liping Deng ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Three Dimensional ◽  
Morphological Characteristics ◽  
Dimensional Structure ◽  
Membrane Structures ◽  
Bordered Pit ◽  
Functional Roles ◽  
Membrane Morphology ◽  
Pit Membrane ◽  
Embolism Resistance

Pit membranes in between neighboring conduits of xylem play a crucial role in plant water transport. In this review, the morphological characteristics, chemical composition and mechanical properties of bordered pit membranes were summarized and linked with their functional roles in xylem hydraulics. The trade-off between xylem hydraulic efficiency and safety was closely related with morphology and properties of pit membranes, and xylem embolism resistance was also determined by the pit membrane morphology and properties. Besides, to further investigate the effects of bordered pit membranes morphology and properties on plant xylem hydraulic functions, here we modelled three-dimensional structure of bordered pit membranes by applying a deposition technique. Based on reconstructed 3D pit membrane structures, a virtual fibril network was generated to model the microflow pattern across inter-vessel pit membranes. Moreover, the mechanical behavior of intervessel pit membranes was estimated from a single microfibril’s mechanical property. Pit membranes morphology varied among different angiosperm and gymnosperm species. Our modelling work suggested that larger pores of pit membranes do not necessarily contribute to major flow rate across pit membranes; instead, the obstructed degree of flow pathway across the pit membranes plays a more important role. Our work provides useful information for studying the mechanism of microfluid flow transport across pit membranes and also sheds light on investigating the response of pit membranes both at normal and stressed conditions, thus improving our understanding on functional roles of pit membranes in xylem hydraulic function. Further work could be done to study the morphological and mechanical response of bordered pit membranes under different dehydrated conditions, as well as the related microflow behavior, based on our constructed model.

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.

Variation in the Structure of Intertracueary Pit Membranes in Abies Sacualinensis, as Observed by Field-Emission Scanning Electron Microscopy

IAWA Journal ◽  
1999 ◽  
Vol 20 (4) ◽  
pp. 375-388 ◽  
Author(s):  
Yuzou Sano ◽  
Yuko Kawakami ◽  
Jun Ohtani
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Field Emission ◽  
Amorphous Materials ◽  
Annual Ring ◽  
Abies Sachalinensis ◽  
Bordered Pit ◽  
Pit Membrane ◽  
Frequency Occurrence ◽  
Scanning Electron

An examination was made of the fine structure of bordered pit membranes in the radial walls between tracheids in the outer sapwood of Abies sachalinensis to improve our understanding of the so-called extended torus, the minute holes in the torus and the imperforate zone near the periphery of the pit membranes, Field-emission scanning electron microscopy revealed that a so-called extended torus was present in many bordered pit membranes. We examined the frequency occurrence of and variations in the extended torus within a single annual ring. The frequency tended to increase from the earlywood to the latewood within a single annual ring. In the tori of many bordered pit membranes, we detected minute holes, and the number and location of such minute holes in a single torus varied among individual pit membranes. The appearance of each minute hole also varied. An imperforate zone was observed near the periphery of the pit membrane. In this imperforate zone, we found amorphous materials, and fine fibrils were visible that were an extension of the fibrillar meshwork of the margo.

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