scholarly journals Studies on the Ontogeny of the Pigment Strand in the Caryopsis of Wheat

1970 ◽  
Vol 23 (5) ◽  
pp. 1153 ◽  
Author(s):  
S-Y Zee ◽  
TP O'brien
Keyword(s):  
Cell Walls ◽  
Meristematic Cells ◽  
Thin Walls ◽  
Pigment Strand ◽  
Days After Anthesis

The grain of wheat has a groove that extends inward nearly to the centre of the grain. At the base of this crease and extending through its length there is a strand of coloured tissue, the pigment strand. At about 3 days after anthesis the cells of this strand of tissue are similar to meristematic cells, possessing thin walls and the usual complement of organelles. At about 9 days after anthesis the cell walls thicken and lignify.

Histological aspects of the cryopreservation of potato

2008 ◽  
Vol 56 (3) ◽  
pp. 341-348
Author(s):  
P. Pepó ◽  
A. Kovács
Keyword(s):  
Cell Wall ◽  
Low Temperatures ◽  
Cell Walls ◽  
Cellular Level ◽  
Adaptive Mechanism ◽  
Epidermal Layer ◽  
Freezing And Thawing ◽  
Meristematic Cells ◽  
Suitable Solution ◽  
Vacuolated Cells

Cryopreservation appears to be a suitable solution for the maintenance of potato germplasms. The protocol described in this paper can be applied for the vitrification and preservation of meristems. During histo-cytological studies it is possible to observe modifications at the cellular level and to understand the adaptive mechanism to low temperatures. Control potato meristem tissue contained a number of meristematic cells with a gradient of differentiation. After freezing there were a large number of vacuolated cells, some of which exhibited broken cell walls and plasmolysis. The thickening of the cell wall, giving them a sinuous appearance, was observed after freezing and thawing the meristems, with ruptures of the cuticle and epidermal layer.

The preprophase band: possible involvement in the formation of the cell wall

1976 ◽  
Vol 22 (2) ◽  
pp. 403-411 ◽  
Author(s):  
M.J. Packard ◽  
S.M. Stack
Keyword(s):  
Cell Wall ◽  
Allium Cepa ◽  
Cell Walls ◽  
Preprophase Band ◽  
Adjacent Cell ◽  
Root Tips ◽  
Meristematic Cells ◽  
Narrow Region ◽  
The Matrix

Numerous vesicles were observed among the microtubules of the “preprophase” band in prophase cells from root tips of Allium cepa. The content of these vesicles looks similar to the matrix of adjacent cell walls, and these vesicles often appear to be involved in exocytosis. In addition, the cell walls perpendicular to the plane of (beneath) the preprophase band are often differentially thickened compared to the walls lying parallel to the plane of the band. Our interpretation of these observations is that the preprophase band may direct or channel vesicles containing precursors of the cell wall to localized regions of wall synthesis. The incorporation of constituents of the cell wall into a narrow region defined by the position of the preprophase band may be a mechanism that ensures unidirecitonal growth of meristematic cells.

Cellular events during wound periderm formation in Dioscorea bulbifera bulbils

1989 ◽  
Vol 67 (10) ◽  
pp. 3090-3102 ◽  
Author(s):  
Ina Knobloch ◽  
Günter Kahl ◽  
Pierre Landré ◽  
Arlette Nougarède
Keyword(s):  
Cell Walls ◽  
Superficial Layer ◽  
Cell Nuclei ◽  
Meristematic Cells ◽  
Cellular Events ◽  
Fluorescence And Electron Microscopy ◽  
Deep Wound ◽  
Dioscorea Bulbifera ◽  
Cytoplasmic Ribosomes ◽  
Periderm Formation

The cytological events induced by a deep wound applied to Dioscorea bulbifera bulbils were studied using specific cytochemical methods and fluorescence and electron microscopy. Following wounding, a superficial layer with lignified (3rd h) and weakly suberized (6th h) cell walls formed in the original starchy parenchyma in contact with the wounded cells. Before the first mitoses (72nd h), an extensive dedifferentiation occurred in the underlying layers and involved reactivation of cell nuclei, nucleoli, and plastids. A concomitant aggregation of cytoplasmic ribosomes into polysomes occurred. Starch hydrolysis in the amyloplasts was evident before the first periclinal divisions. Periclinal divisions occurred in the reactivated cells from the second to the fourth layers beneath the wound. These newly meristematic cells could be divided into two to four new cells, leading to a periderm without a true phellogen. These covering layers degenerated during the period of lignification and weak suberization of cell walls. The thickness of the wound periderm depended on the age of the wounded bulbil.

Water Relations of the Developing Wheat Grain

1980 ◽  
Vol 7 (5) ◽  
pp. 519 ◽  
Author(s):  
EWR Barlow ◽  
JW Lee ◽  
R Munns ◽  
MG Smart
Keyword(s):  
Water Deficit ◽  
Flag Leaf ◽  
Maximum Level ◽  
Grain Filling ◽  
Controlled Environment ◽  
Wheat Grain ◽  
Grain Filling Period ◽  
Pigment Strand ◽  
Days After Anthesis ◽  
Wheat Spike

The physiological and anatomical mechanisms underlying the reduced sensitivity of wheat grain growth to water deficits in the post anthesis period have been investigated. The water potential (Ψ) and water content of the developing wheat grain and of other tissues within the wheat spike and flag leaf were compared under controlled environment and field conditions. In the 14 days following anthesis when the amount of water in each grain was increasing, the Ψ gradient between the grain and the rest of the plant was most pronounced. This Ψ gradient disappeared when the water per grain reached its maximum level (15 days after anthesis). The apparent turgor potential (P) of the wheat grain was very small (less than 0.2 MPa) throughout the grain filling period. When water was withheld 10 and 20 days after anthesis, the grain Ψ changed little despite a large decrease in the Ψ of the glumes, rachis and flag leaf. Grain Ψ showed the same independence during a diurnal cycle of water deficit. The independence of grain Ψ under water deficit conditions may be related initially to the xylem discontinuity in the floral axis and, in longer-term water stress situations, to the deposition of lipid in the pigment strand of the grain itself.

scholarly journals Anatomical traits of sweet pepper (Capsicum annuum L.) fruit

2012 ◽  
Vol 64 (4) ◽  
pp. 181-188 ◽  
Author(s):  
Elżbieta Weryszko-Chmielewska ◽  
Zenia Michałojć
Keyword(s):  
Capsicum Annuum ◽  
Cell Walls ◽  
Sweet Pepper ◽  
Secondary Phloem ◽  
Intercellular Spaces ◽  
Thin Walls ◽  
Small Clusters ◽  
Pepper Cultivar ◽  
Root Feeding ◽  
Scanning Electron

The micromorphology of the epidermis as well as the anatomy of the pericarp and fruit pedicle in <i>Capsicum annuum</i> L., cv. 'Red Knight F<sub>1</sub>', were studied using light and scanning electron microscopy. The pericarp was found to consist of an epidermis with strongly thickened outer walls, several layers of tangential and angular collenchyma as well as multi-layered parenchyma composed of cells of varying size in which very large lobed nuclei were observed. Chromoplasts were found in the cells of the above-mentioned tissues. The inner epidermis of the pericarp was characterized by thick cell walls and numerous straight pits. Among the tissues of the fruit pedicle, we observed epidermis with numerous stomata, collenchyma, chlorenchyma with very large intercellular spaces, small clusters of sclerenchyma, secondary phloem and xylem as well live and dead cells of the pith which were characterized by the presence of thin walls with numerous pits. The structural traits of the pericarp of the red pepper cultivar under study show adaptations to significantly reduced transpiration, which is an important feature during storage. At the same time, the strongly thickened and cutinized walls of the fruit contribute to a reduction in its digestibility and impede nutrient penetration in non-root feeding.

Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

1973 ◽  
Vol 31 ◽  
pp. 468-469
Author(s):  
N.C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Nitric Acid ◽  
Oxalic Acid ◽  
Light Microscopy ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Plant Viruses ◽  
Plant Leaves ◽  
Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

An ultrastructural study of vegetative incompatibility in plants

1978 ◽  
Vol 36 (2) ◽  
pp. 436-437
Author(s):  
Randy Moore
Keyword(s):  
Ultrastructural Study ◽  
Cell Walls ◽  
Growth And Development ◽  
Solanum Pennellii ◽  
Initial Product ◽  
Basic Aspect ◽  
Tissue Interactions ◽  
Graft Interface ◽  
Antigen Antibody ◽  
Standard Fixation

Cell and tissue interactions are a basic aspect of eukaryotic growth and development. While cell-to-cell interactions involving recognition and incompatibility have been studied extensively in animals, there is no known antigen-antibody reaction in plants and the recognition mechanisms operating in plant grafts have been virtually neglected.An ultrastructural study of the Sedum telephoides/Solanum pennellii graft was undertaken to define possible mechanisms of plant graft incompatibility. Grafts were surgically dissected from greenhouse grown plants at various times over 1-4 weeks and prepared for EM employing variations in the standard fixation and embedding procedure. Stock and scion adhere within 6 days after grafting. Following progressive cell senescence in both Sedum and Solanum, the graft interface appears as a band of 8-11 crushed cells after 2 weeks (Fig. 1, I). Trapped between the buckled cell walls are densely staining cytoplasmic remnants and residual starch grains, an initial product of wound reactions in plants.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

Cryosectioning plant roots prepared by high-pressure freezing

1987 ◽  
Vol 45 ◽  
pp. 662-663
Author(s):  
R.E. Crang ◽  
M. Mueller ◽  
K. Zierold
Keyword(s):  
High Pressure ◽  
Cell Walls ◽  
Plant Tissues ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Vitreous State ◽  
Radial Depth ◽  
Irregular Topography ◽  
Considerable Depth ◽  
Conventional Freezing

Obtaining frozen-hydrated sections of plant tissues for electron microscopy and microanalysis has been considered difficult, if not impossible, due primarily to the considerable depth of effective freezing in the tissues which would be required. The greatest depth of vitreous freezing is generally considered to be only 15-20 μm in animal specimens. Plant cells are often much larger in diameter and, if several cells are required to be intact, ice crystal damage can be expected to be so severe as to prevent successful cryoultramicrotomy. The very nature of cell walls, intercellular air spaces, irregular topography, and large vacuoles often make it impractical to use immersion, metal-mirror, or jet freezing techniques for botanical material.However, it has been proposed that high-pressure freezing (HPF) may offer an alternative to the more conventional freezing techniques, inasmuch as non-cryoprotected specimens may be frozen in a vitreous, or near-vitreous state, to a radial depth of at least 0.5 mm.

Characterization of machined polystyrene foam

1989 ◽  
Vol 47 ◽  
pp. 372-373
Author(s):  
C. W. Price ◽  
E. F. Lindsey ◽  
R. M. Franks ◽  
M. A. Lane
Keyword(s):  
Surface Finish ◽  
Cell Walls ◽  
Surface Structures ◽  
Efficient Technique ◽  
Low Density ◽  
Polystyrene Foam ◽  
Planar Surfaces ◽  
Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

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