Conversaziones 1974

1975 ◽  
Vol 29 (2) ◽  
pp. 163-171
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Cell Walls ◽  
Structural Changes ◽  
Vascular Tissue ◽  
Root Systems ◽  
Plant Roots ◽  
Tracer Studies ◽  
Water Move ◽  
Intact Root

CONVERSAZIONES were held this year on 9 May and 27 June. At the first conversazione twenty-seven exhibits and two films were shown. The fine structure of plant roots in relation to transport of nutrient ions and water was demonstrated by Dr D. T. Clarkson of the A.R.C. Letcombe Laboratory, Wantage and Dr A. W. Robards of the Department of Biology, University of York. Two major pathways by which nutrients and water move radially across the cortex towards the central vascular tissue have been distinguished by the use of tracer studies of adsorption by different zones of intact root systems, microautoradiography and electron microscopy. Movement can be apoplastic through cell walls, or symplastic between cells joined by plasmodesmata. As the root ages, structural changes in the endodermis reduce movement in the former pathway but the symplast is not interrupted by the elaboration of endodermal walls because plasmodesmatal connexions remain intact. These observations help explain the contrasting extent to which different ions and water reach the shoot from young and mature parts of root systems.

Temperature Effects on Formation and Fine Structure of Brassica napus Leaf Waxes

1976 ◽  
Vol 24 (3) ◽  
pp. 309 ◽  
Author(s):  
DJ Armstrong ◽  
MI Whitecross
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Brassica Napus ◽  
Growth Temperature ◽  
Temperature Effects ◽  
Structural Changes ◽  
Leaf Waxes ◽  
Surface Waxes ◽  
Biochemical Level

Incorporation of 1-14C-palmitic acid, a precursor of leaf waxes, into leaf strips of Brassica napus was examined by thin section autoradiography and electron microscopy. Label was found to be associated with mitochrondria, Golgi vesicles and endoplasmic reticulum of epidermal cells, and also with the outer epidermal wall across which cuticular lipids are expected to migrate. Variations in growth temperatures produced structural changes in surface waxes as previously reported but no specific correlation could be found between changes in surface fine structure and variations in subcellular morphology. It is concluded that variations in wax fine structure, as influenced by growth temperature, resulted from effects at the biochemical level.

scholarly journals Evidence of Association of Salmonellae with Tomato Plants Grown Hydroponically in Inoculated Nutrient Solution

2002 ◽  
Vol 68 (7) ◽  
pp. 3639-3643 ◽  
Author(s):  
Xuan Guo ◽  
Marc W. van Iersel ◽  
Jinru Chen ◽  
Robert E. Brackett ◽  
Larry R. Beuchat
Keyword(s):  
Nutrient Solution ◽  
Root Systems ◽  
Plant Roots ◽  
Tomato Plants ◽  
Agronomic Practices ◽  
Stems And Leaves ◽  
Pathogen Populations ◽  
Hoagland Nutrient Solution ◽  
Hydroponically Grown ◽  
Intact Root

ABSTRACT The possibility of uptake of salmonellae by roots of hydroponically grown tomato plants was investigated. Within 1 day of exposure of plant roots to Hoagland nutrient solution containing 4.46 to 4.65 log10 CFU of salmonellae/ml, the sizes of the pathogen populations were 3.01 CFU/g of hypocotyls and cotyledons and 3.40 log10 CFU/g of stems for plants with intact root systems (control) and 2.55 log10 CFU/g of hypocotyls and cotyledons for plants from which portions of the roots had been removed. A population of ≥3.38 log10 CFU/g of hypocotyls-cotyledons, stems, and leaves of plants grown for 9 days was detected regardless of the root condition. Additional studies need to be done to unequivocally demonstrate that salmonellae can exist as endophytes in tomato plants grown under conditions that simulate commonly used agronomic practices.

scholarly journals The Fine Structure of the Wheat Scutellum Before Germination

1972 ◽  
Vol 25 (1) ◽  
pp. 9 ◽  
Author(s):  
JG Swift ◽  
TP O'brien
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Coat Protein ◽  
Storage Protein ◽  
Cell Walls ◽  
Lipid Droplets ◽  
Light And Electron Microscopy ◽  
Ground Substance ◽  
Nuclear Chromatin

The structure of the cells of the scutellar epithelium and parenchyma is described and illustrated by light and electron microscopy of air-dry grains and compared with that seen in grains soaked for 3 hr. In the air-dry state, nuclear chromatin is strongly aggregated, mitochondria and plastids appear to be intact, endoplasmic reticulum is present but not abundant, and dictyosomes cannot be readily identified. The ground substance contains an abundance of free ribosomes which appear to coat protein bodies, lipid droplets, and mitochondria. In material soaked only for 3 hr, endoplasmic reticulum and dictyosomes are apparent, the nuclear chromatin has dispersed, and some mobilization of storage protein appears to have begun in the scutellar epithelium. No differences in fine structure of other organelles or in the cell walls could be detected.

scholarly journals Histological changes associated with the graft union development in tomato

2020 ◽  
Author(s):  
Carlos Frey ◽  
José Luis Acebes ◽  
Antonio Encina ◽  
Rafael Álvarez
Keyword(s):  
Cell Walls ◽  
Adventitious Roots ◽  
Structural Changes ◽  
Vascular Tissue ◽  
Graft Union ◽  
Vascular Connection ◽  
Horticultural Crops ◽  
Undifferentiated Cells ◽  
Long Time ◽  
Vascular Connections

Abstract Background. Despite the importance of grafting in agriculture, particularly in horticultural crops such as tomato (Solanum lycopersicum L.), the structural changes that occur during the establishment of a graft are little understood. Using histochemical techniques, the present work examines the progression of the structure of the graft junction in tomato plants over time.Results. At 10 days after grafting, the cell walls of the scion and rootstock in the area of the graft junction were thicker than usual, and undifferentiated cells appeared associated with the pre-existing vascular tissue. New vascular tissue appeared as branches arising from the pre-existing vasculature, as vascular pockets dispersed within the callus, and as the result of the transdifferentiation of parenchyma cells. Areas showing vascular connections between the scion and rootstock were also seen. Adventitious roots appeared on the scion, arising from the pre-existing vasculature. At 20 days, a great deal of vascular tissue was visible, along with large areas showing vascular connection. At 210 days, vestiges of the changes undergone were still visible. However, no adventitious roots persisted. Conclusions. The area of the graft junction undergoes modifications essential for adequate physiological functioning of grafted plant. The cell walls of the adhesion line change during the process. Pre-existing vasculature plays an important role in the appearance of callus tissue, new vascular cells, and adventitious roots. A long time later the tissues maintain vestiges of graft union development.

Cell wall and plasmalemma modifications in diseased and injured plant tissues

1974 ◽  
Vol 52 (5) ◽  
pp. 1005-1009 ◽  
Author(s):  
Harry Wheeler
Keyword(s):  
Cell Wall ◽  
Electron Micrographs ◽  
Cell Walls ◽  
Structural Changes ◽  
Uranyl Acetate ◽  
Plant Roots ◽  
Plant Tissues ◽  
Diseased Plant ◽  
Localized Structures ◽  
Electrolyte Loss

Pathological modifications in structure at the cell wall – plasmalemma interface are common in diseased plant tissues. These modifications vary from small, localized structures which invaginate the protoplast to large, irregularly contoured elaborations which envelop haustoria. Some published electron micrographs suggest that the plasmalemma may be discontinuous in areas adjacent to modified cell walls. Structural changes in cell walls, similar to those in diseased plants, are common in plant roots exposed to uranyl acetate. In such roots, the plasmalemma appeared distinctly discontinuous in cells with highly modified walls, whereas it was continuous in adjacent cells with little or no wall modification. In both types of cells, internal membranes and organelles appeared normal. This suggests that the breaks seen in the plasmalemma were not fixation artifacts. In untreated roots, apparent discontinuities in the plasmalemma were observed only in secretory outer root cap cells which contained masses of mucilaginous material between the wall and protoplast. Since uranyl treatment does not increase the rate of electrolyte loss from tissue, these observations suggest that modified cell walls may assume some of the permeability functions usually attributed to the plasmalemma.

scholarly journals Histological Changes Associated with the Graft Union Development in Tomato

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1479
Author(s):  
Carlos Frey ◽  
José Luis Acebes ◽  
Antonio Encina ◽  
Rafael Álvarez
Keyword(s):  
Cell Walls ◽  
Time Course ◽  
Structural Changes ◽  
Vascular Tissue ◽  
Wall Material ◽  
Histological Techniques ◽  
Vascular Connection ◽  
Horticultural Crops ◽  
Solanum Lycopersicum L ◽  
Undifferentiated Cells

Despite the importance of grafting in horticultural crops such as tomato (Solanum lycopersicum L.), the structural changes that occur during the graft establishment are little understood. Using histological techniques, the present work examines the time course of changes on the anatomical structure of the graft junction in functional tomato homografts and compares it to that of heterografts and non-functional grafts. No apparent differences were detected between homo- and heterografts, showing similar tissue development. At 10 days after grafting, the cell walls of the scion and rootstock in the area of the graft junction were thicker than usual. Undifferentiated cells and new vascular tissue emerged from the pre-existing vasculature. Adventitious roots appeared mainly on the scion, arising from the pre-existing vasculature. At 20 days, more pronounced vascular tissue was visible, along with large areas showing vascular connection. At 210 days, vestiges of the changes undergone in graft development were still visible. Generally, non-functional grafts presented layers of necrotic remains and deposition of cell wall material in the cut edges, impeding the suitable scion-rootstock connection. Our results show that accurate changes in pre-existing vasculature and the cell walls of the adhesion line are crucial to the development of functional grafts.

Changes in the Fine Structure of the Desiccation-Tolerant Sedge Coleochloa setifera (Ridley) Gilly Under Water Stress

1979 ◽  
Vol 27 (5) ◽  
pp. 531 ◽  
Author(s):  
M Bartley ◽  
ND Hallam
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Fine Structure ◽  
Water Stress ◽  
Rough Endoplasmic Reticulum ◽  
Structural Changes ◽  
Chloroplast Membranes ◽  
Fixation Techniques ◽  
Moderate Stress

Electron microscopy demonstrated gross changes to organelles during dehydration, particularly in chloroplasts which lose thylakoids. Plastoglobuli increase in size as internal chloroplast membranes develop into vesicles. An increase in polysomes and in rough endoplasmic reticulum after moderate stress suggested the possibility of increased protein synthesis at this time. The loss of chlorophyll while grana were still evident suggested an ordered destructuring of the chlorophyll. In dry tissue the nucleus remained intact, mitochondria contained few indistinct cristae and chloroplasts appeared as organelles containing vesicles and plastoglobuli. Both aqueous and anhydrous fixation techniques were used to follow h e structural changes on drying.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Fibroblasts During Hypertrophic Scar Formation and Resolution

1973 ◽  
Vol 31 ◽  
pp. 428-429
Author(s):  
C. W. Kischer
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Proliferation ◽  
Fine Structure ◽  
Metabolic Activity ◽  
Hypertrophic Scar ◽  
Normal Skin ◽  
Ground Substance ◽  
Hypertrophic Scars ◽  
Scanning Electron

The morphology of the fibroblasts changes markedly as the healing period from burn wounds progresses, through development of the hypertrophic scar, to resolution of the scar by a self-limiting process of maturation or therapeutic resolution. In addition, hypertrophic scars contain an increased cell proliferation largely made up of fibroblasts. This tremendous population of fibroblasts seems congruous with the abundance of collagen and ground substance. The fine structure of these cells should reflect some aspects of the metabolic activity necessary for production of the scar, and might presage the stage of maturation.A comparison of the fine structure of the fibroblasts from normal skin, different scar types, and granulation tissue has been made by transmission (TEM) and scanning electron microscopy (SEM).

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.

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