scholarly journals A STUDY OF SIEVE ELEMENT STARCH USING SEQUENTIAL ENZYMATIC DIGESTION AND ELECTRON MICROSCOPY

1970 ◽  
Vol 45 (2) ◽  
pp. 383-398 ◽  
Author(s):  
Barry A. Palevitz ◽  
Eldon H. Newcomb
Keyword(s):  
Electron Microscopy ◽  
Sieve Tube ◽  
Cell Types ◽  
Enzymatic Digestion ◽  
Sieve Element ◽  
Branch Points ◽  
Thin Sections ◽  
Sieve Elements ◽  
Hypocotyl Tissue ◽  
Bare Copper

The fine structure of plastids and their starch deposits in differentiating sieve elements was studied in bean (Phaseolus vulgaris L.). Ultrastructural cytochemistry employing two carbohydrases specific for different linkages was then used to compare the chemical nature of "sieve tube starch" (the starch deposited in sieve elements) with that of the ordinary starch of other cell types. Hypocotyl tissue from seedlings was fixed in glutaraldehyde, postfixed in osmium tetroxide, and embedded in Epon-Araldite. Treatment of thin sections on uncoated copper grids with α-amylase or diastase at pH 6.8 to cleave α-(1 → 4) bonds resulted in digestion of ordinary starch grains but not sieve element grains, as determined by electron microscopy. Since α-(1 → 6) branch points in amylopectin-type starches make the adjacent α-(1 → 4) linkages somewhat resistant to hydrolysis by α-amylase, other sections mounted on bare copper or gold grids were treated with pullulanase (a bacterial α-[1 → 6] glucosidase) prior to digestion with diastase. Pullulanase did not digest sieve element starch, but rendered the starch digestible subsequently by α-amylase. Diastase followed by pullulanase did not result in digestion. The results provide evidence that sieve element starch is composed of highly branched molecules with numerous α-(1 → 6) linkages.

scholarly journals THE SARCOPLASMIC RETICULUM IN MUSCLE CELLS OF AMBLYSTOMA LARVAE

1956 ◽  
Vol 2 (4) ◽  
pp. 163-170 ◽  
Author(s):  
Keith R. Porter
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Constant Width ◽  
Muscle Cells ◽  
Cell Types ◽  
Thin Sections ◽  
System A ◽  
Structural Relationships ◽  
Complex Membrane

Electron microscopy of thin sections of muscle fibers in myotomes of Amblystoma larvae has revealed the presence of a complex, membrane-limited system of canaliculi and vesicles which form a lace-like reticulum around and among the myofibrils. This seems to correspond to the sarcoplasmic reticulum of the earlier light microscopists and the endoplasmic reticulum of other cell types. The elements constituting the reticulum are disposed in a pattern which bears a constant relation to the bands of the adjacent myofibrils and is therefore repeated in each sarcomere. At the H band the system is transversely continuous but not so at other levels. Longitudinally continuity is interrupted at the Z bands where large vesicles belonging to adjacent sarcomere segments of the system face off on opposite sides of the band. The opposing faces of these vesicles are flat and separated by a space of more or less constant width, in which are located small, finger-shaped vesicles. In view of these and other close structural relationships with the myofibrils it seems appropriate to assign to the system a role in the conduction of the excitatory impulse.

Vascular system of the floret of Alopecurus carolinianus (Gramineae)

1987 ◽  
Vol 65 (12) ◽  
pp. 2592-2600 ◽  
Author(s):  
Thompson Demetrio Pizzolato
Keyword(s):  
Vascular System ◽  
Sieve Tube ◽  
Sieve Element ◽  
Sieve Elements

The interconnecting vascular system of the floret of Alopecurus carolinianus Walter begins as a single, collateral bundle, which enters the rachilla and becomes reorganized into a diarch pattern while ascending between the glumes. During a pronounced posterior enlargement, the rachilla bundle becomes connected with the median and four lateral bundles of the lemma. Above the trace to the lemma median, elements of a xylem discontinuity surrounded by those of a sieve-element plexus form in the rachilla bundle. Higher, a trace consisting of elements of the xylem discontinuity and the plexus enters the anterior and the posterior stamen. Two bundles, the lowest portion of the pistil vasculature, rise eccentrically from the xylem discontinuity and sieve-element plexus at the level of the stamen traces. The bundles condense into one which rotates counterclockwise and connects with the anterior sieve tube of the pistil. The xylem discontinuity of the bundle now in the pistil begins to diminish, and the sieve elements fan out to the sides and posterior of the xylem discontinuity. From the sieve elements one or two posterolaterals emerge toward the styles. The bundle of diffuse sieve elements in a semicircle behind the diminishing xylem discontinuity is now the placental bundle of the pistil. After its xylem discontinuity and then its sieve elements fade out, the placental bundle merges with the ovule at the chalaza.

Simplified procedures for releasing and concentrating microorganisms from soil for transmission electron microscopy viewing as thin-sectioned and frozen-etched preparations

1975 ◽  
Vol 21 (3) ◽  
pp. 252-262 ◽  
Author(s):  
D. L. Balkwill ◽  
D. P. Labeda ◽  
L. E. Casida Jr.
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Types ◽  
Soil Slurry ◽  
Thin Sections ◽  
Choice Of Procedure ◽  
Transmission Electron ◽  
Cell Release ◽  
Simplified Procedures ◽  
Simplified Procedure

A simplified procedure is presented for releasing and concentrating indigenous microbial cells from soil for viewing by transmission electron microscopy as thin sections or replicas of frozen-etched preparations. This procedure is compared with two others reported earlier, and their relative merits are discussed as concerns the choice of procedure for the cellular information desired from the soil. Freeze-etching showed that the cell types and size distributions for cells which have been released and concentrated from soil are in general agreement with those for cells in a crude soil slurry in which no attempt to release and concentrate cells was made. Microcolonies were present both in the crude slurry and in the discard soil debris centrifugation pellets from the cell release and concentration procedures. In contrast to the historic assumptions, these microcolonies, as well as some individual cells embedded in soil debris could not be broken up and (or) dislodged so that they would be washed from the soil. The relative numbers of these cells remaining with the soil debris, however, could not be quantitated in the present study.

Anatomy and ultrastructure of the endophytic system of Pilostyles thurberi (Rafflesiaceae)

1985 ◽  
Vol 63 (7) ◽  
pp. 1231-1240 ◽  
Author(s):  
Job Kuijt ◽  
D. Bray ◽  
A. R. Olson
Keyword(s):  
Cell Types ◽  
Sieve Element ◽  
Cell Type ◽  
Discontinuous System ◽  
Sieve Elements ◽  
The Third ◽  
Sieve Plates ◽  
Host Parasite ◽  
Anatomy And Ultrastructure ◽  
Sieve Pores

The endophytic system of Pilostyles thurberi Gray consists of initially uniseriate filaments which develop into an anastomosing complex of larger cortical strands and radial sinkers. In the cortical strands three cell types are recognized, two of which differ largely in the density of the cytoplasm, the shape of the nucleus, and the degree to which the cytoplasm becomes plasmolyzed during fixation. The nuclei of both cell types contain two nucleoli which are physically connected by a nucleolar bridge. The third cell type demonstrates sieve plates, including a calloselike substance in the sieve pores and is consequently considered to be a sieve element. The sieve elements appear to form a discontinuous system and are regarded as a vestigial cell type. Plasmodesmal connections across the host–parasite interface have not been observed.

scholarly journals The Culture and Correlative Electron Microscopy of Pollen Mother Cells in Meiosis: Development of Techniques and Some Observations on Selected Topics

2021 ◽  
Author(s):  
◽  
Kenneth George Ryan
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Cell Formation ◽  
Cell Types ◽  
Future Research ◽  
Thin Sections ◽  
Pollen Mother Cells ◽  
Spindle Elongation ◽  
Mother Cells ◽  
Metaphase I

<p>Reliable techniques for the living cell culture and correlative light and electron microscopy (EM) of meiotic pollen mother cells (PMCs) of Iris spuria, Allium triquetrum and Tradescantia flumenensis are described in detail. Living PMCs were successfully cultured in a slide chamber on agar/sucrose medium. Cells were covered with an inert oil to prevent their dehydration, and some cells were cultured from metaphase I to tetrad cell formation over a 20 hour period. Other PMCs were fixed with glutaraldehyde and flat embedded using a modification of the agar sandwich technique of Mole-Bajer and Bajer (1968). This technique was developed to permit the preselection of PMCs at known meiotic stages, for subsequent EM examination. Serial thin sections were cut at known planes of section; and 3-D reconstructions of MT distribution, and MT counts from transverse sections were completed. It was also possible to examine sections of an Iris anaphase I PMC which had been previously studied in life. Anaphase I and II chromosome velocities were analysed in the three species. Mean velocities were approximately 0.5 mu m/min with some variation from cell to cell and between sister half-spindles. In Allium anaphase I there was also variation in chromosome velocity within the half-spindle; and this variation was found not to be related to chromosome position on the metaphase I plate. Spindle elongation was zero in Allium anaphase I and in Iris anaphase II, but was detectable in Allium anaphase II (40%) and in "Iris anaphase I (l5%). The extent of spindle elongation in Tradescantia could not be determined. The kinetochore region in the first meiotic division consisted of two closely appressed, but structurally (and functionally) distinct, sister kinetochores. At meiosis II, the two sister kinetochores were separate from each other and faced opposite poles. The kinetochore arrangement probably changes from side-by-side (meiosis I) to back-to-back (meiosis II) during chromosome recondensation at prophase II in these cells. Bundles of non-kinetochore microtubules (nkMTs) span the interzone between sister chromosome units at metaphase I and II and anaphase II. Bundles of kinetochore MTs (kMTs) do not increase in divergence at any stage of meiosis studied; there was little interaction between nkMTs and kMTs, and MT-MT cross bridges were rare. These observations are not consistent with models of chromosome movement based on MT sliding or zipping. No relationship was found between nkMT distribution and spindle elongation, and the several different nkMT distributions which have been reported for other cell types may be variations on a structural theme. Spindle endoplasmic reticulum (ER) in meiosis II was found to be derived largely from invaginations and evaginations of the nuclear envelope. Growth of existing spindle ER was proposed to account for the doubling in the amount of ER observed between interphase and prometaphase II. Randomly oriented elements of ER, in early prometaphase II spindles may become passively aligned along the interpolar axis and then actively transported polewards at later stages of prometaphase II and metaphase II. Suggestions for future research are offered.</p>

What happens to the normal cytoplasmic features of fish erythrophores when, under identical conditions of culture, the erythrophores are fused with normal rat kidney cells?

1992 ◽  
Vol 50 (1) ◽  
pp. 546-547
Author(s):  
Keith R. Porter ◽  
Karen L. Anderson
Keyword(s):  
Electron Microscopy ◽  
Rat Kidney ◽  
Experimental Studies ◽  
Cell Types ◽  
Small Population ◽  
High Voltage Electron Microscopy ◽  
Thin Sections ◽  
Voltage Electron ◽  
Carbon Coated ◽  
Normal Rat

We have shown that a small population of normal cells can be cultured from the scales of the squirrel fish, Holocentrus rufus. They can be grown directly on Formvar-carbon-coated gold grids and, while still on the grids they can be fixed, stained and dehydrated for high voltage electron microscopy. One of the cell types (epidermal) spreads out on the carbon-coated surface and is thin enough in most parts for conventional (100kV) electron microscopy. The aspect of wholeness represented in these qells should not be overlooked for it provides information that might be missed in a series of thin sections where the sample is obviously smaller. Furthermore, if experimental studies are contemplated, they can be made while the cells are still alive and available for light microscopy.

scholarly journals The Localization of Acid Phosphatase in the Sieve Element of Pisum

1969 ◽  
Vol 22 (4) ◽  
pp. 1051 ◽  
Author(s):  
S-Y Zee
Keyword(s):  
Electron Microscopy ◽  
Acid Phosphatase ◽  
Light Microscopy ◽  
Phosphatase Activity ◽  
Acid Phosphatase Activity ◽  
Lead Nitrate ◽  
Sieve Tube ◽  
Sieve Element ◽  
Recent Advances ◽  
Acid Phosphatase Reaction

Acid phosphatase activity has been detected within the sieve-tube members of plants by many workers using the Gomori technique and light microscopy (Lester and Evert 1965; Flinn and Smith 1967). Unfortunately the limited resolution makes it difficult to determine the specific sites of activity of the reaction product of the enzyme; recent advances in histochemical techniques for electron microscopy have made it possible to investigate more specifically the sites of localization of the acid phosphatase reaction product by using the Gomori lead nitrate technique (Goldfischer, Essner, and Novikoff 1964; Catesson and Czanenski 1967; Bowen 1968; Figier 1968; Wardrop 1968).

Filamentous Component (Slime) in Coniferous Sieve Elements

1972 ◽  
Vol 30 ◽  
pp. 214-215
Author(s):  
Lidija Murmanis ◽  
Irving B. Sachs
Keyword(s):  
Electron Microscopy ◽  
Structural Component ◽  
Pinus Strobus ◽  
Sieve Element ◽  
Sieve Elements ◽  
Double Structure ◽  
Proteinaceous Material ◽  
Fibrillar Component ◽  
Filamentous Material

In the literature, it is agreed that in angiosperm sieve elements, a fibrillar, or filamentous, proteinaceous material is present, but the presence of this material in gymnosperms is not agreed upon. Some authors have reported filamentous material (slime) in Pinaceae by light and by electron microscopy. By contrast, some authors have found no structural component in conifers comparable to the sieve element fibrillar component in angiosperms.This report is an affirmation that filamentous material is present in Pinus strobus L. sieve elements. The finest filamentous unit, when measurable, appears to range from 40-60 A in diameter (Fig. 1, arrows). These filaments have a tendency to accumulate to various degrees. Generally, they aggregate in two; then the double structure measures 120-160 A in diameter (Fig. 1, double arrows), although the distance between two filaments is not constant.

The Fine Structure of Calcoblasts in the Regenerating Sea Urchin Spine

1972 ◽  
Vol 30 ◽  
pp. 162-163
Author(s):  
Barry M. Heatfield ◽  
Dorothy F. Travis
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Calcium Carbonate ◽  
Sea Urchin ◽  
Basal Lamina ◽  
Strongylocentrotus Purpuratus ◽  
Extracellular Fluid ◽  
Cell Types ◽  
Thin Sections ◽  
Sea Urchin Spine

The endoskeleton of echinoderms is composed of fenestrated calcium carbonate (calcite) permeated by interconnecting channels filled with a variety of cell-types and extracellular fluid containing collagen fibrils. To identify and characterize skeletogenic cells and explore the mechanism of skeleton growth in echinoderms, tissues of regenerating spines of the sea urchin Strongylocentrotus purpuratus were examined by electron microscopy.The tip of the young regenerate is composed of two layers of tissue: an outer epidermis and an inner calcified dermis separated by a thin basal lamina (Fig. 1). In the apical dermis the skeleton consists of longitudinally oriented microspines interconnected by horizontal calcite bridges. During preparation of thin sections, skeletal mineral was lost, leaving a hole, indicated by (ms) in Figs. 1, 2, and 4.

scholarly journals The Culture and Correlative Electron Microscopy of Pollen Mother Cells in Meiosis: Development of Techniques and Some Observations on Selected Topics

2021 ◽  
Author(s):  
◽  
Kenneth George Ryan
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Cell Formation ◽  
Cell Types ◽  
Future Research ◽  
Thin Sections ◽  
Pollen Mother Cells ◽  
Spindle Elongation ◽  
Mother Cells ◽  
Metaphase I

<p>Reliable techniques for the living cell culture and correlative light and electron microscopy (EM) of meiotic pollen mother cells (PMCs) of Iris spuria, Allium triquetrum and Tradescantia flumenensis are described in detail. Living PMCs were successfully cultured in a slide chamber on agar/sucrose medium. Cells were covered with an inert oil to prevent their dehydration, and some cells were cultured from metaphase I to tetrad cell formation over a 20 hour period. Other PMCs were fixed with glutaraldehyde and flat embedded using a modification of the agar sandwich technique of Mole-Bajer and Bajer (1968). This technique was developed to permit the preselection of PMCs at known meiotic stages, for subsequent EM examination. Serial thin sections were cut at known planes of section; and 3-D reconstructions of MT distribution, and MT counts from transverse sections were completed. It was also possible to examine sections of an Iris anaphase I PMC which had been previously studied in life. Anaphase I and II chromosome velocities were analysed in the three species. Mean velocities were approximately 0.5 mu m/min with some variation from cell to cell and between sister half-spindles. In Allium anaphase I there was also variation in chromosome velocity within the half-spindle; and this variation was found not to be related to chromosome position on the metaphase I plate. Spindle elongation was zero in Allium anaphase I and in Iris anaphase II, but was detectable in Allium anaphase II (40%) and in "Iris anaphase I (l5%). The extent of spindle elongation in Tradescantia could not be determined. The kinetochore region in the first meiotic division consisted of two closely appressed, but structurally (and functionally) distinct, sister kinetochores. At meiosis II, the two sister kinetochores were separate from each other and faced opposite poles. The kinetochore arrangement probably changes from side-by-side (meiosis I) to back-to-back (meiosis II) during chromosome recondensation at prophase II in these cells. Bundles of non-kinetochore microtubules (nkMTs) span the interzone between sister chromosome units at metaphase I and II and anaphase II. Bundles of kinetochore MTs (kMTs) do not increase in divergence at any stage of meiosis studied; there was little interaction between nkMTs and kMTs, and MT-MT cross bridges were rare. These observations are not consistent with models of chromosome movement based on MT sliding or zipping. No relationship was found between nkMT distribution and spindle elongation, and the several different nkMT distributions which have been reported for other cell types may be variations on a structural theme. Spindle endoplasmic reticulum (ER) in meiosis II was found to be derived largely from invaginations and evaginations of the nuclear envelope. Growth of existing spindle ER was proposed to account for the doubling in the amount of ER observed between interphase and prometaphase II. Randomly oriented elements of ER, in early prometaphase II spindles may become passively aligned along the interpolar axis and then actively transported polewards at later stages of prometaphase II and metaphase II. Suggestions for future research are offered.</p>

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