Occurrence of Membrane-Bound Enzyme Catalyzing the Formation of Ethylene from 1-Aminocyclopropane Carboxylic Acid from Carnation Petals

Methionine (MET) is considered the first committed precursor of ethylene (C2H4), and the pathway has been established as MET → S-adenosylmethionine (SAM) → 1-aminocyclopropane-1-carboxylic acid (ACC) → C2H4. It has been suggested that another pathway to C2H4 may exist, and this pathway has been labeled System II. Our objective was to evaluate several compounds as possible precursors of System II C2H4 production. `White Sim' carnations were placed continuously in 20 mM solutions of MET, ACC, δ-aminolevulinic acid, glutamic acid, α-ketoglutarate, or homocysteine. Deionized water was the control. C2H4 production from the entire flower was measured, and ACC in the basal portion of the petals was quantified. Flowers treated with ACC exhibited the greatest C2H4 production and accumulation of ACC. Homocysteine caused greater production of C2H4 and accumulated more ACC than MET and the other possible precursors. These results suggest that homocysteine may be involved in System II C2H4 production in senescing carnation petals.

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Two Distinct Types of Microfilaments in the Cytoplasm of Human Adenohypophysial Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100073787 ◽

1973 ◽

Vol 31 ◽

pp. 668-669

Author(s):

E. Horvath ◽

K. Kovacs ◽

I. E. Stratmann ◽

C. Ezrin

Keyword(s):

Pituitary Tumors ◽

Average Diameter ◽

Anterior Lobe ◽

Uranyl Acetate ◽

Type I ◽

Breast Cancer Patients ◽

Human Pituitary ◽

Severe Diabetes ◽

Pituitary Glands ◽

Membrane Bound

Surgically removed human pituitary glands as well as pituitary tumors fixed in glutaraldehyde, postfixed in osmium tetroxide, embedded in epon resin, stained with uranyl acetate and lead citrate have been investigated by electron microscopy in order to correlate ultrastructure with functional activity. In the course of this study two distinct types of microfilaments have been identified in the cytoplasm of adenohypophysiocytes.Type I microfilaments (Fig. 1) were found in the cytoplasm of anterior lobe cells of five female subjects with disseminated mammary cancer and two patients with severe diabetes mellitus. The breast cancer patients were treated pre-operatively for various periods of time with different doses of oxysteroids. The microfilaments had an average diameter of JO A, formed parallel bundles, were scattered irregularly in the cytoplasm and were frequently located in the perikaryon. They were not membrane-bound and failed to show any periodicity.

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Intranuclear Crystals in Regenerating Canine Kidneys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072502 ◽

1973 ◽

Vol 31 ◽

pp. 412-413

Author(s):

D.G. Osborne ◽

L.J. McCormack ◽

M.O. Magnusson ◽

W.S. Kiser

Keyword(s):

Epithelial Cell ◽

Epithelial Cells ◽

Tubular Epithelial Cell ◽

Tubular Epithelial Cells ◽

Cell Nuclei ◽

Crystalline Structures ◽

Small Crystals ◽

Membrane Bound

During a project in which regenerative changes were studied in autotransplanted canine kidneys, intranuclear crystals were seen in a small number of tubular epithelial cells. These crystalline structures were seen in the control specimens and also in regenerating specimens; the main differences being in size and number of them. The control specimens showed a few tubular epithelial cell nuclei almost completely occupied by large crystals that were not membrane bound. Subsequent follow-up biopsies of the same kidneys contained similar intranuclear crystals but of a much smaller size. Some of these nuclei contained several small crystals. The small crystals occurred at one week following transplantation and were seen even four weeks following transplantation. As time passed, the small crystals appeared to fuse to form larger crystals.

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Membrane-bound vesicles associated with the microvilli in the midgut of the freshwater microcrustacean, Daphnia magna

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076135 ◽

1983 ◽

Vol 41 ◽

pp. 480-481

Author(s):

Patricia L. Jansma

Keyword(s):

Daphnia Magna ◽

Intestinal Epithelial Cells ◽

Uranyl Acetate ◽

Intestinal Epithelial ◽

Chlamydomonas Reinhardii ◽

Thin Sections ◽

Saturated Water ◽

Cacodylate Buffer ◽

Membrane Bound ◽

Ethanol Series

The presence of the membrane bound vesicles or blebs on the intestinal epithelial cells has been demonstrated in a variety of vertebrates such as chicks, piglets, hamsters, and humans. The only invertebrates shown to have these microvillar blebs are two species of f1ies. While investigating the digestive processes of the freshwater microcrustacean, Daphnia magna, the presence of these microvillar blebs was noticed.Daphnia magna fed in a suspension of axenically grown green alga, Chlamydomonas reinhardii for one hour were narcotized with CO2 saturated water. The intestinal tracts were excised in 2% glutaraldehyde in 0.2 M cacodyl ate buffer and then placed in fresh 2% glutaraldehyde for one hour. After rinsing in 0.1 M cacodylate buffer, the sample was postfixed in 2% OsO4, dehydrated with a graded ethanol series, infiltrated and embedded with Epon-Araldite. Thin sections were stained with uranyl acetate and Reynolds lead citrate before viewing with the Philips EM 200.

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