scholarly journals The Effect of Adenosine 5′-Triphosphate on the Shibata Shift and on Associated Structural Changes in the Conformation of the Prolamellar Body in Isolated Maize Etioplasts

1975 ◽  
Vol 55 (2) ◽  
pp. 393-400 ◽  
Author(s):  
Peter Horton ◽  
Rachel M. Leech
Keyword(s):  
Structural Changes ◽  
Prolamellar Body ◽  
Shibata Shift

scholarly journals FINE STRUCTURAL CHANGES IN PROPLASTIDS DURING PHOTODESTRUCTION OF PIGMENTS

1964 ◽  
Vol 22 (2) ◽  
pp. 443-451 ◽  
Author(s):  
Shimon Klein ◽  
Lawrence Bogorad
Keyword(s):  
Fine Structure ◽  
Levulinic Acid ◽  
Structural Changes ◽  
Prolamellar Body ◽  
Membrane Structures ◽  
Lamellar Structures ◽  
Amino Levulinic Acid ◽  
Stroma Lamellae ◽  
Green Pigments ◽  
Bean Leaves

Etiolated bean leaves supplied δ-amino-levulinic acid in the dark synthesize large amounts of protochlorophyllide which is not converted to chlorophyllide upon illumination of the leaves. The fine structure of the proplastids is not affected by the treatment. When leaves containing "inactive" protochlorophyllide are exposed to light of 700 ft-c for 3 hours, they lose practically all their green pigments. During this period large stacks of closed membrane structures are built up in the region of the prolamellar body. These lamellar structures remain even when no or only traces of pigment are left in the leaves. In untreated control leaves the pigment content remained constant during similar illumination and the structural changes in the plastids consisted of a rearrangement of the vesicles from the prolamellar bodies into strands dispersed through the stroma; lamellae and grana formation occurred later.

Macromolecular Physiology of Plastids

1969 ◽  
Vol 5 (3) ◽  
pp. 757-793
Author(s):  
K. W. HENNINGSEN ◽  
J. E. BOYNTON
Keyword(s):  
Structural Changes ◽  
Spectral Shift ◽  
Primary Leaf ◽  
Prolamellar Body ◽  
Time Interval ◽  
Intermediate Step ◽  
Thin Sections ◽  
Prolamellar Bodies ◽  
Rapid Transformation

Barley seedlings developing at 23 °C in darkness have been studied at various ages for changes in fresh weight, height of shoot, protochlorophyll content and structure of the etioplasts in the primary leaf. Changes of the pigments in vivo, such as the spectral shift of the newly formed chlorophyll and the resynthesis of protochlorophyll, were studied spectrophotometrically prior to and following a 1-min illumination. Concomitantly, leaf tissue was fixed with glutaraldehyde-OsO4 and later analysed in thin sections using the electron microscope. In darkness, protochlorophyll content in the primary leaf, size of the etioplasts, size of the crystalline prolamellar bodies and area of the primary lamellar layers reach their maximum values on the 7th day. Thereafter all the aforementioned parameters decrease, particularly the protochlorophyll content. The structural changes of the prolamellar-body material, rate of the spectral shift of the newly formed chlorophyll and rate of the resynthesis of protochlorophyll in darkness after photoconversion of the original protochlorophyll depend on seedling age. In both 5- and 7-day-old seedlings with high protochlorophyll content, the illumination causes a rapid transformation of the prolamellar bodies. Subsequently in 5-day-old seedlings, a rapid resynthesis of protochlorophyll takes place and the prolamellar bodies recrystallize before dispersal is completed. In the 7-day-old seedlings, resynthesis of protochlorophyll is slower and the prolamellar bodies are largely dispersed into primary lamellar layers before resynthesis of protochlorophyll and reformation of crystalline prolamellar bodies ensue. In 5-day-old seedlings, in which resynthesis of protochlorophyll and recrystallization of the prolamellar bodies are completed within less than 1 h in darkness following illumination, a second illumination effects a more rapid transformation and dispersal of the prolamellar bodies than is observed after the first illumination. In 9- and 11-day-old seedlings, in which the content of protochlorophyll is low, transformation of the prolamellar bodies occurs slowly in darkness following the initial illumination and is not completed within 60 min. No significant protochlorophyll resynthesis and no dispersal of the prolamellar bodies were observed during this time interval. Dispersal of the prolamellar bodies results in an increase in the area of the primary lamellar layers. During reformation of protochlorophyll, a decrease in area of the primary lamellar layers is correlated with an increase in volume and number of the prolamellar bodies. These quantitative relationships between the parameters for prolamellar bodies and primary lamellar layers indicate that, for dispersal and recrystallization of the prolamellar bodies, no significant amount of membrane synthesis is required. Different configurations of the prolamellar bodies can occur: protochlorophyll is associated with the crystalline configurations where the spacing of the tubules is either narrow or wide; chlorophyll is associated with the transformed prolamellar-body configuration. The narrow and wide crystalline configurations appear to be interconvertible, and re-organization does not necessarily involve the primary lamellar layers as an intermediate step. Wide spacing of the tubules coincides with the highest pigment content.

Drought Induced Structural Changes in Developing Chloroplasts of Jalapeno Pepper (Capsicum annuum)

2001 ◽  
Vol 7 (S2) ◽  
pp. 66-67 ◽  
Author(s):  
Kristine Fambrough ◽  
Soumitra Ghoshroy
Keyword(s):  
Structural Changes ◽  
Higher Plants ◽  
Turgor Pressure ◽  
Prolamellar Body ◽  
Control Group ◽  
Time Intervals ◽  
Transmission Electron ◽  
Ultrathin Sections ◽  
And Control ◽  
Pepper Plants

Chloroplasts, present in leaves of higher plants have an extensive, folded network of photosynthetic membranes. These membranes have closely appressed (grana) and non-appressed (stroma) regions and they are responsible for the conversion of solar energy into biochemically useful forms. Light plays an important role for the development of mature chloroplasts from proplastids. However, when seeds germinate in the dark, the proplastids do not form mature chloroplasts and instead they form etioplasts. The etioplasts contain a compact, highly regular lattice of inner membranes called prolamellar body. Exposure of dark grown seedlings to light induces formation of fully mature chloroplasts from etioplasts. Plant growth and development is dependent on various environmental factors and drought has profound effect on plant metabolism. Leaves depend on adequate water for both turgor pressure and photosynthesis. Turgor pressure enables nutrients in the form of carbon and minerals to be transported from soil to leaves where they are needed for synthesis of organic compounds. in this study we evaluated the influence of drought on the ultrastructure of developing chloroplasts in pepper plants.Jalapeno pepper plants were grown from seeds in the dark and drought was induced to experimental group of plants after they developed the first pair of primary leaves. The dark grown control plants received water throughout the drought induction period. At the end of tenth day of drought, plants in both control and experimental groups were exposed to light for up to 48 hours and leaf samples from both groups were obtained at various time intervals after exposure to light. The samples were fixed, dehydrated and embedded for transmission electron microscopy. Ultrathin sections were made, observed under a Hitachi H7000 TEM and data were collected for ultrastructural study. The mature chloroplast and etioplast structures were compared between experimental and control group of plants.

scholarly journals EARLY STAGES IN THE DEVELOPMENT OF PLASTID FINE STRUCTURE IN RED AND FAR-RED LIGHT

1964 ◽  
Vol 22 (2) ◽  
pp. 433-442 ◽  
Author(s):  
Shimon Klein ◽  
G. Bryan ◽  
Lawrence Bogorad
Keyword(s):  
Fine Structure ◽  
Stages Of Change ◽  
Structural Changes ◽  
Red Light ◽  
Prolamellar Body ◽  
Lag Phase ◽  
Prolamellar Bodies ◽  
Chlorophyll Accumulation ◽  
Time Required ◽  
Bean Leaves

Developmental changes in fine structure were studied in plastids of etiolated bean leaves during the time required for the protochlorophyllide-chlorophyllide transformation and the following lag phase prior to chlorophyll accumulation. In agreement with some other workers, two distinct stages of change in the fine structure of proplastids were found to occur upon illumination during this period. The first involves a dissociation of the previously fused units in the prolamellar bodies of the proplastids and occurs simultaneously with the protochlorophyllide-chlorophyllide conversion in light of 655 mµ, but not of 682, 700, or 730 mµ. The effect of the red light could not be reversed by a simultaneously supplied stronger far-red irradiation. The energy requirements for these structural changes parallel those for the pigment conversion. During the following step the vesicles which arose from the fused units of the prolamellar body were dispersed in rows through the stroma, and the prolamellar bodies themselves disappeared. For these changes to occur, higher light energies were required and the leaves had to be illuminated for longer periods. A red preillumination seemed to accelerate the development somewhat. The structural changes could be induced by light of 655 mµ, but also, to a lesser degree, of 730 mµ. No measurable additional chlorophyll accumulated during this period. Thus, the structural changes observed were independent of major changes in pigment content.

Fine Structural Changes in the Microvasculature of the Mouse Pinna: Aging and Radiation Injury

1974 ◽  
Vol 32 ◽  
pp. 54-55
Author(s):  
S. Phyllis Steamer ◽  
Rosemarie L. Devine
Keyword(s):  
Structural Changes ◽  
Radiation Treatment ◽  
Arterial Stenosis ◽  
Ultrastructural Changes ◽  
Vascular Effects ◽  
Microvascular Changes ◽  
Surrounding Connective Tissue ◽  
Fission Neutrons ◽  
Total Body

The importance of radiation damage to the skin and its vasculature was recognized by the early radiologists. In more recent studies, vascular effects were shown to involve the endothelium as well as the surrounding connective tissue. Microvascular changes in the mouse pinna were studied in vivo and recorded photographically over a period of 12-18 months. Radiation treatment at 110 days of age was total body exposure to either 240 rad fission neutrons or 855 rad 60Co gamma rays. After in vivo observations in control and irradiated mice, animals were sacrificed for examination of changes in vascular fine structure. Vessels were selected from regions of specific interest that had been identified on photomicrographs. Prominent ultrastructural changes can be attributed to aging as well as to radiation treatment. Of principal concern were determinations of ultrastructural changes associated with venous dilatations, segmental arterial stenosis and tortuosities of both veins and arteries, effects that had been identified on the basis of light microscopic observations. Tortuosities and irregularly dilated vein segments were related to both aging and radiation changes but arterial stenosis was observed only in irradiated animals.

Evaluation of single-electron movies of glutamine synthetase molecules

1983 ◽  
Vol 41 ◽  
pp. 280-281
Author(s):  
W. Kunath ◽  
E. Zeitler ◽  
M. Kessel
Keyword(s):  
Electron Microscope ◽  
Glutamine Synthetase ◽  
Electron Irradiation ◽  
Structural Damage ◽  
Structural Changes ◽  
Single Electron ◽  
Continuous Series ◽  
Digital Recording ◽  
Recording Device ◽  
Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

Fine Structural Changes in the Adenohypophyses of Rats Following Destruction of the Pituitary Stalk

1977 ◽  
Vol 35 ◽  
pp. 496-497
Author(s):  
K. Kovacs ◽  
E. Horvath ◽  
J. M. Bilbao ◽  
F. A. Laszlo ◽  
I. Domokos
Keyword(s):  
Structural Changes ◽  
Tissue Injury ◽  
Anterior Lobe ◽  
Uranyl Acetate ◽  
Male Rats ◽  
Pituitary Stalk ◽  
Sequence Of Events ◽  
Pituitary Glands ◽  
Electrolytic Lesions ◽  
Ultrathin Sections

Electrolytic lesions of the pituitary stalk in rats interrupt adenohypophysial blood flow and result in massive infarction of the anterior lobe. In order to obtain a deeper insight into the morphogenesis of tissue injury and to reveal the sequence of events, a fine structural investigation was undertaken on adenohypophyses of rats at various intervals following destruction of the pituitary stalk.The pituitary stalk was destroyed electrolytically, with a Horsley-Clarke apparatus on 27 male rats of the R-Amsterdam strain, weighing 180-200 g. Thirty minutes, 1,2,4,6 and 24 hours after surgery the animals were perfused with a glutaraldehyde-formalin solution. The skulls were then opened and the pituitary glands removed. The anterior lobes were fixed in glutaraldehyde-formalin solution, postfixed in osmium tetroxide and embedded in Durcupan. Ultrathin sections were stained with uranyl acetate and lead citrate and investigated with a Philips 300 electron microscope.

Membrane Changes in Polymorphonuclear Leukocytes During Ionophore (A23187) - Induced Lysosomal Release

1977 ◽  
Vol 35 ◽  
pp. 482-483
Author(s):  
P.L. Moore ◽  
P.L. Sannes ◽  
H.L. Bank ◽  
S.S. Spicer
Keyword(s):  
Structural Changes ◽  
Calcium Release ◽  
Clear Understanding ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Extracellular Medium ◽  
Pmn Leukocytes ◽  
Intracellular Ion Concentrations ◽  
Membrane Changes ◽  
Pmn Leukocyte

It is thought that calcium and/or magnesium may play important roles in polymorphonuclear (PMN) leukocyte functions such as chemotaxis, adhesion and phagocytosis. Yet, a clear understanding of the biological roles of these ions has awaited the development of techniques which permit a selective alteration of intracellular ion concentrations. Recently, treatment of cells with the ionophore A23187 has been used to alter intracellular divalent cation concentrations. This ionophore is a lipid soluble antibiotic produced by Streptomyces chartreusensis that complexes with both calcium and magnesium (3) and is believed to carry these ions across biological membranes (4). Biochemical investigations of human PMN leukocytes demonstrate that cells treated with A23187 and extracellular calcium release their lysosomal enzymes into the extracellular medium without rupturing and releasing their soluble cytoplasmic enzymes (5,6). The aim of the present study and and a companion report (7) was to investigate the structural changes that occur in leukocytes during ionophore-induced lysosomal enzyme release.

The Reaction of Brain Structures with OsO4-Zinc-Iodide Stain

1971 ◽  
Vol 29 ◽  
pp. 272-273
Author(s):  
Werner J. Niklowitz
Keyword(s):  
Electron Microscope ◽  
Structural Changes ◽  
Mossy Fiber ◽  
Toxic Metal ◽  
Staining Technique ◽  
Brain Structures ◽  
Oxidase Inhibitor ◽  
Fiber Layer ◽  
Hippocampal Tissue ◽  
Zinc Iodide

After intoxication of rabbits with certain substances such as convulsant agents (3-acetylpyridine), centrally acting drugs (reserpine), or toxic metal compounds (tetraethyl lead) a significant observation by phase microscope is the loss of contrast of the hippocampal mossy fiber layer. It has been suggested that this alteration, as well as changes seen with the electron microscope in the hippocampal mossy fiber boutons, may be related to a loss of neurotransmitters. The purpose of these experiments was to apply the OsO4-zinc-iodide staining technique to the study of these structural changes since it has been suggested that OsO4-zinc-iodide stain reacts with neurotransmitters (acetylcholine, catecholamines).Domestic New Zealand rabbits (2.5 to 3 kg) were used. Hippocampal tissue was removed from normal and experimental animals treated with 3-acetylpyridine (antimetabolite of nicotinamide), reserpine (anti- hypertensive/tranquilizer), or iproniazid (antidepressant/monamine oxidase inhibitor). After fixation in glutaraldehyde hippocampal tissue was treated with OsO4-zinc-iodide stain and further processed for phase and electron microscope studies.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

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