Branch development on leaders of Piceasitchensis

1978 ◽  
Vol 8 (1) ◽  
pp. 121-128 ◽  
Author(s):  
Shelagh M. Baxter ◽  
Melvin G. R. Cannell
Keyword(s):  
Cell Division ◽  
Growth Process ◽  
Lower Branch ◽  
Apical Meristems ◽  
Branch Development ◽  
Needle Primordia

The top whorl of branches on each year's leader on mature P. sitchensis (Bong.) Carr. had more needles and longer needle internodes than branches lower down on the leader. All branches developed as buds for similar periods of time from April to October, but top branch buds developed larger apical meristems which generated needle primordia more rapidly than lower branch buds. In mid-August, top branch buds produced at least 13 primordia per day compared with only 5 per day in basal buds. In the next year, when these preformed buds extended, top branches produced about one and a half times as many cells per needle internode as basal branches, as judged by observing the pith. In both years, cell division was the important growth process affected by 'dominance' mechanisms between branch buds.

scholarly journals The effect of benzothiazolium salt on spruce callus cells

2010 ◽  
Vol 56 (No. 10) ◽  
pp. 463-469 ◽  
Author(s):  
Ľ. Krajnáková ◽  
D. Kákoniová ◽  
D. Lišková ◽  
E. Hlinková
Keyword(s):  
Cell Division ◽  
Picea Abies ◽  
Growth Process ◽  
Growth Parameters ◽  
Growth Hormones ◽  
The Other ◽  
Lag Phase ◽  
The Third ◽  
Stimulation Of

The effect of 3-(benzyloxycarbonylmethyl)-2-benzothiazolinone (SM-550) on the growth parameters, cell division, and cell polymorphism of spruce callus cells (Picea abies L. Karst) was investigated. These results were compared with callus parameters grown on the medium supplemented with NAA. The highest concentration (1 mmol) of SM-550 stimulated the growth process, as well as cell division, shortened the lag-phase, and had a significant effect on cells polymorphism. Its effect was demonstrated especially on long-term culture (3 subcultures – 84 days). On the other hand, the highest stimulation of growth by SM-550 in 1 μmol concentration was determined only in the first subculture. SM-550 in the lowest concentration (1 nmol) used was completely unsuitable in the third subculture, the callus was necrotic and resembled to calli growing on the medium without growth hormones.

ANALYSIS OF THE HISTOCHEMICAL LOCALIZATION OF PEROXIDASE RELATED TO THE DIFFERENTIATION OF PLANT TISSUES

1959 ◽  
Vol 37 (3) ◽  
pp. 449-458 ◽  
Author(s):  
D. S. Van Fleet
Keyword(s):  
Cell Division ◽  
Nucleic Acids ◽  
Future Development ◽  
Continuous System ◽  
Leaf Primordia ◽  
Plant Tissues ◽  
Spiral Pattern ◽  
Adult Tissue ◽  
Bud Formation ◽  
Apical Meristems

Peroxidase is detectible in all tissues but is most reactive, in the basophilic cells of the histogens. Oxidation of applied phenols and aminophenols by peroxidase produces quinones and quinonediimines that are adsorbed by nucleic acids and other basophilic substances in the formative centers of primordia. Localized reactions for peroxidase occur in the axils of leaf primordia prior to bud formation and on the surface of apical meristems in a spiral pattern marking the points for the future development of leaf primordia. Peroxidase is detectible in advance of or accompanying cell division and declines after the division phase; decline of peroxidase at the end of the division phase is related to the increase of phenols, naphthols, and phenolases. Peroxidase declines in all tissues except the phloem; a continuous peroxidase system in the phloem connects primordia with adult tissue. The hypothesis is offered that the cellular units of the phloem peroxidase constitute a continuous system between primordia and adult tissue and is functional in catalyzing the reduction of hydrogen acceptors essential to cell division and the initiation of primordia.

The apical cell of fern roots and shoots: an appraisal of its functional role in development

1985 ◽  
Vol 86 ◽  
pp. 237-243
Author(s):  
Ernest M. Gifford
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Mitotic Index ◽  
Root Development ◽  
Dna Content ◽  
Functional Role ◽  
Apical Cell ◽  
Cell Theory ◽  
Apical Meristems

SynopsisA brief review of the Apical Cell Theory and its relationship to apical growth in pteridophytes is presented. Currently there are two concepts regarding the importance of the apical cell during development. One group of investigators has presented evidence to demonstrate that the apical cell is mitotically active only during early initiation and organisation of apical meristems. Soon the apical cell becomes essentially inactive in cell division, and may undergo endopolyploidy. The second group has provided evidence in support of the original tenet that the apical cell plays an important and continuing role in shoot and root development and does not undergo endopolyploidy. Curiously enough, evidence for both concepts is based essentially upon the same procedures and techniques: histogenesis, determination of the mitotic index and cell-cycle durations, labelling with 3H-thymidine, and cytophotometric measurements of DNA content of the apical cell and subjacent cells.

The Ultrastructure of the Nuclear Events of Binary Fission in Paramecium bursaria and the Effects of Colchicine on Cell Division

1974 ◽  
Vol 32 ◽  
pp. 276-277
Author(s):  
L. M. Lewis
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Condensed Chromatin ◽  
Binary Fission ◽  
Paramecium Bursaria ◽  
Nuclear Events ◽  
Division Axis

The effects of colchicine on extranuclear microtubules associated with the macronucleus of Paramecium bursaria were studied to determine the possible role that these microtubules play in controlling the shape of the macronucleus. In the course of this study, the ultrastructure of the nuclear events of binary fission in control cells was also studied.During interphase in control cells, the micronucleus contains randomly distributed clumps of condensed chromatin and microtubular fragments. Throughout mitosis the nuclear envelope remains intact. During micronuclear prophase, cup-shaped microfilamentous structures appear that are filled with condensing chromatin. Microtubules are also present and are parallel to the division axis.

Stimulated Virus Production in Vinblastine and Cytochalasin-Induced Multinucleate Cells

1970 ◽  
Vol 28 ◽  
pp. 186-187
Author(s):  
Krishan Awtar
Keyword(s):  
Cell Division ◽  
Normal Cell ◽  
Virus Production ◽  
Multinucleate Cells ◽  
Daughter Cells ◽  
Cell Divisions ◽  
Nuclear Membranes ◽  
Division 2 ◽  
Vinblastine Sulfate

Exposure of cells to low sublethal but mitosis-arresting doses of vinblastine sulfate (Velban) results in the initial arrest of cells in mitosis followed by their subsequent return to an “interphase“-like stage. A large number of these cells reform their nuclear membranes and form large multimicronucleated cells, some containing as many as 25 or more micronuclei (1). Formation of large multinucleate cells is also caused by cytochalasin, by causing the fusion of daughter cells at the end of an otherwise .normal cell division (2). By the repetition of this process through subsequent cell divisions, large cells with 6 or more nuclei are formed.

Fundamental Research into Thin Films in a Developing Country

1972 ◽  
Vol 30 ◽  
pp. 500-501
Author(s):  
J.A. Eades ◽  
E. Grünbaum
Keyword(s):  
Thin Films ◽  
Growth Process ◽  
Empirical Process ◽  
Nucleation And Growth ◽  
Research Groups ◽  
Film Research ◽  
Fundamental Research ◽  
Controlled Deposition ◽  
The One ◽  
The University

In the last decade and a half, thin film research, particularly research into problems associated with epitaxy, has developed from a simple empirical process of determining the conditions for epitaxy into a complex analytical and experimental study of the nucleation and growth process on the one hand and a technology of very great importance on the other. During this period the thin films group of the University of Chile has studied the epitaxy of metals on metal and insulating substrates. The development of the group, one of the first research groups in physics to be established in the country, has parallelled the increasing complexity of the field.The elaborate techniques and equipment now needed for research into thin films may be illustrated by considering the plant and facilities of this group as characteristic of a good system for the controlled deposition and study of thin films.

UHV-STM studies of silicon nano-pyramid growth on silicon surface at high temperature

1992 ◽  
Vol 50 (2) ◽  
pp. 1144-1145
Author(s):  
T. Sato ◽  
S. Kitamura ◽  
T. Sueyoshl ◽  
M. Iwatukl ◽  
C. Nielsen
Keyword(s):  
High Temperature ◽  
Relaxation Process ◽  
Thermal Effect ◽  
Bias Voltage ◽  
Silicon Surface ◽  
Growth Process ◽  
Tunneling Current ◽  
Fabrication Technique ◽  
Nano Fabrication ◽  
Electromigration Effect

Recently, the growth process and relaxation process of crystalline structures were studied by observing a SI nano-pyramid which was built on a Si surface with a UHV-STM. A UHV-STM (JEOL JSTM-4000×V) was used for studying a heated specimen, and the specimen was kept at high temperature during observation. In this study, the nano-fabrication technique utilizing the electromigration effect between the STM tip and the specimen was applied. We observed Si atoms migrated towords the tip on a high temperature Si surface.Clean surfaces of Si(lll)7×7 and Si(001)2×l were prepared In the UHV-STM at a temperature of approximately 600 °C. A Si nano-pyramid was built on the Si surface at a tunneling current of l0nA and a specimen bias voltage of approximately 0V in both polarities. During the formation of the pyramid, Images could not be observed because the tip was stopped on the sample. After the formation was completed, the pyramid Image was observed with the same tip. After Imaging was started again, the relaxation process of the pyramid started due to thermal effect.

Effects of substrate quality and annealing on defect structures at GaAs/Si interfaces

1987 ◽  
Vol 45 ◽  
pp. 340-341
Author(s):  
H. L. Tsai ◽  
J. W. Lee
Keyword(s):  
Growth Process ◽  
Molecular Beam ◽  
Substrate Surface ◽  
Lattice Misfit ◽  
Device Fabrication ◽  
Silicon Substrates ◽  
Defect Structures ◽  
Gaas Film ◽  
Substrate Quality ◽  
Gaas On Si

Growth of GaAs on Si using epitaxial techniques has been receiving considerable attention for its potential application in device fabrication. However, because of the 4% lattice misfit between GaAs and Si, defect generation at the GaAs/Si interface and its propagation to the top portion of the GaAs film occur during the growth process. The performance of a device fabricated in the GaAs-on-Si film can be degraded because of the presence of these defects. This paper describes a HREM study of the effects of both the substrate surface quality and postannealing on the defect propagation and elimination.The silicon substrates used for this work were 3-4 degrees off [100] orientation. GaAs was grown on the silicon substrate by molecular beam epitaxy (MBE).

Confocal microscopy of the cytoskeleton in living plant cells following microinjection of fluorescent probes

1993 ◽  
Vol 51 ◽  
pp. 130-131
Author(s):  
Ann Cleary
Keyword(s):  
Cell Division ◽  
Fluorescent Probes ◽  
Actin Filaments ◽  
Intracellular Transport ◽  
Cell Structure ◽  
Plant Cells ◽  
Cell Plate ◽  
Cell Cortex ◽  
Living Plant ◽  
Rhodamine Phalloidin

Microinjection of fluorescent probes into living plant cells reveals new aspects of cell structure and function. Microtubules and actin filaments are dynamic components of the cytoskeleton and are involved in cell growth, division and intracellular transport. To date, cytoskeletal probes used in microinjection studies have included rhodamine-phalloidin for labelling actin filaments and fluorescently labelled animal tubulin for incorporation into microtubules. From a recent study of Tradescantia stamen hair cells it appears that actin may have a role in defining the plane of cell division. Unlike microtubules, actin is present in the cell cortex and delimits the division site throughout mitosis. Herein, I shall describe actin, its arrangement and putative role in cell plate placement, in another material, living cells of Tradescantia leaf epidermis.The epidermis is peeled from the abaxial surface of young leaves usually without disruption to cytoplasmic streaming or cell division. The peel is stuck to the base of a well slide using 0.1% polyethylenimine and bathed in a solution of 1% mannitol +/− 1 mM probenecid.

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