Ultrastructure of teliospores and promycelium and basidiospore formation in the two-spored form of Gymnoconia nitens, one of the causes of orange rust of Rubus

2007 ◽  
Vol 85 (10) ◽  
pp. 935-940 ◽  
Author(s):  
Charles W. Mims ◽  
Elizabeth A. Richardson
Keyword(s):  
Fluorescence Microscopy ◽  
Mitotic Division ◽  
Sequence Of Events ◽  
Transverse Septum ◽  
Rubus Argutus

Gymnoconia nitens (Schwein.) Kern & H. W. Thurston consists of two forms that cause orange rust of Rubus . The teliospores of both of these forms are morphologically identical to aeciospores, but upon germination form promycelia that give rise to either two or four basidiospores. In this study, we examined the teliospores and the sequence of events leading to basidiospore development in the two-spored form of G. nitens. The teliospores of this species are formed in chains from uninucleate sporogenous cells that line the base of each sorus on infected Rubus argutus Link. (blackberry) leaves. Fluorescence microscopy revealed that approximately 90% of the mature teliospores were uninucleate. During germination, the teliospore nucleus migrated into the developing promycelium and underwent a single mitotic division. A transverse septum formed between the two daughter nuclei creating two uninucleate cells. A tapered sterigma arose from each cell and gave rise to a basidiospore. These findings indicate that the basidiospores of the two-spored form of G. nitens were formed in an asexual fashion.

Ultrastructure of basidium and basidiospore development in three species of the fungus Exobasidium

1987 ◽  
Vol 65 (6) ◽  
pp. 1236-1244 ◽  
Author(s):  
Charles W. Mims ◽  
Elizabeth A. Richardson ◽  
Robert W. Roberson
Keyword(s):  
Leaf Surface ◽  
Mitotic Division ◽  
Abaxial Side ◽  
Sequence Of Events ◽  
Transverse Septum ◽  
Abaxial Leaf Surface ◽  
Thin Walled

The sequence of events occurring within basidia of Exobasidium was shown to be quite different from that previously described in one-celled holobasidia. Karyogamy was found to occur in thin-walled hyphal compartments or probasidia comprising part of a stroma-like system within the intercellular leaf spaces. Meiosis also began in these compartments but was not completed until after the nucleus had migrated into the large, prominent metabasidium that became exposed on the abaxial leaf surface. Following sterigmatal development and a postmeiotic mitotic division, usually four to seven basidiospores developed per basidium. Each spore possessed a hilar appendage on its abaxial side, but neither a hilar appendage body nor a hilar droplet was observed. The thin basidiospore wall was continuous with that of its sterigma. Development of a hilar septum delimited the spore from its sterigma. Detached basidiospores of E. vaccinii and E. japonicum became two celled following mitosis and development of a near-median transverse septum. Basidiospores of E. camelliae var. gracilis usually developed three transverse septa. Based on our observations Exobasidium should be placed in the Teliomycetes.

Lymphocyte surface and cytoplasmic changes associated with translational motility and spontaneous capping of Ig

1979 ◽  
Vol 39 (1) ◽  
pp. 137-147
Author(s):  
D.K. Bhalla ◽  
J. Braun ◽  
M.J. Karnovsky
Keyword(s):  
Fluorescence Microscopy ◽  
B Lymphocytes ◽  
Random Distribution ◽  
Thin Sections ◽  
Sequence Of Events ◽  
Opposite Pole ◽  
Translatory Motion ◽  
Surface Immunoglobulins ◽  
Characteristic Features ◽  
Lymphocyte Motility

Murine B-lymphocytes during translatory motion undergo a series of changes with respect to their morphology and distribution of surface immunoglobulins (Ig). The sequence of events comprising these changes was followed by fluorescence microscopy and a correlated detection of surface features by scanning microscopy on exactly the same cell. A round, presumably non-motile lymphocyte exhibited a random distribution of Ig and its surface displayed evenly distributed microvilli. Formation of a ruffled edge at one pole, accompanied by a decreased fluorescence at this pole marked the initial events of lymphocyte motility. In the subsequent stages, the ruffled edge became progressively prominent and displayed a constriction at its base, while the microvilli were displaced to the opposite pole. Ig in such lymphocytes was localized at the trailing, microvilli-rich pole. Thin sections of motile lymphocytes revealed Ig, microtubules, microfilaments and coated vesicles as the characteristic features of the trailing end. These observations may have bearing on the mechanism of lymphocyte motility and spontaneous capping of Ig.

scholarly journals Inhibition by colchicine of the mitogenic stimulation of lymphocytes prior to the S phase.

1975 ◽  
Vol 66 (1) ◽  
pp. 128-144 ◽  
Author(s):  
J L Wang ◽  
G R Gunther ◽  
G M Edelman
Keyword(s):  
Inhibitory Effect ◽  
Mitotic Division ◽  
S Phase ◽  
Resting Cells ◽  
Mitogenic Stimulation ◽  
Sequence Of Events ◽  
Blast Cells ◽  
Thymidine Transport ◽  
Inhibition Of Dna Synthesis ◽  
Stimulation Of

Colchicine, vinblastine, and vincristine inhibit the mitogenic stimulation of lymphocytes by concanavalin A as measured by the incorporation of [3H]thymidine and the appearance of blast cells. The inhibitory effect of colchicine could not be accounted for by diminution in cell viability or by metaphase arrest of mitosis in the stimulated cells. Moreover, the inhibition of [3H]thymidine incorporation was not due to blockage of thymidine transport or inhibition of DNA synthesis inasmuch as addition of colchicine had no effect on cells in the S phase of the cell cycle. The time of inhibition was correlated with the kinetics of cellular commitment to lectin activation and the kinetic data indicated that colchicine blocks stimulation early in the sequence of events following addition of the mitogen. These findings support the hypothesis that cytoplasmic microtubular function plays a role in the commitment of resting cells to undergo mitotic division.

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.

Application of FRAP and digitized fluorescence microscopy to problems in cell membrane dynamics

1988 ◽  
Vol 46 ◽  
pp. 118-119
Author(s):  
K. Jacobson ◽  
A. Ishihara ◽  
B. Holifield ◽  
F. Zhang
Keyword(s):  
Fluorescence Microscopy ◽  
Cell Biology ◽  
Extended Period ◽  
Dynamic Structure ◽  
Living Cells ◽  
Membrane Dynamics ◽  
Molecular Cell Biology ◽  
Image Averaging ◽  
Single Living Cells ◽  
Single Living

Our laboratory is concerned with understanding the dynamic structure of the plasma membrane with particular reference to the movement of membrane constituents during cell locomotion. In addition to the standard tools of molecular cell biology, we employ both fluorescence recovery after photo- bleaching (FRAP) and digitized fluorescence microscopy (DFM) to investigate individual cells. FRAP allows the measurement of translational mobility of membrane and cytoplasmic molecules in small regions of single, living cells. DFM is really a new form of light microscopy in that the distribution of individual classes of ions, molecules, and macromolecules can be followed in single, living cells. By employing fluorescent antibodies to defined antigens or fluorescent analogs of cellular constituents as well as ultrasensitive, electronic image detectors and video image averaging to improve signal to noise, fluorescent images of living cells can be acquired over an extended period without significant fading and loss of cell viability.

Ultrastructure of primary spermatocyte in fish (Tilapia: Oreochromis niloticus): The synaptonemal complex

1986 ◽  
Vol 44 ◽  
pp. 288-289
Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Synaptonemal Complex ◽  
Oreochromis Niloticus ◽  
Short Communication ◽  
Primary Spermatocyte ◽  
Mitotic Division ◽  
Meiotic Cell ◽  
Electron Microscope Level ◽  
Homologous Chromosomes

The Primary Spermatocytes represent a stage in spermatogenesis when the first meiotic cell division occurs. They are derived from Spermatogonium or Stem cell through mitotic division. At the zygotene phase of meiotic prophase the Synaptonemal complex appears in these cells in the space between the paired homologous chromosomes. Spermatogenesis and sperm structure in fish have been studied at the electron microscope level in a few species? However, no work has yet been reported on ultrastructure of tilapia, O. niloticus, spermatozoa and spermatogenetic process. In this short communication we are reporting the Ultrastructure of Primary Spermatocytes in tilapia, O. niloticus, and the fine structure of synaptonemal complexes seen in the spermatocyte nuclei.

Scanning x-ray fluorescence microscopy and principal component analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1752-1753
Author(s):  
Brian Cross
Keyword(s):  
Principal Component Analysis ◽  
Fluorescence Microscopy ◽  
Spatial Resolution ◽  
High Speed ◽  
Image Acquisition ◽  
Principal Component ◽  
Fluorescence Microscope ◽  
Acquisition Rate ◽  
X Ray ◽  
Speed Up

A relatively new entry, in the field of microscopy, is the Scanning X-Ray Fluorescence Microscope (SXRFM). Using this type of instrument (e.g. Kevex Omicron X-ray Microprobe), one can obtain multiple elemental x-ray images, from the analysis of materials which show heterogeneity. The SXRFM obtains images by collimating an x-ray beam (e.g. 100 μm diameter), and then scanning the sample with a high-speed x-y stage. To speed up the image acquisition, data is acquired "on-the-fly" by slew-scanning the stage along the x-axis, like a TV or SEM scan. To reduce the overhead from "fly-back," the images can be acquired by bi-directional scanning of the x-axis. This results in very little overhead with the re-positioning of the sample stage. The image acquisition rate is dominated by the x-ray acquisition rate. Therefore, the total x-ray image acquisition rate, using the SXRFM, is very comparable to an SEM. Although the x-ray spatial resolution of the SXRFM is worse than an SEM (say 100 vs. 2 μm), there are several other advantages.

Desmosomal distribution in the epidermis of a non-contracting human skin equivalent

1992 ◽  
Vol 50 (1) ◽  
pp. 896-897
Author(s):  
L.X. Oakford ◽  
S.D. Dimitrijevich ◽  
R. Gracy
Keyword(s):  
Human Skin ◽  
Basal Layer ◽  
Skin Equivalent ◽  
Tissue Component ◽  
Intact Skin ◽  
Similar Sequence ◽  
Sequence Of Events ◽  
Suprabasal Keratinocytes ◽  
Human Skin Equivalent

In intact skin the epidermal layer is a dynamic tissue component which is maintained by a basal layer of mitotically active cells. The protective upper epidermis, the stratum corneum, is generated by differentiation of the suprabasal keratinocytes which eventually desquamate as anuclear comeocytes. A similar sequence of events is observed in vitro in the non-contracting human skin equivalent (HSE) which was developed in this lab (1). As a part of the definition process for this model of living skin we are examining its ultrastructural features. Since desmosomes are important in maintaining cell-cell interactions in stratified epithelia their distribution in HSE was examined.

Albumin-Induced Endocytic Vacuoles in Tetrahymena Pyrijormis

1975 ◽  
Vol 33 ◽  
pp. 694-695
Author(s):  
L. J. Brenner ◽  
D. G. Osborne ◽  
B. L. Schumaker
Keyword(s):  
Electron Microscopy ◽  
Bovine Serum Albumin ◽  
Bovine Serum ◽  
Protein Concentration ◽  
Tetrahymena Pyriformis ◽  
Sequence Of Events ◽  
Cytoplasmic Bodies ◽  
Food Vacuoles ◽  
Mouse Ascites ◽  
Normal Human

Exposure of the ciliate, Tetrahymena pyriformis, strain WH6, to normal human or rabbit sera or mouse ascites fluids induces the formation of large cytoplasmic bodies. By electron microscopy these (LB) are observed to be membrane-bounded structures, generally spherical and varying in size (Fig. 1), which do not resemble the food vacuoles of cells grown in proteinaceous broth. The possibility exists that the large bodies represent endocytic vacuoles containing material concentrated from the highly nutritive proteins and lipoproteins of the sera or ascites fluids. Tetrahymena mixed with bovine serum albumin or ovalbumin solutions having about the same protein concentration (7g/100 ml) as serum form endocytic vacuoles which bear little resemblance to the serum-induced LB. The albumin-induced structures (Fig. 2) are irregular in shape, rarely spherical, and have contents which vary in density and consistency. In this paper an attempt is made to formulate the sequence of events which might occur in the formation of the albumin-induced vacuoles.

Two-photon excitation fluorescence microscopy in living systems

1993 ◽  
Vol 51 ◽  
pp. 154-155 ◽  
Author(s):  
David W. Piston
Keyword(s):  
Confocal Microscopy ◽  
Fluorescence Microscopy ◽  
Singlet State ◽  
Excited Electronic State ◽  
Input Power ◽  
Two Photon ◽  
Simultaneous Absorption ◽  
Photon Excitation ◽  
Very High ◽  
Two Photon Excitation

Two-photon excitation fluorescence microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In our fluorescence experiments, the final excited state is the same singlet state that is populated during a conventional fluorescence experiment. Thus, the fluorophore exhibits the same emission properties (e.g. wavelength shifts, environmental sensitivity) used in typical biological microscopy studies. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

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