Rhodopsin Particles in the Photoreceptor Membrane of an Insect

Abstract Rhodopsin, Insect Photoreceptor, Freeze Fracture Electron-microscopic examination of freeze-fractured fly retinae has revealed the presence of particles, 80 to 100 Å in diameter, on the photoreceptor membrane. Flies which were raised on a vitamin-A deficient diet show a substantial reduction in the density of such particles. The reduction in particle density is in agreement with the reduction in visual-pigment concentration as measured spectrophotometrically for these flies. These results suggest that the particles are identical with molecules of the visual pigment, rhodopsin.

Download Full-text

A Freeze-Fracture Technique for Examining Human Stratum Corneum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100094759 ◽

1972 ◽

Vol 30 ◽

pp. 298-299

Author(s):

Daniel P. Hannon

Keyword(s):

Electron Microscopy ◽

Sample Preparation ◽

Stratum Corneum ◽

Microscopic Examination ◽

Freeze Fracture ◽

Electron Microscopic Examination ◽

Electron Microscopic ◽

Human Stratum Corneum ◽

Freeze Fracture Electron Microscopy ◽

Fracture Electron

Human stratum corneum is a difficult tissue to process for electron microscopic examination. Most of the difficulty is due to the inability of the chemical fixative to adequately preserve all of the constituents of this tissue. As a result, during sectioning, breaks occur between cells creating voids which preclude any studies of these areas. Also, because the fixative is usually in an aqueous medium, studies of hydrated or dehydrated states are impossible. However, these problems can be overcome by using an alternative method of sample preparation, freeze-fracture electron microscopy.Samples of human skin both untreated and soaked for 20 minutes in 20% glycerin were cut into strips 1 mm wide by 2 mm long and placed in specially made copper discs with a 1 mm deep central cup. Freezing was accomplished by immersion in liquid Freon 22.

Download Full-text

Properties of Isolated Mitochondria of Agaricus Bisporus: Their Relationship to Dormancy and the Germination of Spores

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072733 ◽

1973 ◽

Vol 31 ◽

pp. 458-459

Author(s):

K. S. McCarty ◽

R. F. Weave ◽

L. Kemper ◽

F. S. Vogel

Keyword(s):

Mitochondrial Dna ◽

Ethidium Bromide ◽

Microscopic Examination ◽

Agaricus Bisporus ◽

Osmotic Shock ◽

Electron Microscopic Examination ◽

Electron Microscopic ◽

Isolated Mitochondria ◽

Dna Strands ◽

Cytoplasmic Ribosomes

During the prodromal stages of sporulation in the Basidiomycete, Agaricus bisporus, mitochondria accumulate in the basidial cells, zygotes, in the gill tissues prior to entry of these mitochondria, together with two haploid nuclei and cytoplasmic ribosomes, into the exospores. The mitochondria contain prominent loci of DNA [Fig. 1]. A modified Kleinschmidt spread technique1 has been used to evaluate the DNA strands from purified whole mitochondria released by osmotic shock, mitochondrial DNA purified on CsCl gradients [density = 1.698 gms/cc], and DNA purified on ethidium bromide CsCl gradients. The DNA appeared as linear strands up to 25 u in length and circular forms 2.2-5.2 u in circumference. In specimens prepared by osmotic shock, many strands of DNA are apparently attached to membrane fragments [Fig. 2]. When mitochondria were ruptured in hypotonic sucrose and then fixed in glutaraldehyde, the ribosomes were released for electron microscopic examination.

Download Full-text

Artifact-free electron microscopic immunocytochemistry on rat brain tissue

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100085666 ◽

1991 ◽

Vol 49 ◽

pp. 272-273

Author(s):

Veronika Burmeister ◽

N. Ludvig ◽

P.C. Jobe

Keyword(s):

Microscopic Examination ◽

Free Electron ◽

Electron Microscopic Examination ◽

Ultrastructural Localization ◽

Rabbit Serum ◽

Electron Microscopic ◽

Electron Microscopic Immunocytochemistry ◽

Phosphate Buffered Saline ◽

Rat Brain Tissue ◽

Immune Rabbit

Electron microscopic immunocytochemistry provides an important tool to determine the ultrastructural distribution of various molecules in both normal and pathologic tissues. However, the specific immunostaining may be obscured by artifactual immunoreaction product, misleading the investigator. Previous observations show that shortening the incubation period with the primary antibody from the generally used 12-24 hours to 1 hour substantially reduces the artifactual immunostaining. We now extend this finding by the demonstration of artifact-free ultrastructural localization of the Ca2/calmodulindependent cyclic nucleotide phosphodiesterase (CaM-dependent PDE) immunoreactivity in brain.Anesthetized rats were perfused transcardially with phosphate-buffered saline followed by a fixative containing paraformaldehyde (4%) and glutaraldehyde (0.25%) in PBS. The brains were removed, and 40μm sections were cut with a vibratome. The sections were processed for immunocytochemistry as described by Ludvig et al. Both non-immune rabbit serum and specific CaM-dependent PDE antibodies were used. In both experiments incubations were at one hour and overnight. The immunostained sections were processed for electron microscopic examination.

Download Full-text

Ultrastructural studies of Chlamydia psittaci 6BC variant strains. I. Ultrastructure of the surface layers of egg-passaged 6BC strain

Canadian Journal of Microbiology ◽

10.1139/m73-142 ◽

1973 ◽

Vol 19 (8) ◽

pp. 887-894

Author(s):

Linda Poffenroth ◽

J. W. Costerton ◽

Nonna Kordová ◽

John C. Wilt

Keyword(s):

Chick Embryo ◽

Microscopic Examination ◽

Electron Microscopic Examination ◽

Chlamydia Psittaci ◽

Gram Negative Bacteria ◽

Surface Layers ◽

Electron Microscopic ◽

Gram Negative ◽

Ultrastructural Studies ◽

First Time

Electron microscopic examination of a semipurified Chlamydia psittaci 6BC strain attenuated in chick embryo yolk sac revealed for the first time two morphologically distinct small elementary bodies which differ both in the ultrastructure of their surface layers and in their buoyant densities in sucrose gradients. Also, the morphology of the surface layers of the larger reticulate forms in cell-free systems is described for the first time. Many points of difference between the surface envelopes and internal structure of chlamydial particles and those of Gram-negative bacteria are discussed.

Download Full-text