Biological Sciences: N-Terminal Sequences of Immunoglobulin Heavy and Light Chains from Three Species of Lower Vertebrates

Nature ◽  
1970 ◽  
Vol 228 (5275) ◽  
pp. 991-992 ◽  
Author(s):  
RONALD T. ACTON ◽  
PETER F. WEINHEIMER ◽  
MICHAEL WOLCOTT ◽  
E. EDWARD EVANS ◽  
J. C. BENNETT
Keyword(s):  
Biological Sciences ◽  
Light Chains ◽  
Lower Vertebrates

Dynamical Scattering in Crystalline Biological Specimens. I. Criteria of Validity for Scattering Approximations

1975 ◽  
Vol 33 ◽  
pp. 192-193
Author(s):  
Robert M. Glaeser ◽  
Bing K. Jap
Keyword(s):  
Biological Sciences ◽  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Born Approximation ◽  
Materials Science ◽  
Image Data ◽  
Dynamical Effect ◽  
Crystallographic Structure ◽  
Electron Microscope Image

The dynamical scattering effect, which can be described as the failure of the first Born approximation, is perhaps the most important factor that has prevented the widespread use of electron diffraction intensities for crystallographic structure determination. It would seem to be quite certain that dynamical effects will also interfere with structure analysis based upon electron microscope image data, whenever the dynamical effect seriously perturbs the diffracted wave. While it is normally taken for granted that the dynamical effect must be taken into consideration in materials science applications of electron microscopy, very little attention has been given to this problem in the biological sciences.

Structure of Myosin Subfragment-1 from Electron Microscopy and Crystallography

1988 ◽  
Vol 46 ◽  
pp. 156-157
Author(s):  
Donald A. Winkelmann
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Actin Filaments ◽  
Light Chains ◽  
Myosin Filament ◽  
Primary Role ◽  
Heavy Chains ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1 ◽  
Globular Head

The primary role of the interaction of actin and myosin is the generation of force and motion as a direct consequence of the cyclic interaction of myosin crossbridges with actin filaments. Myosin is composed of six polypeptides: two heavy chains of molecular weight 220,000 daltons and two pairs of light chains of molecular weight 17,000-23,000. The C-terminal portions of the myosin heavy chains associate to form an α-helical coiled-coil rod which is responsible for myosin filament formation. The N-terminal portion of each heavy chain associates with two different light chains to form a globular head that binds actin and hydrolyses ATP. Myosin can be fragmented by limited proteolysis into several structural and functional domains. It has recently been demonstrated using an in vitro movement assay that the globular head domain, subfragment-1, is sufficient to cause sliding movement of actin filaments.The discovery of conditions for crystallization of the myosin subfragment-1 (S1) has led to a systematic analysis of S1 structure by x-ray crystallography and electron microscopy. Image analysis of electron micrographs of thin sections of small S1 crystals has been used to determine the structure of S1 in the crystal lattice.

The Application of Ultra-Thin Sectioning Techniques to Non-Biological Samples

1968 ◽  
Vol 26 ◽  
pp. 332-333
Author(s):  
C. F. Oster
Keyword(s):  
Biological Sciences ◽  
Epoxy Resin ◽  
Cross Sections ◽  
Biological Samples ◽  
Industrial Applications ◽  
Photographic Film ◽  
Silver Particles ◽  
Thin Sectioning ◽  
Embedding Medium

Although ultra-thin sectioning techniques are widely used in the biological sciences, their applications are somewhat less popular but very useful in industrial applications. This presentation will review several specific applications where ultra-thin sectioning techniques have proven invaluable.The preparation of samples for sectioning usually involves embedding in an epoxy resin. Araldite 6005 Resin and Hardener are mixed so that the hardness of the embedding medium matches that of the sample to reduce any distortion of the sample during the sectioning process. No dehydration series are needed to prepare our usual samples for embedding, but some types require hardening and staining steps. The embedded samples are sectioned with either a prototype of a Porter-Blum Microtome or an LKB Ultrotome III. Both instruments are equipped with diamond knives.In the study of photographic film, the distribution of the developed silver particles through the layer is important to the image tone and/or scattering power. Also, the morphology of the developed silver is an important factor, and cross sections will show this structure.

Immunolabelling of glomerular deposits in kidney biopsies routinely fixed in glutaraldehyde

1989 ◽  
Vol 47 ◽  
pp. 910-911
Author(s):  
Ś Lhoták ◽  
I. Alexopoulou ◽  
G. T. Simon
Keyword(s):  
Uv Light ◽  
Kidney Diseases ◽  
Light Chains ◽  
Microscopical Level ◽  
Accurate Identification ◽  
Light Microscopical Level ◽  
Dense Deposits ◽  
Cacodylate Buffer ◽  
Glomerular Deposits ◽  
Prognostic Importance

Various kidney diseases are characterized by the presence of dense deposits in the glomeruli. The type(s) of immunoglobulins (Igs) present in the dense deposits are characteristic of the disease. The accurate Identification of the deposits is therefore of utmost diagnostic and prognostic importance. Immunofluorescence (IF) used routinely at the light microscopical level is unable to detect and characterize small deposits found in early stages of glomerulonephritis. Although conventional TEM is able to localize such deposits, it is not capable of determining their nature. It was therefore attempted to immunolabel at EM level IgG, IgA IgM, C3, fibrinogen and kappa and lambda Ig light chains commonly found in glomerular deposits on routinely fixed ( 2% glutaraldehyde (GA) in 0.1M cacodylate buffer) kidney biopsies.The unosmicated tissue was embedded in LR White resin polymerized by UV light at -10°C. A postembedding immunogold technique was employed

ACTION OF ENZYME DIGESTED PITUITARY GLANDS OF THE SKIPPER-FROG ON THE OVULATION OF THE SAME

1960 ◽  
Vol XXXIII (II) ◽  
pp. 255-260 ◽  
Author(s):  
L. S. Ramaswami ◽  
A. B. Lakshman
Keyword(s):  
Pituitary Gland ◽  
Constant Temperature ◽  
Constant Temperature Bath ◽  
Predominant Role ◽  
Lower Vertebrates ◽  
Pituitary Glands ◽  
Stimulating Factor

ABSTRACT By using enzymes, the gonadotrophic factors in the skipper-frog pituitary glands have been selectively inactivated or destroyed. By incubating a known number of pituitary gland homogenate with ptyalin in a constant temperature bath for 5–6 h the follicle-stimulating factor is inactivated; with trypsin or pepsin, the luteinizing factor is inactivated. Bioassay on gravid skipper-frogs indicate that the ptyalin digested homogenate brings about profuse spawning while the trypsin or pepsin digested homogenates do not. When a combination of ptyalin digested and trypsin digested homogenates is injected into fresh gravid skipper-frogs, poor spawning is brought about. These experiments show that the luteinizing factor alone brings about more profuse spawning than when it is combined with the follicle-stimulating factor. It is likely, therefore, that in the lower vertebrates the luteinizing factor of the pituitary gland plays a more predominant role. The exact proportions in which the different dosages for the control and test animals are administered are also tabulated.

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