scholarly journals HIGH-RESOLUTION AUTORADIOGAPHY

1962 ◽  
Vol 15 (2) ◽  
pp. 189-199 ◽  
Author(s):  
Lucien G. Caro
Keyword(s):  
Bacillus Subtilis ◽  
Point Source ◽  
Cross Sections ◽  
Source Distribution ◽  
Silver Bromide ◽  
Photographic Emulsion ◽  
Nuclear Region ◽  
Electron Microscopic ◽  
Beta Particles ◽  
Extended Sources

The resolution obtainable in electron microscopic autoradiographs, using a photographic emulsion consisting of a monolayer of silver bromide crystals, was investigated theoretically and experimentally. The expected distribution of exposed crystals around a point source was calculated from the geometry of the preparation and from the range distribution of the beta particles emitted by tritium. From such a distribution an autoradiographic resolution of the order of 1000 A can be predicted. From the point source distribution, the expected distribution of grains around bacteriophages labeled with tritium was calculated. This distribution was also measured experimentally in electron microscopic autoradiographs of bacteriophages T-2 labeled with thymidine-H3. The two distributions agreed closely. It was also verified, using the nuclear region in thin cross-sections of Bacillus subtilis labeled with thymidine-H3, that resolutions of the same order were obtained for extended sources. It was concluded that an autoradiographic resolution of 1000 A could be achieved with a presently available commercial emulsion, although emulsions with finer grains might be desirable in some circumstances.

Factors in Photographic Emulsions for Low Dose Electron Crystallography

1980 ◽  
Vol 38 ◽  
pp. 230-231
Author(s):  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
Radiation Damage ◽  
Low Dose ◽  
Damage Effect ◽  
Photographic Emulsion ◽  
Electron Crystallography ◽  
Electron Microscopic ◽  
X Ray ◽  
Signal Contrast ◽  
Diffraction Patterns ◽  
Photographic Emulsions

With the advances in preparing biological materials in a thin and highly ordered form, and in maintaining them hydrated under vacuum, electron crystallography has become an important tool for biological structure investigation at high resolution (1,2). However, the electron radiation damage would limit the capability of recording reflections with low intensities in an electron diffraction pattern. It has been demonstrated that the use of a low temperature stage can reduce the radiation damage effect and that one can expose the specimen with a higher dose in order to increase the signal contrast (3). A further improvement can be made by selecting a proper photographic emulsion. The primary factors in evaluating the suitability of photographic emulsion for recording low dose diffraction patterns are speed, fog level, electron response at low electron exposure, linearity, and usable range of exposure. We have compared these factors with three photographic emulsions including Kodak electron microscopic plate (EMP), Industrex AA x-ray film (AA x-ray) and Kodak nuclear track film (NTB3).

A STATISTICAL THEORY OF APERTURE SYNTHESIS

1967 ◽  
Vol 45 (6) ◽  
pp. 2041-2052
Author(s):  
Ralph J. Gagnon
Keyword(s):  
Point Source ◽  
Random Noise ◽  
Circular Disk ◽  
Brightness Distribution ◽  
Source Distribution ◽  
Base Line ◽  
Fourier Inversion ◽  
Visibility Function ◽  
The Fourier Transform ◽  
Infinite Set

The usual methods of interferometry make use of the Fourier transform relationship which holds between a radio-noise brightness distribution and the complex visibility function which is measured with a pair of antennas. The visibility function is a function of the distance or base line between the antennas. If it were known for all base lines, then the brightness distribution could be found by Fourier inversion. Unfortunately, the visibility function is not known for all base lines and the Fourier inversion is not unique. If the observer wishes to interpret his data by displaying a single possible brightness distribution, then he must choose from the infinite set of brightness distributions which could have produced his data. Previously, the author suggested that this be accomplished by representing the set of possible distributions as a statistical ensemble, and making the choice on a statistical basis so as to minimize the expected mean-square error.In the present communication, the results of the previous paper are presented for the two-dimensional case. The inversion formulas are worked out in detail for the cases of uniform point-source distributions in a square (or rectangle) and in a circular disk, and also for a point-source distribution with a Gaussian envelope taper. It is shown how to extend the point-source results to a distribution of nonpoint sources, and as an example the inversion equations are computed for the case of a distribution of Gaussian-shaped sources distributed with a Gaussian amplitude or density envelope. Finally, the appropriate inversion equations are derived for an observed visibility function which is contaminated with additive zero-mean Gaussian random noise, uncorrelated with the true visibility function.

Effect of various inhibitors on sporulation of Bacillus subtilis crs mutants

1984 ◽  
Vol 30 (11) ◽  
pp. 1337-1343 ◽  
Author(s):  
I. Takahashi ◽  
Dongxu Sun
Keyword(s):  
Bacillus Subtilis ◽  
Microscopic Examination ◽  
Electron Microscopic Examination ◽  
Aliphatic Alcohols ◽  
Wild Type ◽  
Electron Microscopic

The effect of aliphatic alcohols, cerulenin, and NaCl on sporulation of various catabolite-resistant (crs) mutants of Bacillus subtilis was studied. Mutants carrying crsA or crsF mutations were able to sporulate in the presence of these agents. Other crs mutants were resistant to at least one of the inhibitors. Electron microscopic examination revealed that cerulenin blocks sporulation at stage 0 in wild-type cells, suggesting that early sporulation functions are affected by this antibiotic. The results obtained so far suggest that the functions altered in the crs mutants may be related to the membrane.

Acute phase response in exercise. III. Neutrophil and IL-1 beta accumulation in skeletal muscle

1993 ◽  
Vol 265 (1) ◽  
pp. R166-R172 ◽  
Author(s):  
R. A. Fielding ◽  
T. J. Manfredi ◽  
W. Ding ◽  
M. A. Fiatarone ◽  
W. J. Evans ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cross Sections ◽  
Immunohistochemical Staining ◽  
Rating Scale ◽  
Vastus Lateralis ◽  
Interleukin 1 ◽  
Microscopic Analysis ◽  
Neutrophil Infiltration ◽  
Neutrophil Accumulation ◽  
Electron Microscopic

Nine untrained men (22-29 yr) performed 45 min of downhill running (16% incline, 70% of maximum heart rate). Needle biopsies of the vastus lateralis were performed before, 45 min after, and 5 days after exercise. Immunohistochemical staining of muscle cross sections revealed a 135% increase in muscle interleukin-1 beta (IL-1 beta) immediately after and a 250% increase (P < 0.03) 5 days after exercise. Using a rating scale (0-3) for the presence of neutrophils, light microscopic examination showed a significant accumulation of neutrophils in muscle biopsies taken 45 min after and 5 days after exercise [before: 0.5 +/- 0.2, 45 min after: 1.5 +/- 0.3 (P < 0.01), and 5 days after: 1.2 +/- 0.2 (P < 0.04)]. In addition, electron microscopic analysis showed an increase in the percentage of damaged Z-bands relative to total Z-bands [before: 4.8 +/- 3.5%, 45 min after: 32.5 +/- 8.6% (P < 0.05), and 5 days after: 14.1 +/- 3.2%]. Neutrophil accumulation was positively correlated to intracellular Z-band damage (rho = 0.66, P < 0.001). Immunohistochemical staining for IL-1 beta was related to neutrophil accumulation in muscle (rho = 0.38, P < 0.06) and to plasma creatine kinase levels (rho = 0.416, P < 0.04). These data indicate that after eccentric exercise ultrastructural damage to skeletal muscle is associated with neutrophil infiltration and muscle IL-1 beta accumulation.

scholarly journals LOCALIZATION OF MACROMOLECULES IN ESCHERICHIA COLI

1961 ◽  
Vol 9 (3) ◽  
pp. 539-553 ◽  
Author(s):  
Lucien G. Caro
Keyword(s):  
Escherichia Coli ◽  
Poisson Distribution ◽  
Cross Sections ◽  
Morphological Changes ◽  
Nuclear Region ◽  
High Concentration ◽  
Short Pulses ◽  
Thin Sections ◽  
Change Concerns ◽  
Very Short Pulses

If thin sections of Escherichia coli, labeled uniformly with tritium, are radioautographed calculations, based on the distribution of section sizes show that the number of H3 decays per section should be very close to a Poisson distribution. We might, therefore, expect that the distribution of radioautographic grain counts among random cross-sections should follow a Poisson distribution. It can then be inferred that a deviation from a Poisson indicates a high concentration of label in a preferred region. This region can then be identified by analysis of serial section and comparison with electron micrographs. Sections of cells labeled with leucine-H3 gave a Poisson distribution of grain counts, and it was concluded that proteins were distributed fairly uniformly throughout the cell. The situation was not changed if labeled cells were placed in chloramphenicol or if very short pulses of label were used. When Escherichia coli is grown in presence of chloramphenicol a major morphological change concerns the nuclear region: it becomes more regular in outline, nearly spherical, and occupies a smaller proportion of the cell length. The previously described association between DNA labeled with thymidine-H3 and the nuclear region was confirmed by showing that the distribution of the label in the cell followed exactly the morphological changes of the nuclear region. It was also shown that the concentration of DNA in the nuclear region was at least 45 times higher than that of the cytoplasm. Several morphological features of cells grown in chloramphenicol and examined in the electron microscope are discussed.

scholarly journals THE RELATIONSHIP BETWEEN MYOFILAMENT PACKING DENSITY AND SARCOMERE LENGTH IN FROG STRIATED MUSCLE

1967 ◽  
Vol 33 (2) ◽  
pp. 255-263 ◽  
Author(s):  
Philip W. Brandt ◽  
Enrique Lopez ◽  
John P. Reuben ◽  
Harry Grundfest
Keyword(s):  
Cross Sections ◽  
Packing Density ◽  
Sarcomere Length ◽  
Striated Muscle ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Semitendinosus Muscle ◽  
Direct Function ◽  
Microscopic Studies

In cross-sections of single fibers from the frog semitendinosus muscle the number of thick myofilaments per unit area (packing density) is a direct function of the sarcomere length. Our data, derived from electron microscopic studies, fit well with other data derived from in vivo, low-angle X-ray diffraction studies of whole semitendinosus muscles. The data are consistent with the assumption that the sarcomere of a fibril maintains a constant volume during changes in sarcomere length. The myofilament lattice, therefore, expands as the sarcomere shortens. Since the distance between adjacent myofilaments is an inverse square root function of sarcomere length, the interaction of the thick and the thin myofilaments during sarcomere shortening may occur over distances which increase 70 A or more. The "expanding-sarcomere, sliding-filament" model of sarcomere shortening is discussed in terms of the current concepts of muscle architecture and contraction.

scholarly journals The tracks of α -particles and protons in photographic emulsions

1935 ◽  
Vol 150 (870) ◽  
pp. 382-394 ◽  
Keyword(s):  
Large Angle ◽  
Silver Bromide ◽  
Photographic Emulsion ◽  
High Magnification ◽  
Straight Line ◽  
The Subject ◽  
The Individual ◽  
Photographic Emulsions ◽  
Α Particles

1—It has been known for some twenty-five years that when an α -particle passes through a photographic emulsion, the silver bromide grains which it encounters are rendered developable. Kinoshita examined the question in some detail in 1910, and came to the conclusion that, for the emulsions tested, every grain struck by an α -particle can be developed. During the following years Reinganum, Michl, Mayer and others worked on the subject, and showed that after development the track of each separate α -particle is visible, under a high magnification, as a row of developed grains in a straight line. If a spot of radioactive matter, such as radium C, be placed on the surface of a plate, α -particles are emitted in all directions, and produce a halo consisting of a number of tracks radiating from a centre. Photographs of these haloes, and of the individual tracks, were published inter alia by Kinoshita and Ikeuti, and Walmsley and Makower. Some of the large-angle deflections reported by the latter are probably tracks of two separate α -particles arising from the same spot of contamination in the emulsion. In 1925 it was observed by Blau that tracks could also be produced by natural protons ejected from a layer of paraffin by α -particles. It was found, however, that not every grain encountered necessarily becomes developable; owing, doubtless, to the feebler ionization along the path of a proton. This is true at least for the less sensitive emulsions. The protons which result from the disintegration of aluminium when bombarded by α -particles have also been recorded in this way by Blau, and Blau and Wambacher. Furthermore Blau and Wambacher have published results obtained with protons ejected by the passage of neutrons through paraffin, and through the gelatine of the emulsion.

scholarly journals LOCALIZATION OF MACROMOLECULES IN ESCHERICHIA COLI

1961 ◽  
Vol 9 (3) ◽  
pp. 555-565 ◽  
Author(s):  
Lucien G. Caro ◽  
Frederick Forro
Keyword(s):  
Escherichia Coli ◽  
Cross Sections ◽  
Short Pulse ◽  
Large Fraction ◽  
Enzyme Digestion ◽  
Morphological Data ◽  
Nuclear Region ◽  
Serial Sections ◽  
Short Pulses ◽  
E Coli

The distribution of RNA in cells of E. coli 15 T-U- labeled with uridine-H3 was studied by methods involving the analysis of radioautographic grain counts over random thin cross-sections and serial sections of the cells. The results were correlated with electron microscope morphological data. Fractionation and enzyme digestion studies showed that a large proportion of the label was found in RNA uracil and cytosine, the rest being incorporated as DNA cytosine. In fully labeled cells the distribution of label was found to be uniform throughout the cell. The situation remained unchanged when labeled cells were subsequently treated with chloramphenicol. When short pulses of label were employed a localization of a large proportion of the radioactivity became apparent. The nuclear region was identified as the site of concentration. Similar results were obtained when cells were exposed to much longer pulses of uridine-H3 in the presence of chloramphenicol. If cells were subjected to a short pulse of cytidine-H3, then allowed to grow for a while in unlabeled medium, the label, originally concentrated to some extent in the nuclear region, was found dispersed throughout the cell. The simplest hypothesis which accounts for these results is that a large fraction of the cell RNA is synthesized in a region in or near the nucleus and subsequently transferred to the cytoplasm.

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