On the adaptation of autoradiographic techniques for use with the electron microscope

Pelc, S. R.; Coombes, Jason D.; Budd, G. C.

doi:10.1016/0014-4827(61)90272-5

Cited by 69 publications

(23 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…By using thin sections of tissue labeled with tritium and thin layers of fine grain emulsions (Ilford K-5 and L-4), we have obtained autoradiographic resolutions at the subcellular level with little loss in image quality (5,6). Comparable results have been obtained by several authors (7)(8)(9)(10).…”

Section: Introductionsupporting

confidence: 78%

High-Resolution Autoradiogaphy

Lucien

1962

The Journal of Cell Biology

197

View full text Add to dashboard Cite

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-H 3. The two distributions agreed closely. It was also verified, using the nuclear region in thin cross-sections of Bacillus subtilis labeled with thymidine-H 3, that resolutions of the same order were obtained for extended sources.

show abstract

Section: Introductionsupporting

confidence: 78%

High-Resolution Autoradiogaphy

Lucien

1962

The Journal of Cell Biology

197

View full text Add to dashboard Cite

show abstract

“…These two factors considerably reduce the resolution of autoradiographs. The need for multiple ionizations within a AgBr grain to make it capable of being developed and the effects of electron scattering facilitate resolution, however, to the point where localization of Ca4" within a sarcomere is possible (14,15).…”

Section: Theoreticalmentioning

confidence: 99%

“…Since ionizations occur with a certain frequency per unit path length an electron must have a certain minimum path length within the grain to produce the required ionizations. Pelc (15) has estimated that the path of a 0.15 Mev electron must be at least 1000 A for one of the more sensitive grains. It would have to be longer for the 0.25 Mev electron emitted by Ca 4 6.…”

Section: Theoreticalmentioning

confidence: 99%

Autoradiographic Studies of Intracellular Calcium in Frog Skeletal Muscle

Winegrad

1965

The Journal of General Physiology

126

View full text Add to dashboard Cite

Autoradiographs consisting of a 1000 A thick tissue section and a 1400 A thick emulsion film have been prepared from frog toe muscles labeled with Ca 45 . The muscles had been fixed with an oxalate-containing osmium solution at rest at room temperature, at rest at 4 0°C , during relaxation following K+ depolarization or after prolonged depolarization. From 6 to 39 per cent of K+ contracture tension was produced during fixation. The grains in the autoradiographs were always concentrated in the center 0.2 to 0.3 /A of the I band and the region of the overlapping of the thick and thin filaments. The greater the tension produced during fixation, the greater was the concentration in the A band and the smaller the concentration in the I band. Autoradiographs of two muscles fixed by freeze-substitution resembled those of muscles which produced little tension during osmium fixation. Muscles which shortened during fixation produced fewer grains. In the narrow (<2.0 /j) sarcomeres of the shortened muscles, grain density decreased with decreasing sarcomere width. A theoretical analysis of the significance of these grain distributions is proposed and discussed.A considerable body of evidence has been accumulated to suggest that calcium plays a critical role in excitation-contraction coupling in muscle. Small amounts of calcium are necessary for maximum contraction and maximum adenosine-triphosphatase activity in muscle models (1, 31) Associated with contraction of intact muscle fibers there is an accelerated exchange of calcium probably involving both membrane and intracellular calcium (2, 3). Hill has shown on theoretical grounds that insufficient time exists between membrane depolarization and muscle activation for a substance to diffuse from the cell surface to the cell center (4). Therefore, the "activator" which directly initiates the contraction must either be transmitted by a process faster than diffusion or must be stored inside the cell at a site near the contractile proteins. Huxley and Taylor have shown that the membrane excitation may be con-455

show abstract

“…Ultrathin sections on 200-mesh Formvar-coated grids were attached to glass slides which were then evenly coated with a preformed gel layer of Ilford L4 photographic emulsion applied with a loop (Pelc, Coombes and Budd, 1961 ;Caro, van Tubergen and Kolb, 1962). The slides were incubated with a drying agent for 14-21 days at 4"C, and then developed with Kodak Microdol X for 3 min., fixed in acid fixative for 7 min.…”

Section: Autoradiographymentioning

confidence: 99%