The electron microscopy of F-actin

Rozsa, G.; Szent‐Györgyi, Albert; Wyckoff, Ralph W. G.

doi:10.1016/0006-3002(49)90130-4

Cited by 51 publications

(9 citation statements)

References 3 publications

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“…Filaments formed from actin in vitro have dimensions, when seen by electron microscopy (17,19), which are close to those found in muscle.…”

Section: Elongation Of the I Bandsupporting

confidence: 56%

Sarcomere Size in Developing Muscles of a Tarsonemid Mite

Aronson

1961

The Journal of Cell Biology

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The embryo ofa tarsonemid mite was found to be suitable for in vivo observations of muscle development by polarization microscopy. The four dorsal muscles of the metapodosoma each contain three sarcomeres, the anterior two of which can be seen clearly. These sarcomeres can be identified and followed during much of their development. Sarcomeres are about 2. 5 micra long when first detected and increase in length until they are about IO micra long. The change in length is associated with a slow, approximately constant rate of increase in the length of the A region, and an initially slow then much more rapid increase in the length of the I band. Preceding the period when the I band elongates rapidly there is an increase in the diameter of the muscle fibers and an increase in the retardation of the A band. A, I, Z, and H bands are visible during most of these changes. The change in A band length has been interpreted in terms of the growth of the A filaments which have been observed by electron microscopy in muscles of other animals. It is suggested that the exceptionally long sarcomeres in this mite result from the early fixing of the number of sarcomeres in a given muscle fiber.The development of the striated muscle sarcomere is poorly understood despite many investigations of muscle differentiation. With light microscopy a uniform filamentous structure has been seen before striations are observable (1-4), but investigations by electron microscopy (5, 6) indicate that the sarcomere period may be present before A bands are detectable. Details of A, I, and H band formation have not been described.Polarization microscopy is especially suitable for the study of some aspects of muscle structure in vivo. Muscles thin enough for good resolution by polarization microscopy, using a rectified (7) lens system, were observed in a tarsonemid mite. During a period of about 36 hours preceding the first contractions, changes in sarcomere length and in A and I band length could be followed in the living animal. METIIODSMites collected and identified by Heinemann 1 as Tarsonemus randsi were kept in culture (8) on Fusarium oxyporum at 25°C. Embryos selected when muscles are first apparent may be flattened, and most will develop and hatch when mounted in mineral oil which has been saturated with water.Observations were made with a X 97, N.A. 1.25, strain-free immersion objective, 2 using a model P-42 American Optical Company polarizing microscope? The substage of this microscope was modified to 1 I am indebted to Mr. Richard Heinemann for a culture of Tarsonemus randsi and for advice on maintaining the culture. 2 American Optical Company. These lenses were specially selected for their strain-free qualities.

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“…Filaments formed from actin in vitro have dimensions, when seen by electron microscopy (17,19), which are close to those found in muscle.…”

Section: Elongation Of the I Bandsupporting

confidence: 56%

Sarcomere Size in Developing Muscles of a Tarsonemid Mite

Aronson

1961

The Journal of Cell Biology

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“…A similar example of increasing the practical resolution of the electron micrographs by using negative staining is the demonstration of the isolated actin filaments by Hanson and Lowy (24). These authors showed two helically wound strands composed of spherical subunits forming the filament, whereas with the shadow casting method, in spite of high technical performance, Rozsa, Szent-GySrgyi, and Wyckoff (25) could not see the detailed structure.…”

Section: Discussionmentioning

confidence: 99%

An Electron Microscope Examination of Urinary Mucoprotein and Its Interaction With Influenza Virus

Bayer

1964

The Journal of Cell Biology

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A hemagglutination-inhibitory mucoprotein from h u m a n urine has been studied with the electron microscope. It consists of filaments, with diameters of 40 to > 2 4 0 A , composed of smaller fibrils. In the two-dimensional projection of the electron micrographs, the single fibrils often show a zig-zag course with a periodicity of 100 to 140 A; the single branch of a zigzag measures about 60 A in length and either 20 or 40 A in width. Still thinner fibrillar elements are observable with diameters of l0 A or less. In three-dimensional aspect, the zig-zag structure might be a helix. The fibril-bundle (or filament) reveals a complicated configuration. Heat treatment at 70°C shows some indication of denaturation (e.g. filaments are shorter), whereas at 80°C almost complete degradation of the protein into individual zig-zag elements or smaller pieces is attained. The interaction between influenza virus particles and inhibitory mucoprotein consists of the attachment of a fiber molecule to the virus projections at several sites and frequently on more than one virus particle.

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“…Astbury (1947), among others (see Corey and Wyckoff, 1936), has also considered the possibility of particulate aggregation, but suggestions of this type have remained nebulous. While perhaps not strictly fibrous, the tobacco mosaic virus gels, studied by Bernal and Fankuchen (1941) by X-ray means and recently by Wyckoff (1949) with the electron microscope, offer one of the outstanding examples of this type of organization. Even with this excellent case as a guide, and with detailed diffraction data available, it has not always been immediately apparent as to how this view was to be adapted for the true protein fibers.…”

Section: Small-angle Dijraclion By Keratin Fibersmentioning

confidence: 99%

“…Of direct bearing on the keratin-myosin clase of fibrous proteins are the results with the actin of muscles, which readily undergoes a globular. fibrous transformation (Straub, 1943) that can be followed with the electron microscope Astbury, Perry, Reed, and Spark, 1947;Rozsa, Szent-Gyorgyi, and Wyckoff, 1949). Bailey (1949) has described tropomyosin, which he regards as a large globular monomer of myosin, suggesting also that similar particulate units are present in the keratins as well (see also Astbury, Reed and Spark, 1948).…”

mentioning

confidence: 99%