scholarly journals MITOSIS AND INTERMEDIATE-SIZED FILAMENTS IN DEVELOPING SKELETAL MUSCLE

1968 ◽  
Vol 38 (3) ◽  
pp. 538-555 ◽  
Author(s):  
H. Ishikawa ◽  
R. Bischoff ◽  
H. Holtzer
Keyword(s):  
Skeletal Muscle ◽  
Chick Embryos ◽  
Myogenic Cells ◽  
Thin Filaments ◽  
New Class ◽  
Single Section ◽  
Myosin Filaments ◽  
Obvious Association ◽  
Mitotic Inhibitors ◽  
Cells Cultured

A new class of filaments intermediate in diameter between actin and myosin filaments has been demonstrated in skeletal muscle cells cultured from chick embryos. These filaments, which account for the majority of free filaments, average 100 A in diameter. They may run for more than 2 µ in a single section and can be distinguished in size and appearance from the thick and thin filaments assembled into myofibrils. The 100-A filaments are seen scattered throughout the sarcoplasm at all stages of development and show no obvious association with the myofibrils. The 100-A filaments are particularly conspicuous in myotubes fragmented by the mitotic inhibitors, colchicine and Colcemid. In addition, filaments similar in size and appearance to those found in myotubes are present in fibroblasts, chondrocytes, and proliferating mononucleated myoblasts. The 100-A filaments are present in cells arrested in metaphase by mitotic inhibitors. Definitive thick (about 150 A) or thin (about 60 A) myofilaments are not found in skeletal myogenic cells arrested in metaphase. Myogenic cells arrested in metaphase do not bind fluorescein-labeled antibody directed against myosin or actin. For these reasons, it is concluded that not all "thin" filaments in myogenic cells are uniquely associated with myogenesis.

scholarly journals Connectin filaments in stretched skinned fibers of frog skeletal muscle.

1984 ◽  
Vol 99 (4) ◽  
pp. 1391-1397 ◽  
Author(s):  
K Maruyama ◽  
H Sawada ◽  
S Kimura ◽  
K Ohashi ◽  
H Higuchi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Electron Microscopic ◽  
Thin Filaments ◽  
Thin Sections ◽  
Cytoskeletal Structure ◽  
Present Information ◽  
Sds Page ◽  
Myosin Filaments ◽  
Elastic Protein ◽  
Passive Stretch

Indirect immunofluorescence microscopy of highly stretched skinned frog semi-tendinous muscle fibers revealed that connectin, an elastic protein of muscle, is located in the gap between actin and myosin filaments and also in the region of myosin filaments except in their centers. Electron microscopic observations showed that there were easily recognizable filaments extending from the myosin filaments to the I band region and to Z lines in the myofibrils treated with antiserum against connectin. In thin sections prepared with tannic acid, very thin filaments connected myosin filaments to actin filaments. These filaments were also observed in myofibrils extracted with a modified Hasselbach-Schneider solution (0.6 M KCl, 0.1 M phosphate buffer, pH 6.5, 2 mM ATP, 2 mM MgCl2, and 1 mM EGTA) and with 0.6 M Kl. SDS PAGE revealed that connectin (also called titin) remained in extracted myofibrils. We suggest that connectin filaments play an important role in the generation of tension upon passive stretch. A scheme of the cytoskeletal structure of myofibrils of vertebrate skeletal muscle is presented on the basis of our present information of connectin and intermediate filaments.

scholarly journals In situ reconstitution of myosin filaments within the myosin-extracted myofibril in cultured skeletal muscle cells.

1982 ◽  
Vol 92 (2) ◽  
pp. 324-332 ◽  
Author(s):  
M Taniguchi ◽  
H Ishikawa
Keyword(s):  
Skeletal Muscle ◽  
Salt Solution ◽  
Muscle Cells ◽  
High Salt ◽  
Skeletal Muscle Cells ◽  
Thin Filaments ◽  
Skeletal Muscle Myosin ◽  
Myosin Filaments ◽  
Glycerinated Muscle

We studied the in situ reconstitution of myosin filaments within the myosin-extracted myofibrils in cultured chick embryo skeletal muscle cells using the electron microscope and polarization microscope. Myosin was first extracted from the myofibrils in glycerinated muscle cells with a high-salt solution containing 0.6 M KCl. When rabbit skeletal muscle myosin was added to the myosin-extracted cells in the high-salt solution, thin filaments in the ghost myofibrils were bound with myosin to form arrowhead complexes. Subsequent dilution of KCl in the myosin solution to 0.1 M resulted in the formation of thick myosin filaments within the myofibrils, increasing the birefringence of the myofibrils. When Mg-ATP was added such myosin-reassembled myofibrils were induced either to form supercontraction bands or to restore the sarcomeric arrangement of thick and thin filaments. Under the polarization microscope, vibrational movement of the myofibrils was seen transiently upon addition of Mg-ATP, often resulting in a regular arrangement of myofibrils in register. These myofibrils, with reconstituted myosin filaments, structurally and functionally resembled the native myofibrils. The findings are discussed with special reference to the myofibril formation in developing muscle cells.

scholarly journals Electron microscopy of synthetic myosin filaments. Evidence for cross-bridge. Flexibility and copolymer formation.

1975 ◽  
Vol 67 (1) ◽  
pp. 93-104 ◽  
Author(s):  
T D Pollard
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Structural Features ◽  
Length Frequency ◽  
Single Population ◽  
Skeletal Muscle Myosin ◽  
Distinctive Features ◽  
Myosin Filaments ◽  
The Mean ◽  
Muscle Myosin

Electron micrographs of negatively stained synthetic myosin filaments reveal that surface projections, believed to be the heads of the constituent myosin molecules, can exist in two configurations. Some filaments have the projections disposed close to the filament backbone. Other filaments have all of their projections widely spread, tethered to the backbone by slender threads. Filaments formed from the myosins of skeletal muscle, smooth muscle, and platelets each have distinctive features, particularly their lengths. Soluble mixtures of skeletal muscle myosin with either smooth muscle myosin or platelet myosin were dialyzed against 0.1 M KC1 at pH 7 to determine whether the simultaneous presence of two types of myosin would influence the properties of the filaments formed. In every case, a single population of filaments formed from the mixtures. The resulting filaments are thought to be copolymers of the two types of myosin, for several reasons: (a) their length-frequency distribution is unimodal and differs from that predicted for a simple mixture of two types of myosin filaments; (b) their mean length is intermediate between the mean lengths of the filaments formed separately from the two myosins in the mixture; (c) each of the filaments has structural features characteristic of both of the myosins in the mixture; and (d) their size and shape are determined by the proportion of the two myosins in the mixture.

scholarly journals The Intracellular Site of Calcium Activation of Contraction in Frog Skeletal Muscle

1970 ◽  
Vol 55 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Saul Winegrad
Keyword(s):  
Skeletal Muscle ◽  
Room Temperature ◽  
Half Time ◽  
Frog Skeletal Muscle ◽  
Calcium Efflux ◽  
Transverse Tubules ◽  
Calcium Activation ◽  
Thin Filaments ◽  
Almost All ◽  
Terminal Cisternae

Radioautography has been used to localize 45Ca in isotopically labeled frog skeletal muscle fibers which had been quickly frozen during a maintained tetanus, a declining tetanus, or during the period immediately following a tetanus or a contracture. During a tetanus almost all of the myofibrillar 45Ca is localized in the region of the sarcomere occupied by the thin filaments. The amount varies with the tension being developed by the muscle. The movement of calcium within the reticulum from the tubular portion to the terminal cisternae during the posttetanic period has a half-time of about 9 sec at room temperature and a Q10 of about 1.7. Repolarization is not necessary for this movement. Evidence is given to support the notion that most calcium efflux from the cell occurs from the terminal cisternae into the transverse tubules.

Calcium-induced movement of troponin-I relative to actin in skeletal muscle thin filaments

Science ◽  
1990 ◽  
Vol 247 (4948) ◽  
pp. 1339-1341 ◽  
Author(s):  
T Tao ◽  
B. Gong ◽  
P. Leavis
Keyword(s):  
Skeletal Muscle ◽  
Troponin I ◽  
Thin Filaments

Effect of taxol on the interaction of tubulin with myosin filaments

1984 ◽  
Vol 62 (9) ◽  
pp. 878-884 ◽  
Author(s):  
Toshihiro Fujii ◽  
Tatsuo Suzuki ◽  
Akira Hachimori ◽  
Michiyo Fujii ◽  
Yoshiyuki Kondo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Atpase Activity ◽  
Cross Section ◽  
Molar Ratio ◽  
Tubulin Polymerization ◽  
Myosin Filaments ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The interaction between polymerized tubulin from porcine brain and myosin from rabbit skeletal muscle was examined. The addition of myosin to the solution of tubulin polymerized by taxol resulted in a remarkable increase in turbidity within a few minutes at 37 °C, and a dense and stable precipitate was formed. The maximal molar ratio of tubulin bound to myosin was calculated to be about 4, while the value was about 2 when 6S tubulin was used. Both podophyllotoxin and colchicine suppressed the taxol-dependent increase of the binding of tubulin to myosin, but only when they were preincubated with tubulin prior to addition of taxol. 6S tubulin inhibited with aetin-activated Mg2+-ATPase activity of myosin, and polymerized tubulin inhibited the Mg-ATPase more than 6S tubulin. Dense precipitates of tubulin and myosin were observed by thin-section electron microscopy. Microtubules were observed to be entangled in myosin filaments and single microtubules were occasionally surrounded by five myosin filaments in a cross section, similar to actin–myosin arrays in muscle. After incubation of tubulin with myosin, taxol was able to induce tubulin polymerization in the same way as it polymerized microtubules in the absence of myosin.

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