scholarly journals Connectin filaments link thick filaments and Z lines in frog skeletal muscle as revealed by immunoelectron microscopy.

1985 ◽  
Vol 101 (6) ◽  
pp. 2167-2172 ◽  
Author(s):  
K Maruyama ◽  
T Yoshioka ◽  
H Higuchi ◽  
K Ohashi ◽  
S Kimura ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Microscopic Study ◽  
Immunoelectron Microscopy ◽  
Striated Muscle ◽  
Polyclonal Antibodies ◽  
Frog Skeletal Muscle ◽  
Junction Region ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Elastic Protein

In an earlier study connectin, an elastic protein of striated muscle, was found to be associated with "gap filaments" originating from the thick filaments in the myofibril, but it was not clear whether it extends to Z lines or not (Maruyama, K., H. Sawada, S. Kimura, K. Ohashi, H. Higuchi, and Y. Umazume, 1984, J. Cell Biol., 99:1391-1397). In the present immunoelectron microscopic study using polyclonal antibodies against native connectin, we have concluded that the connectin structures are directly linked to Z lines from the thick (myosin) filaments in myofibrils of skinned fibers of frog skeletal muscle. There were five distinct antibody-binding stripes in each half of the A band and two stripes in the A-I junction region. Deposits of antibodies were recognized in I bands and Z lines. We suggest that connectin filaments run alongside the thick filaments, starting from a region approximately 0.15 micron from the center of the A band.

scholarly journals LOCALIZATION OF MYOSIN FILAMENTS IN SMOOTH MUSCLE

1968 ◽  
Vol 37 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Robert E. Kelly ◽  
Robert V. Rice
Keyword(s):  
Smooth Muscle ◽  
Cross Section ◽  
Striated Muscle ◽  
Thick Filament ◽  
Longitudinal Axis ◽  
Thin Filaments ◽  
Chicken Gizzard ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Muscle Myosin

Thick myosin filaments, in addition to actin filaments, were found in sections of glycerinated chicken gizzard smooth muscle when fixed at a pH below 6.6. The thick filaments were often grouped into bundles and run in the longitudinal axis of the smooth muscle cell. Each thick filament was surrounded by a number of thin filaments, giving the filament arrangement a rosette appearance in cross-section. The exact ratio of thick filaments to thin filaments could not be determined since most arrays were not so regular as those commonly found in striated muscle. Some rosettes had seven or eight thin filaments surrounding a single thick filament. Homogenates of smooth muscle of chicken gizzard also showed both thick and thin filaments when the isolation was carried out at a pH below 6.6, but only thin filaments were found at pH 7.4. No Z or M lines were observed in chicken gizzard muscle containing both thick and thin filaments. The lack of these organizing structures may allow smooth muscle myosin to disaggregate readily at pH 7.4.

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 Relaxed tarantula skeletal muscle has two ATP energy-saving mechanisms

2021 ◽  
Vol 153 (3) ◽  
Author(s):  
Weikang Ma ◽  
Sebastian Duno-Miranda ◽  
Thomas Irving ◽  
Roger Craig ◽  
Raúl Padrón
Keyword(s):  
Skeletal Muscle ◽  
Energy Saving ◽  
Striated Muscle ◽  
Mammalian Skeletal Muscle ◽  
X Ray Diffraction ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Refractory State ◽  
Increasing Temperature ◽  
Induced Changes

Myosin molecules in the relaxed thick filaments of striated muscle have a helical arrangement in which the heads of each molecule interact with each other, forming the interacting-heads motif (IHM). In relaxed mammalian skeletal muscle, this helical ordering occurs only at temperatures >20°C and is disrupted when temperature is decreased. Recent x-ray diffraction studies of live tarantula skeletal muscle have suggested that the two myosin heads of the IHM (blocked heads [BHs] and free heads [FHs]) have very different roles and dynamics during contraction. Here, we explore temperature-induced changes in the BHs and FHs in relaxed tarantula skeletal muscle. We find a change with decreasing temperature that is similar to that in mammals, while increasing temperature induces a different behavior in the heads. At 22.5°C, the BHs and FHs containing ADP.Pi are fully helically organized, but they become progressively disordered as temperature is lowered or raised. Our interpretation suggests that at low temperature, while the BHs remain ordered the FHs become disordered due to transition of the heads to a straight conformation containing Mg.ATP. Above 27.5°C, the nucleotide remains as ADP.Pi, but while BHs remain ordered, half of the FHs become progressively disordered, released semipermanently at a midway distance to the thin filaments while the remaining FHs are docked as swaying heads. We propose a thermosensing mechanism for tarantula skeletal muscle to explain these changes. Our results suggest that tarantula skeletal muscle thick filaments, in addition to having a superrelaxation–based ATP energy-saving mechanism in the range of 8.5–40°C, also exhibit energy saving at lower temperatures (<22.5°C), similar to the proposed refractory state in mammals.

A HISTOCHEMICAL AND ELECTRON MICROSCOPIC STUDY OF SKELETAL MUSCLE IN A CASE OF POMPE'S DISEASE (GLYCOGENOSIS II)

PEDIATRICS ◽  
1966 ◽  
Vol 37 (2) ◽  
pp. 249-259
Author(s):  
Robert Darrell Cardiff
Keyword(s):  
Skeletal Muscle ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Striated Muscle ◽  
Electron Microscopic ◽  
Pompe’S Disease ◽  
Pompe's Disease ◽  
Microscopic Studies ◽  
Alpha Glucosidase ◽  
Glycogenosis Ii

1. A case of Pompe's disease (glycogenosis II) without biochemically or histochemically demonstrable alpha-glucosidase activity is described. 2. Histochemical studies of skeletal muscle suggested that the glycogen is frequently stored as an acid mucopolysaccharide. 3. Electron microscopic studies revealed that the major glycogen deposits in most tissue were within membrane-limited sacs. Striated muscle was an exception because major deposits were frequently extrasaccular. 4. The findings in this case are discussed in relation to current concepts of Pompe's disease. In view of the extrasaccular glycogen deposits in skeletal muscle, it is suggested that an extralysosomal factor plays a significant role in the pathogenesis of Pompe's disease.

scholarly journals Elastic behavior of connectin filaments during thick filament movement in activated skeletal muscle.

1989 ◽  
Vol 109 (5) ◽  
pp. 2169-2176 ◽  
Author(s):  
R Horowits ◽  
K Maruyama ◽  
R J Podolsky
Keyword(s):  
Skeletal Muscle ◽  
Calcium Ions ◽  
Striated Muscle ◽  
Muscle Protein ◽  
Thick Filament ◽  
Elastic Behavior ◽  
Constant Length ◽  
Thick Filaments ◽  
Band Spacing ◽  
Antibody Label

Connectin (also called titin) is a huge, striated muscle protein that binds to thick filaments and links them to the Z-disc. Using an mAb that binds to connectin in the I-band region of the molecule, we studied the behavior of connectin in both relaxed and activated skinned rabbit psoas fibers by immunoelectron microscopy. In relaxed fibers, antibody binding is visualized as two extra striations per sarcomere arranged symmetrically about the M-line. These striations move away from both the nearest Z-disc and the thick filaments when the sarcomere is stretched, confirming the elastic behavior of connectin within the I-band of relaxed sarcomeres as previously observed by several investigators. When the fiber is activated, thick filaments in sarcomeres shorter than 2.8 microns tend to move from the center to the side of the sarcomere. This translocation of thick filaments within the sarcomere is accompanied by movement of the antibody label in the same direction. In that half-sarcomere in which the thick filaments move away from the Z-disc, the spacings between the Z-disc and the antibody and between the antibody and the thick filaments both increase. Conversely, on the side of the sarcomere in which the thick filaments move nearer to the Z-line, these spacings decrease. Regardless of whether I-band spacing is varied by stretch of a relaxed sarcomere or by active sliding of thick filaments within a sarcomere of constant length, the spacings between the Z-line and the antibody and between the antibody and the thick filaments increase with I-band length identically. These results indicate that the connectin filaments remain bound to the thick filaments in active fibers, and that the elastic properties of connectin are unaltered by calcium ions and cross-bridge activity.

The site and state of myosin in intestinal smooth muscle

1973 ◽  
Vol 265 (867) ◽  
pp. 219-222 ◽  
Keyword(s):  
Smooth Muscle ◽  
Cross Sections ◽  
Striated Muscle ◽  
Mechanical Tension ◽  
Constant Length ◽  
Substantial Modification ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Resting Muscle ◽  
Longitudinal Layer

The longitudinal layer of the guinea-pig ileum represents a highly advantageous specimen for the study of vertebrate smooth muscle structure. In this muscle we regularly observed thick filaments, consisting presumably of myosin, in longitudinal as well as in cross-sections, if the samples were fixed at constant length, i.e. standing under mechanical tension. Thick filaments were regularly present also in muscles relaxed by atropine. On the other hand, thick filaments were absent in many cases in slack muscles in K+ contracture. As a consequence, we regard myosin filaments as regular constituents of smooth muscle, independently of the functional state. Their absence in electronmicrographs taken from slack muscles seems an artefact due to processing. We observed the same artefact in bee-wing muscle, i.e. in a striated muscle, too. This fact indicates the importance of mechanical tension and polymer crystallization in the survival of myosin filaments. On the basis of a recent work of Ladik, Biczó and Garamvölgyi we discuss how tension may be exerted on the myosin filaments of the resting muscle. Anyway, the sliding model seems valid also for vertebrate smooth muscle, without any substantial modification.

scholarly journals Recent X-ray Diffraction and Electron Microscope Studies of Striated Muscle

1967 ◽  
Vol 50 (6) ◽  
pp. 71-83 ◽  
Author(s):  
H. E. Huxley
Keyword(s):  
Active Sites ◽  
Striated Muscle ◽  
Structural Features ◽  
Actin Binding ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
The Cross ◽  
Cross Bridges

The sliding filament model for muscular contraction supposes that an appropriately directed force is developed between the actin and myosin filaments by some process in which the cross-bridges are involved. The cross-bridges between the filaments are believed to represent the parts of the myosin molecules which possess the active sites for ATPase activity and actin-binding ability, and project out sidewise from the backbone of the thick filaments. The arrangement of the cross-bridges is now being studied by improved low-angle X-ray diffraction techniques, which show that in a resting muscle, they are arranged approximately but not exactly in a helical pattern, and that there are other structural features of the thick filaments which give rise to additional long periodicities shown up by the X-ray diagram. The actin filaments also contain helically arranged subunits, and both the subunit repeat and the helical repeat are different from those in the myosin filaments. Diffraction diagrams can be obtained from muscles in rigor (when permanent attachment of the cross-bridges to the actin subunits takes place) and now, taking advantage of the great increase in the speed of recording, from actively contracting muscles. These show that changes in the arrangement of the cross-bridges are produced under both these conditions and are no doubt associated in contraction with the development of force. Thus configurational changes of the myosin component in muscle have been demonstrated: these take place without any significant over-all change in the length of the filaments.

Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers

1977 ◽  
Vol 35 ◽  
pp. 576-577
Author(s):  
Joachim R. Sommer ◽  
Nancy R. Wallace
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Granular Material ◽  
Nuclear Envelope ◽  
Intracellular Calcium ◽  
Ruthenium Red ◽  
Threshold Concentration ◽  
Rapid Freezing ◽  
Frog Skeletal Muscle ◽  
Electrical Isolation

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.

Electron Probe Analysis of Muscle

1982 ◽  
Vol 40 ◽  
pp. 398-401
Author(s):  
A. V. Somlyo ◽  
H. Shuman ◽  
A. P. Somlyo
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Resting State ◽  
Binding Sites ◽  
Electron Probe ◽  
Frog Skeletal Muscle ◽  
Electron Probe Analysis ◽  
Probe Analysis

Electron probe analysis of frozen dried cryosections of frog skeletal muscle, rabbit vascular smooth muscle and of isolated, hyperpermeab1 e rabbit cardiac myocytes has been used to determine the composition of the cytoplasm and organelles in the resting state as well as during contraction. The concentration of elements within the organelles reflects the permeabilities of the organelle membranes to the cytoplasmic ions as well as binding sites. The measurements of [Ca] in the sarcoplasmic reticulum (SR) and mitochondria at rest and during contraction, have direct bearing on their role as release and/or storage sites for Ca in situ.

Sign in / Sign up

Export Citation Format

Share Document