scholarly journals Polymorphism of myofibrillar proteins of rabbit skeletal-muscle fibres. An electrophoretic study of single fibres

1982 ◽  
Vol 207 (2) ◽  
pp. 261-272 ◽  
Author(s):  
G Salviati ◽  
R Betto ◽  
D Danieli Betto
Keyword(s):  
Light Chain ◽  
Light Chains ◽  
Muscle Fibres ◽  
Myofibrillar Proteins ◽  
Myosin Heavy Chains ◽  
Heavy Chains ◽  
Single Fibres ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Slow Twitch Fibre

Rabbit predominantly fast-twitch-fibre and predominantly slow-twitch-fibre skeletal muscles of the hind limbs, the psoas, the diaphragm and the masseter muscles were fibre-typed by one-dimensional polyacrylamide-gel electrophoresis of the myofibrillar proteins of chemically skinned single fibres. Investigation of the distribution of fast-twitch-fibre and slow-twitch-fibre isoforms of myosin light chains and the type of myosin heavy chains, based on peptide ‘maps’ published in Cleveland. Fischer, Kirschner & Laemmli [(1977) J. Biol. Chem. 252, 1102-1106], allowed a classification of muscle fibres into four classes, corresponding to histochemical types I, IIA, IIB and IIC. Type I fibres with a pure slow-twitch-type of myosin were found to be characterized by a unique set of isoforms of troponins I, C and T, in agreement with the immunological data of Dhoot & Perry [(1979) Nature (London) 278, 714-718], by predominance of the beta-tropomyosin subunit and by the presence of a small amount of an additional tropomyosin subunit, apparently dissimilar from fast-twitch-fibre alpha-tropomyosin subunit. The myofibrillar composition of type IIB fast-twitch white fibres was the mirror image of that found for slow-twitch fibres in that the fast-twitch-fibre isoforms only of the troponin subunits were present and the alpha-tropomyosin subunit predominated. Type IIA fast-twitch red fibres showed a troponin subunit composition identical with that of type IIB fast-twitch white fibres. On the other hand, a unique type of myosin heavy chains was found to be associated with type IIA fibres. Furthermore, the myosin light-chain composition of these fibres was invariably characterized by a small amount of LC3F light chain and by a pattern that was either a pure fast-twitch-fibre light-chain pattern or a hybrid LC1F/LC2F/LC3F/LC1Sb light-chain pattern. By these criteria type IIA fibres could be distinguished from type IIC intermediate fibres, which showed coexistence of fast-twitch-fibre and slow-twitch-fibre forms of myosin light chains and of troponin subunits.

scholarly journals Myosin content of individual human muscle fibers isolated by laser capture microdissection

2016 ◽  
Vol 310 (5) ◽  
pp. C381-C389 ◽  
Author(s):  
Charles A. Stuart ◽  
William L. Stone ◽  
Mary E. A. Howell ◽  
Marianne F. Brannon ◽  
H. Kenton Hall ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Type I ◽  
Fiber Types ◽  
Myosin Heavy Chains ◽  
Heavy Chains ◽  
Slow Twitch ◽  
Type I Fibers ◽  
Fast Twitch ◽  
Laser Capture

Muscle fiber composition correlates with insulin resistance, and exercise training can increase slow-twitch (type I) fibers and, thereby, mitigate diabetes risk. Human skeletal muscle is made up of three distinct fiber types, but muscle contains many more isoforms of myosin heavy and light chains, which are coded by 15 and 11 different genes, respectively. Laser capture microdissection techniques allow assessment of mRNA and protein content in individual fibers. We found that specific human fiber types contain different mixtures of myosin heavy and light chains. Fast-twitch (type IIx) fibers consistently contained myosin heavy chains 1, 2, and 4 and myosin light chain 1. Type I fibers always contained myosin heavy chains 6 and 7 (MYH6 and MYH7) and myosin light chain 3 (MYL3), whereas MYH6, MYH7, and MYL3 were nearly absent from type IIx fibers. In contrast to cardiomyocytes, where MYH6 (also known as α-myosin heavy chain) is seen solely in fast-twitch cells, only slow-twitch fibers of skeletal muscle contained MYH6. Classical fast myosin heavy chains (MHC1, MHC2, and MHC4) were present in variable proportions in all fiber types, but significant MYH6 and MYH7 expression indicated slow-twitch phenotype, and the absence of these two isoforms determined a fast-twitch phenotype. The mixed myosin heavy and light chain content of type IIa fibers was consistent with its role as a transition between fast and slow phenotypes. These new observations suggest that the presence or absence of MYH6 and MYH7 proteins dictates the slow- or fast-twitch phenotype in skeletal muscle.

scholarly journals Relative synthesis of cardiac contractile proteins. Evidence for synthesis from the same precursor pool

1981 ◽  
Vol 194 (3) ◽  
pp. 673-678 ◽  
Author(s):  
C D Evans ◽  
S S Schreiber ◽  
M Oratz ◽  
M A Rothschild
Keyword(s):  
Light Chain ◽  
Contractile Proteins ◽  
Light Chains ◽  
Myosin Heavy Chains ◽  
Perfused Heart ◽  
Precursor Pool ◽  
Heavy Chains ◽  
Cardiac Contractile ◽  
Specific Activities ◽  
Cardiac Contractile Proteins

The relative molar synthesis of cardiac contractile proteins has been measured in the perfused heart under control haemodynamic conditions. This synthesis, of myosin heavy chains, individual light chains (1 and 2), actin and tropomyosin, was determined from isolated guinea-pig hearts perfused for 3h simultaneously with constant specific radioactivities and concentrations of [3H]lysine and [3H]phenylalanine.The data strongly suggest that all of the proteins studied were synthesized from the same precursor pools of lysine and phenylalanine, since the ratio of the specific activities of the two labels was the same in all of the proteins. Measurement of molar synthesis of each contractile protein was the same with either labelled amino acid. Under control haemodynamic-perfusion conditions, the relative molar synthesis of the contractile proteins was actin greater than heavy chains greater than light chain 2 greater than light chain 1 greater than tropomyosin.

Muscle sarcomere lesions and thrombosis after spaceflight and suspension unloading

1992 ◽  
Vol 73 (2) ◽  
pp. S33-S43 ◽  
Author(s):  
D. A. Riley ◽  
S. Ellis ◽  
C. S. Giometti ◽  
J. F. Hoh ◽  
E. I. Ilyina-Kakueva ◽  
...  
Keyword(s):  
Weight Bearing ◽  
Eccentric Contraction ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Myosin Isoforms ◽  
Myofibrillar Proteins ◽  
Fatty Acid Binding ◽  
Fast Myosin ◽  
Slow Twitch ◽  
Fast Twitch

Spaceflight (flight) and tail suspension-hindlimb unloading (unloaded) produced significant decreases in fiber cross-sectional areas of the adductor longus (AL), a slow-twitch antigravity muscle. However, the mean wet weight of the flight AL muscles was near normal, whereas that of the suspension unloaded AL muscles was significantly reduced. Interstitial edema within the flight AL, but not in the unloaded AL, appeared to account for this apparent disagreement. In both experimental conditions, the slow-twitch oxidative fibers atrophied more than the fast-twitch oxidative-glycolytic and fast-twitch glycolytic fibers. Immunostaining showed that slow-twitch oxidative fibers expressed fast myosin, producing hybrid fibers containing slow and fast myosin isoforms. Two-dimensional gel electrophoresis of flight AL muscles revealed increased content of fast myosin light chains and decreased amounts of slow myosin light chains and fatty acid-binding protein. In the flight AL, absolute mitochondrial content decreased, but the relatively greater breakdown of myofibrillar proteins maintained mitochondrial concentration near normal in the central intermyofibrillar regions of fibers. Subsarcolemmal mitochondria were preferentially lost and reduced below normal concentration. Elevated fiber immunostaining for ubiquitin conjugates was suggestive of ubiquitin-mediated breakdown of myofibrillar proteins. On return to weight bearing for 8–11 h, the weakened atrophic muscles exhibited eccentric contraction-like lesions (hyperextension of sarcomeres with A-band filaments pulled apart and fragmented), tearing of the supporting connective tissue, and thrombosis of the microcirculation. Segmental necrosis of muscle fibers, denervation of neuromuscular junctions, and extravasation of red blood cells were minimal. Lymphocyte antibody markers did not indicate a significant immune reaction. The flight AL exhibited threefold more eccentric-like lesions than the unloaded AL; the high reentry G forces experienced by the flight animals, but not the unloaded group, possibly accounted for this difference. Muscle atrophy appears to increase the susceptibility to form eccentric contraction-like lesions after reloading; this may reflect weakening of the myofibrils and extracellular matrix. Microcirculation was also compromised by spaceflight, such that there was increased formation of thrombi in the post-capillary venules and capillaries. This blockage led to edema by 8–11 h after resumption of weight bearing by the COSMOS 2044 rats. The present findings indicate that defective microcirculation most likely accounted for the extensive tissue necrosis and microhemorrhages observed for COSMOS 1887 rats killed 2 days after landing.

scholarly journals Polymorphism of myosin light chains. An electrophoretic and immunological study of rabbit skeletal-muscle myosins

1982 ◽  
Vol 203 (3) ◽  
pp. 529-540 ◽  
Author(s):  
D Biral ◽  
E Damiani ◽  
P Volpe ◽  
G Salviati ◽  
A Margreth
Keyword(s):  
Light Chain ◽  
Vastus Lateralis ◽  
Light Chains ◽  
Enzyme Linked Immunosorbent Assay ◽  
Immunological Study ◽  
Slow Twitch Muscle ◽  
Fast Twitch Muscle ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Muscle Myosin

Antibodies specific for rabbit fast-twitch-muscle myosin LCIF light chain were purified by affinity chromatography and characterized by both non-competitive and competitive enzyme-linked immunosorbent assay (ELISA) and a gel-electrophoresis-derived assay (GEDELISA). The antibodies did not cross-react with myosin heavy chains, and were weakly cross-reactive with the LC2F [5,5′-dithio-(2-nitrobenzoic acid)-dissociated] light chain and with all classes of dissociated light chains (LC1Sa, LC1Sb and LC2S), as well as with the whole myosin, from hind-limb slow-twitch muscle. The immunoreactivity of myosins with a truly mixed light-chain pattern (e.g. vastus lateralis and gastrocnemius) correlated with percentage content of fast-twitch-muscle-type light chains. A more extensive immunoreactivity was observed with diaphragm and masseter myosins, which were also characterized, respectively, by a relative or absolute deficiency of LC1Sa light chain. Furthermore, it was found that the LC1Sb light chain of masseter myosin is antigenically different from its slow-twitch-muscle myosin analogue, and is immunologically related to the LC1F light chain. Rabbit masseter muscle from its metabolic and physiological properties and the content, activity and immunological properties of sarcoplasmic-reticulum adenosine triphosphatase, is classified as a red, predominantly fast-twitch, muscle. Therefore our results suggest that the two antigenically different iso-forms of LC1Sb light chain are associated with the myosins of fast-twitch red and slow-twitch red fibres respectively.

Subunit composition of rodent isomyosins and their distribution in hindlimb skeletal muscles

1987 ◽  
Vol 63 (5) ◽  
pp. 2101-2110 ◽  
Author(s):  
R. W. Tsika ◽  
R. E. Herrick ◽  
K. M. Baldwin
Keyword(s):  
Light Chain ◽  
Skeletal Muscles ◽  
Slow Light ◽  
Muscular Activity ◽  
Light Chains ◽  
Fiber Types ◽  
Myosin Isoforms ◽  
Adult Skeletal Muscle ◽  
Physiological Importance ◽  
Fast Twitch

Three adult skeletal muscle sarcomeric myosin heavy chain (MHC) genes have been identified in the rat, suggesting that the expressed native myosin isoforms can be differentiated, in part, on the basis of their MHC composition. This study was undertaken to ascertain whether the five major native isomyosins [3 fast (Fm1, Fm2, Fm3), 1 slow (Sm), and 1 intermediate (Im)], typically expressed in the spectrum of adult rat skeletal muscles comprising the hindlimb, could be further differentiated on the basis of their MHC profiles in addition to their light chain composition. Results show that in muscles comprised exclusively of fast-twitch glycolytic (FG) fibers and consisting of Fm1, Fm2, and Fm3, such as the tensor fasciae latae, only one MHC, designated as fast type IIb, could be resolved. In soleus muscle, comprised of both slow-twitch oxidative and fast-twitch oxidative-glycolytic fibers and expressing Sm and Im, two MHC bands were resolved and designated as slow/cardiac beta-MHC and fast type IIa MHC. In muscles expressing a mixture of all three fiber types and a full complement of isomyosins, as seen in the plantaris, the MHC could be resolved into three bands. Light chain profiles were characterized for each muscle type, as well as for the purified isomyosins. These data suggest that Im (IIa) consists of a mixture of fast and slow light chains, whereas Fm (IIb) and Sm (beta) isoforms consist solely of fast- and slow-type light chains, respectively. Polypeptide mapping of denatured myosin extracted from muscles expressing contrasting isoform phenotypes suggests differences in the MHC primary structure between slow, intermediate, and fast myosin isotypes. These findings demonstrate that 1) Fm, Im, and Sm isoforms are differentiated on the bases of both their heavy and light chain components and 2) each isomyosin is distributed in a characteristic fashion among rat hindlimb skeletal muscles. Furthermore, these data suggest that the ratio of isomyosins in a given muscle or muscle region is of physiological importance to the function of that muscle during muscular activity.

scholarly journals Fate of surrogate light chains in B lineage cells.

1996 ◽  
Vol 183 (2) ◽  
pp. 421-429 ◽  
Author(s):  
K Lassoued ◽  
H Illges ◽  
K Benlagha ◽  
M D Cooper
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
Light Chain ◽  
Light Chains ◽  
Receptor Complex ◽  
Surrogate Light Chain ◽  
Heavy Chains ◽  
Receptor Component ◽  
B Lineage ◽  
Receptor Assembly

Biosynthesis of the immunoglobulin (Ig) receptor components and their assembly were examined in cell lines representative of early stages in human B lineage development. In pro-B cells, the nascent surrogate light chain proteins form a complex that transiently associates in the endoplasmic reticulum with a spectrum of unidentified proteins (40, 60, and 98 kD) and Bip, a heat shock protein family member. Lacking companion heavy chains, the surrogate light chains in pro-B cells do not associate with either the Ig(alpha) or Ig(beta) signal transduction units, undergo rapid degradation, and fail to reach the pro-B cell surface. In pre-B cells, by contrast, a significant portion of the surrogate light chain proteins associate with mu heavy chains, Ig(alpha), and Ig(beta) to form a stable receptor complex with a relatively long half-life. Early in this assembly process, Bip/GRP78, calnexin, GRP94, and a protein of approximately 17 kD differentially bind to the nascent mu heavy chains. The 17-kD intermediate is gradually replaced by the surrogate light chain protein complex, and the Ig(alpha) and Ig(beta) chains bind progressively to the mu heavy chains during the complex and relatively inefficient process of pre-B receptor assembly. The results suggest that, in humans, heavy chain association is essential for surrogate light chain survival and transport to the cell surface as an integral receptor component.

scholarly journals Effect of Age and Sex on Histomorphometrical Characteristics of Two Muscles of Laticauda Lambs

2010 ◽  
Vol 79 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Salvatore Velotto ◽  
Ettore Varricchio ◽  
Maria Rosa Di Prisco ◽  
Tommaso Stasi ◽  
Antonio Crasto
Keyword(s):  
Muscle Fibre ◽  
Fibre Type ◽  
Succinic Dehydrogenase ◽  
Longissimus Dorsi ◽  
Multiple Birth ◽  
Muscle Fibres ◽  
Type Area ◽  
Muscle Tissues ◽  
Slow Twitch ◽  
Fast Twitch

The aim of the present experiment was to determine the effect of sex and age on histochemical and morphometric characteristics of muscle fibres (myocytes) in lambs born by single, twin, triplet and quadruplet birth. Thirty lambs were slaughtered at 60 days of age; thirty were weaned at 60 days and fed until 120 days with flakes (60%) and food supplements, and then slaughtered. Muscle tissues were obtained from two muscles, namely m. semitendinosus and m. longissimus dorsi of all lambs. For each fibre type, area perimeter and diameter (maximum and minimum) were measured and slow-twitch oxidative fibres, fast-twitch glycolytic fibres, fast-twitch oxidative-glycolytic fibres were histochemically differentiated. The muscles were stained for myosin ATPase, and succinic dehydrogenase. At 60 days, females had fibres larger than males, whereas the opposite was observed at 120 days. Besides, at 60 days, the lambs born by single birth had fibres larger than those born by multiple birth, whereas the opposite was observed at 120 days. Single lambs were heavier than twin lambs and multiple lambs. Fast-twitch glycolytic fibres had the largest size, followed by slow-twitch oxidative and fast-twitch oxidative glycolytic fibres. The dimensions of fibre types in m. longissimus dorsi were larger than in m. semitendinosus (P < 0.001).These muscle fibre characteristics are thought to be important factors influencing meat quality, which is often related to metabolic and contractile properties as determined by the muscle fibre type distribution.

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