Treatment with beta bungarotoxin blocks muscle spindle formation in fetal rats

Development ◽  
1990 ◽  
Vol 110 (2) ◽  
pp. 483-489
Author(s):  
J. Kucera ◽  
J.M. Waldro
Keyword(s):  
Peripheral Nerves ◽  
Muscle Fibers ◽  
Muscle Spindles ◽  
Myosin Isoforms ◽  
Myosin Heavy Chains ◽  
Heavy Chains ◽  
Intrafusal Fibers ◽  
Intramuscular Nerves ◽  
Fetal Rats ◽  
Intramuscular Nerve

Sensory and motor fibers of peripheral nerves were irreversibly destroyed in fetal rats by administering beta bungarotoxin (BTX) on embryonic day 16 or 17, after assembly of primary myotubes, but before the formation of muscle spindles. Soleus muscles of toxin-treated fetuses and their untreated littermates were removed just prior to birth and were examined by light microscopy of serial transverse sections for the presence of spindles and immunocytochemical expression of several isoforms of myosin heavy chains (MHC). Untreated muscles exhibited numerous spindles that were innervated by branches of intramuscular nerves and contained muscle fibers expressing a slow-tonic MHC isoform characteristic of the intrafusal but not extrafusal fibers. Toxin-treated muscles were devoid of intramuscular nerve bundles and perineurial structures. Encapsulations of muscle fibers resembling spindles were absent and no myotubes expressed the slow-tonic MHC isoform associated with intrafusal fibers in beta BTX-treated muscles. Thus, the assembly of muscle spindles, formation of the spindle capsule, and transformation of undifferentiated myotubes into the intrafusal fibers that contain spindle-specific myosin isoforms all depend on the presence of innervation in prenatal rat muscles.

scholarly journals Shortening velocity and myosin heavy chains of developing rabbit muscle fibers.

1985 ◽  
Vol 260 (27) ◽  
pp. 14403-14405 ◽  
Author(s):  
P J Reiser ◽  
R L Moss ◽  
G G Giulian ◽  
M L Greaser
Keyword(s):  
Muscle Fibers ◽  
Rabbit Muscle ◽  
Myosin Heavy Chains ◽  
Shortening Velocity ◽  
Heavy Chains

scholarly journals Chronic denervation of rat hemidiaphragm: maintenance of fiber heterogeneity with associated increasing uniformity of myosin isoforms.

1985 ◽  
Vol 100 (1) ◽  
pp. 161-174 ◽  
Author(s):  
U Carraro ◽  
D Morale ◽  
I Mussini ◽  
S Lucke ◽  
M Cantini ◽  
...  
Keyword(s):  
Light And Electron Microscopy ◽  
Myosin Isoforms ◽  
Myosin Heavy Chains ◽  
Denervated Muscle ◽  
Slow Myosin ◽  
Heavy Chains ◽  
Fast Myosin ◽  
Long Time ◽  
Chronic Denervation

During several months of denervation, rat mixed muscles lose slow myosin, though with variability among animals. Immunocytochemical studies showed that all the denervated fibers of the hemidiaphragm reacted with anti-fast myosin, while many reacted with anti-slow myosin as well. This has left open the question as to whether multiple forms of myosin co-exist within individual fibers or a unique, possibly embryonic, myosin is present, which shares epitopes with fast and slow myosins. Furthermore, one can ask if the reappearance of embryonic myosin in chronically denervated muscle is related both to its re-expression in the pre-existing fibers and to cell regeneration. To answer these questions we studied the myosin heavy chains from individual fibers of the denervated hemidiaphragm by SDS PAGE and morphologically searched for regenerative events in the long term denervated muscle. 3 mo after denervation the severely atrophic fibers of the hemidiaphragm showed either fast or a mixture of fast and slow myosin heavy chains. Structural analysis of proteins sequentially extracted from muscle cryostat sections showed that slow myosin was still present 16 mo after denervation, in spite of the loss of the selective distribution of fast and slow features. Therefore muscle fibers can express adult fast myosin not only when denervated during their differentiation but also after the slow program has been expressed for a long time. Light and electron microscopy showed that the long-term denervated muscle maintained a steady-state atrophy for the rat's life span. Some of the morphological features indicate that aneural regeneration events continuously occur and significantly contribute to the increasing uniformity of the myosin gene expression in long-term denervated diaphragm.

scholarly journals Quantitative electrophoretic analysis of myosin heavy chains in single muscle fibers

2001 ◽  
Vol 90 (5) ◽  
pp. 1927-1935 ◽  
Author(s):  
Boris A. Tikunov ◽  
H. Lee Sweeney ◽  
Lawrence C. Rome
Keyword(s):  
Muscle Fibers ◽  
Electrophoretic Analysis ◽  
Single Fiber ◽  
Fiber Types ◽  
Single Muscle ◽  
Myosin Heavy Chains ◽  
Single Fibers ◽  
Heavy Chains ◽  
Cross Bridges ◽  
Whole Muscle

To better understand the molecular basis of the large variation in mechanical properties of different fiber types, there has been an intense effort to relate the mechanical and energetic properties measured in skinned single fibers to those of their constituent cross bridges. There is a significant technical obstacle, however, in estimating the number of cross bridges in a single fiber. In this study, we have developed a procedure for extraction and quantification of myosin heavy chains (MHCs) that permits the routine and direct measurement of the myosin content in single muscle fibers. To validate this method, we also compared MHC concentration measured in single fibers with the MHC concentration in whole fast-twitch (psoas and gracilis) and slow-twitch (soleus) muscles of rabbit. We found that the MHC concentration in intact psoas (184 μM) was larger than that in soleus (144 μM), as would be expected from their differing mitochondrial content and volume of myofibrils. We obtained excellent agreement between MHC concentration measured at the single fiber level with that measured at the whole muscle level. This not only verifies the efficacy of our procedure but also shows that the difference in concentration at the whole muscle level simply reflects the concentration differences in the constituent fiber types. This new procedure should be of considerable help in future attempts to determine kinetic differences in cross bridges from different fiber types.

Postnatal expression of myosin heavy chains in muscle spindles of the rat

1989 ◽  
Vol 179 (4) ◽  
pp. 369-376 ◽  
Author(s):  
Jan Kucera ◽  
Jon M. Walro
Keyword(s):  
Muscle Spindles ◽  
Myosin Heavy Chains ◽  
Heavy Chains

scholarly journals Myosin types and fiber types in cardiac muscle. II. Atrial myocardium.

1982 ◽  
Vol 95 (3) ◽  
pp. 838-845 ◽  
Author(s):  
L Gorza ◽  
S Sartore ◽  
S Schiaffino
Keyword(s):  
Right Atrium ◽  
Muscle Fibers ◽  
Interatrial Septum ◽  
Myosin Heavy Chains ◽  
Atrial Myocardium ◽  
Crista Terminalis ◽  
Heavy Chains ◽  
Bovine Heart ◽  
Atrial Muscle ◽  
The Right

Antibodies were produced against myosins isolated from the left atrial myocardium (anti-bAm) and the left ventricular myocardium (anti-bVm) of the bovine heart. Cross-reactive antibodies were removed by cross-absorption. Absorbed anti-bAm and anti-bVm were specific for the myosin heavy chains when tested by enzyme immunoassay combined with SDS gel electrophoresis. Indirect immunofluorescence was used to determine the reactivity of atrial muscle fibers to the two antibodies. Three populations of atrial muscle fibers were distinguished in the bovine heart: (a) fibers reactive with anti-bAm and unreactive with anti-bVm, like most fibers in the left atrium; (b) fibers reactive with both antibodies, especially numerous in the right atrium; (c) fibers reactive with anti-bVm and unreactive with anti-bAm, present only in the interatrial septum and in specific regions of the right atrium, such as the crista terminalis. These findings can be accounted for by postulating the existence of two distinct types of atrial myosin heavy chains, one of which is antigenically related to ventricular myosin. The tendency for fibers labeled by anti-bVm to occur frequently in bundles and their preferential distribution in the crista terminalis, namely along one of the main conduction pathways between the sinus node and the atrioventricular node, and in the interatrial septum, where different internodal tracts are known to converge, suggests that these fibers may be specialized for faster conduction.

Non-neural and neural expression of myosin heavy chains by regenerated intrafusal fibers of rats

1991 ◽  
Vol 122 (2) ◽  
pp. 213-217 ◽  
Author(s):  
Jon M. Walro ◽  
Jan Kucera ◽  
Rebecca Narvy
Keyword(s):  
Myosin Heavy Chains ◽  
Heavy Chains ◽  
Intrafusal Fibers

scholarly journals Neonatal and adult myosin heavy chains form homodimers during avian skeletal muscle development.

1991 ◽  
Vol 113 (2) ◽  
pp. 303-310 ◽  
Author(s):  
S Lowey ◽  
G S Waller ◽  
E Bandman
Keyword(s):  
Skeletal Muscle ◽  
Muscle Development ◽  
Coiled Coil ◽  
Myosin Isoforms ◽  
Myosin Heavy Chains ◽  
Electron Microscopic ◽  
Hybrid Species ◽  
Heavy Chains ◽  
Stage Of Development ◽  
Microscopic Techniques

Myosin isoforms contribute to the heterogeneity and adaptability of skeletal muscle fibers. Besides the well-characterized slow and fast muscle myosins, there are those isoforms that appear transiently during the course of muscle development. At a stage of development when two different myosins are coexpressed, the possibility arises for the existence of heterodimers, molecules containing two different heavy chains, or homodimers, molecules with two identical heavy chains. The question of whether neonatal and adult myosin isoforms can associate to form a stable heterodimer was addressed by using stage-specific monoclonal antibodies in conjunction with immunological and electron microscopic techniques. We find that independent of the ratio of adult to neonatal myosin, depending on the age of the animal, the myosin heavy chains form predominantly homodimeric molecules. The small amount of hybrid species present suggests that either the rod portion of the two heavy chain isoforms differs too much in sequence to form a stable alpha-helical coiled coil, or that the biosynthesis of the heavy chains precludes the formation of heterodimeric molecules.

scholarly journals HISTOCHEMISTRY OF MUSCLE SPINDLES IN SNAKES OF NATRIX SPECIES

1974 ◽  
Vol 22 (9) ◽  
pp. 881-886 ◽  
Author(s):  
D. J. PALLOT ◽  
JANIS TABERNER
Keyword(s):  
Adenosine Triphosphatase ◽  
Muscle Fibers ◽  
Succinic Dehydrogenase ◽  
Muscle Spindles ◽  
Intermediate Level ◽  
The Other ◽  
Intrafusal Fiber ◽  
Intrafusal Fibers ◽  
Low Levels

The muscle spindles of snakes consist of a single intrafusal fiber; in addition to this, two types of spindles are found. We have studied the histochemistry of the snake intrafusal fibers. One type of spindle, the long capsule spindle intrafusal fiber, is characterized by high levels of the enzymes myosin adenosine triphosphatase, succinic dehydrogenase and phosphorylase; the other type, the short capsule spindle intrafusal fiber, is characterized by low levels of myosin adenosine triphosphatase and phosphorylase and an intermediate level of succinic dehydrogenase. The short capsule spindle intrafusal fiber is thus histochemically similar to the tonic extrafusal fibers, whereas the long capsule spindle intrafusal fiber is similar to the twitch extrafusal muscle fibers. The long capsule spindle is concerned mainly with monitoring static length, the short capsule spindle with monitoring changes in length. It is interesting that the histochemical profiles of long and short capsule spindle intrafusal fibers are similar to the mammalian bag and chain fibers, respectively.

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