Cross-striated Muscle Research Articles

Isolated, mononucleated, striated muscle can undergo pluripotent transdifferentiation and form a complex regenerate.

Isolated, mononucleated, cross-striated muscle of a medusa can be activated by collagenase treatment to transdifferentiate completely to various new cell types and to regenerate autonomously the sexual (without gametes) and feeding organ of the animal. Under these circumstances all isolated muscle fragments produce smooth muscle cells and a glandular cell type (y-cells). When culture conditions are appropriate, endoderm is also formed, followed by regeneration of a complex organ of seven or eight new non-muscle cell types, including nematocytes, digestive, secretory, gland, interstitial, and presumably nerve cells.

Modification of frescon action in Lymnaea stagnalis smooth and cross-striated muscles by agents that alter potential-dependent or receptor-operated calcium permeability

The calcium entry blockers sodium nitroprusside (10 −2 M) and sodium pentobarbital (5 × 10 −3 M) had different effects on high-potassium-induced and Frescon-induced contractures in a smooth and a cross-striated muscle of the snail Lymnaea stagnalis. This suggests that Frescon causes an increase in sarcolemmal calcium permeability by a mechanism which is different from that utilized by high extracellular potassium.

The Ionic Basis of the Resting Potential in a Cross-Striated Muscle of the Aquatic Snail Lymnaea Stagnalis

ABSTRACT The mean resting potential in the heart ventricle muscle cells of the freshwater snail Lymnaea stagnalis was found to be – 61·2±3·5(..)mV (ranging from –56mV to –68mV). The average intracellular potassium concentration was estimated to be 51·5 ± 14·6 (..) m (ranging from 27·8 m to 77·3 m). The membrane of the heart ventricle muscle cells appears to be permeable to both potassium and chloride, as changes in the extracellular concentration of either of these ions resulted in a change in the membrane potential. A ten-fold change in the extracellular potassium concentration was associated with a 50·4 ± 3·8 (..) mV slope when the potassium concentration was above about 6 m. Deviations from the straight-line relation predicted for a potassium electrode could be accounted for by introducing a term for sodium permeability. The ionic basis of the membrane potential in these cells can be described by a modified form of the Goldman-Hodgkin-Katz equation.

Calcium entry blockers inhibit contractures induced by the molluscicide Frescon in Lymnaea stagnalis smooth and cross-striated muscles

The molluscicide Frescon induces irreversible contracture in smooth and cross-striated muscles of the freshwater snail Lymnaea stagnalis. This contracture can be inhibited or reversed by elevated Mg 2+ and reduced Ca 2+ concentrations, by the heavy metals Ni 2+, Co 2+, and Mn 2+, by the rare earth La 3+, and by the calcium channel blocker D-600. The removal of extracellular Ca 2+ also prevents the expression of Frescon action. These results are consistent with the hypothesis that Frescon causes an increase in the Ca 2+ permeability of the sarcolemma.

The effect of the molluscicide Frescon on smooth and cross-striated muscles of Lymnaea stagnalis and Helix aspersa

The molluscicide Frescon ( N-(triphenylmethyl)morpholine) induces prolonged, irreversible contractions (contractures) in the isolated heart ventricle, penis retractor, and foot muscles of the aquatic snail Lymnaea stagnalis. It also causes contracture of the penis retractor muscle, but not the heart ventricle, of the terrestrial snail Helix aspersa. Since Frescon-induced contracture is not accompanied by a depolarization of the sarcolemma of Lymnaea heart ventricle muscle cells, it is suggested that the action of this molluscicide is associated with a membrane potential-independent activation of the contractile machinery. The rapid response of Lymnaea musculature to Frescon suggests that the direct contracture-inducing action of this molluscicide could explain its toxicity to the whole animal.

A comparison of the action of Frescon with calcium ionophore A23187

The molluscicide Frescon and the divalent cation ionophore A23187 both induce prolonged contractures in smooth and cross-striated muscles of Lymnaea stagnalis. An analysis of the actions of these two agents under different ionic conditions suggests that they act by different mechanisms. Calcium-free saline completely blocked the action of Frescon, but only reduced the magnitude of A23187-induced contractures. Furthermore, the calcium entry blockers D-600 and lanthanum did not prevent the ionophore-induced contractures in contrast to their complete inhibition of Frescon action. Lanthanum, however, reduced the magnitude of A23187-induced contractures, but only to the same extent as that achieved with calcium-free saline. It is concluded that whereas both Frescon and A23187 increase the permeability of the sarcolemma to extracellular Ca 2+, only the ionophore releases intracellular Ca 2+ as well.

Evidence that Frescon-induced contractures in Lymnaea stagnalis muscles do not depend on intracellular calcium stores: A comparison with caffeine action

The action of the molluscicide Frescon, which induces contractures in smooth and cross-striated muscles of the freshwater snail Lymnaea stagnalis, was compared with the action of caffeine. The results indicate that the latter agent promotes contractions in Lymnaea muscles by releasing Ca 2+ from intracellular stores. Such a release could not be attributed to the action of Frescon. Furthermore, the molluscicide did not appear to alter muscle function at the level of the contractile apparatus as it did not affect the time course of caffeine-induced contractions. These results favor the hypothesis that Frescon increases sarcolemmal Ca 2+ permeability.

The Structure and Operation of the Obliquely Striated Supercontractile Somatic Muscles in Nematodes.

The structure of nematode somatic muscles is reviewed. They are obliquely striated and, therefore, supercontractile because they change in length to an exceptional extent by both myofilament interdigitation and shearing. A model is developed which shows that shearing is generated by interdigitation under specified structural conditions. It is concluded that the ability to supercontract is functionally associated with a hydrostatic skeleton, because obliquely striated muscles occur in a wide range of unrelated Phyla and a functionally identical muscle has evolved from cross-striated muscle in other animals with a hydrostatic skeleton, particularly certain insect larvae. Two, possibly 3, morphologically distinct groups of muscles exist in the Nematoda which correspond to the Classes Enoplea, Rhabditea and Chromadorea. Parallel sequences of change occur in the first 2, in which the contractile layer increases in area, the sarcomeres become smaller, and the Z-system more regular. Descriptive terms are redefined, thus: platymyarian, quasi-platymyarian, shallow coelomyarian, and coelomyarian occur in Rhabditea; cubomyarian, regular cubomyarian, and stratimyarian occur in Enoplea; and a characteristic chromadorid-circomyarian is known from 2 Chromadorea. The structure of the muscles corresponds well to the higher nematode classification, except in the Order Spirurida which may have arisen from the Enoplea and not the Rhabditea as generally accepted.

Myosin isoenzymes in cultured human muscle.

Cultured human muscle grown aneurally and innervated by the ventral part of fetal rat spinal cord was examined using antimyosin antibodies specific for isomyosins from fast and slow mammalian skeletal muscle. Cultured muscle displayed multiple reactivity with antibodies against both types of myosins, with no evident compartmentalization of different forms of myosin into different muscle cells, such as seen in adult muscle. Innervation of cultured muscle resulted in better growth and longer survival of cultured muscle and its more advanced maturation, with a larger number of cross-striated muscle fibers. The pattern of immunofluorescence reaction, however, was the same in both innervated and noninnervated cultured muscle.

Unusual extraction of α-actinin from the adductor muscles of bivalve molluscs

1. 1. In contrast to rabbit skeletal muscle α-actinin, which is extracted only by low ionic strength solutions, scallop α-actinin has been extracted in a wide range of ionic strength and its relative content is maximal in physiological ionic strength solutions. 2. 2. The yield of α-actinin from scallop myofibrils sharply increases in the presence of NaHCO 3 which may be used for isolation of α-actinin from molluscs muscles. 3. 3. NaHCO 3-solution completely removes α-actinin from scallop myofibrils, although α-actinin from rabbit skeletal muscles has not been extracted by NaHCO 3. 4. 4. It is suggested that these differences are connected with structural differences in the Z-line of cross-striated muscles of scallop and rabbit.

15] Preparation and properties of M-line proteins

This chapter provides the preparation and properties of M-Line proteins. Neither the protein composition nor the detailed function of the M line, the electron-dense structure running transversely through the middle of the H-zone of the sarcomere of cross-striated muscle, is yet fully known. So far only two proteins—the M-type isoprotein of creatine kinase (MM-CK) and the M r = 165,000 protein now called myomesin—have been identified as true M-line proteins. The procedures for the preparation of total creatine kinase from rabbit muscle, from chicken skeletal and heart muscle as well as from chicken brain is described in this chapter.The purification of the M-line MM-CK is best achieved by first preparing well-washed isolated myofibrils from which MM-CK can then be extracted. It is found that ability of antibodies to distinguish between the MM and the BB isoenzymes of CK can be used to detect specifically one or the other homodimeric enzyme by several immunological techniques, such as immune overlay technique, indirect immunofluorescence technique, and immune electron microscopy.

Cytosolic androgen receptor in regenerating rat levator ani muscle.

The development of the cytosolic androgen receptor was studied after degeneration and regeneration of the rat levator ani muscle after a crush lesion. Muscle regeneration appears to recapitulate myogenesis in many respects. It therefore provides a model tissue in sufficiently in large quantity for investigating the ontogenesis of the androgen receptor. The receptor in the cytosol of the normal levator ani muscle has binding characteristics similar to those of the cytosolic receptor in other androgen-sensitive tissues. By day 3 after a crush lesion of the levator ani muscle, androgen binding decreased to 25% of control values. This decrease was followed by a 4-5 fold increase in hormone binding, which attained control values by day 7 after crush. Androgen binding remained stable at the control value up to day 60 after crushing. These results were correlated with the morphological development of the regenerating muscle after crushing. It is concluded that there is little, if any, androgen receptor present in the early myoblastic stages of regeneration; rather, synthesis of the receptor may occur after the fusion of myoblasts and during the differentiation of myotubes into cross-striated muscle fibres.

The structure of smooth and striated portions of the adductor muscle of the valves in a scallop

The smooth and cross-striated portions in the scallop's adductor muscle of the valves are examined by thin sectioning and freeze-fracture. Three types of junctions are identified on the surface membrane: (1) peripheral couplings between elements of the sarcoplasmic reticulum and plasmalemma—these are more numerous in the tonic smooth than in the phasic cross-striated adductor; (2) fasciae and hemifasciae adherentes, which allow in series and in parallel adhesions from cell to cell and from cell to connective tissue, respectively—the structure is similar in both types of fibers, but hemifasciae are more numerous in the smooth portion; (3) gap junctions—these are quite numerous in both types of fibers. Their presence is correlated to the fact that end plates are rare, and fibers are shorter than the length of the muscle. In the cross-striated muscle evidence is presented for the intercalated growth of sarcomeres.

The Mr 165,000 M-protein myomesin: a specific protein of cross-striated muscle cells.

The tissue specificity of chicken 165,000 M-protein, tentatively names "myomesin", a tightly bound component of the M-line region of adult skeletal and heart myofibrils, was investigated by immunological techniques. Besides skeletal and heart muscle, only thymus (known to contain myogenic cells) was found to contain myomesin. No myomesin could however, be detected in smooth muscle or any other tissue tested. This result was confirmed in vitro on several cultured embryonic cell types. Only skeletal and heart muscle cells, but not smooth muscle or fibroblast cells, showed the presence of myomesin. When the occurrence and the distribution of myomesin during differentiation of breast muscle cells in culture were studied by the indirect immunofluorescence technique, this protein was first detected in postmitotic, nonproliferating myoblasts in a regular pattern of fluorescent cross-striations. In electron micrographs of sections through young myotubes, it could be shown to be present within the forming H-zones of nascent myofibrils. In large myotubes the typical striation pattern in the M-line region of the myofibrils was observed. Synthesis of myomesin measured by incorporation of [35S]methionine into immunoprecipitable protein of differentiating cells increased sharply after approximately 48 h in culture, i.e., at the time when the major myofibrillar proteins are accumulated. No significant amounts of myomesin were, however, found in cells prevented from undergoing normal myogenesis by 5'-bromodeoxyuridine. The results indicate that myomesin (a) is a myofibrillar protein specific for cross-striated muscle, (b) represents a highly specific marker for cross-striated muscle cell differentiation and (c) might play an important role in myofibril assembly and/or maintenance.

Morphofunctional and phylogenetic relations in helical muscles

Abstract The distribution of obliquely (helical) and cross-striated muscles, and their physiological and mechanical properties, are analyzed throughout the zoological scale in relation to the presence and the functional requirements of different types of skeletal systems. It is suggested that helical fibres are an evolutionary answer to the appearing of the hydroskeleton, being able to develop high active tensions also in conditions of superelongation. The mechanism by which this unique property is realized depends on the possibility of a typical change in the relationships between thick and thin filaments of the same sarcomere.

Muscles à striation oblique et à striation transversale chez les Annélides Polychètes

Abstract Ohlique- and cross-striated muscles in polichaetes. Most annelids, chiefly polychaetes, have muscles of oblique double striation or of helical striation. Yet special evolutionary processes may induce profound changes in the structure of muscles in two polychaete families, the Syllidae and Nereidae. At time of reproduction they can undergo somatic metamorphoses termed stolonisation and epitoky. Many of their muscles de-differentiate partly or wholly, and then they redifferentiate into epitokous fibres, characterized by thick, shorter filaments of smaller diameter, and rich in mitochondria and glycogen. Besides, there are some examples of muscle fibres non-helical in type worth investigating, for they show, first, an absence of a direct relation between phylogeny and fibre type (obliquely or transversely striated, or smooth), and, secondly, an absence of transitions between smooth and cross-striated fibres (the proventriculus in Syllidae), and between the latter and fibres of oblique simple striati...

Biochemical and ultrastructural aspects of Mr 165,000 M-protein in cross-striated chicken muscle.

To better understand the relationship between the Mr 165,000 M-line protein (M-protein) and H-zone structure in skeletal and in cardiac muscle, as well as the possible interaction of M-protein with another skeletal muscle M-line component, the homodimeric creatine kinase isoenzyme composed of two M subunits (MM-CK), we performed biochemical, immunological, and ultrastructural studies on myofibrils extracted by different procedures. In contrast to MM-CK, M-protein could not be completely removed from myofibrils by low ionic strength extraction. Fab-fragments of antibodies against M-protein could not release M-protein quantitatively from either breast or heart myofibrils but remained bound to the myofibrillar structure, whereas monovalent antibodies against MM-CK cause the specific release of MM-CK and the concomitant disappearance of the M-line from chicken skeletal muscle myofibrils. When MM-CK was removed from skeletal myofibrils by low ionic strength extraction or, more specifically, by incubation with anti-MM-CK Fab, M-protein was still not released quantitatively upon treatment with anti-M-protein Fab as judged from immunofluorescence data. In the ultrastructural investigation of low ionic strength extracted muscle fibers, M protein could be localized in two stripes on both sides of the former M-line, suggesting a reduced attachment to the residual H-zone structure, whereas the specific removal of MM-CK resulted in the same dense staining pattern for M-protein within the M-line as observed in untreated fibers. However, the binding of M-protein to the residual M-line structure seemed to be reduced, as a considerable amount of this protein could be identified in the supernate of sequentially incubated myofibrils. The results indicate a strong binding of M-protein within the H-zone structure of skeletal as well as heart myofibrils.

Efficiency of light diffraction by cross-striated muscle fibers under stretch and during isometric contraction

When light is diffracted by a single frog muscle fiber the intensities I kappa of the different orders kappa (kappa = 1,2,3) strongly depend on the angle between the axis of the incident beam and the fiber axis. Maximum intensity is not obtained with perpendicular incidence (omega = 0 degree) but at angles that can be calculated for each order number and sarcomere length using Bragg's formula. In analogy to techniques developed for x-ray structure analysis of mosaic crystals we have rotated the fiber around an axis perpendicular to the fiber axis and to the incident beam axis within an angular range delta omega = +/- 35 degrees and recorded the light intensities I kappa. Diffraction efficiencies defined as E kappa = integral of I kappa d omega were studied as a function of sarcomere length and during isometric contraction. The sarcomere length dependences of the efficiencies E kappa of the first three orders show characteristic trends. E1 increases with fiber stretch, E2 has a minimum at a sarcomere length near 2.8 micrometers, and E3 has a maximum near 2.5 micrometers. These trends as well as the observed efficiency ratios are in fairly good agreement with predictions by the intensity formula developed for x-ray structure analysis. During isometric contraction, the diffraction efficiencies of the fiber decrease, with the decreases becoming greater the higher the order number. These decreases might be caused by a longitudinal displacement of myofibrils of up to 0.4 micrometers. The efficiency of light diffraction strongly depends on the tonicity of the bathing fluid. Hypertonic (3/2 x normal) solution reduces E1 to less than half, hypotonic (2/3 x normal) solution increases E1 to almost twice the value obtained in normal Ringer's solution.

Interpretation of light diffraction by cross‐striated muscle as Bragg reflexion of light by the lattice of contractile proteins.

1. The diffraction spectrum obtained by illuminating a cross-striated muscle fibre with a narrow beam of monochromatic light generally shows asymmetry of light intensity between left and right spectral lines. 2. The asymmetry of light intensity in left and right spectral lines is reversed when the fibre is rotated by 180 degrees. This indicates that intensities of the spectral lines are determined more by Bragg reflexion than by simple diffraction as in a plane grating. Populations of myofibrils with differing tilt of lattice planes must exist in each illuminated fibre segment to account for simultaneous Bragg reflexion to the left- and right-hand sides. 3. The light intensity of spectral lines shows a complicated dependence on the angle at which the incident beam is directed against the fibre. This 'intensity distribution' seems to reflect the specific myofibrillar arrangement at the site of illumination. 4. The intensity distributions of the left and right first order lines show close correlation if the deflexion of the incident beam differs by twice the Bragg angle. 5. The deflexion angle of the incident beam at which maximum intensity in spectral lines is obtained depends on sarcomere length as predicted by Bragg's formula. 6. Intensities of the first and second order lines are little correlated when recorded at the same beam deflexion, but are well correlated when recorded at beam deflexions calculated from Bragg's formula. 7. When a diffraction line is scanned perpendicularly to the meridional plane, the light intensity shows fluctuations resembling those obtained by beam deflexion within the meridional plane.

Ultrastructural study of medullomyoblastoma

A case of cerebellar medullomyoblastoma in a young boy was investigated by electron microscopy. The neuroectodermal component shows the characteristics of a desmoplastic medulloblastoma. The mesodermal component consists of more or less differentiated cross-striated muscle cells. Undifferentiated muscle cells are very similar to proliferated endothelial cells of blood vessels within the muscular component, so that an origin of this component from pluripotential endothelial cells of the vessel wall is suggested. This tumor is considered a malignant teratoid because of the derivation from two blastodermic layers and because of the midline localization in children suggesting a malformative origin.