Histological observations on precystic merogony and metrocyte formation of Sarcocystis rauschorum (Apicomplexa: Sarcocystidae) in varying lemmings, Dicrostonyx richardsoni

1985 ◽  
Vol 63 (12) ◽  
pp. 2907-2912 ◽  
Author(s):  
Richard J. Cawthorn ◽  
Ronald J. Brooks
Keyword(s):  
Cardiac Muscle ◽  
Dose Response ◽  
Striated Muscle ◽  
Cyst Formation ◽  
Endogenous Development

This study was designed to elucidate the early endogenous development of Sarcocystis rauschorum (Apicomplexa: Sarcocystidae) in varying lemmings, Dicrostonyx richardsoni. After determining the dose–response effects of sporocysts of S. rauschorum on lemmings (doses greater than 500 sporocysts were lethal during hepatic merogony), sporocysts were administered to additional lemmings that were killed beginning 1 day postinoculation (DPI) and continuing to 15.0 DPI. Merogony of S. rauschorum occurs in hepatocytes 4 – 6 DPI; merozoites were also found in leucocytes 5 – 6 DPI in liver impression smears. Cyst formation began 9.0 DPI in striated muscle (rarely in cardiac muscle) and only metrocytes were present to 15.0 DPI. Overall, S. rauschorum has only one precystic generation of merogony, in hepatocytes, and then rapidly forms cysts containing metrocytes in striated musculature.

scholarly journals Skeletal and Cardiac Muscle Disorders Caused by Mutations in Genes Encoding Intermediate Filament Proteins

2021 ◽  
Vol 22 (8) ◽  
pp. 4256
Author(s):  
Lorenzo Maggi ◽  
Manolis Mavroidis ◽  
Stelios Psarras ◽  
Yassemi Capetanaki ◽  
Giovanna Lattanzi
Keyword(s):  
Muscular Dystrophy ◽  
Cardiac Muscle ◽  
Intermediate Filament ◽  
Striated Muscle ◽  
Congenital Muscular Dystrophy ◽  
Left Ventricular ◽  
Intermediate Filament Proteins ◽  
Muscle Disorders ◽  
Genes Encoding ◽  
Molecular Aspects

Intermediate filaments are major components of the cytoskeleton. Desmin and synemin, cytoplasmic intermediate filament proteins and A-type lamins, nuclear intermediate filament proteins, play key roles in skeletal and cardiac muscle. Desmin, encoded by the DES gene (OMIM *125660) and A-type lamins by the LMNA gene (OMIM *150330), have been involved in striated muscle disorders. Diseases include desmin-related myopathy and cardiomyopathy (desminopathy), which can be manifested with dilated, restrictive, hypertrophic, arrhythmogenic, or even left ventricular non-compaction cardiomyopathy, Emery–Dreifuss Muscular Dystrophy (EDMD2 and EDMD3, due to LMNA mutations), LMNA-related congenital Muscular Dystrophy (L-CMD) and LMNA-linked dilated cardiomyopathy with conduction system defects (CMD1A). Recently, mutations in synemin (SYNM gene, OMIM *606087) have been linked to cardiomyopathy. This review will summarize clinical and molecular aspects of desmin-, lamin- and synemin-related striated muscle disorders with focus on LMNA and DES-associated clinical entities and will suggest pathogenetic hypotheses based on the interplay of desmin and lamin A/C. In healthy muscle, such interplay is responsible for the involvement of this network in mechanosignaling, nuclear positioning and mitochondrial homeostasis, while in disease it is disturbed, leading to myocyte death and activation of inflammation and the associated secretome alterations.

scholarly journals The subcellular distribution of dystrophin in mouse skeletal, cardiac, and smooth muscle.

1991 ◽  
Vol 115 (2) ◽  
pp. 411-421 ◽  
Author(s):  
T J Byers ◽  
L M Kunkel ◽  
S C Watkins
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Plasma Membrane ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Adherens Junctions ◽  
Myotendinous Junction ◽  
Elevated Concentration ◽  
Western Blots ◽  
Functional Roles

We use a highly specific and sensitive antibody to further characterize the distribution of dystrophin in skeletal, cardiac, and smooth muscle. No evidence for localization other than at the cell surface is apparent in skeletal muscle and no 427-kD dystrophin labeling was detected in sciatic nerve. An elevated concentration of dystrophin appears at the myotendinous junction and the neuromuscular junction, labeling in the latter being more intense specifically in the troughs of the synaptic folds. In cardiac muscle the distribution of dystrophin is limited to the surface plasma membrane but is notably absent from the membrane that overlays adherens junctions of the intercalated disks. In smooth muscle, the plasma membrane labeling is considerably less abundant than in cardiac or skeletal muscle and is found in areas of membrane underlain by membranous vesicles. As in cardiac muscle, smooth muscle dystrophin seems to be excluded from membrane above densities that mark adherens junctions. Dystrophin appears as a doublet on Western blots of skeletal and cardiac muscle, and as a single band of lower abundance in smooth muscle that corresponds most closely in molecular weight to the upper band of the striated muscle doublet. The lower band of the doublet in striated muscle appears to lack a portion of the carboxyl terminus and may represent a dystrophin isoform. Isoform differences and the presence of dystrophin on different specialized membrane surfaces imply multiple functional roles for the dystrophin protein.

scholarly journals THE ULTRASTRUCTURE OF FROG VENTRICULAR CARDIAC MUSCLE AND ITS RELATIONSHIP TO MECHANISMS OF EXCITATION-CONTRACTION COUPLING

1968 ◽  
Vol 38 (1) ◽  
pp. 99-114 ◽  
Author(s):  
Nancy A. Staley ◽  
Ellis S. Benson
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Structural Features ◽  
Mammalian Skeletal Muscle ◽  
Striated Muscles ◽  
Thin Filaments ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Dense Granules

Frog ventricular cardiac muscle has structural features which set it apart from frog and mammalian skeletal muscle and mammalian cardiac muscle. In describing these differences, our attention focused chiefly on the distribution of cellular membranes. Abundant inter cellular clefts, the absence of tranverse tubules, and the paucity of sarcotubules, together with exceedingly small cell diameters (less than 5 µ), support the suggestion that the mechanism of excitation-contraction coupling differs in these muscle cells from that now thought to be characteristic of striated muscle such as skeletal muscle and mammalian cardiac muscle. These structural dissimilarities also imply that the mechanism of relaxation in frog ventricular muscle differs from that considered typical of other striated muscles. Additional ultrastructural features of frog ventricular heart muscle include spherical electron-opaque bodies on thin filaments, inconstantly present, forming a rank across the I band about 150 mµ from the Z line, and membrane-bounded dense granules resembling neurosecretory granules. The functional significance of these features is not yet clear.

scholarly journals Quantitative Proteomic Identification of Six4 as the Trex-Binding Factor in the Muscle Creatine Kinase Enhancer

2004 ◽  
Vol 24 (5) ◽  
pp. 2132-2143 ◽  
Author(s):  
Charis L. Himeda ◽  
Jeffrey A. Ranish ◽  
John C. Angello ◽  
Pascal Maire ◽  
Ruedi Aebersold ◽  
...  
Keyword(s):  
Creatine Kinase ◽  
Cardiac Muscle ◽  
Magnetic Beads ◽  
Striated Muscle ◽  
Regulatory Element ◽  
Mouse Heart ◽  
Muscle Creatine Kinase ◽  
Adult Skeletal Muscle ◽  
Binding Factor ◽  
Muscle Creatine

ABSTRACT Transcriptional regulatory element X (Trex) is a positive control site within the Muscle creatine kinase (MCK) enhancer. Cell culture and transgenic studies indicate that the Trex site is important for MCK expression in skeletal and cardiac muscle. After selectively enriching for the Trex-binding factor (TrexBF) using magnetic beads coupled to oligonucleotides containing either wild-type or mutant Trex sites, quantitative proteomics was used to identify TrexBF as Six4, a homeodomain transcription factor of the Six/sine oculis family, from a background of ∼900 copurifying proteins. Using gel shift assays and Six-specific antisera, we demonstrated that Six4 is TrexBF in mouse skeletal myocytes and embryonic day 10 chick skeletal and cardiac muscle, while Six5 is the major TrexBF in adult mouse heart. In cotransfection studies, Six4 transactivates the MCK enhancer as well as muscle-specific regulatory regions of Aldolase A and Cardiac troponin C via Trex/MEF3 sites. Our results are consistent with Six4 being a key regulator of muscle gene expression in adult skeletal muscle and in developing striated muscle. The Trex/MEF3 composite sequence ([C/A]ACC[C/T]GA) allowed us to identify novel putative Six-binding sites in six other muscle genes. Our proteomics strategy will be useful for identifying transcription factors from complex mixtures using only defined DNA fragments for purification.

scholarly journals Chemical and immunochemical characteristics of tropomyosins from striated and smooth muscle

1974 ◽  
Vol 141 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Peter Cummins ◽  
S. Victor Perry
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Cardiac Muscle ◽  
Skeletal Muscles ◽  
Striated Muscle ◽  
Β Subunit ◽  
Muscle Type ◽  
Amphibian Species ◽  
Species Specific ◽  
Immunochemical Characteristics

1. On electrophoresis in dissociating conditions the tropomyosins isolated from skeletal muscles of mammalian, avian and amphibian species migrated as two components. These were comparable with the α and β subunits of tropomyosin present in rabbit skeletal muscle. 2. The α and β components of all skeletal-muscle tropomyosins contained 1 and 2 residues of cysteine per 34000g respectively. 3. The ratio of the amounts of α and β subunit present in skeletal muscle tropomyosins was characteristic for the muscle type. Muscle consisting of slow red fibres contained a greater proportion of β-tropomyosin than muscles consisting predominantly of white fast fibres. 4. Mammalian and avian cardiac muscle tropomyosins consisted of α-tropomyosin only. 5. Mammalian and avian smooth-muscle tropomyosins differed both chemically and immunologically from striated-muscle tropomyosins. 6. Antibody raised against rabbit skeletal α-tropomyosin was species non-specific, reacting with all other striated muscle α-tropomyosin subunits tested. 7. Antibody raised against rabbit skeletal β-tropomyosin subunit was species-specific.

scholarly journals Multiple regulatory elements contribute differentially to muscle creatine kinase enhancer activity in skeletal and cardiac muscle.

1993 ◽  
Vol 13 (5) ◽  
pp. 2753-2764 ◽  
Author(s):  
S L Amacher ◽  
J N Buskin ◽  
S D Hauschka
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Regulatory Elements ◽  
High Level Expression ◽  
Muscle Creatine Kinase ◽  
Skeletal Myocytes ◽  
E Box ◽  
Nonmuscle Cells ◽  
High Level

We have used transient transfections in MM14 skeletal muscle cells, newborn rat primary ventricular myocardiocytes, and nonmuscle cells to characterize regulatory elements of the mouse muscle creatine kinase (MCK) gene. Deletion analysis of MCK 5'-flanking sequence reveals a striated muscle-specific, positive regulatory region between -1256 and -1020. A 206-bp fragment from this region acts as a skeletal muscle enhancer and confers orientation-dependent activity in myocardiocytes. A 110-bp enhancer subfragment confers high-level expression in skeletal myocytes but is inactive in myocardiocytes, indicating that skeletal and cardiac muscle MCK regulatory sites are distinguishable. To further delineate muscle regulatory sequences, we tested six sites within the MCK enhancer for their functional importance. Mutations at five sites decrease expression in skeletal muscle, cardiac muscle, and nonmuscle cells. Mutations at two of these sites, Left E box and MEF2, cause similar decreases in all three cell types. Mutations at three sites have larger effects in muscle than nonmuscle cells; an A/T-rich site mutation has a pronounced effect in both striated muscle types, mutations at the MEF1 (Right E-box) site are relatively specific to expression in skeletal muscle, and mutations at the CArG site are relatively specific to expression in cardiac muscle. Changes at the AP2 site tend to increase expression in muscle cells but decrease it in nonmuscle cells. In contrast to reports involving cotransfection of 10T1/2 cells with plasmids expressing the myogenic determination factor MyoD, we show that the skeletal myocyte activity of multimerized MEF1 sites is 30-fold lower than that of the 206-bp enhancer. Thus, MyoD binding sites alone are not sufficient for high-level expression in skeletal myocytes containing endogenous levels of MyoD and other myogenic determination factors.

scholarly journals Immunoelectron microscopic studies of desmin (skeletin) localization and intermediate filament organization in chicken cardiac muscle.

1983 ◽  
Vol 96 (6) ◽  
pp. 1736-1742 ◽  
Author(s):  
K T Tokuyasu ◽  
A H Dutton ◽  
S J Singer
Keyword(s):  
Cardiac Muscle ◽  
Intermediate Filaments ◽  
Striated Muscle ◽  
Three Dimensional ◽  
Major Protein ◽  
Protein Subunit ◽  
Double Labeling ◽  
Adult Chicken ◽  
Microscopic Studies ◽  
Intercalated Disk

We studied the localization of desmin (skeletin), the major protein subunit of muscle-type intermediate filaments, in adult chicken cardiac muscle by high resolution immunoelectron microscopic labeling of ultrathin frozen sections of the intact fixed tissues. We carried out single labeling for desmin and double labeling for both desmin and either vinculin or alpha-actinin. In areas removed from the intercalated disk membranes, we observed desmin labeling between adjacent Z-bands in every interfibrillar space. Where these spaces were wide and contained mitochondria, convoluted strands of desmin labeling bridged between the periphery of neighboring Z-bands and the mitochondria. The intermediate filaments appeared to be organized in a more three-dimensional manner within the interfibrillar spaces of cardiac as compared to skeletal muscle. Near the intercalated disks, desmin labeling was intense within the interfibrillar spaces, but was completely segregated from the microfilament attachment sites (fascia adherens) where vinculin and alpha-actinin were localized. Desmin therefore appears to play no role in the attachment of microfilaments to the intercalated disk membrane. We discuss the role of intermediate filaments in the organization of cardiac and skeletal striated muscle in the light of these and other results.

The Anatomy of the Sarcoplasmic Reticulum in Vertebrate Skeletal Muscle: Its Implications for Excitation Contraction Coupling

1982 ◽  
Vol 37 (7-8) ◽  
pp. 665-678 ◽  
Author(s):  
Joachim R. Sommer
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Action Potential ◽  
Cardiac Muscle ◽  
Calcium Release ◽  
Striated Muscle ◽  
Band Region ◽  
Terminal Cisterna ◽  
Transmitter Substance ◽  
Main Components

Abstract The sarcoplasmic reticulum in situ is an intricate tubular network that surrounds the contractile material in striated muscle cells. Its topographical relationship to other intracellular components, especially the myofibrils, is rather rigidly mainiained by a cytoskeleton which enmeshes Z line material and sarcoplasmic reticulum and, ultimately, is anchored at the plasmalemma. As a result, the two main components of the sarcoplasmic reticulum, the junctional SR and the free SR, retain their typical location in the A band region and in the I band region, respectively. The junc­tional SR, which is thought to be the site for calcium storage and release for contraction, is, thus, always well within one micron of the regulatory proteins associated with the actin filaments. The junctional SR, a synonym for terminal cisterna applying to both skeletal and cardiac muscle, is generally held to be involved in the translation of the action potential into calcium release, mainly because of the close topographic apposition between the junctional SR and the plasmalemma, especially in skeletal muscle. This attractive structure-function correlation is challenged by the observation that in bird cardiac muscle 80% of the junctional SR is spacially far removed from plas­malemma, the site of electrical activity. This anomalous topography is not in conflict with the notion that translation of the action potential into calcium release may be accomplished by a dif­fusible transmitter substance, e.g. calcium. Any hypothesis dealing with this problem must ac­ count for the anatomy of the bird heart.

Long non-coding RNAs (lncRNAs) in skeletal and cardiac muscle: potential therapeutic and diagnostic targets?

2016 ◽  
Vol 130 (24) ◽  
pp. 2245-2256 ◽  
Author(s):  
Julie R. McMullen ◽  
Brian G. Drew
Keyword(s):  
Cardiac Muscle ◽  
Striated Muscle ◽  
Cell Types ◽  
Diagnostic Tools ◽  
Transcriptional Networks ◽  
Sequencing Technology ◽  
Enormous Amount ◽  
Non Coding Rnas ◽  
Novel Therapeutic ◽  
Muscle Potential

The recent discovery that thousands of RNAs are transcribed by the cell but are never translated into protein, highlights a significant void in our current understanding of how transcriptional networks regulate cellular function. This is particularly astounding when we consider that over 75% of the human genome is transcribed into RNA, but only approximately 2% of RNA is translated into known proteins. This raises the question as to what function the other so-called ‘non-coding RNAs’ (ncRNAs) are performing in the cell. Over the last decade, an enormous amount of research has identified several classes of ncRNAs, predominantly short ncRNAs (<200 nt) that have been confirmed to have functional significance. Recent advances in sequencing technology and bioinformatics have also allowed for the identification of a novel class of ncRNAs, termed long ncRNA (lncRNA) (>200 nt). Several studies have recently shown that long non-coding RNAs (lncRNAs) are associated with tissue development and disease, particularly in cell types that undergo differentiation such as stem cells, cancer cells and striated muscle (skeletal/cardiac). Therefore, understanding the function of these lncRNAs and designing strategies to detect and manipulate them, may present novel therapeutic and diagnostic opportunities. This review will explore the current literature on lncRNAs in skeletal and cardiac muscle and discuss their recent implication in development and disease. Lastly, we will also explore the possibility of using lncRNAs as therapeutic and diagnostic tools and discuss the opportunities and potential shortcomings to these applications.

scholarly journals Protein kinase A–dependent modulation of Ca2+ sensitivity in cardiac and fast skeletal muscles after reconstitution with cardiac troponin

2009 ◽  
Vol 133 (6) ◽  
pp. 571-581 ◽  
Author(s):  
Douchi Matsuba ◽  
Takako Terui ◽  
Jin O-Uchi ◽  
Hiroyuki Tanaka ◽  
Takao Ojima ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Cardiac Muscle ◽  
Protein Kinase A ◽  
Striated Muscle ◽  
Physiological Mechanism ◽  
Adrenergic Stimulation ◽  
Fast Skeletal Muscle ◽  
Psoas Muscles ◽  
Kinase A

Protein kinase A (PKA)-dependent phosphorylation of troponin (Tn)I represents a major physiological mechanism during β-adrenergic stimulation in myocardium for the reduction of myofibrillar Ca2+ sensitivity via weakening of the interaction with TnC. By taking advantage of thin filament reconstitution, we directly investigated whether or not PKA-dependent phosphorylation of cardiac TnI (cTnI) decreases Ca2+ sensitivity in different types of muscle: cardiac (porcine ventricular) and fast skeletal (rabbit psoas) muscles. PKA enhanced phosphorylation of cTnI at Ser23/24 in skinned cardiac muscle and decreased Ca2+ sensitivity, of which the effects were confirmed after reconstitution with the cardiac Tn complex (cTn) or the hybrid Tn complex (designated as PCRF; fast skeletal TnT with cTnI and cTnC). Reconstitution of cardiac muscle with the fast skeletal Tn complex (sTn) not only increased Ca2+ sensitivity, but also abolished the Ca2+-desensitizing effect of PKA, supporting the view that the phosphorylation of cTnI, but not that of other myofibrillar proteins, such as myosin-binding protein C, primarily underlies the PKA-induced Ca2+ desensitization in cardiac muscle. Reconstitution of fast skeletal muscle with cTn decreased Ca2+ sensitivity, and PKA further decreased Ca2+ sensitivity, which was almost completely restored to the original level upon subsequent reconstitution with sTn. The essentially same result was obtained when fast skeletal muscle was reconstituted with PCRF. It is therefore suggested that the PKA-dependent phosphorylation or dephosphorylation of cTnI universally modulates Ca2+ sensitivity associated with cTnC in the striated muscle sarcomere, independent of the TnT isoform.

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