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At least 19 recordsLinked to original sources
PubMed1976

Cyclic AMP in developing muscle of the rhesus monkey: effect of prostaglandin E.

Cyclic AMP levels, measured by a competitive protein-binding assay and by a prelabeling technique with adenine-14 C, were determined on fetal, infant, and adult heart, diaphragm, and skeletal muscle of the rhesus monkey (Macaca mulatta); the effect of PGE on cyclic AMP accumulation was also studied. The levels of cyclic AMP were higher in the 3 types of muscle from 150-day fetuses (91% of term) than in adult muscles and even higher at 78-100 days fetal age, and histological evidence indicated that by 65 days gestation, the majority of the rhesus skeletal muscle cells are in the myotube stage. These data agree with the observation in cell cultures that a decrease in cyclic AMP is correlated with fusion of myoblasts to form myotubes. PGE (2.8 MUM) stimulated cyclic AMP accumulation in all the fetal series, even in the earliest series (47% of term), as well as in all the adult series.

Age Factors↗
PubMed1978

Fast and slow myosin in developing muscle fibres.

Slow and fast isoenzymes of myosin coexist in all the fibres of a fast-twitch mammalian muscle during early development. They later become segregated into different populations of fibres. Slow myosin is most abundant when the speed of contraction of the muscle is slow and the fibres are multiply innervated; its synthesis in the majority of the fibres seems to be 'switched off' when the speed of contraction increases and the fibres become innervated by single motoneurones.

Animals↗
PubMed2026

Effects of rumen fluid transplantation on longissimus dorsi muscle development in Xizang sheep: An association analysis based on transcriptomic and serum metabolomic profiles.

This study aimed to investigate the effects of rumen fluid transplantation (RFT) on the growth and development of the longissimus dorsi muscle in female Xizang sheep. After RFT, muscle lightness differed significantly between the two groups, with the LDC group showing significantly higher lightness than the LDT group. In contrast, no significant differences were observed between groups in other muscle phenotypic traits, including drip loss, pH, cooking loss, shear force, redness, and yellowness. Antioxidant-related indices (SOD, GSH-PX, MDA, CAT, and T-AOC) also showed no significant differences between groups. Histological analysis revealed that muscle fiber length, width, and density were significantly greater in the experimental group than in the control group. Transcriptomic analysis identified 515 differentially expressed genes (DEGs), of which 419 were downregulated. KEGG analysis indicated that genes involved in muscle development-related pathways, such as cell adhesion and the PI3K-Akt signaling pathway, were predominantly downregulated. Key serum metabolites (L-kynurenine, IPA, allantoin, and propionylcarnitine) showed highly significant positive correlations with muscle fiber growth indices. In contrast, metabolites such as l-carnitine, acetylcarnitine, and citrulline were negatively correlated with muscle fiber growth, but positively correlated with the expression of muscle structure-related genes (COL11A1 and EFNA5) and with meat lightness. Overall, this study provides new insights into the potential molecular basis by which RFT influences muscle growth and development. However, the mechanisms by which RFT affects muscle development and meat quality-related traits remain unclear and warrant further investigation.

Animals↗
PubMed1979

Contractile protein isozymes in muscle development: identification of an embryonic form of myosin heavy chain.

The nature of the myosin heavy chain in embryonic muscle tissue, cultured muscle cells, and several adult muscles was investigated. After denaturation with sodium dodecyl sulfate, purified rat myosins were subjected to partial proteolytic cleavage or immunological analysis using microcomplement fixation. Three types of myosin heavy chains could be demonstrated by both approaches. Whereas adult muscles contain fast- or slow-type myosin heavy chains, embryonic tissue and cultured muscle cells harbor a distinct embryonic form. The existence of this distinct form further characterizes the isozymic transitions of contractile proteins during muscle development.

Aging↗
PubMed2026

Comprehensive Analysis of miRNAs and Predicted Protein Interaction Networks in Skeletal Muscle Development of Myostatin-Deficient Rabbits.

Myostatin (MSTN), encoded by the MSTN gene, is a critical negative regulator of skeletal muscle mass. This study aims to identify and characterize the miRNAs involved in the development of the double-muscling phenotype in MSTN-deficient rabbits. We performed high-throughput sequencing to analyze the miRNA expression profiles in gluteus maximus tissue from wild type (MSTN+/+) and MSTN-KO (MSTN+/- and MSTN-/- inclusive) rabbits. Differentially expressed miRNAs (DEmiRNAs) were identified, and their potential target genes were predicted. Functional enrichment analysis of these target mRNAs was conducted using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database to elucidate the involved biological pathways and regulatory networks. A total of 25 DEmiRNAs (13 downregulated and 12 upregulated, |log2FC|&#x2009;&#x2265;&#x2009;1.0, adjusted p&#x2009;<&#x2009;0.05) and 1178 differentially expressed mRNAs (408 upregulated and 770 downregulated, |log2FC|&#x2009;&#x2265;&#x2009;2.0, adjusted p&#x2009;<&#x2009;0.05) were identified in MSTN-KO compared to MSTN+/+ rabbits. Bioinformatics analysis revealed that the target genes of these DEmiRNAs were significantly enriched in key pathways governing muscle growth and metabolism, including the PI3K-Akt signaling pathway, MAPK signaling pathway, and pathways related to ECM-receptor interaction and insulin signaling. Notably, many predicted target mRNAs are expressed by genes that encode key inhibitors of myogenesis (e.g., HDAC4) and major extracellular matrix components (e.g., COL4A3, POSTN). Our results demonstrate that MSTN deficiency induces a distinct and widespread change in the miRNA expression landscape of skeletal muscle.

Animals↗
PubMed1976

Naturally-occurring degeneration in chick muscle development: ultrastructure of the M. complexus.

Ultrastructural study of the M. complexus muscle of the chick embryo has demonstrated two populations of fibres: the more common is the normal myotube or muscle fibre, which was observed in various stages of development; the other shows myofibrillar contractions which, at their greatest degree, produce the appearance of an amorphous mass of myofilaments. The contracted fibre had rounded and swollen mitochondria, and vacuoles (autophagic) containing glycogen, and it exhibited a cleavage of the cell which isolated the nuclear region from the main body of the fibre. When the fibres were less contracted they resembled degenerative mammalian fast-twitch-oxidative-glycolytic fibres after immobilization. The more normal fibre population was identical with that of the pectoralis muscle, which was used as a control. These results suggest that the contracted fibres are degenerating, which agrees with conclusions by earlier investigators using light miscroscopy.

Animals↗
PubMed1975

Acetylcholine receptor turnover in membranes of developing muscle fibers.

[125I mono-iodo-alpha-bungarotoxin is used as a specific marker in a description of acetylcholine receptor metabolism. It is concluded that acetylcholine receptors in the surface membranes of chick and rat myotubes developing in cell cultures have a half-life of 22-24 h. Alpha-bungarotoxin (bound to a receptor which is removed from the membrane) is degraded to monoiodotyrosine which appears in the medium. Several observations are consistent with a model in which receptors or alpha-bungarotoxin-receptor complexes are internalized and then degraded: (a) the rate of appearance of iodotyrosine does not reach its maximal rate until 90 min after alpha-bungarotoxin is bound to the surface receptors; (b) 2,4-dinitrophenol, reduced temperature, and cell disruption all inhibit the degradation process. The degradation of surface receptors is not coupled to the process by which receptors are incorporated into the membrane. Evidence suggest that receptors are incorporated into the surface membrane from a presynthesized set of receptors containing about 10% as many alpha-bungarotoxin binding sites as does the surface. Additionally, a third set of acetylcholine receptors is described containing about 30% as amny binding sites as does the surface. These "hidden" recptors are not precursors yet are not readily accessible for binding of extracellular alpha-bungarotoxin. These findings are discussed in relation to both plasma membrane biosynthesis and control of chemosensitivity in developing and denervated skeletal muscle.

Animals↗
PubMed1979

Synthesis of the calcium transport ATPase of sarcoplasmic reticulum and other muscle proteins during development of muscles cells in vivo and in vitro.

The effect of medium Ca2+ concentration upon the concentration and the rate of synthesis of muscle proteins was investigated in chicken pectoralis muscle cultures. There is an easily identifiable class of muscle protein which includes the Ca2+-ATPase of sarcoplasmic reticulum, myosin, troponin C, ATP : creatine phosphotransferase, muscle specific actin, tropomysin 1 and 2, and muscle hemagglutinin, which show a large increase in concentration during normal development. The increased synthesis of these proteins was inhibited, without inhibition of cell proliferation, in culture media of relatively low Ca2+ concentration, 0.05--0.3 mM, where fusion was prevented. Similar medium Ca2+ concentration was required for the expression of all these proteins, suggesting their coordinate regulation. The proteins are denoted as 'calcium-modulated proteins'. The increased Ca2+ transport activity of sarcoplasmic reticulum in cultured chicken pectoralis muscle cells during development at 1.8 mM medium calcium concentration represents de novo synthesis of the Ca2+ transport ATPase, as shown by immunoprecipitation, active site labeling and direct identification of the Ca2+ transport ATPase on two-dimensional gel electropherograms of whole muscle homogenates. The concentration and the turnover rate of the majority of the muscle proteins is not affected significantly by medium Ca2+ concentration between 0.06 and 1.8 mM. It is proposed that increase in cytoplasmic free Ca2+ concentration during fusion plays a central role in the regulation of the synthesis of calcium-modulated proteins.

Acetylcholinesterase↗
PubMed1977

Transitional stages in the histochemical development of muscle fibres during post-natal growth.

Serial frozen sections of longissimus dorsi muscles from seven pigs at different live weights (13 to 127 kg) were reacted for ATPase by the calcium method at an alkaline pH and for NADH oxidative activity. One hundred muscle fibres from each animal were identified individually in serial sections and their staining intensity was measured with a microscope photometer at 600 nm. For each section, staining intensity of fibres (% tranmission) was measured and converted to the nearest one-tenth unit of the range from the darkest to the lightest staining fibres. Frequency of occurrence of fibre types was plotted on a 10 X 10 grid using the range co-ordinates for NADH oxidative activity (vertical) and ATPase activity (horizontal). The commonly recognized histochemical fibre types in this muscle appeared as crowded areas in the grid but, in many cases, these areas were part of a continuous 'L' shaped range, a continuous but skewed distribution with regard to NADH oxidative activity was detected. In fibres with NADH oxidative activity of 0.6 to 1.0 units of the range, a continuous but irregular distribution with regard to ATPase activity was detected. Within this range, there was some evidence of a growth-related shift towards weaker ATPase activity.

Adenosine Triphosphatases↗
PubMed1976

Postnatal cytochemical development of muscle fibers in segmental tail muscles of the rat.

Postnatal development of extrafusal and intrafusal muscle fibers was examined histochemically in segmental tail muscles of the rat. At birth all fibers show a strong reaction for myosin ATPase, uniformity in diameter, and homogeneity in staining intensity. During the first postnatal week, the muscle fibers undergo gradual hypertrophy and hyperplasia but they all maintain the same intense homogeneous staining pattern for the enzyme. By day 9, further differentiation of the muscle fibers results in the formation of a second intrafusal fiber type while the extrafusal fibers are still relatively homogeneous. Finally, two kinds of extrafusal fiber and a third type of intrafusal fiber can be distinguished by day 21. This histochemical fiber pattern is essentially maintained in the adult. These findings show that fiber type development in rat tail muscles lags behind the usual time course of myogenesis known to occur in more rostral regions of the animal. It also indicates that histochemical differentiation of intrafusal fibers in these muscles does not parallel that which occurs in extrafusal fibers. It is likely that arrival and initial contact of sensory nerve terminals on developing intrafusal fibers at day 7 directly influences their relatively early histochemical heterogeneity.

Adenosine Triphosphatases↗
PubMed1979

Ultrastructure of human intramuscular blood vessels in development.

Muscles from human foetuses of nine weeks to nine months development were examined by electron microscopy. Capillaries, arteries and veins are frequent in the human foetal muscle at all stages of development. At nine weeks the vessels have the appearance of capillaries and basement membrane lies around the endothelial cells forming them. The capillaries are of continuous type which do not have apertures in their walls. Tight junctions are seen at some zones of adjacent endothelial cells of the capillaries. Sometimes, pericytes are also seen. At sixteen weeks vessels having the features of veins and of arteries can be identified between the muscle cells. Regarding the arteries, some of the endothelial cells are united to the smooth muscle cells and the intimal elastic lamina is interrupted where these cells approximate. The significance of this junction may be to anchor the intima to the media.

Arteries↗
PubMed1979

Muscle abnormalities in coeliac disease: studies on gross motor development and muscle fibre composition, size and metabolic substrates.

In 11 children with coeliac disease gross motor development was assessed before and during diet treatment using the gross motor subscale of the Denver developmental screening test. ATP, creatine phosphate (CP), glycogen and lactate concentrations, muscle fibre size and fibre composition were measured in specimens obtained by needle biopsy from the vastus lateralis muscle. Before treatment, gross motor development was delayed. ATP, and to a lesser extent, CP and glycogen concentrations were lowered compared to a control group. After treatment, gross motor development was normal and no differences in ATP, CP or glycogen concentrations were found compared to the control group. Fibre size seemed unaffected by the disease. The percentage of type 1 fibres was significantly lower before treatment, compared to values obtained during treatment and from the control group. Whether these metabolic changes were due to the coeliac disease per se or the inactivity which it causes was not possible to establish. In humans, only altered neurogenic influence on the muscles has been previously shown to give changes in fibre composition.

Adenosine Triphosphate↗
PubMed1977

Ca+2-accumulating components in developing skeletal muscle.

This ultrastructural study on the localization of Ca+2 in developing skeletal muscle indicates that the formation of calcium-accumulating components begins during embryonic development. Both oxalate and pyroantimonate techniques are used to localize Ca+2 in distinct cellular components of chick pectoral and sartorius muscles. Two major sites for Ca+2 accumulation are present in ultrathin sections of embryonic and post-embryonic muscles: the terminal cisternae of the sarcoplasmic reticulum and specific lines in the I-bands. Calcium oxalate-accumulating vesicles are present in the smallest recognizable myotubes at the twelfth day of incubation, but calcium-accumulating components are not seen at myofibrillar I-band sites until the fourteenth to seventeenth days of incubation. The fact that myofibrils first form and later in development accumulate a Ca+2-binding component suggests that this Ca+2-binding component is not necessary for the formation of myofibrils, but is added to myofibrils before hatching to serve a probable regulatory role in contraction.

Age Factors↗