Utilization of ascorbic acid during post-embryonic development of chick skeletal muscle.

Ascorbic acid is utilized during the post-embryonic differentiation of skeletal muscle fibres in chick. While the fibres lose their heterogeneity with regard to ascorbic acid, they continue to exhibit differences in their metabolic rates in terms of the succinate dehydrogenase activity throughout life.     

Biosynthesis of ascorbic acid in chick embryos

Summary Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.I am grateful to Dr R. Jenness (Univ. of Minnesota) for the generous gift of L-gulonolactone and to Dr B. Sanders (Univ. of Texas) for the chick embryo samples     

Biosynthesis of ascorbic acid in chick embryos

Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.     

Myosin heavy chains in fast skeletal muscle of chick embryo

Summary The peptide map obtained by electrophoresis after digestion of purified myosin heavy chains from pectoralis muscle of embryonic chicken with theStaphylococcus aureus V8 protease, produces a peptide pattern very similar but not identical to that of adult fast myosin. In fact, some components that are present in a small amount in the map of slow adult myosin are visible in the embryonic pattern.Acknowledgments. I wish to acknowledge the enthusiastic encouragement of Dr Ugo Carraro and the help of Prof. Stefano Schiaffino's group and of Dr Marcello Cantini for embryonic tissue isolation. The skillful technical assistance of Mr Silvio Belluco is also gratefully acknowledged. This work was supported in part by a grant of Muscular Dystrophy Association of America to Prof. Massimiliano Aloisi.     

Changes in ascorbic acid content in denervated frog gastrocnemius muscle

Zusammenfassung Nach Denervierung des Gastrocnemius beim Frosch waren die Konzentrationen der l-Ascorbinsäure, Dehydro-l-Ascorbinsäure (DHA) und Diketoguloniksäure (DKA) im Nieren- und Nebennierengewebe unverändert. DHA und DKA fehlten, während ihre Konzentrationen in der Leber trotz Ascorbinsäurezunahme gleichmässig verteilt waren.     

Lipid and phospholipid content and fatty acid composition of the chick lung during embryonic development

Summary The evolution of total phospholipid, phosphatidylcholine and phosphatidylethanolamine content of chick lung during embryonic development is in good agreement with morphological data. Saturated fatty acids are predominant. A sex-linked difference is observed in the evolution of phosphatidylcholine.     

Histotopochemistry of ascorbic acid during the formation of carrageenin granuloma

Zusammenfassung Es wird die Histotopochemie der Askorbinsäure im Laufe der Karagenin-Granulombildung untersucht. Die Askorbinsäure ist an die Fibroblasten, eventuell an die junge Faserstruktur gebunden, die sich in einer unmittelbaren Nähe des Fibroblasten-Cytoplasmas befindet. Es wird angenommen, dass sich die Askorbinsäure an der Hydroxylation von Prolin oder Lysin beteiligt, und dass dieser Prozess am intensivsten in den Fibroblastenzellen vor sich geht.

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Acknowledgment: I should like to thank Ing. B.Cmuchalová of the laboratories of Dr. M. Chvapil for supplying the experimental material.     

Lipid and phospholipid content and fatty acid composition of the chick lung during embryonic development.

The evolution of total phospholipid, phosphatidylcholine and phosphatidylethanolamine content of chick lung during embryonic development is in good agreement with morphological data. Saturated fatty acids are predominant. A sex-linked difference is observed in the evolution of phosphatidylcholine.     

6-azauridine in brain tissue during chick embryonal development

Résumé 10 mg d'azauridine-6 ont été injectés dans les ufs au 4è et au 8è jour d'incubation. Dans nos précédentes expériences, cette dose a provoqué des malformations dans les embryons du poulet. La concentration de l'azauridine-6 a été déterminée dans le cerveau des embryons et on a trouve qu'elle varie de 0,48–1,16 mg pour 1 g du poids sec du cerveau, du 14è au 20è jour d'incubation.     

Retinoic acid maintains human skeletal muscle progenitor cells in an immature state

Muscle satellite cells are resistant to cytotoxic agents, and they express several genes that confer resistance to stress, thus allowing efficient dystrophic muscle regeneration after transplantation. However, once they are activated, this capacity to resist to aggressive agents is diminished resulting in massive death of transplanted cells. Although cell immaturity represents a survival advantage, the signalling pathways involved in the control of the immature state remain to be explored. Here, we show that incubation of human myoblasts with retinoic acid impairs skeletal muscle differentiation through activation of the retinoic-acid receptor family of nuclear receptor. Conversely, pharmacologic or genetic inactivation of endogenous retinoic-acid receptors improved myoblast differentiation. Retinoic acid inhibits the expression of early and late muscle differentiation markers and enhances the expression of myogenic specification genes, such as PAX7 and PAX3. These results suggest that the retinoic-acid-signalling pathway might maintain myoblasts in an undifferentiated/immature stage. To determine the relevance of these observations, we characterised the retinoic-acid-signalling pathways in freshly isolated satellite cells in mice and in siMYOD immature human myoblasts. Our analysis reveals that the immature state of muscle progenitors is correlated with high expression of several genes of the retinoic-acid-signalling pathway both in mice and in human. Taken together, our data provide evidences for an important role of the retinoic-acid-signalling pathway in the regulation of the immature state of muscle progenitors.     

Relationship between light diffraction intensity and tension development in frog skeletal muscle

Summary Laser diffraction intensity decrease in active muscles precedes tension development at sarcomere lenghts below 2.76 m, but not at greater lenghts. This suggests that the time lag is caused by random sarcomere shortenings inside each myofibril.     

Reactivity of cat skeletal muscle vessels to noradrenaline during induced respiratory alkalosis

Zusammenfassung Die respiratorische Alkalose steigert den Effekt des Noradrenalins auf Skelettmuskelgefässe. Eine durchschnittliche Steigerung des pH von 0.2 Einheiten wird benötigt, um eine merkliche Änderung herbeizuführen. Die vorliegenden Resultate lassen vermuten, dass die Steigerung in erster Linie auf die pH-Veränderung zurückzuführen ist und nicht auf die gleichzeitige Senkung der CO₂-Spannung.     

Laminins during muscle development and in muscular dystrophies

Cellular interactions with the extracellular matrix during muscle formation and in muscular dystrophy have received increased interest during the past years. Laminins constitute a growing family of proteins with complex expression patterns in forming basement membranes during muscle development. In skeletal muscle, laminins constitute major ligands for cell surface receptors involved in the transmission of force from the cell interior, but laminins might also influence signal transmission events during muscle formation and in muscle regeneration. During myogenesis the laminin alpha1 chain is present around the epithelial somite; but later, in forming muscle, the laminin alpha1 chain is restricted to the myotendinous junction. The laminin alpha2, alpha4 and alpha5 chains are major laminin chains in the muscle basement membrane during muscle formation, but laminin alpha4 and alpha5 chains are absent in adult muscle. The importance of laminins for muscle integrity is manifested in congenital muscular dystrophies with defects in the laminin alpha2 chain. There is no good evidence for the presence of laminin alpha1 chain in dystrophic muscle, but some other fetal muscle laminins can be detected in dystrophic muscle. Characterization of laminin expression patterns in muscular dystrophies might be of diagnostic and therapeutic value. In this paper, we review the recent publications on the biological functions of muscle laminins and discuss their roles in skeletal muscle.     

On the presence of glycogen in the rhombencephalon of chick embryos during development

Riassunto Viene condotto uno studio sulla distribuzione del glicogeno nel romboencefalo dell'embrione di pollo durante lo sviluppo. I risultati delle indagini condotte hanno messo in evidenza una caratteristica localizzazione del glicogeno nell'abbozzo del ponte e del bulbo più evidente in embrioni dal 7° al 13° giorno di incubazione. Tale reperto viene discusso nel suo significato.     

Electrophoretic profiles of proteins and glycoproteins of chick embryo fibroblasts during development]

The variations of proteins and glycoproteins of Chick embryo fibroblasts are studied during development. This investigation is carried out using polyacrylamide disc gel electrophoresis in SDS. Two glycoproteins of high apparent molecular weight (250,000 and 200,000) undergo quantitative modification: they increase from the 8th to 12th day of development and then remain unchanged to the 16th day. They are cell surface components as suggested by fluorescamine labelling and trypsin sensitivity. The results are discussed in terms of relationship between tumor- and embryo cells.     

Susceptibility of chick neural retina to viral multiplication in vitro during embryonic development

Decrease in the susceptibility of embryonic chick neural retina cultures to the multiplication of various viruses was observed with increasing age of the embryo. In contrast the retinal cells supported the multiplication of Sindbis virus irrespective of the age when they were infected with the viral RNA. These results suggest that the restricted multiplication of the viruses observed is due to the modulated inability of the cell to process the adsorbed viruses for subsequent replication.