[Calcium localization in the degenerating myotubes of developing skeletal muscle in the chick embryo]. / Lokalizatsiia kal'tsiia v destruktivnykh miotrubkakh razvivaiushchikh skeletnykh myshts kurinogo émbriona.

Ca-accumulating formations found in degenerating myotubes of chick embryo by pyroantimonate technique have been identified as membrane bound bodies in the material fixed routinely for electron microscopy. These bodies seem to represent initial stages of a lipid degeneration of membranous structures. It is assumed that calcification of single degenerating subcellular structures may limit spreading necrosis over the whole cell.

[Calcium in the developing skeletal muscles of the chick embryo]. / Kal'tsii v razvivaiushchikhsia skeletnykh myshtsakh kurinogo émbriona.

The osmium-pyroantimonate technique was used for the ultrastructural study of Ca2+-localization in two types of chick embryo skeletal muscles: m. pectoralis and m. soleus. In 8- and 12-day old embryos the pyroantimonate precipitate was found on plasmalemma, condensed chromatine and ribosomes and in N-lines of I-band. During myogenesis (15-, 21-day old embryos) the calcium precipitate is redistributed from the above mentioned sites to terminal cisternae and N-line of I-band. It is proposed that calcium of N-lines may be involved in the glycogenolysis, its association with the muscle contraction occurring particularly at early developmental stages.

[Role of membrane structure in the formation of the myofibrillar system in myogenesis]. / O roli membrannykh struktur v formirovanii miofibrilliarnogo apparata v miogeneze.

The leading role of membranes in the formation of the myofibrillar system at different stages of chick embryo development (on the 8th, 12th, 15th day) was considered. At the early stages the myofibrillar assembly depends mainly on the plasma membrane (myofibrils are located beneath the sarcolemma) and later on it depends on the developing sarcoplasmic reticulum and T-system. It was shown that transverse tubules invaginating from the plasma membrane are the framework for the forming myofibrillar system, and thin filaments are attached to the transverse tubules at the sites of future Z-lines. These results support the idea that Z-lines originate from the membrane. Destruction of the membrane elements provokes disorganization of myofibrillar contractile material.

[Analysis of labeled leucine incorporation by nerve cells of a cultured spinal cord ganglion]. / Analiz vkliucheniia mechenogo leitsina nervnymi kletkami kul'tiviruemogo spinnomozgovogo gangliia.

The protein-synthesizing apparatus of sensitive neural cells was analysed in mature mammals at cultivation. Spinal cervical ganglia of mature rabbits were cultivated by the method of rotating tubes up to 4 days in a usual medium and in an amino-acid-enriched medium. The labelling level was defined radioautographically and by radioactivity of protein and acid-solving cell fractions registered by the scintillation methods. In order to obtain the fractions, Rose's method for dividing neural and glial cells in our modification was used. The glial neural cells were demonstated by our investigation to preserve their ability to incorporate the labelled leucine during any period of cultivation. The medium enriched with precursors of protein synthesis contributes to a more intensive incorporation of amino acid into protein and into the pool on the 4th day of cultivation, while the enriched medium sharply decreases radioactivity in the pool on the 1st day of cultivation. Intensity of the labelled leucine incorporation into the neurons drops towards the center of the explantat. The results obtained by the two methods coinside.

[RNA synthesis in mammalian nerve cells in vitro]. / Issledovanie sinteza RNK v nervnykh kletkakh mlekopitaiushchikh v usloviiakh in vitro.

Neurons of spinal ganglia of adult rabbits were cultivated during 4 days in rolling tubes, RNA synthesis of these neurons being determined by radioautography. In neurons of isolated ganglia, 1 hour following isolation, RNA synthesis was active and decreased up to 64% compared to the initial level only at the fourth day of cultivation. In small neurons, RNA synthesis was more active than in large ones. After addition of exogenous RNA precursors into the medium, the uptake of 3H-uridine increased, especially in large neurons.

[14C-leucine incorporation by the nerve and glial cells of a cultured spinal ganglion]. / Vkliuchenie 14C-leitsina nervnymi i glial'nymi kletkami kul'tiviruemogo spinal'nogo gangliia.

Spinal ganglia of adult rabbits were cultured in the routine and protein synthesis precursors-enriched media. On days I and 4 of cultivation, the intensity of 14C-leucine incorporation in protein and in acid soluble fraction of nerve and glial cells was determined. The tissue of the spinal ganglion keeps incorporating 14C-amino acid, into neurons and glia, for all the tested periods of cultivation with both the media employed. The curves of incorporation into the above fractions of nerve and glial cells cultured in the routine medium display similar patterns of changes, whereas those obtained from the enriched medium observations appear to be anti-fasic. The enrichment of the medium results also in less pronounced fluctuations in the intensity of the labeled amino acid in protein and 14C-leucine pool, on the tested periods of cultivation, which may provide more stable conditions of the explant's survival.