[Spatial distribution of synthetic activity in zone-forming colonies of soil Streptomycetes]. / Prostranstvennoe raspredelenie sinteticheskoi aktivnosti v zonoobrazuiushchikh koloniiakh pochvennogo streptomitseta.

The space distribution of synthetic activity in the substrate mycelium gyphs--structure growth units of a quasiorganism of the radiant fungus, was studied by the method of microspectral analysis. A detailed map of the distribution on the alpha-parameter (which reflects the level of synthetic activity) from the cross section of a living streptomyces colony was constructed. The data obtained support with a high reliability the earlier supposition that the maximum of synthetic activity is in the growth zone and the minimum synthetic activity is in the globular regions of formation of air mycelium protogyphs. The use of objectivity characteristics made it possible to thoroughly study the development of globular structures, the precursors and sources of formation of air mycelium concentric zones on colony surface.

[Rhythmical sporogenesis in Streptomyces colonies. A one-dimensional model]. / Ritmichnyi sporogenez v koloniiakh streptomitseta. Odnomernaia model'.

A one-dimensional model imitating the growth and zone formation of a colony of the radiant fungus streptomycete on a synthetic agar nutrient medium with pyruvate, glucose, or succinate as a limiting source of energy and carbon was considered. The key parameters were determined whose values depend on the composition of nutrient medium and environmental conditions.

[The reaction of endoplasmic reticulum of Mauthner cells of Xenopus laevis tadpoles in response to the partial denervation]. / Reaktsiia éndoplasmaticheskogo retikuluma na chastichnuiu denervatsiiuMautnerovskikh neironov golovastikov shportsevoi liagushki.

The structure of the Mauthner cells in Xenopus laevis tadpole was investigated by light- and electron microscopy in norm and after early unilateral enucleation. It was found that enucleation at early stages caused a delay in morphological development of the contralateral neurons during embryogenesis. We observed a decrease in size of the soma and nucleus and in the number of dendrites, a marked structural underdevelopment of the majority of cell organoids, as well as proliferation and hypertrophy of transversal cisternae in the contralateral Mauthner cells. The ipsilateral neurostructure remained normal in embryogenesis. The data obtained suggest the availability of some unknown powerful afferent contralateral input to Mauthner cells from the optical analyzer.

[Morphogenesis of Mauthner neurons of Xenopus laevis tadpoles following early unilateral eye enucleation]. / Morfogenez Mauthner neironov golovastikov shportsevoi liagushki v usloviiakh rannei odnostoronnei énukleatsii glaza.

The connection between Mauthner neuron (CMN) and visual analyzer in Xenopus laevis tadpoles was studied using these neurons capacity to change their morphogenesis during the development in case of interruption of their connections with afferent fibres. In phase 31 of development tadpoles were subjected to unilateral enucleation of eye. Morphogenesis of contralateral (experimental) and ipsilateral (control) MN with respect to the operated eye was followed up. Comparison with intact Mauthner neuron of the tadpole of the same age who were not exposed to operation was conducted. Contralateral MN were found to be delayed in development phases 47 and 50. This was associated with 1.5-3.3 fold difference in neuron body central section area and 2-3 fold differences in nuclear section area. Three-dimensional reconstruction revealed lower number of cell processes in contralateral MN as well as decline in their length and diameter. Control and intact MN showed no difference similar to experimental and control ones in phase 41. The data obtained indicate that MN of Xenopus laevis tadpole possess powerful ipsilateral connections originating from the side of visual analyzer and contralateral ones from the side of the eye. This affects MN development and in contrast to octavolateral system (including vestibular apparatus and organs of lateral line) controls the contralateral neuron.

[The cultivation of fragments of the parotid venom-secreting gland in the common adder (Vipera berus)]. / Kul'tivirovanie fragmentov okoloushnoi iadosekretiruiushchei zhelezy gadiuki obyknovennoi.

The primary culture of the Vipera berus poison-secretory parotid gland has been obtained. The morphology of the intact secretory epithelium and epithelial cells cultured in different conditions has been examined by light and electron microscopy. The secretory epithelium cells were able to survive in the cultural medium and to adapt to in vitro conditions maintaining their nearly normal ultrastructure corresponding to the stage of active poison secretion commonly observed in epithelial cells of the native gland.

[The ultrastructure of the neuromuscular synapses at different stages in the development of the embryos and tadpoles of the clawed toad]. / Ul'trastruktura nervno-myshechnykh sinapsov na raznykh stadiakh razvitiia émbrionov i golovastikov shportsevoi liagushki.

Myoneural synapses were studied in embryos and tadpole of Xenopus laevis on different stages of development using light and electron microscopy. On embryonal stages, during hatching and on stages of tadpole myoneural synapses vary in in appearance, number of organelles and extent of formation of different synaptic specialisations. During the process of myoneural contacts forming in the development of amphibians, terminal is the first to form, followed by the Schwann cell, that covers it, and postsynaptic plication forms in the last turn. When the embryo of Xenopus laevis becomes a tadpole some of its terminals contain significant number of large synaptic vesicles united into clusters both in cytoplasm and near to active zones (together with small ones). This heterogeneity was not found on earlier stages. A suggestion is made on possible participation of two different axons in the innervation of myotomic muscular fibres of tadpole of Xenopus laevis.

[The structure of the reticulum of Mauthner's neurons in tadpoles of the clawed toad grown under increased gravitational force]. / Stroenie retikuluma Mautnerovskikh neironov golovastikov shportsevoi liagushki, vyrashchennykh pri povyshennoi sile tiazhesti.

The ultrastructure of the Mauthner cells (M-cells) and the behaviour of Xenopus laevis tadpoles, reared from eggs under increased gravity (2.9 g) which changes the activity of an afferent vestibular input, were investigated. Besides, a study was made of tadpoles after the hindbrain ablation at earlier embryonal stages which significantly altered the microenvironment of M-cells. It is shown that experimental treatments enhance the proliferation of endoplasmic reticulum and its derivatives, so called subsurface cisterns, in the subsynaptic areas. Some structural changes of the synaptic active zones and the cytoskeleton of M-cells were also noticed. It is assumed that the development of the endoplasmic reticulum promotes an intense removal of calcium ions from subsynaptic areas. The plasticity of the endoplasmic reticulum together with other ultrastructural changes apparently stipulate the adaptation of neurons to changed conditions of functioning.

[The cytoskeleton of the Mauthner neurons in the guppy after returning from an orbital flight]. / Sostoianie tsitoskeleta Mautnerovskikh neironov guppi posle vozvrashcheniia iz orbital'nogo poleta.

The ultrastructural investigations of the Mauthner neurons (M-cells) of P. reticulata were performed on the return of the fishes after a two weeks orbital flight, the M-cells of fishes from different control groups being simultaneously examined. The structure of M-cells from the experimental fishes was shown to be severely damaged. The changes involved the synaptic apparatus, postsynaptic areas, mitochondria and other organelles of the cytoplasm and the nucleus. Particular changes were seen in the neuronal cytoskeleton. While in the M-cells of intact fishes these were seen as evenly distributed microfilaments and neurofilaments, in the M-cells of experimental fishes the cytoskeleton looked as alternating bundles of condensed filaments. The first indications of cytoskeleton damage appeared in M-cells of the guppy from transport control group and strengthened in fishes from the group of synchronous control. Thus, the data obtained give us a possibility to suggest that the return on the Earth and following readaptation after a prolonged flight at conditions of microgravity and consequent disfunction of vestibular apparatus may result in the damage of central neurons receiving vestibular afferentation (such as M-cells). That, in turn, may be a cause of functional disorders of the central nervous system, including the nerve centres maintaining the organs of motion. These facts are necessary to take into consideration when more prolonged cosmic flights are planned.

[Ultrastructure of the Mauthner neurons in goldfish fry after their adaptation to vestibular stimulation]. / Ul'trastruktura Mautnerovskikh neironov mal'kov zolotoi rybki posle adaptatsii k vestibuliarnoi stimuliatsii.

The ultrastructure of the Mauthner cells (M-cells) of goldfish fries was investigated under four different functional states: a) intact (native fishes), b) fatigue (intact fishes subjected to a prolonged vestibular stimulation), c) adapted (intact fishes after a prolonged training session of the daily short vestibular stimuli), d) excited (adapted fishes subjected to a prolonged vestibular stimulation). It has been first found that the fatigue of the M-cells may result in destructive changes of their cytoskeleton. Besides, in the afferent synapses of both adapted and excited M-cells numerous dense-cored vesicles were revealed near the active zones. The data show the neuronal cytoskeleton to be the central target susceptible to damage upon stimulation. The training leads presumably to stabilization of the cytoskeleton ultrastructure. The dense-cored vesicles were suggested to play an active role in the process.