TIP GROWTH OF NEUROSPORA CRASSA IN THE CONDITIONS OF THE RESOURCE DEFICIENCY: IMPAIRMENTS IN THE COHERENCE OF ELONGATION, BRANCHING, AND SEPTATION.

With the aid of intracellular fluorescent probes, peculiarities of elongation, branching, septation, and nucleus morphology have been studied in isolated 400-µm-long apical fragments of Neurospora crassa hyphae growing for several hours without the influx of the nutrient materials from the mycelium. We found that: 1) the diameter and growth rate of newly developing branches decreased as compared to intact mycelium (from 10-20 to 6.5 ± 0.4 µm and from 24 ± 1 to 6.7 ± 0.5 µm/min, respectively), but the initial orientation of growth did not change; 2) the branching rhythm was altered; abnormally long internode distances appeared (up to 1471 µm), and the development of some side-branch buds ceased; 3) the character of the septation remained unchanged, as well as the hyphal segment length (68 ± 2 µm). In hyphae growing for 4.5-5.0 h in isolation from the whole mycelium, the distance between the tip and the first septum was 210 ± 15 µm, which was comparable with the respective value in intact mycelium, whereas the mean distance between the growth tip and the first side branch (492 ±127 µm) and the dispersion of this parameter was considerably higher than in intact mycelium. In branches growing in isolation from the intact mycelium for 1.5-4.5 h, the length of the nucleus- free apical zones near the growth tip (from 5 to 33 µm) and the nucleus morphology were similar to the respective characteristics known for the N. crassa mycelium. The experimental model described here can be used for the investigations of molecular and genetic mechanisms regulating the interactions between intracellular structures involved in the tip growth of N. crassa.

Structural and functional organization of growing tips of Neurospora crassa Hyphae.

Data are presented on a variety of intracellular structures of the vegetative hyphae of the filamentous fungus Neurospora crassa and the involvement of these structures in the tip growth of the hyphae. Current ideas on the molecular and genetic mechanisms of tip growth and regulation of this process are considered. On the basis of comparison of data on behaviors of mitochondria and microtubules and data on the electrical heterogeneity of the hyphal apex, a hypothesis is proposed about a possible supervisory role of the longitudinal electric field in the structural and functional organization of growing tips of the N. crassa hyphae.

[Organization of mitochondria in the growing hyphae of Neurospora crassa].

In vivo fluorescent labeling of mitochondria in Neurospora crassa showed the concentration of filamentous mitochondria within 30 µm of apex in growing hyphae. These mitochondrial assemblies propagated forward with the elongation of hyphae, split and segregated as the growing tip bifurcated and formed de novo when new branches formed farther away from the apex. The efficiency of the mitochondria concentration in the apical 30 µm zone is related to the growth rate and identical in hyphae cultivated in glucose- and sorbitol-containing media. The obtained data are discussed in connection with the behavior of microtubules in growing hyphae as well as with the electric heterogeneity of N. crassa hyphal apex described previously.

[Effect of superficial reflexotherapy (redox-therapy) on the psychophysiological status of athletes].

The objective of this study was to evaluate the influence of superficial reflexotherapy (redox-therapy) on the psychophysiological status of athletes. It was shown to have positive effect on central and peripheral hemodynamics and beneficial action on neurovegetative regulation of the blood circulatory system. These effects depend on the choice of applicators and the duration of therapy. Superficial reflexotherapy can be used alone or in combination with physiotherapy.

Energy transfer via cell-to-cell junctions. Ouabain-resistant cells maintain a membrane potential in ouabain-sensitive cells.

Animal cell cooperation has been studied in a mixed cell culture. Membrane potentials of human embryonic cells and hamster BHK-21 cells were recorded by intracellular microelectrodes. The Na+/K(+)-ATPase inhibitor ouabain (1 x 10(-6) M; 2 h) caused strong depolarisation of the human cells in pure culture. The same treatment reduced only slightly the membrane potential in the hamster cells in pure or mixed cultures, as well as in the human cells in mixed culture. The above data can be explained by effective ion fluxes through heterotypic gap junctions in mixed culture. Thus, in the presence of ouabain the Na+/K(+)-ATPase of hamster cells creates transmembrane differences of the electrochemical potential of ions not only in the hamster cells, but in the human cells as well.

Transcellular ionic currents studied by intracellular potential recordings in Neurospora crassa hyphae. Transfer of energy from proximal to apical cells.

Membrane potentials, input resistances, and electric coupling in the apical parts of N. crassa growing hyphae were recorded with the aid of intracellular microelectrodes. It was revealed that the apical cells were always depolarized by 10 to 30 mV as compared to the adjacent proximal cells. The septal pore maintained an electrical resistance of 4 to 6 M omega. The calculated values of the endogenous electrical current passing through the septal pore varied between 0.5 and 1 nA. Electrical isolation of the apical cells resulted in their depolarization from 120-150 mV to 40-60 mV, characteristics of the membrane potential value of N. crassa adult hyphae with completely blocked electrogenic pumps. A simultaneous increase in the input resistance value from 15-20 M omega to 40-80 M omega was observed. The above data can be explained assuming that H+-ATPase activity was greatly lowered in the apical cells. Thus in the intact hyphae with electrically coupled cells energy is transferred from the proximal hyphal compartments to the apical ones.

Energetic cooperation via ion-permeable junctions in mixed animal cell cultures.

Low ouabain concentration (1 x 10(-6) M) is shown to decrease intracellular K+ (K+in) and to increase intracellular Na+ (Na+in) in human fibroblast cell cultures. The same ouabain concentration was without effect upon K+in ad Na+in in rodent cultures such as BHK-21, mouse fibroblasts and rat glyoma C6 cells. K+in and Na+in in the mixed cultures of human and BHK-21 fibroblasts or human and mouse fibroblasts were found to be resistant to 1 x 10(-6) M ouabain whereas that of the mixtures of human and rat glyoma C6 cells proved to be ouabain-sensitive. The gap-junction-mediated dye transfer was revealed between human and BHK-21 cells. Such an effect was very small in the human-C6 cell mixed culture. It is concluded that cells with active ion pumps can support the maintenance of K+ and Na+ gradients in cells with inactive pumps, provided that effective ion transport via gap junctions takes place.

Electrical properties and ability to form low-resistance junctions in rat neoplastic cells LW13K2 and RsK4.

Clonal lines of Lewis rat neoplastic fibroblastoid LW13K2 cells and epithelioid RsK4 cells were used to study the changes in membrane potential, input resistance and the capability to form low-resistance junctions upon RSV transformation. The drop of MP in RsK4 cells was accompanied by the acquisition of temperature dependence. The input resistance was simultaneously increased. This was considered to be a consequence of the decrease in potassium current across the cell membrane and of a change in the mechanism of potassium transport which became energy dependent. Examination of fluorescent tracer (n.w. 330) diffusion which was negative in the homotypic situation in both cell lines confirmed only the relative independence of these cells in culture. In the heterotypic situation LW13K2 in contact with normal mouse embryo fibroblasts gave positive results whereas RsK4 were almost negative.

[Highly permeable contacts between epithelial cells in culture]. / Vysokopronitsaemye kontakty mezhdu épitelial'nymi kletkami v kul'ture

Cultured epithelial cells producing monolayered sheets were used to study intercellular contacts permeable to sodium fluorescein. Cells in dense cultures were more capable of forming permeable junctions than cells of sparse cultures. In addition, the standard microelectrode technique revealed some differences in cellular membrane potentials in dense and sparse cultures. A possible correlation is discussed between intercellular contact formation and other features of cells depending on cell culture density.

[Changes in intercellular exchange intensity in an L cell culture]. / Izmeneniia intensivnosti mezhkletochnogo obmena v kul'ture kletok L.

Intercellular junctions permeable to fluorescein Na were studied with the aid of intracellular glass microelectrodes in the cultures of transformed mouse-embryo cells (L-strain). The degree of coupling was correlated with the cell culture density. In addition, the degree of coupling increased after short-time incubated of the cells with 1mM lanthanum. Such an incubation did not influence other features of cells: the value of the membrane potential, the character of growth or the inclusion of the vital dye neutral red. Some other factors stimulated cellular aggregation (concanavalin A, protamine, decreasing the pH) but did not influence the degree of coupling.

[Effect of Novocaine on the stimulation by lanthanum of intercellular exchange]. / Vliianie novokaina na stimuliatsiiu lantanom mezhkletochnogo obmena.

Some influences on intercellular junctions permeable to Fluorescein Na were studied with the aid of intracellular glass microelectrodes in the cultures of transformed mouse--embryo kidney cells (MTR) and fibroblast--like cells (L). 1 mM of lanthanum increased the degree of coupling by 2 or 3 times. The preceeding incubation of cells with a 0.02% procaine solution protected them from the influence of lanthanum. A possible mechanism of concurrence between lanthanum and procaine on intercellular junctions is discussed.

[Highly permeable intercellular junctions in normal and transformed fibroblast cultures]. / Vysokopronitsaemye mezhkletochnye kontakty v kul'turakh normal'nykh itransformirovannykh fibroblastov

Intercellular junctions permeable to ions and fluorescein Na were studied with the aid of intracellular microelectrodes in the cultures of normal and transformed mouse-embryo and hamster-embryo fibroblast-like cells. Normal cells were effectively coupled by the highly permeable junctions. In cultures of 7 types of transformed cells, 3 types of coupling were detected: effective, decreased, and fully reduced couplings. The degree of uncoupling was not correlated with morphological patterns of malignization and tumorogeneity of transformed cultures. The decrease of permeability of intercellular junctions to ions and small molecules is concluded not to be necessary for malignization.

[Electrical characteristics of normal and transformed fibroblasts in tissue culture]. / Elektricheskie kharakteristiki normal'nykh i transformirovannykh fibroblastov v kulture tkani

The two-electrode method of input resistance measuring was shown to give lower values of resistance compared with the one-electrode balance method. Gradual growth of estimates of input resistance and membrane potential in the cause of experiment is associated with decrease in the shunting effect of the electrode puncture. The mean values of steady Rin of sparse and confluent culture did not differ when the cells were electrically disconnected (38 plus or minus 1.2 MO and 41 plus or minus 1.8 MO respectively) and differed in electrically coupled fibroblasts (54 plus or minus 4.9 MO --sparse; 29 plus or minus 2.2 MO -- confluent culture). This difference is thought to be associated with shunting effect of electrical connections. The specific resistance of membrane was estimated in normal and transformed fibroblasts.

[Ultrastructure of the specialized intercellular contacts in an L-cell culture treated with low concentrations of lanthanum]. / Ul'trastruktura spetsializirovannykh mezhkletochnykh kontaktov v kul'ture L-kletok, obrabotannoi nizkimi kontsentratsiiami lantana.

The electron microscope study of L-cells treated with 1 mM lanthanum has shown an increased amount of gap-like junctions and a decreased number of tight junctions compared to the norm. No damage in the plasma membrane structure and other cell organoids was observed. This may suggest that following the above treatment, the amplified intercellular exchange is associated with the increase in the quantity of intercellular highly permeable junctions. In this case lanthanum may serve as a membrane structure modificator. This effect must be taken into account when the electron microscopists use the lanthanum label for studying specialized intercellular junctions.

[Analysis of the cable structure of blue-green algae]. / Analiz kabel'noi struktury sine-zelenykh vodoroslei.

Peculiarities of electrical responses under local illumination of filamentous cyanobacteria (blue-green algae). Phormidium uncinatum were studied by means of extracellular electrodes. Recording of electrical responses at different distances from the exposure place and comparison of these data with the results obtained on physical model of Ph. uncinatum end expected response parameters computed made it possible to estimate the parameters of the cable which can serve as the object model: RC=440 c/cm2 and lambda min greater than or equal to 0.07 cm. According to these values and taking membrane capacity as C=10(-6) phi/cm2, intracellular resistance Rm=10(7) Ohm and conductivity of the surface membrane G less than or equal to 10(-6) I/Ohm cm2 were estimated.

[Propagation of electrical potential changes in filamentous cyanobacteria]. / Rasprostraniaiushchiesia izmeneniia élekltricheskogo potentsiala u nitchatykh tsianobakterii.

Possible energy transmission along conjugating membranes was investigated. It was found by extracellular electrodes that under local illumination of blue-green algae Phormidium uncinatum the electrical current propagated along trichomes. The form and sign of the responses show that e. m. f. appears in the illumination region, which generates on the cellular membrane the potential difference with a negative charge inside the cell. The initiated transmembrane potential difference propagates along the filament of Ph, uncinatum like along a cable. The hypothesis concerning a cable structure of Ph, uncinatum was supported in the experiments with intersection of algae, and with intracellular injection of fluorescein showing the existence of direct diffusion exchange through cellular interfaces.

[Influence of light on membrane potential of Neurospora crassa cells]. / Vliianie sveta na membrannyi potentsial kletok Neurospora crassa.

In experiments with left atrial and right ventricular tissues fast sodium current (INa) was decreased by substituting sucrose for sodium in Tyrode's solution and with antiarrhythmic drugs--INa blockers (lidocaine, diphenylhydantoine and ethmozine). It was shown that INa decrease results in the growth of refractoriness (R) of the cardiac tissues. The hypothesis is advanced that the R growth caused by INa decrease is one of the mechanisms of selective sensitiveness of ischemic heart tissues to antiarrhythmic drugs--INa blockers.

[Populations of higher plants found in the area of influence of the Semipalatinsk proving grounds]. / Izuchenie populiatsii vysshikh rastenii, nakhodiashchikhsia v zone vliianiia Semipalatinskogo poligona.

Population of Scotch pine and crested wheat grass growing on the territories of Semipalatinsk testing ground and contaminated during the traits of nuclear weapon, and in the control region differ by a number of genetic and cytogenetic trials. Besides, it is evident that the investigation of the nature of genetic anomalies and their association with radiation factors in the problem more complicated than merely to recognize the fact of their availability. This calls for further investigations.

[Children's health as a subject to sanitary and hygienic monitoring]. / Zdorov'e detei kak ob"ekt sotsial'no-gigienicheskogo monitoringa.

Sanitary and hygienic monitoring in town near Moscow evaluated health of children living in areas under various ecologic circumstances. The results proved that living near automobile roads and in town's industrial district is associated with considerably lower health state of the children. Increased level of acoustic exposure in the district corresponds to more frequent appeals to medical establishments for cardiovascular care.