Adaptation to salt stress in a salt-tolerant strain of the yeast Yarrowia lipolytica.

We have studied the cellular mechanisms underlying adaptation to salt stress in a newly isolated osmo- and salt-tolerant strain of the yeast Yarrowia lipolytica. When cells are incubated in the presence of 9% NaCl, a rapid change in their size and shape is observed. Salt stress is accompanied by an increase in the intracellular level of glycerol, free amino acids (notably proline and aliphatic amino acids), and Na+, as well as by changes in lipid and fatty acid composition.

[The detection of the herpes simplex virus 1 and 2 antigens in clinical specimens by using monoclonal antibodies]. / Detektsiia antigena virusa prostogo gerpesa 1 i 2 tipa pri pomoshchi monoklonal'nykh antitel v klinicheskikh obraztsakh.

The possibility of using monoclonal antibodies (McAb), obtained earlier, for the detection of herpes simplex virus (HSV) in clinical specimens taken from sick and infected persons was studied. The examination of 90 persons revealed that the mixture of McAb 4A and 2C could effectively detect the presence of HSV antigen in the indirect immunofluorescence assay (IFA) directly in cells contained in cytological preparations (smears, scrapes, impressions) obtained from different organs of patients. The search of optimum combinations of McAb for the detection of HSV antigens by the method of the solid-phase enzyme immunoassay (EIA) was carried out. This study, made on purified HSV used as an experimental model, revealed that the maximum sensitivity could be achieved with the use of two McAb (4f6 and 7c4) out of three McAb (4f6, 7c4 and 3d10). The approbation of both variants of EIA on clinical specimens taken from 99 patients (blood clots, seminal fluid, scrapes of cervical canal cells, peripheral blood lymphocytes) showed that the addition of McAb 3d10 made it possible to detect 8 more positive specimens. 754 specimens from 337 patients were studied with the use of McAb-based EIA, and in 204 of these patients (61%) HSV antigen was detected. The results obtained with the use of our McAb were compared with the data obtained with certified commercial test systems. The coincidence of the EIA data with those obtained with the use of the Murex Wellcozyme HSV test system (UK) was registered in 75% of cases (in 15 out of 20 cases). The coincidence of the IFA data with those obtained with the use of the Sanofi test system (France) was observed in all 19 cases (100%).

[The functioning of mammalian mitochondria injected into fish embryos]. / Funktsionirovanie mitokhondrii mlekopitaiushchikh, in''etsirovannykh v zarodyshi ryb.

The possibility of mammalian mitochondria functioning in fish embryos has been studied. Suspension of mitochondria isolated from the mouse fibroblast B-82/cap (chloramphenicol-resistant) and B-82 (chloramphenicol sensitive) cell cultures, were injected into the fertilized loach eggs. These embryos with an artificially increased number of mouse mitochondria developed and lived till the larval stages. Activity of cytochrome oxidase in these embryos was 1.5-2 times that in the control several hours after the injection, decreased during development and reached the control level by the gastrula stage. If these embryos with artificially increased number of mouse mitochondria were incubated in presence of chloramphenicol, only embryos that contained mitochondria from chloramphenicol-resistant cells survived, thus suggesting that the injected mitochondria do not degrade but are preserved and function in the cytoplasm of developing loach embryos.

[Regulation of the number and function of mitochondria during artificial increase of their mass in fish embryos]. / Reguliatsiia kolichestva i funktsii mitokhondrii pri iskusstvennom uvelichenii ikh massy v zarodyshakh ryb.

The mechanisms of mitochondrial mass reduction were investigated by microinjection of mitochondria in developing loach embryos. This reduction can be due to the degradation of the injected mitochondria or to the triggering of regulatory mechanisms. In the latter case the decrease of mitochondrial excess should be caused by exogenous and endogenous mitochondria of the embryos. When the protein-labelled mitochondria were injected into unlabelled eggs or the unlabelled mitochondria were injected into the eggs containing labelled mitochondria, the label content in the mitochondrial protein was decreased 2-fold within 12 hours and then remained unchanged at later stages of embryogenesis. After injection of 3H-labelled mitochondria into the 14C-labelled eggs the 3H/14C ratio in the mitochondrial protein during embryogenesis remained unchanged. These data suggest that the restoration of the normal amount of the mitochondrial mass is caused by the triggering of regulatory mechanisms. Oxygen uptake in the embryos with the artificially increased amount of mitochondria is maintained at a control level or even below control, i. e. undergoes regulation. In the homogenates of these embryos the regulatory control is absent and oxygen uptake is proportional to the amount of mitochondria.

[Injection of mitochondria into oocytes and fertilized eggs]. / In'ektsiia mitokhondrii v ootsity i oplodotvorennye iaitsa.

The suspension of mitochondria isolated from the loach embryos or the frog heart were injected in the oocytes or fertilized eggs of the loach, newt, toad and frog in the amount roughly equivalent to the content of mitochondria in the egg. After the injection the oocytes did not differ during several days from the normal ones and the fertilized eggs of the loach, newt and South Afican clawed toad developed normally. The activity of cytochrome oxidase in the injected oocytes was kept at a somewhat higher level (1.4 to 1.9 vs 1.0 in the control) during several days. In the developing eggs the activity of cytochrome oxidase began to decrease from the blastula stage and attained rapidly the control level. The decrease of the enzyme activity is due to non-specific degradation of excessive mitochondria or to compensatory inactivation of the enzyme ensuring the maintenance of its normal activity during the development.

[Expression of paternal genes controlling cytochrome oxidase activity in hybrid fish]. / Ekspressiia ottsovskikh genov, kontroliruiushchikh aktivnost' tsitokhromoksidazy v razvitii gibridov ryb.

The heat resistance of the oxygen consumption by the mitochondria, temperature dependence of the Michaelis' constant (CM) and heat resistance of cytochrome oxidase were studied in the embryos and larvae of fish hybrids (Misgurnus X Brachydanio). The oxygen consumption by the mitochondria from the larvae of Misgurnus ceased (following the 10 min heating) at 50 degrees, from Brachydanio at 54 degrees and from the hybrids at 52 degress suggesting control of the respiratory function. CM of cytochrome oxidase has the same minimum in the larvae of Misgurnus and Brachydanio, therefore this criterion was not used to study the genetic control in their hybrids. The heat resistance of cytochrome oxidase (T50) differed in Misgurnus and Brachydanio and was of intermediate value in their hybrids. At the early stages of hybrid development T50 was of maternal type (Misgurnus) but beginning from the mid-gastrula stage T50 increased and attained the maximum prior to the hatching. Chloramphenicol did not affect the increase of T50 in hybrids, but actinomycin decreased it almost down to the level characteristic of Misgurnus. The data obtained suggest that the genetic control of cytochrome oxidase activity begins earlier than that of other studied enzymes.