The Role of LAM Genes in the Pheromone-Induced Cell Death of S. cerevisiae Yeast.

Lam1-4 proteins perform non-vesicular transport of sterols from the plasma membrane to the endoplasmic reticulum. Disruption of their function leads to an increase in the content of sterols in the plasma membrane. In mammals, homologs of Lam proteins are responsible for the internalization of plasma cholesterol. The biological role of Lam proteins in yeast remains unclear, since the strains lacking individual LAM genes do not display any pronounced phenotype. Deletion of LAM1 (YSP1) gene inhibits the regulated death of Saccharomyces cerevisiae yeast cells induced by the mating pheromone. Here, we investigated whether LAM2 also plays a role in the cell death induced by the excess of mating pheromone and assessed genetic interactions between LAM2 and genes responsible for ergosterol biosynthesis. We have shown that LAM2 deletion partially prevents pheromone-induced death of yeast cells of the laboratory strain W303, while deletions of three other LAM genes - LAM1, LAM3, and LAM4 - does not provide any additional rescuing effect. The UPC2-1 mutation in the transcription factor UPC2 gene, which leads to the excessive accumulation of sterols in the cell, promotes cell survival in the presence of the pheromone and shows additivity with the LAM2 deletion. On the contrary, LAM2 deletion stimulates pheromone-induced cell death in the laboratory strain BY4741. We have found that the deletion of ergosterol biosynthesis genes ERG2 and ERG6 reduces the effect of LAM2 deletion. Deletion of LAM2 in the Δerg4 strain lacking the gene of the last step of ergosterol biosynthesis, significantly increased the proportion of dead cells and decreased the growth rate of the yeast suspension culture even in the absence of the pheromone. We suggest that the absence of the effect of LAM2 deletion in the Δerg6 and Δerg2 strains indicates the inability of Lam2p to transport some ergosterol biosynthesis intermediates, such as lanosterol. Taken together, our data suggest that the role of Lam proteins in the regulated death of yeast cells caused by the mating pheromone is due to their effect on the plasma membrane sterol composition.

[Scent as an element of subjective assessment of young males and females].

In 46 male and 19 female students who were both donors and recipients of scent samples, we studied effects of the menstrual cycle phase, reproductive health, sexual motivation, and sexual experience on subjective assessment of intensity and pleasantness of the sweat scent. The sweat samples were collected by the 60-min long exposure of a filter paper in the armpit. Then the male and female samples were reciprocally assessed olfactorily with respect to their intensity, unpleasantness/pleasantness, and association with male or female. It has been established that the cycle phase affects statistically significantly the coincidence of subjective assessments by the unpleasant/pleasant scale, which different recipients were giving to the same scent samples. Their coincidence in the non-receptive state is replaced by the non-coincidence at the receptive cycle phase, which indicates an increase in the contribution of the recipient's individual properties to the variability of scent assessments. In girls in the non-receptive state there is noted the reverse correlation between the strength and pleasantness of the male scent. In the receptive state, they become tolerant to intensive male scents. At non-regular menstrual cycles, the female scent is assessments by young males as less pleasant. At the same time, the girls themselves with the cycle disturbances assess higher the male scent samples as compared with reproducibly healthy girls. The first sexual experience decreases the subjective assessments given by girls to the male scent samples. The young males, on the contrary, increase assessments given by girls to the male scent samples. The young males, on the contrary, increase assessments of the female scent on having acquired the sexual experiment. Coefficients of correlation of the mutual assessments of scent pleasantness of young males and females are progressingly rising with increase of biological and social significance of the search for optimal partner. Thus, effect of psychophysiological and social factors on assessments of pleasantness of scent samples aggress well with requirements, to which the reproductively significant non-verbal signal should fit.

[The activation of specific immunity in male mice stimulates fertility of their breeding partners: the phenomenon of lot's daughters].

In previous experimental studies on laboratory mice, it was shown that activation of specific immunity by injection with sheep red blood cells (SRBC) lessens males' sexual olfactory attractiveness for intact females. However, reduced attractiveness can decrease males' reproductive efficiency only under the conditions of free mating, which is not obligatory for natural populations. The goal of this work was to study the influence of immunoenhancement on sexual behavior and reproductive output of outbred ICR male mice. Males, either injected with saline (control group) or SRBC-treated, were kept with intact females during 5 days after injection. While the number of fertile copulations was practically equal in both groups, the potential (ovulated ova) and actual (number of embryos) fecundity was significantly higher in females having been paired off with SRBC-treated males. Main reproductive effects were registered at 3-5th day after injection, when specific antibody-forming process starts and males' scent becomes less attractive for females. On the base of previous and present data, the hypothesis is proposed that if the quality of a non-alternative mating partner is compromised by activation of specific immunity, a female tries to maximize its reproductive output (due to low chance of repeated copulation). This responsibility for the next generation is reminiscent of the Bible story about Lot and his daughters, and may help to sustain the species existence under conditions of parasitic press.

[Redistribution of immune defence in male mice exposed by female scent].

Since scent marks of mice are harbored by parasites, their sniffing during olfactory search of the mating partner leads to increase of the infection risk. A hypothesis that sexual signals can induce, along with the reproductive behavior, non-specific immune defense against respiratory infections is tested in the present paper. It was found in the experiments on outbred ICR mice that the scent of soiled bedding from cages with mature females stimulated leukocyte intervention to the upper air-ways. Migration of the white blood cells to lung tissue was accompanied with a more prominent immune and endocrine responeses to intranasal application of the bacterial lipopolysacharide (LPS). In particular, LPS administration to male mice treated by female scent was resulted in much greater amount of leukocyte aggregations in the peribronchial areas than that was found in the males kept isolated from the female signals. The female scent also enhanced adrenocortical response to LPS administration, which was coincided with statistically significant increase of IL-1beta concentration in hypothalamus. So, chemical signals of the mature female induce travel of white blood cells to the upper air-waya in the scent treated male mice. It can increase resistance to respiratory infections, on the one hand, and aggravates stress response to inhalation of the bacterial compounds, on the other hand.

Hepatocarcinoma-29, a metastasizing transplantable mouse tumor inducing cachexia.

Here we describe an experimental tumor, hepatocarcinoma-29: transplantable strain of this tumor is maintained in an ascitic form in CBA/LacYIcgn mice in Institute of Cytology and Genetics of SD of RAS. After inoculation into the thigh muscles, the tumor induces anorexia, progressing loss of fat and muscle tissues, and physiological changes specific for cachexia: leukocytosis, hypoglycemia, and hypercorticism. The tumor metastasizes to all vital viscera and leads to animal death from renal failure.

[Study of tumor cells sensitivity in patients with acute leukemia to cytokines and their combined use with drugs in vitro by MTT analysis]. / Izuchenie chuvstvitel'nosti opukholevykh kletok bol'nykh ostrym leikozom k tsitokinam i ikh sochetannomu primeneniiu s khimiopreparatami in vitro metodom MTT-analiza.

MTT analysis has yielded data on the sensitivity of leukemia cells isolated from 64 patients with acute leukemia to the cytokines G-KSF?, GM-KSF, interferon-alpha 2b and their combined use with drugs, such as cytosar, vepeside, doxorubicin, vincrastine, L-asparaginase. The mean in vitro survival of leukemia cells in children with acute lymphoblast cell leukemia (ALCL) was 1.9 times less than that in acute myeloblast cell leukemia (AMCL) (p < 0.001), that in new cases of ALL was 2.3 times less than in relapses (p = 0.024). The stimulating effect of GM-KSF on the survival rates of leukemia cells was seen in 64.7% of patients with AML. That of GM-KSF was recorded in 21.4% of cases. The survival of lymphoblast cells isolated from children with ALL did not differ greatly in the absolute majority of cases (by more than 30%) in the presence of growth factor in the medium. The cytotoxicity of XII with medium growth factor decreased in most cases. However, some cases (more frequently in AML than ALCL) displayed a higher cytotoxicity of XII, particularly cytosar in the presence of G-KSF and GM-KSFG; LC50 of Ara-C decreased by 30% or more in the presence of growth factor in 36% of patients. Incubation with interferon alpha 2b caused a reduction in the survival of leukemia cells, which was more pronounced in children with ALL. Interferon-alpha 2b caused an increase in the cytotoxic effect of XII on leukemia cells in ALL to a greater extent; cytosar, vepeside, and doxorubicin enhanced the effect by 1.47, 1.39, and 2.35 times, respectively.