Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress

Aim. To investigate the influence of carbonyl/oxidative stress induced by glyoxal, methylglyoxal and hydrogen peroxide on the survival of Saccharomyces cerevisiae, defective for different parts of TOR- signaling pathway, grown on glucose or fructose. Methods. The assessment of number of colony-form...

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Автор: Valishkevych, B.V.
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Опубліковано: Інститут молекулярної біології і генетики НАН України 2014
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Цитувати:Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress / B.V. Valishkevych // Вiopolymers and Cell. — 2014. — Т. 30, № 5. — С. 358-364. — Бібліогр.: 44 назв. — англ.

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spelling nasplib_isofts_kiev_ua-123456789-1545352025-02-23T20:22:57Z Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress Чутливість дріжджів Sассharomyces cerevisiae, дефектних за різними ділянками сигнального шляху TOR, до карбонільного/оксидативного стресу Чувствительность дрожжей Sассharomyces cerevisiae, дефектных по различным участкам сигнального пути TOR, к карбонильному/окислительному стрессу Valishkevych, B.V. Genomics, Transcriptomics and Proteomics Aim. To investigate the influence of carbonyl/oxidative stress induced by glyoxal, methylglyoxal and hydrogen peroxide on the survival of Saccharomyces cerevisiae, defective for different parts of TOR- signaling pathway, grown on glucose or fructose. Methods. The assessment of number of colony-forming units to determine the yeast reproductive ability. Results. It was shown that at certain concentrations the mentioned above toxicants caused an increase in yeast survival, indicating the hormetic effect. Conclusions. The TOR signaling pathway is involved in the hormetic effect, but it is specific for each strain and depends on the type of carbohydrate in the incubation medium. Мета. Дослідити вплив карбонільного/оксидативного стресу, індукованого гліоксалем, метилгліоксалем та пероксидом водню, на виживання штамів S. cerevisiae, дефектних за різними ділянками TOR-сигнального шляху, за умов їхнього росту у середовищі із глюкозою чи фруктозою. Методи. Оцінка репродуктивної здатності методом визначення кількості колонієутворювальних одиниць. Результати. Показано, що у певних концентраціях дія вищезазначених агентів викликає підвищення рівня виживання. Це свідчить про наявність горметичного ефекту. Висновки. Шлях TOR залучений до горметичного ефекту всіх використаних токсикантів, проте наявність даного ефекту є специфічною для кожного штаму та залежить від типу вуглеводу у середовищі інкубації. Цель. Исследовать влияние карбонильного/окислительного стресса, индуцированного глиоксалем, метилглиоксалем и пероксидом водорода, на выживание штаммов Sассharomyces cerevisiae, дефектных по разным участками TOR-сигнального пути, в условиях их роста в среде с глюкозой или фруктозой. Методы. Оценка репродуктивной способности в результате определения количества колоний-образующих единиц. Результаты. Показано, что в определенных концентрациях действие вышеупомянутых агентов вызывает повышение уровня выживания, что свидетельствует о наличии горметического эффекта. Выводы. Путь TOR вовлечен в горметический эффект всех использованных токсикантов, однако наличие данного эффекта является специфическим для каждого штамма и зависит от типа углевода в среде инкубации. 2014 Article Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress / B.V. Valishkevych // Вiopolymers and Cell. — 2014. — Т. 30, № 5. — С. 358-364. — Бібліогр.: 44 назв. — англ. 0233-7657 DOI: http://dx.doi.org/10.7124/bc.0008B2 https://nasplib.isofts.kiev.ua/handle/123456789/154535 579.222 : 577.124.3 : 577.24 en Вiopolymers and Cell application/pdf Інститут молекулярної біології і генетики НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
language English
topic Genomics, Transcriptomics and Proteomics
Genomics, Transcriptomics and Proteomics
spellingShingle Genomics, Transcriptomics and Proteomics
Genomics, Transcriptomics and Proteomics
Valishkevych, B.V.
Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress
Вiopolymers and Cell
description Aim. To investigate the influence of carbonyl/oxidative stress induced by glyoxal, methylglyoxal and hydrogen peroxide on the survival of Saccharomyces cerevisiae, defective for different parts of TOR- signaling pathway, grown on glucose or fructose. Methods. The assessment of number of colony-forming units to determine the yeast reproductive ability. Results. It was shown that at certain concentrations the mentioned above toxicants caused an increase in yeast survival, indicating the hormetic effect. Conclusions. The TOR signaling pathway is involved in the hormetic effect, but it is specific for each strain and depends on the type of carbohydrate in the incubation medium.
format Article
author Valishkevych, B.V.
author_facet Valishkevych, B.V.
author_sort Valishkevych, B.V.
title Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress
title_short Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress
title_full Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress
title_fullStr Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress
title_full_unstemmed Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress
title_sort sensitivity of saccharomyces cerevisiae defective in tor signaling pathway to carbonyl/oxidative stress
publisher Інститут молекулярної біології і генетики НАН України
publishDate 2014
topic_facet Genomics, Transcriptomics and Proteomics
url https://nasplib.isofts.kiev.ua/handle/123456789/154535
citation_txt Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress / B.V. Valishkevych // Вiopolymers and Cell. — 2014. — Т. 30, № 5. — С. 358-364. — Бібліогр.: 44 назв. — англ.
series Вiopolymers and Cell
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AT valishkevychbv čuvstvitelʹnostʹdrožžejsassharomycescerevisiaedefektnyhporazličnymučastkamsignalʹnogoputitorkkarbonilʹnomuokislitelʹnomustressu
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fulltext GENOMICS, TRANSCRIPTOMICS AND PROTEOMICS UDC 579.222 : 577.124.3 : 577.24 Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress B. V. Valishkevych Vassyl Stefanyk Precarpathian National University 57, Shevchenko Str., Ivano-Frankivsk, Ukraine, 76018 b.homza@ukr.net Aim. To investigate the influence of carbonyl/oxidative stress induced by glyoxal, methylglyoxal and hydrogen peroxide on the survival of Saccharomyces cerevisiae, defective for different parts of TOR- signaling pathway, grown on glucose or fructose. Methods. The assessment of number of colony-forming units to determine the yeast reproductive ability. Results. It was shown that at certain concentrations the mentioned above toxicants caused an increase in yeast survival, indicating the hormetic effect. Conclusions. The TOR signaling pathway is invol- ved in the hormetic effect, but it is specific for each strain and depends on the type of carbohydrate in the incuba- tion medium. Keywords: Saccharomyces cerevisiae, glucose, fructose, TOR-signaling pathway, carbonyl/oxidative stress. Introduction. The lack of nutrients and/or energy in the cell alternating with periods of their sufficient amount makes the cell to switch the stages of anabolism and ca- tabolism [1]. TOR-pathway (target of rapamycin) is an important mechanism to respond to these needs. For the first time, this pathway has been described as a target of rapamycin, which is produced by bacteria Streptomy- ces hygroscopicus. Investigation of the S. cerevisae ra- pamycine-resistant mutants has clarified the mechanism of the antibiotic effects 2. It should be noted that the ba- ker's yeast S. cerevisae is an effective model system to study a variety of molecular mechanisms, because many of them are similar to those in higher eukaryotes [3–6]. In the early 1990s, using genetic screening the TOR1 and TOR2 proteins in baker's yeast were identified as the mediators of the rapamycin toxic effects in the yeast [7, 8]. TOR is a conservative atypical serine/threonine kinase that «senses» different internal and external sig- nals regulating cell growth, protein biosynthesis and metabolism. TOR kinase can exist as two complexes: the rapamycin-sensitive TORC1 and rapamycin-resis- tant TORC2 [9, 10]. Furthermore, the complexes are controlled by different regulatory molecules and affect the variety of anabolic and catabolic processes [11]. The identification of TOR as an integral component of the signaling pathway PI3/AKT, suppressed at carcino- genesis, and cross-action between the tumor-suppres- sor p53-cascade and TOR, suggest a unique role of the TOR complex in processes of cell growth. In fact, there are various aspects of regulation of TOR kinase. One of them may be interaction between the kinase and the major signaling cascades of a cell, that allows its use as a target in treatments of cancer, diabetes, and obesity [12–14]. Although the TOR function is not well under- stood, it is known that it is a central component of the complex signaling system which regulates the size of cell, its proliferation and the size of a whole organism [14]. The connection between TOR-pathway and meta- bolism of some proteins and other biomolecules has been well studied [15, 16], whereas the interplay between TOR signaling cascade and carbohydrate metabolism is not clarified. The inhibition or deletion of TOR signaling path- way extends chronological and replicative lifespan of yeast [17–19]. It is shown that the influence of TOR on yeast lifespan is intracellular: blocking TOR1 leads to 358 ISSN 0233–7657. Biopolymers and Cell. 2014. Vol. 30. N 5. P. 358–364 doi: http://dx.doi.org/10.7124/bc.0008B2 � Institute of Molecular Biology and Genetics, NAS of Ukraine, 2014 359 the increased mitochondrial respiration during the loga- rithmic growth phase and simultaneously increases the generation of reactive oxygen species. It is also known that TOR takes part in the growth of yeast cells under stress conditions, since it regulates the transcriptional factor MSN2/4 [20, 21] which controls the gene expres- sion in response to the environmental challenges, inclu- ding heat shock and hydrogen peroxide exposure [22]. The cells lacking TOR1 are sensitive to osmotic stress, oxidative stress, high external pH, and high or low tem- perature [20]. There are several lines of evidence indicating that genetic interference with TORC1 or its translation ex- tends life span. TORC1 inhibits the SKN-1 and DAF-16 expression and activity, at least partially by increasing mRNA translation. TORC2 regulates the SKN-1 nuclear occupancy in a nutrient-dependent manner. DAF-16 is required for longevity that derives from inhibition of TORC1, but not TORC2. SKN-1 is essential for the TORC1 or TORC2 inhibition to extend life span. When TORC1 is inhibited, SKN-1 increases transcription of the TORC1 pathway genes in a feedback loop [23]. Why does TOR respond to the environmental stress? One explanation is that TOR as a central controller of cell growth may respond to several different types of stress to ensure that growth occurs only when overall conditions are favorable [20]. The phenomenon of hormesis as biphasic adaptive response to low doses of stressors, including reactive oxygen species, is widely known [24–26]. Hormesis ta- kes part in the induction of cellular protection, and re- cent studies suggest that these protective effects are ca- pable of slow aging in model organisms [27]. Other pos- sible way to increase lifespan of organisms is calorie restriction, particularly restriction of carbohydrates, which is considered to be the most replicable strategy in the physiological aging slowdown and delay of the age-related pathological changes [28]. Recently, it has been shown that the rate of aging and reproductive ability of yeast [29, 30], as well as its resistance to stress depend on the concentration and ty- pe of monosaccharide in the cultivation medium [31]. Since the relationships between TOR-pathway and car- bohydrates are not completely understood, the aim of this work is to investigate the effect of carbonyl/oxi- dative stress induced by glyoxal, methylglyoxal and hydrogen peroxide on the survival of yeast, defective in different parts of TOR-signaling pathway and grown on glucose or fructose. Materials and methods. S. cerevisiae strains used in the study were: wild type JK9-3da with the follow- ing genotype MATa leu2–3,112 ura3–52 rme1 trp1 his4 GAL + SH121 (JK9-3da, tor2::ADE2-3/YCplac111: :tor2-21ts) and SH221 (JK9-3da, tor1::HIS3-3 tor2: :ADE2-3/YCplac111::tor2-21ts) kindly provided by Professor Michael Hall (University of Basel, Switzer- land). The strains are marked as follows: wt, �tor1, �tor2 and �t�or1�tor2. The JK9-3da were kept on YPD (yeast, pepton, dextrose) rich cultivation medium, the other three strains were kept on SD-Leu (synthetic dextrose medium without leucine) to prevent loss of the plasmid (YCplac111) [32]. Chemicals used: yeast extract, peptone («Fluka», Germany); glucose, fructose, glyoxal, methylglyoxal («Sigma», USA). All other reagents were from local suppliers (Ukraine) and were of analytical grade. Yeast cells were grown at 28 oC with shaking at 175 rpm in a liquid medium YPD containing 1 % yeast ex- tract, 2 % peptone, and 2 % glucose or fructose. Ali- quots of experimental cultures were resuspended in the medium with glyoxal, methylglyoxal or hydrogen pero- xide at appropriate concentrations and incubated for 1 h at 28 oC. Control cells were incubated in the same way but without addition of toxicants. Reproductive ability was analyzed after yeast treatment with the respective reagent by plating in triplicate on YPD agar after pro- per dilution. The plates were incubated at 28 oC for one day and the colony forming units (CFU) counted [33]. Repro- ductive ability was expressed as percentage of total amount of cells plating on YPD agar. Results and discussion. The carbonyl/oxidative stress is considered as a state resulting from the increa- sing concentrations of reactive carbonyl compounds and reactive oxygen species. They are harmful because of their ability to participate in nonenzymatic processes that are poorly controlled by cells. Such processes inclu- de, first of all, free radical oxidation and nonenzymatic glycation. The compounds like glyoxal, methylglyoxal, and hydrogen peroxide cause carbonyl and oxidative stress on the one hand, and on the other, they are the con- sequence of the mentioned above stresses [34–37]. The VALISHKEVYCH B. V. activity of antioxidant enzymes increased in response to the stressor effects. It is known that the TOR signaling pathway may regulate stress resistance in yeast [38]. Fig. 1, A, shows the survival of parental strain cells (wt), incubated in a medium with glucose (left) or fruc- tose (right) for 1 h under stress conditions. As can be seen, the survival of yeast in most cases decreased as compared to the control after cell incubation with all toxicants used in this study. It should be mentioned that the type of carbohydrate in the incubation medium also affects the survival of yeast cells, since after the treat- ment with glyoxal, methylglyoxal and hydrogen peroxi- de the cells grown on fructose showed higher viability than the glucose-grown cells. A similar effect was also observed in the �tor1 strain (Fig. 1, B) – under the stress conditions the fructose-grown cells (Fig. 1, B, right) sur- vived better than yeast grown on glucose (Fig. 1, B, left). In the case of the �tor2 mutant (Fig. 1, C), no significant differences between yeast incubated with glucose and fructose were observed. However, the survival of yeast reduced after the incubation with glyoxal and methyl- glyoxal as compared to the control, whereas the incuba- tion with hydrogen peroxide led to the opposite effect. This can be explained by the fact that hydrogen peroxi- de is less harmful than glyoxal or methylglyoxal at the concentrations used. In the case of the �tor1�tor2 doub- le mutant (Fig. 1, D), we observed completely contrary situation: the cells grown on glucose (left) survived bet- ter than those grown on fructose (right). We suppose that this peculiarity can be explained by some compensatory mechanism in the �tor1�tor2 strain. For example, it is known that proteinkinases Snf1p/AMP, Sch9, PKA, MAP similarly to the TOR are nutrient sensors, and per- haps they promote better survival of cells grown in a medium with glucose [39]. Thus, the parental strain demonstrated the highest sensitivity to glyoxal, methylglyoxal and hydrogen pe- roxide as compared with its derivatives. This is in accor- dance with the previous data showing that the inhibi- tion of TOR genes promotes better survival due to com- pensatory mechanisms [39]. The determination of the number of colony-for- ming unit is a widely used test for the reproductive abi- lity in yeast [33]. Therefore, next we compared the sur- vival of yeast strains defective in different parts of TOR- signaling pathway under carbonyl/oxidative stress indu- ced by different concentrations of hydrogen peroxide, glyoxal and methylglyoxal. H2O2 is a small, uncharged molecule, therefore it can easily penetrate through the cell membrane and react with the cellular components, far away from the place of its synthesis. Hydrogen peroxide is a rather stable compound with not very high reactivity. However, an increase in the H2O2 intracellular concentration can be dangerous for the cell due to the production of highly re- active hydroxyl radical �OH in the presence of transi- tion metal ions [40]. Fig. 2 demonstrates that low concentration of hydro- gen peroxide has hormetic effect. The parental strain (wt) incubated with 25 mM hydrogen peroxide in glu- cose had the highest colony-forming ability (CFU), whereas the wt cells grown in medium with fructose de- monstrated this phenomenon at 50 mM hydrogen pero- xide. It is in accordance with the recent data, which show- ed that fructose defends the yeast against H2O2-induced stress better than glucose [31]. It also worth mentioning that S. cerevisiae JK9-3da (wt) is found to be more resis- tant to hydrogen peroxide than S. cerevisiae YPH250. For example, the S. cerevisiae YPH250 ability to form colonies increased by 30 % after yeast treatment with 2.5 mM H2O2 comparing to untreated control cells [24]. In the case of �tor1�tor2, the highest CFU was found at 5 mM hydrogen peroxide regardless of the type of carbohydrate in the medium. Simultaneously, there was no clear hormetic effect in the single mutant strains �tor1 and �tor2 exposed to the same conditions. How- ever, in the presence of glucose CFU gradually increa- sed with increasing hydrogen peroxide concentration up to 2.5 mM, after which the CFU number decreased. The single mutants grown in the presence of fructose showed a decrease in the CFU number with increasing concentrations of hydrogen peroxide, and the hormetic effect was not found. It should also be noted that the sur- vival of yeast incubated in fructose was significantly higher in parental strain (wt) and single mutants (�tor1 and �tor2) under the mentioned above conditions. Per- haps such yeast resistance to the stressors can be related to a higher intensity of oxidative processes in the pre- sence of fructose, which stimulates the defensive me- chanisms against stress [31, 34–35]. There were no sig- nificant differences for the �tor1�tor2 cells incubated with different carbohydrates. 360 SENSITIVITY OF SACCHAROMYCES CEREVISIAE DEFECTIVE IN TOR SIGNALING PATHWAY Glyoxal is highly reactive dialdehyde, which is ma- inly formed in the cell as an intermediate of glycation [34, 41]. Its formation is also associated with the gly- oxylate metabolism [37, 42]. Now let us consider the survival of yeast S. cerevisi- ae, defective in different parts of TOR-signaling path- way, under conditions of the carbonyl/oxidative stress induced by glyoxal (Fig. 3). A significant increase in survival was observed for the strains wt and �tor2 ex- posed to glyoxal at concentration of 5 mM in the pre- sence of glucose. At the same time, there were no hor- metic effects in the yeast cells incubated in the presence of fructose, as well as in �tor1 and �tor1�tor2 incuba- ted with any carbohydrate used. Additionally, CFU for wt and �tor2 strains was higher in the presence of fruc- tose than of glucose. There was opposite situation un- der conditions with 5 mM glyoxal: the survival in the presence of glucose was significantly higher compared to fructose-grown cells. This trend continued at most concentrations of glyoxal used in wild strain and single mutants. We did not find any similar trend in the double mutant strain. Methylglyoxal is a by-product of glycation, metabo- lism of carbohydrates, ketone bodies, threonine catabo- lism, etc. [37, 42, 43]. It is also known that methylgly- oxal is formed as a result of nonenzymatic degradation of phosphotriose – intermediates of glycolysis [36, 42, 43]. Formation of methylglyoxal in this case is due to the elimination of phosphate with glyceraldehyde-3- phosphate and dihydroxyacetone phosphate [37, 44]. Fig. 4 demonstrates the survival of S. cerevisiae cells, defective in different parts of TOR-signaling path- 361 VALISHKEVYCH B. V. K 1 2 3 G luc ose Fruc tose K 1 2 3 A B C D 0 10-2 10 -4 0 10 -2 10-4 0 10 -2 10-4 0 10-2 10-4 0 10 -2 10-4 0 10 -2 10 -4 0 10 -2 10 -4 0 10 -2 10 -4 D el u ti on Fig. 1. The effect of glyoxal, methylglyoxal and hydro- gen peroxide (1 h stress) on the survival of S. cerevisiae parental strain (wt) (A), �tor1 (B), �tor2 (C) and �tor1�tor2 (D) grown in me- dium with glucose (left) or fructose (right): K – Cont- rol; 1 – 800 mM glyoxal; 2 – 20 mM methylglyoxal; 3 – 50 mM H 2 O 2 . Cells dilutions in yeast suspension are in- dicated on the vertical 362 SENSITIVITY OF SACCHAROMYCES CEREVISIAE DEFECTIVE IN TOR SIGNALING PATHWAY Concentration of hydrogen peroxide, mM 0 0 2,5 5 25 50 100 C F U 0 0 2,5 5 25 50 100 C F U k k k k k# k# k# k# k# k# k# k# k# k# k# k k# k# k# k40 80 120 I k k* k*k* k* * k#* k#* k#* k#* k#* #* k#* k#*k#* k#* k#* #* kk# k k# k## 40 80 120 160 II 1 2 3 4 Fig. 2. The effects of various con- centrations of hydrogen peroxi- de on the reproductive ability of S. cerevisiae parental strain (wt) and its derivatives (�tor1, �tor2, and �tor1�tor2) grown on glu- cose (I) or fructose (II) (M ± m, n = = 4–8). Significantly different from the (*) respective glucose- grown strain, (k) control (with- out hydrogen peroxide), (#) pa- rental strain with Ð < 0.05 kk k k k kk#k# k# k# # kkk k# k# # kk# # k # 0 100 200 300 400 0 5 40 400 800 1600 C F U # k k#* k#*k#* k#* * kk#*k#k#* k#* kk#k#*k* k#* #* kk# k# k#* #* 0 100 200 300 0 5 40 400 800 1600 C F U Concentration of glyoxal, mM I II 1 2 3 4 Fig. 3. The effects of various con- centrations of glyoxal on the re- productive ability of S. cerevi- siae parental strain (wt) and its de- rivatives (�tor1, �tor2, and �tor1�tor2) grown on glucose (I) or fructose (II) (M ± m, n = = 3–6). Significantly different from the (*) respective glucose- grown strain, (k) control (with- out glyoxal), (#) parental strain with Ð < 0.05 Concentration of methylglyoxal, mM k k k k k k k k# # # # kk#k# k##k # kk#k#k# k# 0 100 200 0 0,5 1 2 5 40 C F U k k* k* k* k * kk#*k*k#* k#* # k k# k k#*k#* #* k*k#* k#* k#k*# 0 40 80 120 160 200 0 0,5 1 2 5 40 C F U I II 1 2 3 4 Fig. 4. The effects of various con- centrations of methylglyoxal on the reproductive ability of S. ce- revisiae parental strain (wt) and its derivatives (�tor1, �tor2, and �tor�tor2) grown on glucose (I) or fructose (II) (M ± m, n = 3–7). Significantly different from the (*) respective glucose-grown strain, (k) control (without me- thylglyoxal), (#) parental strain with Ð < 0.05 way, under methylglyoxal exposure. In the parental strain (wt) the highest CFU was observed in the presence of glucose and 0.5, 2, and 5 mM methylglyoxal, whereas in the cells, grown on fructose, this phenomenon occur- red at 1 and 5 mM methylglyoxal. In the �tor1�tor2, hormetic effect occurred at 0.5 mM methylglyoxal in the cells incubated with glucose, and in the �tor2 it to- ok place after incubation with 1 mM methylglyoxal on the same carbohydrate. There was no hormetic effect in another single mutant �tor1 with any of the studied car- bohydrates. Also, we found higher survival of mutant cells grown in the presence of glucose than of those grown with fructose in most cases. Thus, comparing the influence of hydrogen peroxi- de and glycation agents (glyoxal and methylglyoxal) on the yeast grown on glucose or fructose one may suggest that the toxicants demonstrate hormetic effects. Moreover, the effect is specific for the strains and depends on the type of carbohydrate in the incubation medium. Hormetic effect was found in parental strain (wt) at concentrations: 25 mM hydrogen peroxide (in- creased by 55 % comparing to the control), 5 mM gly- oxal (increased by 68 % comparing to the control) and 2 mM methylglyoxal (4.6-fold higher comparing to the control) in glucose, whereas in the presence of fructose the largest number of colonies was detected at 50 mM hydrogen peroxide (increased by 28 % comparing to the control) and 5 mM methylglyoxal (2.1-fold higher comparing to the control). In the case of �tor1, the high- est CFU was found at 2.5 mM of hydrogen peroxide (increased by 22 % to the control) and 5 mM of glyoxal (increased by 17 % comparing to the control) in the glu- cose containing medium. In the �tor2 strain, hormetic effects were revealed at 2.5 mM hydrogen peroxide (in- creased by 50 % comparing to the control), 5 mM gly- oxal (2.3-fold higher comparing to the control) and 1 mM methylglyoxal (increased by 48 % comparing to the control) with glucose. The strain �tor1�tor2 incuba- ted with 5 mM hydrogen peroxide (increased by 32 % comparing to the control) and 0.5 mM methylglyoxal (increased by 25 % comparing to the control) in glu- cose had the highest CFU, whereas the cells, grown in medium with fructose, demonstrated this phenomenon only at 5 mM hydrogen peroxide (increased by 34 % comparing to the control). The mutant strains are cha- racterized by a higher proliferative activity, which may be explained by the involvement of important compen- satory mechanisms, in particular, the kinases Snf1p/ AMP, Sch9, PKA, MAP. Acknowledgements. The author is grateful to her supervisor Dr. Halyna Semchyshyn, and to Prof. Mi- chael Hall for providing the strains of S. cerevisiae. ×óòëèâ³ñòü äð³æäæ³â Sàññharomyces cerevisiae, äåôåêòíèõ çà ð³çíèìè ä³ëÿíêàìè ñèãíàëüíîãî øëÿõó TOR, äî êàðáîí³ëüíîãî/îêñèäàòèâíîãî ñòðåñó Á. Â. Âàë³øêåâè÷ Ðåçþìå Ìåòà. Äîñë³äèòè âïëèâ êàðáîí³ëüíîãî/îêñèäàòèâíîãî ñòðåñó, ³í- äóêîâàíîãî ãë³îêñàëåì, ìåòèëãë³îêñàëåì òà ïåðîêñèäîì âîäíþ, íà âèæèâàííÿ øòàì³â S. cerevisiae, äåôåêòíèõ çà ð³çíèìè ä³ëÿí- êàìè TOR-ñèãíàëüíîãî øëÿõó, çà óìîâ ¿õíüîãî ðîñòó ó ñåðåäîâèù³ ³ç ãëþêîçîþ ÷è ôðóêòîçîþ. Ìåòîäè. Îö³íêà ðåïðîäóêòèâíî¿ çäàòíîñò³ ìåòîäîì âèçíà÷åííÿ ê³ëüêîñò³ êîëîí³ºóòâîðþâàëüíèõ îäèíèöü. Ðåçóëüòàòè. Ïîêàçàíî, ùî ó ïåâíèõ êîíöåíòðàö³ÿõ ä³ÿ âèùåçàçíà÷åíèõ àãåíò³â âèêëèêຠï³äâèùåííÿ ð³âíÿ âèæèâàííÿ. Öå ñâ³ä÷èòü ïðî íàÿâí³ñòü ãîðìåòè÷íîãî åôåêòó. Âèñíîâêè. Øëÿõ TOR çàëó÷åíèé äî ãîðìåòè÷íîãî åôåêòó âñ³õ âèêîðèñòàíèõ òîêñèêàíò³â, ïðîòå íàÿâí³ñòü äàíîãî åôåêòó º ñïåöèô³÷íîþ äëÿ êîæíîãî øòàìó òà çàëåæèòü â³ä òèïó âóãëåâîäó ó ñåðåäîâèù³ ³íêóáàö³¿. Êëþ÷îâ³ ñëîâà: Saccharomyces cerevisiae, ãëþêîçà, ôðóêòî- çà, ñèãíàëüíèé øëÿõ TOR, êàðáîí³ëüíèé/îêñèäàòèâíèé ñòðåñ. ×óâñòâèòåëüíîñòü äðîææåé Sàññharomyces cerevisiae, äåôåêòíûõ ïî ðàçëè÷íûì ó÷àñòêàì ñèãíàëüíîãî ïóòè TOR, ê êàðáîíèëüíîìó/îêèñëèòåëüíîìó ñòðåññó Á. Â. Âàëèøêåâè÷ Ðåçþìå Öåëü. Èññëåäîâàòü âëèÿíèå êàðáîíèëüíîãî/îêèñëèòåëüíîãî ñòðåñ- ñà, èíäóöèðîâàííîãî ãëèîêñàëåì, ìåòèëãëèîêñàëåì è ïåðîêñèäîì âîäîðîäà, íà âûæèâàíèå øòàììîâ Sàññharomyces cerevisiae, äå- ôåêòíûõ ïî ðàçíûì ó÷àñòêàìè TOR-ñèãíàëüíîãî ïóòè, â óñëîâè- ÿõ èõ ðîñòà â ñðåäå ñ ãëþêîçîé èëè ôðóêòîçîé. Ìåòîäû. Îöåíêà ðåïðîäóêòèâíîé ñïîñîáíîñòè â ðåçóëüòàòå îïðåäåëåíèÿ êîëè÷å- ñòâà êîëîíèé-îáðàçóþùèõ åäèíèö. Ðåçóëüòàòû. Ïîêàçàíî, ÷òî â îïðåäåëåííûõ êîíöåíòðàöèÿõ äåéñòâèå âûøåóïîìÿíóòûõ àãåí- òîâ âûçûâàåò ïîâûøåíèå óðîâíÿ âûæèâàíèÿ, ÷òî ñâèäåòåëüñò- âóåò î íàëè÷èè ãîðìåòè÷åñêîãî ýôôåêòà. Âûâîäû. Ïóòü TOR âî- âëå÷åí â ãîðìåòè÷åñêèé ýôôåêò âñåõ èñïîëüçîâàííûõ òîêñèêàí- òîâ, îäíàêî íàëè÷èå äàííîãî ýôôåêòà ÿâëÿåòñÿ ñïåöèôè÷åñêèì äëÿ êàæäîãî øòàììà è çàâèñèò îò òèïà óãëåâîäà â ñðåäå èíêó- áàöèè. Êëþ÷åâûå ñëîâà: Saccharomyces cerevisiae, ãëþêîçà, ôðóê- òîçà, TOR-ñèãíàëüíûé ïóòü, êàðáîíèëüíûé/îêèñëèòåëüíûé ñòðåññ. REFERENCES 1. 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