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The role of the nascent polypeptide-associated complex (NAC) subunit β in Arabidopsis thaliana response to various abiotic stresses
Šesták, Petr ; Fíla, Jan (advisor) ; Vosolsobě, Stanislav (referee)
Nascent polypeptide-associated complex (NAC) represents a heterodimeric complex composed of an α- and a β-subunit. It is conserved in eukaryotic organisms and has also been found in archaea. This complex binds to newly synthesized proteins emerging from the ribosome and participates in their targeting to the endoplasmic reticulum. In plants, the NAC complex has been studied in the context of tolerance to various abiotic stresses. In our laboratory, we have previously characterized a T-DNA insertion mutant of Arabidopsis thaliana in both NACβ-encoding genes that exhibited a number of phenotypic defects. These included for instance the appearance of more floral organs, reduced pollen grain germination, and the production of shorter siliques with less seeds inside. The aim of this diploma thesis was to characterize the role of the NACβ subunit in Arabidopsis thaliana during seed germination under osmotic and salt stress. We have shown that the absence of NACβ leads to a reduced seed germination and a prolonged germination time, as does overexpression of this subunit. We further studied whether stress conditions affect the transcript levels of individual genes encoding for both NAC subunits by RT-qPCR. In order to investigate the molecular mechanisms by which the studied complex could influence the...
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Metabolite production by some strains of industrial yeasts in various phases of cell growth
Jankeje, Kristína ; Kubešová,, Jitka (referee) ; Kočí, Radka (advisor)
Presented bachelor thesis is focused on industrial application of chosen yeast strains. Principal interest of work is to study production of primary and secondary metabolites during individual growth phases. Optimal growth conditions as well as influence of exogenous stress factors (mainly oxidative and/or salt stress) on cell growth and yeast metabolism are discussed. In experimental part growth curve of industrial strain Phaffia rhodozyma was determined. Biomass increase (maximum in 90th hour 5,441 g/l), astaxanthin production (secondary metabolite) and/or ergosterol biosynthesis (primary metabolite) were observed. The best ration of astaxanthin to total carotenoids was 50 %. Next studied metabolite was ergosterol, its total amount in dry biomass was 0.11 %. In conclusion astaxanthin amounts produced in optimal growth conditions were compared with yields obtained under stress cultivations. Results of stress experiments illustrate positive influence of stress factors on cell growth as well as on astaxanthin biosynthesis. Low concentration of salt (2% NaCl) added in inoculum with 5 mM hydrogen peroxide in production medium would be the best combination in industrial applications.
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Natural sources and sinks of volatile chlorinated hydrocarbons in the spruce forest ecosystem
Štangelová, Pavla ; Tesařová, Eva (advisor) ; Pavlík, Milan (referee)
Biogeochemical cycle of chlorine, particularly the formation of organically bound chlorine is still not well understood. In continental ecosystems chlorides act as source of chlorine, and also as a stress factor. Chlorides originate from precipitation of marine cloud masses. Organically bound chlorine in the environment is formed naturally by biotical and abiotical way. The biotical factors are microorganisms, plants, soil enzymes and animals. Volatile chlorinated hydrocarbons (VOCl) represent one group of organically bound chlorines. Several volatile chlorinated hydrocarbons reacts with atmospheric ozone, consequently causing depletion of the ozone layer. The most important known terrestrial source of volatile chlorinated hydrocarbons is the spruce forest ecosystem. Chlorine in the soil can be transformed by microorganisms into organically bound chlorine or translocated by transpiration stream in plants, where they are also transformed enzymatically into organically bound chlorine, and both of them can be emitted into the atmosphere. Too large amounts of chloride can affect the physiological functions of plants. In this thesis experiments were designed for measuring the natural emissions of volatile halogenated hydrocarbons from plants and fungi, with various periods of incubation, and also to...
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Natural sources and sinks of volatile chlorinated hydrocarbons in the spruce forest ecosystem
Štangelová, Pavla ; Tesařová, Eva (advisor) ; Pavlík, Milan (referee)
Biogeochemical cycle of chlorine, particularly the formation of organically bound chlorine is still not well understood. In continental ecosystems chlorides act as source of chlorine, and also as a stress factor. Chlorides originate from precipitation of marine cloud masses. Organically bound chlorine in the environment is formed naturally by biotical and abiotical way. The biotical factors are microorganisms, plants, soil enzymes and animals. Volatile chlorinated hydrocarbons (VOCl) represent one group of organically bound chlorines. Several volatile chlorinated hydrocarbons reacts with atmospheric ozone, consequently causing depletion of the ozone layer. The most important known terrestrial source of volatile chlorinated hydrocarbons is the spruce forest ecosystem. Chlorine in the soil can be transformed by microorganisms into organically bound chlorine or translocated by transpiration stream in plants, where they are also transformed enzymatically into organically bound chlorine, and both of them can be emitted into the atmosphere. Too large amounts of chloride can affect the physiological functions of plants. In this thesis experiments were designed for measuring the natural emissions of volatile halogenated hydrocarbons from plants and fungi, with various periods of incubation, and also to...
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Detection of Hsp70 protein in plants exposed to various stress factors.
Lengálová, Alžběta ; Hýsková, Veronika (advisor) ; Liberda, Jiří (referee)
! Plants are continuously exposed to various stress conditions. Being sessile, they are not able to escape from adverse conditions. Therefore, they have developed specific defence mechanisms. Most studies focus on plant responses to a single type of stress. However, plants in nature must cope with a variety of stresses at the same time. In this work, the effects of heat shock on the interaction of tabaco (Nicotiana tabacum L.) with the Potato virus Y (PVY) were investigated. Obviously, heat stress is associated with the synthesis of Hsp70 protein, which has many important functions alleviating adverse effects of stress conditions (e.g. Hsp70 participates in refolding or degradation of damaged proteins and protein syntetis de novo). The effect of Hsp70 during viral infection is still not fully understood, some studies revealed Hsp70 as a part of viral multiplication and transport processes in plant. In the first experiment performed in this work, higher levels of PVYNTN virus was found in tobacco plants that have been exposed to heat shock after inoculation than in plants only infected. The amount of the virus corresponded with the amount of Hsp70 protein detected immunochemically using a specific antibody. It seems that the plant response to combination of heat stress with viral infection is a...
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The effect of abiotic stress on cucumber plants (Cucumis sativa L.)
Plisková, Veronika ; Hýsková, Veronika (advisor) ; Müller, Karel (referee)
The exposure of plants to high salt concentrations causes accumulation of sodium ions. This leads to the inability of the plants to uptake water, a disturbance of ion homeostasis, a decrease in photosynthesis and oxidative stress. As a result of the salt stress, the availability of NADPH decreases. The adaptation to the concentrations of salt depends on plant's ability to compensate for the decreased availability of NADPH, which can be further used in antioxidative cycles and the synthesis of antioxidative compounds and osmoprotectants. In this work, the reduction of relative water content, a decrease in the Rubisco enzyme activity, an increase of Hsp70 in the leaves and an increase in the accumulation of sodium ions was shown in cucumber plants (Cucumis sativa L. convar. Jogger F1) exposed to salt stress (100 mM NaCl). As a consequence of salt stress, an increase in the activity of NADPH providing enzymes was found. Particularly on the second and third day of salt stress, an increase in the activity (up to 270 %) of: NADP-isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase, NADP-malic enzyme, non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase in leaves was detected. The activity of less abundant NADP-dehydrogenases (glucose 1-dehydrogenase, gluconate 2-dehydrogenase, galactose...
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Metabolite production by some strains of industrial yeasts in various phases of cell growth
Jankeje, Kristína ; Kubešová,, Jitka (referee) ; Kočí, Radka (advisor)
Presented bachelor thesis is focused on industrial application of chosen yeast strains. Principal interest of work is to study production of primary and secondary metabolites during individual growth phases. Optimal growth conditions as well as influence of exogenous stress factors (mainly oxidative and/or salt stress) on cell growth and yeast metabolism are discussed. In experimental part growth curve of industrial strain Phaffia rhodozyma was determined. Biomass increase (maximum in 90th hour 5,441 g/l), astaxanthin production (secondary metabolite) and/or ergosterol biosynthesis (primary metabolite) were observed. The best ration of astaxanthin to total carotenoids was 50 %. Next studied metabolite was ergosterol, its total amount in dry biomass was 0.11 %. In conclusion astaxanthin amounts produced in optimal growth conditions were compared with yields obtained under stress cultivations. Results of stress experiments illustrate positive influence of stress factors on cell growth as well as on astaxanthin biosynthesis. Low concentration of salt (2% NaCl) added in inoculum with 5 mM hydrogen peroxide in production medium would be the best combination in industrial applications.
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