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Biosynthesis of lower polyketide chains in manumycin antibiotics - the length-affecting factors
Kolek, Jan ; Petříček, Miroslav (advisor) ; Seydlová, Gabriela (referee)
Manumycin antibiotics represent an important class of secondary metabolites produced by Streptomyces bacteria. They belong to a big class of polyketide metabolites and posses significant antimicrobial, anti-inflammatory, antitumor, and many other biological activities. They are characterized by two short polyketide chains, which are attached to a central subunit. Polyketide chains are synthesized by enzymes of the iterative type II polyketide-synthase. Mechanism of regulation of the polyketide chains length has not been known yet. Understanding mechanism can lead to biosynthesis of novel manumycin antibiotics with predetermined chain lengths what may improve their biological activities in favour of a practical use of these compounds. We prepared a mutant strain of asukamycin producer Streptomyces nodosus ssp. asukaensis with deletion of genes coding for type I/II β-ketoacylsynthase and protein AsuC14, which is a potential factor affecting lower polyketide chain length, for the identification of the chain length factor in manumycin antibiotics producers. Next, the genes for type I/II β-ketoacylsynthase and potential chain length-affecting factor C14 from strains producing manumycins with variable length of the lower polyketide chains were expressed in this mutant strain. Our results demonstrate...
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Struktura společenstev hálky tvořících členovců na vrbách
KADLEC, Jan
In this thesis, I examined ecological factors that affect diversity and abundance of galls on willows. I focused on the effects of host-plant phylogeny, host-plant defences, and the effects of interactions among herbivorous guilds. I show that gall abundace is mainly affected by host-plant nutrients, while the defensive traits have only marginal effect. The effect of host-plant phylogeny seems to differ betwen groups of gall-forming arthropod taxa, with several of gall forming species on willows being polyphangous and showing only limited response to willow phylogeny. On the whole, the response of gallers largely differes from the response of less specialized guilds of herbivores.
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Liquid Chromatography Methods for Analysis of Actinomycete Secondary Metabolites - Potential Antibiotics
Kameník, Zdeněk ; Nesměrák, Karel (advisor) ; Cvačka, Josef (referee) ; Bosáková, Zuzana (referee)
(EN) This dissertation thesis contains scientific results achieved in the field of analytical chemistry, particularly liquid chromatography. The major part of the results has been published in prestigious international journals in five papers. In addition to that, relevant yet unpublished results have been included as well. In general terms, the work presented here contributed to the concerted efforts to tackle the current lack of novel antibiotics. Specifically, high-performance liquid chromatography (HPLC) and ultra high-performance liquid chromatography (UHPLC) techniques coupled to a variety of detection systems have been employed for analysis of antibiotics and actinomycete secondary metabolites. The first thematic part describes the development of liquid chromatography methods for analysis of lincomycin precursors, lincomycin precursor analogues, and lincomycin derivatives. The methods have been applied to study lincomycin biosynthetic pathway and obtain improved lincomycin derivatives by mutasynthesis. The second thematic part aims at investigating alternative approaches for analysis of antibiotics. Firstly, the core-shell particle and the sub-2 μm particle chromatographic columns were compared. The core-shell particle columns compatible with HPLC proved to be a convenient alternative to the...
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The effect of mycorrhiza on production of plant secondary metabolites
Pikorová, Markéta ; Albrechtová, Jana (advisor) ; Rydlová, Jana (referee)
Mycorhizal symbiosis, mutualistic relationship between symbiotic fungus and plant roots, is ranked among important interspecies interactions. It is indicated that about 90% terrestrial vascular plants live in this symbiosis. Arbuscular mycorrhiza (AM) is the most often occurring type of mycorrhiza and simultaneously the most often occurring type of symbiosis of higher plants. Approximately 80% of all of plant species form this symbiosis. By symbiotic coexistence with fungus plant often gains benefits as for example higher tolerance against stress factors, resistance against pathogens or improvement of nutrient uptake. In recent years in series of works is detected that mycorrhiza positively influences production of plant secondary metabolites. This influence can display quantitativelyby increase of metabolite in plant and also qualitatively by change spectrum of substances produced. These substances can have importance in different spheres for human. Medicinal research regularly extends spectum of substances with bioactive effect which have origin just in the plant secondary metabolism. Target of this thesis is, by the form of literary retrieval, to create an overview of recent state of research regarding of influence of mycorhizal symbiosis on content of secondary metabolites in plants, especially...
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Biological study of hemp activity
HELLEROVÁ, Šárka
The aim of my study is to evaluate the impact of seed density on yields of hemp, which was cultivated in two areas, and subsequently to assess biological efficiency of infusion from hemp on fibroblastoidal line of mammalian cells L292. Afterthat in the case of above mentioned biological test we want to find out, if the density and different parts of plant will have an impact on efficiency of extract.
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Cytotoxic effect of some cyanobacterial crude extracts and metabolites against selected human cancer lines, especially focusing on pancreatic cancer cell line PaTu
VICKOVÁ, Kateřina
Cancer is disease that affects human population for many thousands of years. Fortunately fighting cancer is more and more effective. This is mainly thanks to combining different strategies of therapy and progress in novel drug development and research. Cyanobacteria are emerging as an important source of novel bioactive secondary metabolites which provides an opportunity for new drug discovery. The aim of this study was evaluation of three cyanobacterial strains for in vitro cytotoxicity against human cancer cell lines, with special focus on pancreatic cancer cells. Crude extracts and chromatographic fractions were tested for their possible use (effectiveness) as selective cytotoxic and/or pro-apoptotic agents. Probably novel compound with anti-proliferative activity was found and isolated by HPLC-MS techniques.
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Anabaena - Phenotypic and genotypic diversity of planktonic strains in fishponds and reservoirs of the Czech Republic
ZAPOMĚLOVÁ, Eliška
Morphological diversity of 61 Anabaena populations of 13 morphospecies was described under the field conditions of Czech fishponds and reservoirs. Polyphasic approach was then applied in classification of 45 clonal strains isolated from those populations. Detailed morphological analyses were performed and partial 16S rRNA gene sequences were obtained for 33 of the strains, and secondary metabolite production was evaluated in 20 strains. Plasticity of morphological characteristics under varied conditions of light, temperature, nitrogen and phosphorus was studied in selected strains, as well as their temperature and light growth requirements. The results were then discussed with respect to the delimitation of single Anabaena morphospecies. A new genus Sphaerospermum was defined for the morphospecies Anabaena kisseleviana, A. reniformis and Aphanizomenon aphanizomenoides, whose phenotypic and genotypic features differed considerably from all other Anabaena morphospecies. Unique information was provided on the occurrence and distribution of A. reniformis and Aph. aphanizomenoides in the Czech Republic.
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Cytotoxicity of the filamentous cyanobacteria in relation to its ecology
TOMEK, Petr
The aims of this study was to screen a cytotoxic activity in 53 strains of the genera Nostoc and Anabaena and to compare occurence of active isolates within different ecological groups. Selected cytotoxic strains were subjected to HPLC/MS analysis to identify their extracts composition. Isolates with strong cytotoxic effect containing unknown substances were fractionated to obtain pure fraction of this compound. Finally, the selected strains toxicity dependence on time and concentration was evaluated.
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