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Polymer carriers for nuclear medicine
Sedláček, Ondřej
In the thesis, we developed and studied a novel polymer delivery system for the DNA-intercalator bearing radioisotope iodine-125. Auger electrons emitting radioisotopes (such as iodine-125 or indium-111) are a potentially effective cancer treatment. Their use as an effective cancer therapy requires that they will be transported within close proximity of DNA, where they induce double-strand breaks leading to the cell death. This type of therapy may be even more beneficial when associated with drug delivery systems. The DNA intercalators proved to be effective carriers for the delivery of Auger electron emitters into DNA. Therefore, the new radioiodinated DNA-intercalating ellipticinium derivatives were synthesized and characterized. These compounds were linked to N-(2-hydroxypropyl) methacrylamide copolymer with narrow molecular weight distribution via acid-sensitive hydrazone linker. The structure of the linker plays a crucial role in the biological effectivity of the delivery system, so it was optimized to be stable at pH 7.4 (representing the pH of blood plasma), whereas in slightly acidic pH in endosomes after the cell internalization, the radioiodine-containing biologically active intercalator is rapidly released from its polymer carrier. The intercalating ability of the active compound was...
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Polymer carriers for nuclear medicine
Sedláček, Ondřej
In the thesis, we developed and studied a novel polymer delivery system for the DNA-intercalator bearing radioisotope iodine-125. Auger electrons emitting radioisotopes (such as iodine-125 or indium-111) are a potentially effective cancer treatment. Their use as an effective cancer therapy requires that they will be transported within close proximity of DNA, where they induce double-strand breaks leading to the cell death. This type of therapy may be even more beneficial when associated with drug delivery systems. The DNA intercalators proved to be effective carriers for the delivery of Auger electron emitters into DNA. Therefore, the new radioiodinated DNA-intercalating ellipticinium derivatives were synthesized and characterized. These compounds were linked to N-(2-hydroxypropyl) methacrylamide copolymer with narrow molecular weight distribution via acid-sensitive hydrazone linker. The structure of the linker plays a crucial role in the biological effectivity of the delivery system, so it was optimized to be stable at pH 7.4 (representing the pH of blood plasma), whereas in slightly acidic pH in endosomes after the cell internalization, the radioiodine-containing biologically active intercalator is rapidly released from its polymer carrier. The intercalating ability of the active compound was...
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Diversity and abundances of birds along altitudinal gradients of Cameroon Mountains
Dubský, Marek ; Sedláček, Ondřej (advisor) ; Reif, Jiří (referee)
The aim of this thesis is to describe the changes of bird species diversity along elevation gradient on six mounts in Cameroon and nearby Bioko island. The results of the analyses confirm most of the defined hypotheses, especially they show that species diversity declines with altitude and rises with area. Cluster analysis shows the similarity of individual mountains in particular altitude zones. Despite the original hypothesis, mount Cameroon is found to be most similar to mount Kupé, although high mountain assemblages of mount Cameroon and Bioko island are very alike as well. The absolutely highest diversity was detected on mount Cameroon and mount Kupé, but above 2100 m above sea level mounts Oku and Manenguba are the most diverse. The results of this thesis contribute to a clearer notion about factors influencing species diversity; however, more thorough data (particularly from mount Nlonako) and data extension for e.g. bird abundance would enrich the study and it would enable us to perform more detailed diversity analysis, especially an analysis of competition relationship among species. Key words Species diversity, Cameroon, bird assemblages, elevational gradient
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The role of interspecific competition in ecological differentiation and speciation in two passerine species, Luscinia megarhynchos and Luscinia luscinia
Sottas, Camille Pauline ; Reifová, Radka (advisor) ; Krist, Miloš (referee) ; Sedláček, Ondřej (referee)
(in English) Interspecific competition is assumed to play an important role in the morphological and ecological differentiation of co-occurring species and could contribute to their speciation. However, empirical studies showing a direct association between competition, ecological niche divergence and specific morphological adaptations are scarce. This thesis focuses on the role of interspecific competition in the differentiation and the evolution of reproductive isolation between two closely related passerine species: the common nightingale (Luscinia megarhynchos) and the thrush nightingale (Luscinia luscinia). Both species are insectivorous and have similar ecological niches. They have diverged 1.8 Mya and their areas currently overlap in a secondary contact zone, where both species still occasionally hybridize. Previous studies have reported an accentuate bill size divergence in sympatric populations compared to allopatric populations, suggesting that interspecific competition might have resulted in feeding niche divergence between the two species in sympatry. Within this PhD thesis, I have studied potential associations between bill morphology divergence, diet composition, habitat use and gut microbiota composition. We found that the two nightingale species have diverged in feeding niche in...
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Species traits and ecological conditions linked to bird colonisation of cities
Grünwald, Jan ; Reif, Jiří (advisor) ; Sedláček, Ondřej (referee)
Human settlements are a novel habitat type and species must respond to its ongoing expansion. For effective conservation of biodiversity, it is important to understand the mechanisms underlying these responses. This thesis focuses on urbanization in birds, from both the individual and community perspectives. The aim of this thesis is to find out if there are any "pre-adaptations" in some bird species to be successful city dwellers or if all birds can potentially exploit the urban environment when local conditions allow. According to the reviewed literature, I conclude that the urbanization in birds is not a universal pattern, but there are some specific traits shared by most of the urban birds. The successful urban species are mostly omnivorous or granivorous, they breed in trees or in cavities and, they are often ecological generalists. They are sometimes represented by non-native species occurring in the cities all over the world.
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Conservation of populations on the edge of geographical distribution
Pešová, Lucie ; Sedláček, Ondřej (advisor) ; Šípek, Petr (referee)
Populations on the edge of the range are often considered less valuable for conservation with regard to core populations of the species. These populations are often small, isolated and less genetically variable, and are therefore more prone to extinction. On the other hand, there are some studies claiming that some peripheral populations could have genetically unique allels which could help them adapt to changing environmental conditions. They thus have a big speciation potential. Peripheral populations could also occur behind state borders, where the species has conservation status, despite the fact that it is a common species somewhere else in its range. Due to this contradiction, peripheral populations are a delicate topic of discussion in the scientific community. In this paper I summarized the features of populations on the edge and also factors which limit them. Furthermore, population dynamics of these populations and summary of the main genetic processes taking place in small populations are outlined here. Next there are arguments for and against conservation of populations on the edge. In conclusion I give model examples of species on the periphery, demonstrating their features and reasons for their possible conservation. Key words: population, conservation, peripheral, marginal, range...
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Porous polymer networks prepared from ethynylpyridines
Titlová, Štěpánka ; Sedláček, Jan (advisor) ; Sedláček, Ondřej (referee)
Series of new micro/mesoporous polymer networks with high content of pyridine segments was prepared. For the preparation were used ethynylpyridine type of monomers which were successfully homopolymerized and copolymerized with hydrocarbon diethynylarenes by chain-growth coordination polymerization catalyzed with [Rh(NBD)acac] complex. Polymerizations provided polyacetylene networks with main chains densely cross- linked by pyridine or arylene links. Prepared pyridine networks showed specific surface area SBET from 308 m2 /g to 923 m2 /g and variable content of pyridine segments in an interval from 3,27 mmol/g to 7,86 mmol/g. In networks, pyridine segments made part of interchain links or side groups. Networks with pyridine segments were successfully quaternized by heterogeneous postpolymerization reaction with bromoethane to form well covalently defined networks containing N-ethylpyridinium segments. Quaternized networks containing pyridinim segments in amount from 2,41 mmol/g to 4,24 mmol/g had preserved micro/mesoporous texture with values of SBET from 331 m2 /g to 592 m2 /g. Polyacetylene networks with N-ethylpyridinium segments were prepared also by catalyst-free (spontaneous) quaternization polymerization of diethylpyridines. These networks were worse covalently defined and had proved lower...
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Effect of type of discrimination task on rate and effectiveness of discrimination learning to avoid aposematic prey in avian predators
Jůnová, Lenka ; Exnerová, Alice (advisor) ; Sedláček, Ondřej (referee)
During the proces of learning to distinguish between edible and inedible prey, predators can encounter different types of prey either sequentially (one at a time) or simultaneously. Sequential as well as simultaneous presentation are used as experimental designs for testing discrimination learning of bird predators in relation to aposematic prey. These tasks can differ in difficulty level for predator which can affect test results; however, rate and effectivity of discrimination learning in sequential and simultaneous tasks have never been experimentally compared. We tested effect of type of discrimination task on effectivity of discrimination learning and memorability of prey discrimination in adults and juveniles great tits (Parus major) in two sequential tasks (regular and random) and one simultaneous task (multiple- choice). The birds learned to discriminate between edible and inedible artificial prey on the first day, and we investigated memorability of prey on the second day. We used colour (alternative red/green) or pattern (alternative dots/stripes) as discrimination cue. Results showed that tits learned to discriminate by colour cue better than by pattern cue. Adult tits learned to discriminate better than juveniles independently on task type. Effect of age and sex was shown in some tasks...
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Signalling of personality and stress response by secondary sexual traits in a socially monogamous passerine
Tesař, David ; Tomášek, Oldřich (advisor) ; Sedláček, Ondřej (referee)
Secondary sexual traits play an irreplaceable role in the reproduction of a range of animals and are used as quality and fitness sensors during pairing of individuals. Expression of these traits, ornamentes, can correlated with an individual's personal and behavioral strategies. In the case of melanin ornaments, not only the relationships with personal individuals are considered, but there is the possible connections with stress resistance and the level of stress responses too. This hypothesis is based on the pleiotropic effect of the melanocortin system, which can be used during melanogenesis but also in the production of hormones that contribute to range of stress responses. The aim of this work was to clarify the relationship between an individual's ornaments, his stress response and individuality in the barn swallows (Hirundo rustica rustica). In this work the relationship between selected ornaments and the stress reaction of the organism, stressed glucose levels measured 15 minutes after a stress stimulus, was tested. Both sexes showed a correlation between area of white tail spots and stress response. Only for males a relationship with the length of outermost tail feathers was found and a correlation with the color saturation of feathers on the throat was shown for females. The second part of...
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Determinants of abundances in terrestrial vertebrates
Kundelová, Tereza ; Storch, David (advisor) ; Sedláček, Ondřej (referee)
The abundance of animals differs between species, however, they also vary in area and time. These differences relate to biotic and abiotic factors as well as to ecological characteristics of particular species. Studies focusing on these factors are aiming to answer the question; how and what influences the abundance of these species. Besides clarifying the dependence of abundance on particular factors, studies also try to ascertain which key factors are necessary for the determination of abundance. The most frequently studied factor is body size, but trophic level, specialization, net primary productivity, and competition also play a significant role in determination. However, all these factors explain only a small proportion of interspecific variability in abundances. This thesis focuses on terrestrial vertebrates; however, mainly on birds and mammals; since, these two taxa are the most studied. Key words: abundance, population density, terrestrial vertebrates, body size, competition, energy flux
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