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Root - shoot junction (collet) development
Hermann, Jiří ; Žárský, Viktor (advisor) ; Tylová, Edita (referee)
Although the root-shoot junction (collet) of adult plants is a well-identifiable part of the plant body, its development has, surprisingly till now, escaped serious research attention. The junction is a key region in the life of plants, as it connects two contrasting plant life environments and involves important changes in developmental programs - underground vs aboveground. The junction in angiosperms is first established during the embryogenesis phase of development in the form of the broad embryonic root- hypocotyl transition region, and it continues to develop further after seed germination during the individual's growth. The most important organ in this process is the hypocotyl, which exhibits considerable developmental plasticity, allowing extraordinary elongation in etiolated dark growth but also initiating formation of adventitious roots upon the deetiolation. During each stage of the junction's development, auxin signalling and polar auxin transport play a crucial role. Most of the research focuses on the development of the junction in the model organism Arabidopsis thaliana. The significance of the phylogenetic origin of the junction is also discussed from the perspective of the evolutionary origin of roots vs shoots and embryos evolution. This work aims to provide an overview of the...
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Ontogenetic changes in antipredator defence strategies
Schusterová, Zoe ; Exnerová, Alice (advisor) ; Šípek, Petr (referee)
Changes in antipredatory strategies are a timely topic because they help us understand the benefits and limitations of each strategy. They can also help explain certain behaviors of animals at a given ontogenetic stage. My thesis summarizes the existing knowledge on this phenomenon. The first chapter provides an overview of taxa in which the change of antipredatory strategy during ontogeny has been described. I then focus on the antipredatory mechanisms subject to change. I then present hypotheses explaining the origin of antipredatory strategy change and the benefits it confers on animals. Finally, factors that may influence strategy change are discussed. Keywords: antipredatory strategy, predation, aposematism, crypsis, mimicry
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Early ontogeny of the cell's circadian clock
Knapová, Adéla ; Sumová, Alena (advisor) ; Vácha, Martin (referee)
This thesis focuses on the development and function of the circadian system, which regulates biological processes in the body according to the 24-hour cycle. The circadian system and its key components, including the suprachiasmatic nuclei of the hypothalamus and peripheral oscillators, are introduced. The molecular operation of the circadian clock, which is influenced by two loops, is also discussed. A major theme is the ontogeny of the circadian clock, which occurs autonomously during embryonic stem cell differentiation. This process is influenced by various factors such as ultradian rhythms of the segmentation clock and the influence of maternal factors. However, not all signals are essential for the development of these clocks, and especially their rhythms, as revealed by in vitro methods. Furthermore, the thesis discusses how the behaviour of embryonic stem cells differs from cells differentiated from them, and why the circadian clock is dysfunctional in these cells. The work provides a deeper understanding of the ontogeny of the circadian system, its rhythms, and its regulatory mechanisms - that is, when, where and under what circumstances the clock starts to form and "tick".
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The influence of maternal care on the development of the circadian clock during ontogeny
Straková, Lucie ; Sumová, Alena (advisor) ; Spišská, Veronika (referee)
This bachelor thesis focuses on the importance of maternal care in early ontogeny on the development of circadian rhythms and further physiological development. The central clock oscillator (SCN) is most strongly synchronized by the external environment through the rhythms of light and dark. However, during ontogeny, when the main and peripheral oscillators first develop, maternal signals are the main synchronizers for the offspring. Thus, integration between mother and offspring is fundamental to the proper synchronization of the developing offspring's circadian clock, and the mother, through her behavior, can negatively or positively influence its setting. Attention is therefore paid to breastfeeding as a nowadays neglected factor of motherhood that has a strong influence. The composition of breast milk has proven beneficial effects over artificial diets, and breastfeeding has benefits for the health and circadian rhythm of mothers and their offspring. Premature infants are exposed to artificial conditions and weaned from maternal care, similar to offspring in cross-foster experiments. The observation of these effects on the development of their circadian rhythms again only confirms the importance of maternal care. Key words: maternal care, circadian rhythms, ontogeny, breastfeeding
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Ontogeny of neural mechanisms of episodic memory
Šafová, Lucie ; Nekovářová, Tereza (advisor) ; Blahna, Karel (referee)
Two brain structures in particular - the hippocampus and the prefrontal cortex (PFC) - are essential for episodic memory, the ability to recall personal experiences with details of time, place, and event. It is their developmental changes that contribute significantly to the progressive development of episodic memory. The hippocampus is a complex structure composed of several subregions that is crucial to the function of the neural basis of episodic memory. Findings show that both neuronal changes within the hippocampus and changes in its volume and the volume of hippocampal subfields influence episodic memory. As in the hippocampus, changes in the prefrontal cortex also affect episodic memory, with the PFC being among the last regions to fully mature and affecting the accuracy of recalling contextual details of episodic memories. The transfer of information between brain regions is also crucial for episodic memories, and is provided by white matter connections (fornix, cingulum, uncinate fasciculus). This thesis summarizes the knowledge about the structures and mechanisms involved in the development of episodic memory and mentions the factors that influence its development. Keywords: episodic memory, ontogeny, hippocampus, prefrontal cortex, synaptic plasticity
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Retrospective analysis focused on finding the most successful clubs in the education of young hockey talents in the 70s, 80s and 90s in the Czech Republic
RŮŽEK, Josef
The aim of this bachelor thesis was to find out the most successful clubs in development of young hockey players in seventies, eighties, and nineties in Czech Republic. In the analytical part we were interested in development of ice-hockey player and physiological conditions. We were also concerned with professional army sport. In synthetic part we mentioned all ice-hockey clubs, which played their part in developing top ice-hockey players. We also described five best ice-hockey clubs. We found out that in last 30 years there were 202 representational players, including 21 goalkeepers, 69 defenders and 112 attackers, on major tournaments. The most successful club was HC Dukla Jihlava, because of their program, which helped 54 players till they reach twenty years of age.
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Hormonal synchronization of fetal circadian clocks in suprachiasmatic nuclei
Kapsdorferová, Viktória ; Sumová, Alena (advisor) ; Sehadová, Hana (referee)
Rhythmic non-light maternal signals, such as various behavioral, neurohumoral or metabolic factors, may play a key role in synchronization of the fetal circadian clock. This diploma thesis focuses more closely on the possible role of leptin and dopamine in the hormonal synchronization of the fetal central clock resides in the suprachiasmatic nuclei of the hypothalamus. A transgenic mouse fetus, which has luciferase fused to the clock gene Period 2, was used as an experimental model. This allowed us to monitor the operation of the fetal central clock in real time by recording the bioluminescence of tissue explants. Exogenous administration of dopamine during the decline in bioluminescence at normalized circadian time 15 induces larger phase delays compared to vehicle. Leptin, on the other hand, can participate in the development of spontaneous rhythms by stabilizing the integrity of the circadian rhythm, manifested by slowing down the rhythm dampening. At the level of individual cellular oscillators, significant regional differences in amplitude and period were not observed using bioluminescence microscopy. However, a slight dispersion of cell phases was observed after administration of dopamine during decreasing bioluminescence. In the case of leptin, there was a prolongation of period of the cell...
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triggers of asexual reproduction: on the crosslink between hybridization, asexuality, polyploidy and speciation on example of Cobitidae loaches
Marta, Anatolie ; Janko, Karel (advisor) ; Arai, Katsutoshi (referee) ; Trachtulec, Zdeněk (referee)
(in English) Sexual reproduction is considered a nearly universal feature of all eukaryotic organisms and has been hypothesized to be their ancestral state. Sexual reproduction is mainly represented by meiotic division, recombination, production of haploid gametes and fertilization. Although molecular and cytological mechanisms underlying meiosis are highly conservative they may be disrupted in numerous ways leading to the emergence of so-called asexual lineages. The proximate origins of asexuality may differ for particular taxa. In vertebrates, asexuality frequently is triggered by interspecific hybridization. Nowadays "classical" theories predict that asexuals should not be able to persist on a long-term evolutionary scale. However, the hybrid lineages have to overcome short-term disadvantages, such as postzygotic barriers ranging from complete hybrid sterility to altered meiosis resulting in asexual reproduction and even ploidy elevation. Despite that hybrid sterility is one of the most common outcomes of interspecific hybridization, however various lineages found their ways to alleviate these problems and produce viable clonal gametes. The knowledge about proximate mechanisms of unreduced gamete formation in asexual lineages is very limited as many studies were restricted due to methodological...
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Consequences of perinatal insult on brain excitability in immature and adult rats
Fábera, Petr ; Mareš, Pavel (advisor) ; Pokorný, Jaroslav (referee) ; Ošlejšková, Hana (referee)
Perinatal insult may lead to a permanent impairment of brain function resulting in the development of epilepsy. Status epilepticus (SE) in immature rats leads to hippocampal hyperexcitability. The functional and morphological changes of the hippocampus are similar to those seen in human temporal lobe epilepsy. The excitability may be influenced by adenosine. Adenosine acts its anticonvulsant effect by activation of A1 receptors (A1R). The concentration of adenosine is regulated by adenosine kinase (ADK) present in two isoforms - ADK-L and -S. The main goal of the thesis is to elucidate the changes in A1R and ADK isoforms expression during intact brain development and after SE. A1R agonist 2-chloro-N6- cyclopentyladenosine (CCPA), as well as inhibition of ADK by 5-iodotubercidin (5-ITU), may bolster the anticonvulsant effect, but their action may correspond with the level of A1R and ADK. Hippocampal excitability in immature rats after LiCl-pilocarpine SE was studied by the model of hippocampal afterdischarges (ADs) and correlated with changes of A1R and ADK in the hippocampus. ADs demonstrated significantly decreased hippocampal excitability shortly after SE induction, whereas significant hyperexcitability accompanied by spontaneous seizures in older rats was shown. Increasing ADK-S expression...
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