National Repository of Grey Literature 19 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Mathematical modeling of early embryogenesis processes
Dunajová, Michaela ; Šejnoha, Jiří (advisor) ; Drutovič, David (referee)
1 Abstract: Early embryogenesis is a fundamental phenomenon of developmental biology, which involves the establishment of the first structures within embryos. The work focuses on mathematical spatial models of mammalian blastulation, which were created based on spatial approach. We discuss and compare six mo- dels, which simulate the differentiation of cell lines and the formation of blas- tocyst structures. Models are based on local rules, using considerable cellular abstraction. Models focus on the processes of differentiation of the blastomere into the trophoectoderm and the inner cell mass, followed by the establishment of the structure of the epiblast and the primitive endoderm.
The influence of postural ontogenesis on morphological development of trunk
Hladíková, Veronika ; Kobesová, Alena (advisor) ; Šafářová, Marcela (referee)
This bachelor thesis engages in an influence of postural ontogenesis on formation of anatomical structures of trunk. Postural ontogenesis depends on maturation of the central nervous system, which stimulates automatic, accurately timed recruitment of muscles to posture. At the same time with postural muscle activation, morphogenesis of the skeleton is finishing. As a consequence of abnormal motor development, there are deviations in bone shape and in setting of joints. The thesis is focused on the description of a morphological development of spinal curves, thorax and abdominal wall. The development of cervical lordosis and the shape of the upper part of thorax is linked to the development of motor functions of upper limbs. The significant milestone is an ability to lift and hold head above the surface in prone position. The development of lumbar lordosis and the shape of the lower part of thorax is determined by motor functions of lower limbs, which are firstly manifested by lifting lower limbs in supine position. The development of sitting, stance and gait plays a crucial role. The development of abdominal wall is assessed by presence, or rather absence of diastasis recti abdominis, which is related to the quality of muscle coordination in this area. Practical part of the thesis devotes to...
Morfogeneze orálního skeletu mihule ve vztahu k evoluci čelistí
Romášek, Marek ; Černý, Robert (advisor) ; Jandzík, Dávid (referee)
4 Neural crest-derived cellular cartilage is one of the defining characteristics of vertebrates. Elaboration of this tissue and its patterning allowed the evolution of jaws in the gnathostome lineage. Together these hallmarks helped jawed vertebrates become one of the dominant taxons in the animal kingdom. Lampreys, as basal jawless vertebrates, lie at a unique phylogenetic position that makes them ideal organisms for the study of evolution of vertebrate/gnathostome novelties. Larval lampreys possess a special oral skeleton composed of a tissue related to cartilage, termed mucocartilage. Despite considerable attention that has been paid to the evolutionary significance of mucocartilage, it is not yet clear, how this unique feature arises in development and to what extent it is homologous to gnathostome jaws. In this study, the development of oro-pharyngeal region was analyzed in the sea lamprey Petromyzon marinus. SEM imaging revealed shaping and topographic relationships of embryonic tissues, detailed plastic histology coupled with expression analyses of several molecular markers were used to describe origin, histogenesis and morphogenesis of mucocartilage. Furthermore, genetic regulation of the tissue was investigated in order to identify its unique or shared features. Mucocartilage is seen to...
Ontogeny of exaggerated structures in dung beetles (Coleoptera: Scarabaeinae)
Žídek, Radim ; Šípek, Petr (advisor) ; Hanus, Robert (referee)
E n g l i s h a b s t r a c t Horns of scarab beetles represent a secondary sexual characters present mostly in males, to whom they serve as weapons in combats over the acces to females. In many species, two discrete male forms occur, "horned" and "hornless", which employ different reproductive strategies. Adult body size and horn morphology are determined by nutritional conditions encountered by larvae during their development. Switching between developmental pathways is accomplished by circulating levels of juvenile hormone (JH) which reflect body size, and genetically determined threshold of sensitivity to it. When body size is larger then threshold, horn growth occur, whereas if it's not, a brief pulse of ecdysone reprogramme the development and hornless adult emerge. Reprogramming the development encompass modifications of the insulin receptor pathway as well as changes in exact domains of genes expression envolved in specifying the proximodistal axis of the developing horn. Development of horns is morphologically reminiscent that of other insect appendages, with which it shares the expression of genes wingless, decapentaplegic, Distal-less, dachshund, homothorax, aristaless and EGFR, parts of gene regulatory network ensuring origin of the outgrowth of the cuticle. Some of them are expressed through...
Diversity, distribution, phylogeny and ecology of the genus Micrasterias (Desmidiales)
Trumhová, Kateřina ; Šťastný, Jan (advisor) ; Bestová, Helena (referee)
The genus Micrasterias comprises one of the most beautiful organisms. It attracts, due to its spectacularly shaped cells, the attention of scientist and amateur biologist almost for almost 200 years. This thesis summarizes the current knowledge about these extraordinary organisms. The first part deals with the morphology and the life cycle of these algae. They share a unique type of reproduction (conjugation) with the other representatives of the class Zygnematophyceae. The second part concerns phylogeny of this genus. Several morphologically distinct species have been revealed with the aid of molecular phylogenetic methods to belong to the genus Micrasterias. A polyphasic evaluation of three species complexes within this genus also revealed an extensive hidden diversity. The last chapters summarize the knowledge about the influence of hidden diversity and accelerated morphological evolution on our understanding of diversity and biogeography of these organisms.
Stress induced morphogenic response in plant root system
Otradovcová, Michala ; Soukup, Aleš (advisor) ; Vaňková, Radomíra (referee)
The root system architecture adjustment is one of the possible plant reactions to stress effects of environmental conditions. The shape of root system is jointly formed by the root apical meristem activity, the rate of elongation of root cells and by the degree of formation, developement and organization of secondary and adventitious roots. This paper aims to describe basic mechanisms of the root system developement and outline the morphological and regulatory changes occuring during development while being affected by selected stress factors.
Evolutionary and theoretical aspects of the biological work of Bohumil Němec
Loginov, Ivan ; Hermann, Tomáš (advisor) ; Žárský, Viktor (referee)
Plant physiologist Bohumil Němec is one of the most important people in the history of Czech science. In this thesis, crucial concepts and theories that B. Němec developed in his scientific and popularizing publications are described and put in context. In addition, materials from the personal fond of B. Němec located in the Archive of the CAS were used. Particular questions tackled in this thesis are those of stimuli transmission in plants, the starch-statolith theory of gravitropism, morphaesthesia, organogenes, Němec's approach to evolutionary theory, and genetics, and the division of organisms in two groups. Moreover, Němec's role in the contemporary debates about vitalism, mechanism, and the effect of these two philosophies on the approach towards scientific research is indicated. By that, Němec's transition from the mechanism to the so-called physiology of stimuli (Rheizphysiologie) is illustrated. The outcome of the thesis is broadening the knowledge in the history of plant physiology, especially the history of the natural sciences in the Czech context.
Morphogenesis and Viscoelastic Properties of Dimethacrylate Networks
Bystřický, Zdeněk ; Lehocký, Marián (referee) ; Bradna, Pavel (referee) ; Jančář, Josef (advisor)
Tato dizertační práce se zabývá studiem morfogeneze dimethakrylátových sítí. V práci byly využity zjednodušené systémy založené na monomerech, které bývají typicky využívány jako složky matric pryskyřičných kompozitních materiálů využívaných v oblasti záchovné stomatologie. Kinetika a mechanismy formování polymerních sítí byly studovány především s ohledem na strukturu jednotlivých monomerů, jejich vzájemný molární poměr a koncentraci iniciačního systému využitého pro radikálovou polymeraci. Vypočtené profily konverze funkčních skupin a reakčních rychlostí byly využity jako základ pro pochopení a interpretaci mechanismů morfogeneze sítí a porovnání se známými modely. Dále byla studována kinetika termické degradace, která je s morfologií vytvrzených sítí přímo spjata. V rámci takto charakterizovaných systémů byla stanovena teplotní závislost dynamického modulu a byl popsán vztah mezi supra-molekulární strukturou dimethakrylátových sítí a jejich viskoelastickou odezvou v daném teplotním rozmezí. Kinetika polymerace byla studována pomocí diferenční kompenzační foto-kalorimetrie (DPC) a infračervené spektroskopie (FTIR). Proces termické degradace byl analyzován pomocí termo-gravimetrické analýzy (TGA). Viskoelastické parametry byly charakterizovány pomocí dynamicko-mechanické analýzy (DMA). Reaktivita jednotlivých systémů je přímo odvozena od molekulární struktury monomerů, která ovlivňuje mobilitu reagujících složek v průběhu polymerace. Kinetika polymerace je řízena především difúzí, přičemž její rychlost je dána tuhostí monomerní páteře, koncentrací funkčních skupin a vlivem fyzikálních interakcí. Omezená mobilita rostoucích řetězců, postranních funkčních skupin i samotných monomerů vede k monomolekulární terminaci makro-radikálů a omezení stupně konverze funkčních skupin. Vzhledem k tomu, že k zásadnímu omezení mobility dochází již v počáteční fázi polymerace, tj. v bodu gelace, je případná termodynamická nestabilita vedoucí k fázové separaci polymerujícího systému potlačena a proces kopolymerace je ve své podstatě náhodný. To bylo prokázáno i prostřednictvím identifikace jedné teploty skelného přechodu u charakterizovaných kopolymerů. Heterogenní charakter morfogeneze je spjat s rozdílnou reaktivitou postranních funkčních skupin. V počátečních fázích polymerace dochází k propagaci reakcí postranní funkční skupiny s radikálem na stejném rostoucím řetězci, což vede ke vzniku tzv. primárního cyklu. Pravděpodobnost cyklizace souvisí především s flexibilitou monomerní páteře. Heterogenita polymerace je charakterizována vznikem vnitřně zesítěných struktur, tzv. mikrogelů, a jejich následným spojováním. Tuhost monomeru naopak přispívá k vyšší efektivitě zesítění a více homogenní morfologii vytvrzené sítě. Heterogenita dimethakrylátových sítí se odráží v mechanismu termické degradace, přičemž přítomnost strukturně odlišných domén vede k rozkladu ve dvou krocích. Průběh soufázového modulu a teplota skelného přechodu korelují s tuhostí polymerních sítí, efektivitou zesítění a přítomností fyzikálních interakcí, které vyztužují strukturu sítě nad rámec kovalentního zesítění. Heterogenní morfologie sítí se projevuje rozšiřováním spektra relaxačních časů. Experimentální data jsou v kvalitativní shodě s existujícími numerickými modely popisujícími kinetiku radikálové polymerace multifunkčních monomerů.
Overview of phylogeny, systematics and diversity of genus Ulva (Ulvophyceae) and biotechnological use of these algae
Kantnerová, Veronika ; Neustupa, Jiří (advisor) ; Němcová, Yvonne (referee)
The genus Ulva represents a remarkable group of organisms, with number of species. It belongs to the class Ulvophyceae, one of the major groups of chlorophytic green algae and it is characterized by a typical dual morphology and isomorphic haplo-diplontic life cycle. This work is a summary of existing knowledge related to this algal genus with regard to the phylogeny, diversity and ecology, which is relatively interesting due to the ability of these algae to adapt to a wide range of abiotic conditions. It also focuses on the development of thallus morphology of these algae, especially with relation to an interesting and very important role of symbiotic bacteria in this process and, last but not least, on the biotechnological utilization that has great potential for the future, especially in terms of the utilization of Ulva as an alternative renewable energy source, a food supplement with high content of important proteins, minerals and vitamins, or as a source of polysaccharides, the so-called "ulvans", which are now investigated for their biological activity and application in human medicine. Key words: Ulva, Ulvophyceae, phylogeny, morphogenesis, biotechnology, ekology, diversity
Are there any temperature related changes in morphological integration of Micrasterias cells?
Buchtová, Edith ; Neustupa, Jiří (advisor) ; Kleisner, Karel (referee)
Micrasterias rotata is a phylogenetically and morphologically well defined species that is widely distributed in Central Europe in a broad temperature gradient. For its complex cell shape Micrasterias rotata is a suitable model organism for cell morphogenesis research. This thesis investigated whether there could be a different pattern in morphological integration resulting from the temperature stress in Micrasterias rotata cells cultivated on a temperature gradient. The optimum and a limits of growth on the temperature gradient were related to the sampling locations of the studied strains isolated from a lowland wetland and an high alpine lake. Differences in the growth rates among the strains suggested a local adaptation to the climatic conditions of the original locations but relatively high values of the assumed optimum growth temperature suggested an intra- species evolutionary adaptation. The temperature-related size reduction rule was not confirmed; however, a similar pattern of variation in shape occurred in both strains. The morphological integration analysis has basically confirmed that the Micrasterias cell is composed of a number of morphological modules related to its differentiation into the lobes and sublobes. Integration between the lobes of the opposite semicell was primarily...

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