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Effect of ubiquitin-proteasome system on spermiogenesis in mammals
Kroumanová, Kristýna ; Petelák, Aleš (advisor) ; Krejčová, Tereza (referee)
Spermiogenesis is a complicated process in which the haploid spermatids differentiate into morphologically mature sperm. Morphological changes include condensation of chromatin and histone-to-protamine replacement, fusion of Golgi-derived vesicles to form acrosomal cap, flagellum formation, reduction of cytoplasmic volume and organelles rearrangement. Ubiquitin-proteasome system plays a key role in these processes. Ubiquitination is a posttranslational modification, leading to the labelling of intracellular proteins targeted for degradation by 26S proteasome. Importance of sperm ubiquitination, is supported by the fact, that deficiency of ubiquitin-proteasome system can lead to infertility at various degrees. During the subsequent sperm maturation in the epididymis extracellular ubiquitination of abnormal sperm and sperm quality control take place. Ubiquitin-proteasome system plays a key role during fertilization, when the sperm 26S proteasome is co-responsible in zona pellucida penetration. The purpose of this assay is to describe the effect of ubiquitin- proteasome system during different stages of spermiogenesis in mammals.
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Photoreceptors properties in strictly subterranean African mole-rats
Krejčová, Tereza ; Němec, Pavel (advisor) ; Kott, Ondřej (referee)
4 Photoreceptor properties and distribution in strictly subterranean African mole-rats (Rodentia, Bathyergidae) The visual system of subterranean rodents is assumed to be regressed in response to their lightless ecotope. According to the prevailing doctrine, negative or non-selective processes have driven evolutionary regression of the visual system in many unrelated groups of rodents that has adopted strictly subterranean mode of life. Among rodents this has been exemplified by detailed studies of the blind mole-rat Spalax ehrenbergi. However, recent studies involving a larger spectrum of subterranean rodent species demonstrated unexpected diversity of retinal properties and visual system designs among subterranean rodent species and thus challenged the widely held view that the visual system has undergone extensive convergent evolution in subterranean mammals. This paper examines the presence, the distribution, and photoreceptor properties in the African mole-rats (Bathyergidae, Rodentia). It describes rodopsin, S- and L-opsin expression patterns, photoreceptor densities and rod/cones proportions in five species of bathyergid mole-rats, namely Bathyergus suillus, Georychus capensis, Fukomys damarensis, Cryptomys natalensis and Heliophobius argenteocinereus. Spectral cone types and rods were assessed...
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Effect of hydrogen sulphide on aging of porcine oocytes in vitro
Krejčová, Tereza ; Petr, Jaroslav (advisor) ; Ješeta, Michal (referee)
Unfertilized or parthenogenetically non-activated porcine oocytes matured in vitro conditions are subjected to a process known as aging. During such development, porcine oocytes undergo the complex of the structural and functional changes, which can result in spontaneous parthenogenetic activation, fragmentation or lysis. After three days of culture in our condition, 23% of oocytes remained at the stage of metaphase II, 48% of oocytes were spontaneously parthenogenetically activated, 26% of oocytes were subjected to fragmentation and 3% of oocytes were lysed. The complete suppression of porcine oocyte fragmentation during the process of aging occurred during oocytes cultured in medium with sulphide donor Na2S in concentrations 150 µM and 300 µM. Inhibition of enzymes catalyzing the synthesis of hydrogen sulfide in the oocytes during the process of aging (cystathionine-gamma-lyase and cystathionine beta-synthase), iniciates earlier onset of oocytes fragmentation. The effect of both inhibitors could be completely reversed by using sulphide donor Na2S. The process of aging in porcine oocytes significantly reduces the success of the activation processes. Parthenogenetic activation occurred in 94% of pig oocytes, which were not subjected to aging. The proportion of activated oocytes after exposure to 24...
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Communication Strategy Proposal for the Ski Resort Šacberk
Krejčová, Tereza ; Kramláčková, Agáta (referee) ; Konečná, Zdeňka (advisor)
The aim of this thesis is to propose the communication mix for Šacberk Ski Resort. The objective of this thesis is the improvement of communication with customers and promotion of the company. Advertising campaign should make all the advantages of the company more visible. Diploma thesis evaluates current situation of the mix and proposes improvements and expansion of the advertising campaign to other regions of the Czech Republic. The new communication mix should lead to improving the current situation, gaining new customers and keeping current customers.
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