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Molecular aspects of mammalian oocyte and embryo quality
Chyská, Anna ; Vaškovičová, Michaela (advisor) ; Jansová, Denisa (referee)
According to statistics in the Czech Republic, up to 20 % of couples experience infertility, which is still rising. One of the infertility treatment options is to undergo one of the assisted reproduction methods. In vitro fertilization (IVF) is among the most commonly used methods. In order to increase the success rate of fertilization, it is preferable to have a quality oocyte with specific characteristics. Such an oocyte is then a prerequisite for a good quality embryo, a correct course of pregnancy, and proper fetal development. Meiosis, a key step in oocyte formation, is regulated by complex signalling pathways. If these pathways are dysfunctional, the chances of the oocyte developing into a competent embryo are reduced. For example, errors in segregation during meiosis lead to aneuploidy, which is a major cause of miscarriages and birth defects. Therefore, understanding the signaling pathways can help identify the origin of the errors that result in aneuploidy and thus contribute to improving women's reproductive health. Key words: aneuploidy, spindle, in vitro fertilization, spindle assembly checkpoint, oocyte quality, chromosome segregation
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Significance of androgens of adrenal origin in polycystic ovary syndrome and hirsutism
Varausová, Anežka ; Vítků, Jana (advisor) ; Jansová, Denisa (referee)
The adrenal cortex is the source of a wide range of steroid hormones. Mineralocorticoids, glucocorticoids and, last but not least, androgens are synthesized here. The most abundant adrenal androgen is dehydroepiandrosterone sulfate, whose androgenic potency is not high, but it forms a reservoir in the circulation and can subsequently be metabolized to more potent androgens. Another androgen formed in the adrenal cortex is 11β-hydroxy-androstenedione. This steroid also has low androgenic potency, but its importance lies in the fact that it serves as a precursor of the active androgens - 11-oxygenated derivatives of testosterone and dihydrotestosterone. Besides their high androgenic potency, their relatively high levels in circulation prompt attention to be paid to these steroid hormones in all endocrine disorders where classical androgens are monitored. The determination of these androgens is suggested in polycystic ovary syndrome and idiopathic hirsutism, among others, where it could explain the discrepancy between the intensity of clinical symptoms and testosterone and dihydrotestosterone levels. The aim of this thesis is to review the scientific knowledge on the relationship between 11-oxygenated androgens and the mentioned endocrine disorders. Keywords: steroid, adrenal cortex, androgen,...
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Identification of key regulators of gene expression in mammalian oocyte and embryo
Jansová, Denisa ; Šušor, Andrej (advisor) ; Gahurová, Lenka (referee) ; Lin, Chih-Jen Lance (referee)
Mammalian oocyte is a highly differentiated cell which gives rise to an embryo after fertilization. Importantly, fully-grown oocytes become transcriptionally inactive at the end of the growth phase. During following stages of development, i. e. meiotic maturation of the oocyte and early embryonic development, only transcripts previously synthesized and stored are used. The tight correlation between mRNA distribution and subsequent protein localization and function provides a mechanism of spatial and temporal regulation of gene expression used by various cell types. However, not much is known about mRNA localization and translation in the mammalian oocyte and early embryo. The aim of my thesis was to determine the localization of transcripts and components of translational machinery in the mammalian oocyte and embryo and to uncover the mechanisms of spatiotemporal regulation of translation as a prerequisite for correct oocyte and embryo development. We have shown that nuclei of both mouse and human oocytes contain RNA molecules and RNA binding proteins. Following the nuclear envelope breakdown (NEBD), translational hot-spots occur in the area surrounding the nuclear region. We suppose that mRNAs previously retained in the nucleus are released to the cytoplasm during NEBD and their subsequent...
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