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Evolutionary aspects of (epi)genetic determination of laterality with a special focus on upper limb
Holoubková, Tereza ; Daňková, Pavlína (advisor) ; Struška, Michal (referee)
Handedness is one of the most distinct asymmetries of the human body. There is approximately 90 % of right-handers in the population, which is the strongest bias in handedness among all primates. Handedness is connected with lateralization of brain for language and is determined both genetically and by the environment. Genetic determination of the handedness has not been yet figured out, although there are many candidate genes and regions. In addition to candidate genes, the genetic determination is shaped by the epigenetic mechanisms and the role of testosterone. Handedness occurred alongside the beginning of the human population development, approximately in the Middle Pleistocene, with the same percentage of left-handers as today. Handedness polymorphism is maintained in the population based on the frequency-dependent model because of the advantages and disadvantages associated with left-handedness.
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The role of epigenetic mechanisms in opiate dependence
Hronová, Anna ; Novotný, Jiří (advisor) ; Netolický, Jakub (referee)
Addiction and tolerance develop with the chronic use of opioids. Opioid drug abuse has social, economic and health consequences. The most commonly abused opioid drug is heroin, but so is morphine, which is used in medicine as an analgesic. Drug dependence includes potentially long-term behavioural abnormalities that are induced by repeated use of opioid drugs. The persistence of behavioural chan- ges suggests that there are long-term changes in gene expression. Research has shown the crucial role of epigenetic mechanisms in managing long-term changes in gene expression. Studies have revealed increased levels of permissive histone acetylation, decreased levels of repressive histone methylation, and changes in DNA methylation patterns and non-coding RNA expression. Within the action of opioids, these epigenetic modifications are limited to the mesolimbic and limbic systems, which play a role in the processing of emotions, motivation or reward. There is still much work to be done in the field of research into the influence of epigenetic mechanisms in opiate dependence. However, research to date has significantly shifted the understanding of how opioids cause permanent changes in brain function with their results and findings.
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Role of sequence context in DNA methylation
Polák, Jan ; Fischer, Lukáš (advisor) ; Širl, Marek (referee)
Cytosine methylation of DNA is a pivotal epigenetic mark, which contributes to the regulation of the gene expresion, silencing of transposable elements, and co-defines chromatine state. There are three cytosine contexts: CG, CHG and CHH (where H stands for C, A, or T). Arabidopsis thaliana (and plants in general) has an arsenal of molecular mechanisms capable of cytosine methylation in all of its contexts. That said, there are two tasks at hand: maintaining of pre-existing methylation and if need be, creating new methylated spots. The actual process of maintaining of the methylation depends on the cytosine context. Methylation of symmetrical contexts of CG and CHG can utilize the information about the methylation pattern from the second DNA strand. The aymmetrical context of CHH, and also CHG need to look for this information elsewhere: in the methylation of the lysine 9 of H3 histone. This creates a self-reinforcing loop and a crosstalk between two epigenetic mechanisms. Maintaince of methylation of CHH is also navigated by small RNA complementary to the locus in question. This mechanism of enzyme navigating by RNA is also used in establishing a new methylated site for all of the contexts. CG methylation is most prevalent in both heterochromatine and euchromatine. It also has a special functions...
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Integration site distribution of expressed proviruses
Miklík, Dalibor ; Hejnar, Jiří (advisor) ; Kejnovský, Eduard (referee) ; Indik, Stanislav (referee)
To establish efficient expression of their genes, retroviruses integrate proviral copies into the genomes of the cells they have infected. Epigenetic events, however, silence expression of the integrated proviruses. This silencing protects host cells from harmful viral spread, but also creates a reservoir of latent proviruses that subsequently hinders the cure of retroviral (e.g., HIV-1) infections. Furthermore, the silencing of retrovirus-derived integrative vectors complicates their application in transgenesis and gene therapy. The goal of this thesis is to describe the interaction between retroviral expression and host (epi)genomic environment at the site of proviral integration. To pursue the goal, we sought to define the (epi)genomic environment of the proviruses, which expression is not affected by the epigenetic silencing. Diverse retroviral vectors derived from avian sarcoma and leukosis virus (ASLV), murine leukemia virus (MLV), and human immunodeficiency virus type 1 (HIV-1) were used as model retroviral systems, and expression stability of the vectors in human cell lines was examined. In order to identify the features unique to integration sites of the active proviruses, we sorted the cells positive for the proviral expression, identified their proviral integration sites, and compared them to...
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The role of SIRT1 during in vitro maturation of oocytes
Landsmann, Lukáš ; Nevoral, Jan (advisor) ; Šolc, Petr (referee)
SIRT1 histone deacetylase acts towards many epigenetic and non-epigenetic targets. The involvement of SIRT1 in oocyte maturation is assumed and the importance of ooplasmic SIRT1 pool for further destiny of matured oocyte is strongly suggested. We hypothesized that SIRT1 play role of the signal molecule in mature oocyte through selected epigenetic and non- epigenetic regulation. We observed SIRT1 re-localization in mature oocyte and the association with spindle microtubules. In matured oocyte, SIRT1 shows a spindle-like pattern and spindle- specific SIRT1 action is supported decreasing α-tubulin acetylation. Based on the observation of histone code in immature and matured oocytes, we suggest that SIRT1 is mostly predestined for epigenetic mode of action in germinal vesicle (GV) of immature oocyte. Accordingly, SIRT1- driven trimethylation of histone H3 on lysine K9 in matured oocyte is considered to be an inheritance of GV epigenetic transformation. Taken together, our observations point out the dual spatiotemporal SIRT1 action in oocyte capable to be switched from epigenetic to the non- epigenetic mode of action readily depending on meiosis progress. Keywords: oocyte, SIRT1, histone, developmental competence, tubuline, epigenetics
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Analysis of dosage effect of speciation gene Prdm9 on fertility of mouse hybrids
Flachs, Petr ; Trachtulec, Zdeněk (advisor) ; Stopka, Pavel (referee) ; Král, Jiří (referee)
(eng) The phenomenon of hybrid sterility represents one of the evolutionary mechanisms that enables speciation. Only a few speciation genes have been uncovered. The only one found in mammals is Prdm9 (PR-domain 9). Data in the literature on the involvement of Prdm9 in decreased fertility of various semifertile hybrid males of house mouse subspecies were scarce before the results of this thesis were completed, despite that such males are much more frequent in nature than the fully sterile ones. Utilizing a panel of genetic tools and a battery of phenotyping tests, this thesis shows a central role of Prdm9 in fecundity of hybrids, including many fertility disorders and age dependency. Both increasing and reducing the Prdm9 gene dosage significantly elevated fertility parameters. Surprisingly, even the allele that in one copy causes full hybrid sterility increased F1 hybrid fertility when present in multiple copies. The PRDM9 protein also plays a role in identifying the sites of meiotic recombination. This study also points out the principles of allelic competition in determination of the sites of preferred recombination (hotspots), which suggests a possible link between both previously described Prdm9 roles. This thesis summarizes a set of three logically interconnected publications with the ambition...
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Epigenetic regulation of HLA genes asociated with celiac disease
Hudec, Michael ; Černá, Marie (advisor) ; Hušáková, Markéta (referee)
Introduction: HLA class II system presents one of the most important mechanism in immune system, which is able to recognise pathogens and damaged cells. Some HLA class II alleles are associated with autoimmune diseases, for example celiac disease, which is typical by chronic inflammation of small intestine and other following symptoms. The risk HLA class II variants are DQ2 and DQ8. Epigenetic mechanisms that regulates gene expression, especially methylation of cytosine in promoter region of DQ2 and/or DQ8 alleles, could have influence on development of T lymphocytes in the thymus, where T-lymphocytes develop and pass a few stages in, and only the survival clones can be part of function immune system. Aim: The aim of this study is to compare methylation level of promoter regions of HLA DQ2 and DQ8 alleles between celiac patients and healthy controls. Another goal is to compare expression level of DQ2 and DQ8 variants between these two groups. Methods: DNA and RNA were isolated from full blood of two sets of donors. DNA was converted by bisulphite conversion and then amplified by Nested PCR. The PCR product was cloned to bacteria. Than positive colonies were selected. Subsequent methylation analysis was performed. RNA was converted to cDNA by Reverse transcription. Relative expression was analyzed...
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Role of long non-coding RNAs in plants
Klodová, Božena ; Honys, David (advisor) ; Novotný, Marian (referee)
Long non-coding RNAs (lncRNAs) represent a group of transcripts with length greater than 200 nucleotides having low coding potential. It is a group of regulatory ribonucleic acid (RNA) still not fully understood but with significant potential in many biological processes across different species. For animals, many important lncRNA regulators and their roles in a range of events including their involvement in carcinogenic diseases have been reported. However, particular mechanisms of functions are often yet to be discovered. Considering plants, economically important species such as rice, maize or soybean are of particular interest. There are still only several fully annotated transcripts. However, with the constant improvement of sequencing and bioinformatic methods, the importance of lncRNA (for example in pathogen resistance or plant reproduction) becomes clear. This bachelor thesis reviews up-to-date knowledge about lncRNAs and their roles in plants. It also describes the difficulties of lncRNA research and discusses their future potential.
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Reproductive and epigenetic parameters in sperm connected to the disruptive development and early embryo loss.
Flintová, Jennifer ; Hortová, Kateřina (advisor) ; Petelák, Aleš (referee)
DNA methylation, histone modifications and regulation by non-coding RNAs are considered to play vital role in embryonal development and gametogenesis. Epigenetic mechanisms are not only inwardly programmed, but are massively affected by numerous exogenous aspects. Environmetal pollution and unhealthy parental lifestyle are two major factors related to impaired fertility status, abberant embryonal development of progeny. Some altered epigenetic marks can be transmitted to offspring generations, however in some cases these aberrations may be reversed by adequate lifestyle interventions. Since epigenetic regulations and genes responsible for spermatogenesis are conserved among vertebrates, studies based on animal models are highly relevant for understanding mechanisms causing impaired fertility and overall health in humans. Key words: Epigenetics, sperm, endocrine disruptors, hypoxia, lifestyle, transgenerational effect.
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The role of histone post-translational modifications in the regulation of gene expression in plants
Chromý, Jakub ; Čermák, Vojtěch (advisor) ; Holá, Dana (referee)
Chromatin structure, gene expression and consequently many important aspects of the plant development are under control of epigenetic regulation. Within epigenetic regulation, histones and their modifications play a pivotal role. The N-terminal tails of histones are dynamically modified by covalent post-translational modifications (PTMs). These modifications are key regulators modulating chromatin structure and thus regulating gene expression. In angiosperms, one of the processes finely regulated at the epigenetic level is the flowering. Flowering represents a very complex process, that is relevant for the study of epigenetic regulation as well as for practical application. In this work, I summarize current knowledge of the role of histone PTMs in the regulation of gene expression in plants, focused predominantly on two key regulators of flowering in Arabidopsis - FLC and FT.
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