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Meiotic effect of MutS homolog 6 (Msh6) mutation in two mouse subspecies
Fusek, Karel ; Forejt, Jiří (advisor) ; Reifová, Radka (referee)
To study hybrid sterility our laboratory uses mouse strains PWD/Ph (PWD), derived from Mus musculus musculus wild mice and the common laboratory strain C57BL/6J (B6) mostly of Mus musculus domesticus origin as a model. Crossing between PWD female and B6 male results in sterile male progeny. F1 hybrid males carry defects in the repair mechanisms of asymmetric double-strand DNA breaks (DSBs). Functional interplay of SPO11 and PRDM9 proteins in the meiotic prophase I is necessary for repairs. Its defect leads to incorrect synapse formation between homologous chromosomes, leading to halt in spermatogenesis and thus male sterility. The formation of DSBs and their subsequent repair is essential for first meiotic division. The working hypothesis stems from the findings in yeast model, where supposed antirecombinatorial mechanism of mismatch repair genes Msh6 and Msh2 prevents DSBs repairs during meiosis. Despite the functional mechanism of these two genes is not explicitly known, existence of similar repair system in mice is presumed. Variety of methods was implemented in this thesis. The effects of Msh6 deletion on meiotic prophase I and sperm maturation were performed by designing guide RNAs for CRISPR/Cas9 for creation of three knock-outs in B6 mice. The PCR was used to amplify regions adjacent to the...
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Gene order in eukaryotic genomes: an analysis using sequence-based gene expression data
Divina, Petr ; Forejt, Jiří (advisor) ; Pačes, Jan (referee) ; Mokrejš, Martin (referee)
ZÁVĚRY 61 6. ZÁVĚRY 6.1. Analýza genů exprimovaných v myším varleti a jejich uspořádání v genomu Pomocí expresního profilování metodou SAGE (sériová analýza genové exprese) byl vytvořen katalog genů exprimovaných ve varleti dospělých myší. Byly identifikovány poziční klastry genů na chromosomech obsahující geny s preferenční expresí ve varleti. Tyto klastry obsahovaly signifikantně vyšší počet genů než v náhodně vygenerovaných genomech. Geny specificky exprimované v somatických buňkách myšího varlete byly signifikantně obohacené na chromosomu X, což podporuje teorii o hromadění genů preferenčně exprimovaných v samčích tkáních na chromosomu X. Geny exprimované z chromosomu X byly ochuzené v transkriptomu celého myšího varlete, což je v souladu s představou o inaktivaci chromosomu X během prvního meiotického dělení. Byla vytvořena veřejně přístupná internetová databáze Mouse SAGE Site, která shromažďuje expresní data z myších tkání a buněčných liniích vytvořená pomocí metody SAGE. 6.2. Genový obsah chromosomu Z kura domácího Chromosom Z kura domácího byl signifikantně obohacený o geny preferenčně exprimované v samčím mozku. ZÁVĚRY 62 Geny s preferenční expresí v samičím mozku vykazovaly náznak ochuzení na chromosomu Z. Podobně, geny specificky exprimované ve vaječnících byly na chromosomu Z...
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DNA Microarrays and Bioinformatics in Biomedical Research
Ivánek, Robert ; Forejt, Jiří (advisor) ; Martásek, Pavel (referee) ; Beneš, Ivan (referee)
Abstr€gt DNA microanays ť€present a relatively novel tecbnique for qualitative and quartitative analysis of nucleic acids. In various modificďions tbis tecbniqueďows expressionmalysis' comparative genomic Mridizatiotr, micronNe profiling, analysis of geire regulation md deteďon ďpolymorpbism or mutations.In this thesisI presentan overview ďvarious types of microarays and theř applióations in biomedical reserch. I documett their usefulnessful severalprojecb aimedatidentificatioaof diseasecausinggenes(Mucopolysaoetaidosis lII€, ATP syntbasedefieielrcy),at moleculaÍchaae*erizatim ď h'man disws using cell lines (clear cell renal carcinoma,acutemyeloid leukaenia) or meute modďs (meiotic ďlonoiug of unsynapsedcbronatin). My work de'monsbtes that oompetentapplication of microarray techiqge4. bve pobqtiel to speed rrp biomedicď re"searcáod already bocane one of its frrndmental analyticalapproaches. ' t
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Meiotic effect of MutS homolog 6 (Msh6) mutation in two mouse subspecies
Fusek, Karel ; Forejt, Jiří (advisor) ; Reifová, Radka (referee)
To study hybrid sterility our laboratory uses mouse strains PWD/Ph (PWD), derived from Mus musculus musculus wild mice and the common laboratory strain C57BL/6J (B6) mostly of Mus musculus domesticus origin as a model. Crossing between PWD female and B6 male results in sterile male progeny. F1 hybrid males carry defects in the repair mechanisms of asymmetric double-strand DNA breaks (DSBs). Functional interplay of SPO11 and PRDM9 proteins in the meiotic prophase I is necessary for repairs. Its defect leads to incorrect synapse formation between homologous chromosomes, leading to halt in spermatogenesis and thus male sterility. The formation of DSBs and their subsequent repair is essential for first meiotic division. The working hypothesis stems from the findings in yeast model, where supposed antirecombinatorial mechanism of mismatch repair genes Msh6 and Msh2 prevents DSBs repairs during meiosis. Despite the functional mechanism of these two genes is not explicitly known, existence of similar repair system in mice is presumed. Variety of methods was implemented in this thesis. The effects of Msh6 deletion on meiotic prophase I and sperm maturation were performed by designing guide RNAs for CRISPR/Cas9 for creation of three knock-outs in B6 mice. The PCR was used to amplify regions adjacent to the...
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Genomic architecture and molecular mechanisms of hybrid sterility in mice.
Vališková, Barbora ; Forejt, Jiří (advisor) ; Janko, Karel (referee) ; Macholán, Miloš (referee)
Hybrid sterility is one of the reproductive isolation mechanisms restricting gene flow between the related species and leading to speciation. PR domain containing 9 (Prdm9), the only known vertebrate hybrid sterility gene, determines the sites of programmed DNA double-strand breaks (DSBs) and thus specifies hotspots of meiotic recombination but in hybrids between two mouse subspecies causes failure of meiotic chromosome synapsis and hybrid male sterility. In the present study on sterile hybrids, the five smallest autosomes were more prone to asynapsis. To manipulate with the synapsis rate, random stretches of consubspecific homology were inserted into several autosomal pairs. Twenty seven or more megabases of consubspecific sequence fully restore synapsis in a given autosome. Further, at least two symetric DN double-strand breaks per chromosome were necessary for successful synapsis. Moreover, F1 hybrids had sperm when synapsis was rescued in at least three of four segregating chromosomes. To verify the assumption of a lack of symmetric DSBs in meiotic chromosomes of sterile males the chemotherapeutic drug cisplatin was used to induce exogenous DNA DSBs. Cells treated with 5 mg/kg and 10 mg/kg of cisplatin showed increased number of DSBs monitored by immunostaining of RPA and DMC1 sites and...
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Meiotic homologous recombination and hybrid sterility
Gergelits, Václav ; Forejt, Jiří (advisor) ; Macholán, Miloš (referee) ; Munclinger, Pavel (referee)
(English) Meiotic homologous recombination, homologous chromosomes synapsis, and F1 hybrid sterility (enabling formation of species) are mutually interconnected phenomenons, one being the prerequisite to the latter. In the present thesis, these phenomenons were investigated on a genetic and mechanistic level using a mouse subspecies as a model. Noncrossovers (NCOs, gene conversions), 90% prevalent resolution of Prdm9- determined meiotic double-strand breaks (DSBs), were uniquely identified and characterized on a chromosome-wide level. The mean gene conversion tract length, based on 94 NCOs events, was calculated to be 32 bp. On a local level, the NCOs overlapped the known hotspots of PRDM9-controlled histone trimethylation and DSB formation, indicating their origin in the standard meiotic DSB repair pathway. On chromosome-wide level, NCO and CO distributions differed, in particular COs being relatively preferred over NCOs in subtelomeric regions. A specific subset of nonparental/asymmetric NCOs and COs was underrepresented in our datasets, proposing their problematic repair, hypothetically enabled by sister chromatids, and thus not contributing to indispensable homologous synapsis. Genome-wide crossover (CO) rates, genetically and mechanistically crucial ~10% of DSB repair, were proven to be...
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