I am a senior scientist working in Genetics, Epigenetics and Biochemistry at the Institute of Molecular Genetics - Czech Academy of Sciences in Prague.
Figure S1 shows male DMC1 hotspot activity in Hstx2 locus. Figure S2 contains examples of <i&g... more Figure S1 shows male DMC1 hotspot activity in Hstx2 locus. Figure S2 contains examples of <i>Fmr1nb</i> expression at mRNA and protein level. Figure S3 shows domain structure of FMR1NB. Figure S4 shows comparison of litter size generated by B6.DX.1s and B6.DX.1s.<i>Fmr1nb<sup>-</sup></i> males. Figure S5 shows comparison of fertility parameters achieved by B6.<i>Fmr1nb</i><sup>-</sup> and B6.DX.1s.<i>Fmr1nb</i><sup>-</sup> males and their wild type counterparts. Figure S6 shows frequency of apoptotic cells in testes of B6.<i>Fmr1nb</i><sup>-</sup> and B6.DX.1s.<i>Fmr1nb</i><sup>-</sup> males. Table S1 contains microsatellite markers used for genotyping the X chromosome. Table S2 contain individual molecules report from DNA samples used for optical maps. Table S3 shows parameters of individual reference assemblies For optical mapping. Table S4 is compose...
Hybrid sterility is a critical step in the evolution of reproductive barriers between diverging t... more Hybrid sterility is a critical step in the evolution of reproductive barriers between diverging taxa during the process of speciation. Recent studies of young subspecies of the house mouse revealed a multigenic nature and frequent polymorphism of hybrid sterility genes as well as the recurrent engagement of the meiosis-specific gene PR domain-containing 9 (Prdm9) and X-linked loci. Prdm9-controlled hybrid sterility is essentially chromosomal in nature, conditioned by the sequence divergence between subspecies. Depending on the Prdm9 interallelic interactions and the X-linked Hstx2 locus, the same homologs either regularly recombine and synapse, or show impaired DNA DSB repair, asynapsis, and early meiotic arrest. Thus, Prdm9-dependent hybrid sterility points to incompatibilities affecting meiotic recombination as a possible mechanism of reproductive isolation between (sub)species.
ABSTRACTF1 hybrids between mouse inbred strains PWD and C57BL/6 represent the most thoroughly gen... more ABSTRACTF1 hybrids between mouse inbred strains PWD and C57BL/6 represent the most thoroughly genetically defined model of hybrid sterility in vertebrates. Hybrid male sterility can be fully reconstituted from three components of this model, namely thePrdm9hybrid sterility gene, intersubspecific homeology ofMus musculus musculusandMus musculus domesticusautosomes, and the X-linkedHstx2locus.Hstx2modulates the extent ofPrdm9-dependent meiotic arrest and harbors two additional genetic factors responsible for intersubspecific introgression-induced oligospermia (Hstx1) and reduced global meiotic recombination rate (Meir1). To facilitate positional cloning and to overcome the recombination suppression within the 4.3 Mb genomicDob interval encompassing theHstx2locus we designedHstx2-CRISPR and SPO11/Cas9 transgenes aimed to induce DNA double-strand breaks specifically within theHstx2locus. The resulting recombinant reduced theHstx2locus to 2.70 Mb (Chr X:66.51-69.21 Mb). The newly defined...
Orderly segregation of chromosomes during meiosis requires that crossovers form between homologou... more Orderly segregation of chromosomes during meiosis requires that crossovers form between homologous chromosomes by recombination. Programmed DNA double-strand breaks (DSBs) initiate meiotic recombination. We identify ANKRD31 as a critical component of complexes of DSB-promoting proteins which assemble on meiotic chromosome axes. Genome-wide, ANKRD31 deficiency causes delayed recombination initiation. In addition, loss of ANKRD31 alters DSB distribution owing to reduced selectivity for sites that normally attract DSBs. Strikingly, ANKRD31 deficiency also abolishes uniquely high rates of recombination that normally characterize pseudoautosomal regions (PARs) of X and Y chromosomes. Consequently, sex chromosomes do not form crossovers leading to chromosome segregation failure in ANKRD31-deficient spermatocytes. These defects are accompanied by a genome-wide delay in assembling DSB-promoting proteins on axes and a loss of a specialized PAR-axis domain that is highly enriched for DSB-prom...
Hybrid sterility is one of the reproductive isolation mechanisms leading to speciation. Prdm9, th... more Hybrid sterility is one of the reproductive isolation mechanisms leading to speciation. Prdm9, the only known vertebrate hybrid-sterility gene, causes failure of meiotic chromosome synapsis and infertility in male hybrids that are the offspring of two mouse subspecies. Within species, Prdm9 determines the sites of programmed DNA double-strand breaks (DSBs) and meiotic recombination hotspots. To investigate the relation between Prdm9-controlled meiotic arrest and asynapsis, we inserted random stretches of consubspecific homology on several autosomal pairs in sterile hybrids, and analyzed their ability to form synaptonemal complexes and to rescue male fertility. Twenty-seven or more megabases of consubspecific (belonging to the same subspecies) homology fully restored synapsis in a given autosomal pair, and we predicted that two or more DSBs within symmetric hotspots per chromosome are necessary for successful meiosis. We hypothesize that impaired recombination between evolutionarily ...
A 5'-enhancer-lacking construct of the mouse MHC class I H-2Kb gene is stimulated by interfer... more A 5'-enhancer-lacking construct of the mouse MHC class I H-2Kb gene is stimulated by interferons in a similar manner as a 5'-enhancer-containing H-2Kb gene. This ability is markedly reduced upon introducing a second deletion removing the first and second intron of the H-2Kb gene. Computational analysis of the deleted stretch reveals the presence of the interferon-stimulated response element (ISRE) in the middle of the second intron. The identified sequence exhibits typical ISRE characteristics in gel retardation experiments. A fragment containing the 5'-enhancer interferon responsive sequence competes effectively in the binding reactions. These results strongly suggest that the second intron of the H-2Kb gene participates in interferon stimulation via the identified ISRE sequence.
Transcription termination by RNA polymerase I (Pol I) is a stepwise process. First the elongating... more Transcription termination by RNA polymerase I (Pol I) is a stepwise process. First the elongating RNA polymerase is forced to pause by DNA-bound transcription termination factor (TTF-I). Then the ternary transcription complex is dissociated by PTRF, a novel factor that promotes release of both nascent transcripts and Pol I from the template. In this study we have investigated the ability
It has recently been proposed that primary mutations in genes involved in fatty acid and lipid me... more It has recently been proposed that primary mutations in genes involved in fatty acid and lipid metabolism may contribute to the pathogenesis of insulin resistance and dyslipidemia often observed in spontaneous forms of hypertension. In the current study in the spontaneously hypertensive rat (SHR), we mapped and sequenced the gene encoding a key transcription factor known as ADD1 (adipocyte determination and differentiation factor 1) or SREBP-1c (sterol regulatory element binding protein- c) that has recently been identified as a master regulator of genes involved in the hepatic control of lipid and carbohydrate metabolism. We found that (1) the gene for ADD1/SREBP-1c maps to a region of rat Chromosome 10 previously reported to contain a quantitative trait locus involved in the regulation of hepatic cholesterol levels and (2) the SHR harbors a valine-to-methionine substitution in the COOH terminal portion of the ADD1/SREBP-1 protein that is not present in 44 other strains of laboratory rats. These findings, together with previous studies showing that transgenic expression of SREBP-1 isoforms has major effects on hepatic fatty acid and cholesterol biosynthesis, suggest that naturally occurring variation in the gene encoding the SREBP-1 isoforms might contribute to inherited variation in lipid metabolism in the SHR versus other strains of rats. These results should serve to motivate future transfection studies of the effect of the SHR mutant on SREBP-1 expression and activation in vitro, as well as the development of congenic and transgenic strains of SHR to investigate the effects of different variants of SREBP-1 on carbohydrate and lipid metabolism in vivo.
Figure S1 shows male DMC1 hotspot activity in Hstx2 locus. Figure S2 contains examples of <i&g... more Figure S1 shows male DMC1 hotspot activity in Hstx2 locus. Figure S2 contains examples of <i>Fmr1nb</i> expression at mRNA and protein level. Figure S3 shows domain structure of FMR1NB. Figure S4 shows comparison of litter size generated by B6.DX.1s and B6.DX.1s.<i>Fmr1nb<sup>-</sup></i> males. Figure S5 shows comparison of fertility parameters achieved by B6.<i>Fmr1nb</i><sup>-</sup> and B6.DX.1s.<i>Fmr1nb</i><sup>-</sup> males and their wild type counterparts. Figure S6 shows frequency of apoptotic cells in testes of B6.<i>Fmr1nb</i><sup>-</sup> and B6.DX.1s.<i>Fmr1nb</i><sup>-</sup> males. Table S1 contains microsatellite markers used for genotyping the X chromosome. Table S2 contain individual molecules report from DNA samples used for optical maps. Table S3 shows parameters of individual reference assemblies For optical mapping. Table S4 is compose...
Hybrid sterility is a critical step in the evolution of reproductive barriers between diverging t... more Hybrid sterility is a critical step in the evolution of reproductive barriers between diverging taxa during the process of speciation. Recent studies of young subspecies of the house mouse revealed a multigenic nature and frequent polymorphism of hybrid sterility genes as well as the recurrent engagement of the meiosis-specific gene PR domain-containing 9 (Prdm9) and X-linked loci. Prdm9-controlled hybrid sterility is essentially chromosomal in nature, conditioned by the sequence divergence between subspecies. Depending on the Prdm9 interallelic interactions and the X-linked Hstx2 locus, the same homologs either regularly recombine and synapse, or show impaired DNA DSB repair, asynapsis, and early meiotic arrest. Thus, Prdm9-dependent hybrid sterility points to incompatibilities affecting meiotic recombination as a possible mechanism of reproductive isolation between (sub)species.
ABSTRACTF1 hybrids between mouse inbred strains PWD and C57BL/6 represent the most thoroughly gen... more ABSTRACTF1 hybrids between mouse inbred strains PWD and C57BL/6 represent the most thoroughly genetically defined model of hybrid sterility in vertebrates. Hybrid male sterility can be fully reconstituted from three components of this model, namely thePrdm9hybrid sterility gene, intersubspecific homeology ofMus musculus musculusandMus musculus domesticusautosomes, and the X-linkedHstx2locus.Hstx2modulates the extent ofPrdm9-dependent meiotic arrest and harbors two additional genetic factors responsible for intersubspecific introgression-induced oligospermia (Hstx1) and reduced global meiotic recombination rate (Meir1). To facilitate positional cloning and to overcome the recombination suppression within the 4.3 Mb genomicDob interval encompassing theHstx2locus we designedHstx2-CRISPR and SPO11/Cas9 transgenes aimed to induce DNA double-strand breaks specifically within theHstx2locus. The resulting recombinant reduced theHstx2locus to 2.70 Mb (Chr X:66.51-69.21 Mb). The newly defined...
Orderly segregation of chromosomes during meiosis requires that crossovers form between homologou... more Orderly segregation of chromosomes during meiosis requires that crossovers form between homologous chromosomes by recombination. Programmed DNA double-strand breaks (DSBs) initiate meiotic recombination. We identify ANKRD31 as a critical component of complexes of DSB-promoting proteins which assemble on meiotic chromosome axes. Genome-wide, ANKRD31 deficiency causes delayed recombination initiation. In addition, loss of ANKRD31 alters DSB distribution owing to reduced selectivity for sites that normally attract DSBs. Strikingly, ANKRD31 deficiency also abolishes uniquely high rates of recombination that normally characterize pseudoautosomal regions (PARs) of X and Y chromosomes. Consequently, sex chromosomes do not form crossovers leading to chromosome segregation failure in ANKRD31-deficient spermatocytes. These defects are accompanied by a genome-wide delay in assembling DSB-promoting proteins on axes and a loss of a specialized PAR-axis domain that is highly enriched for DSB-prom...
Hybrid sterility is one of the reproductive isolation mechanisms leading to speciation. Prdm9, th... more Hybrid sterility is one of the reproductive isolation mechanisms leading to speciation. Prdm9, the only known vertebrate hybrid-sterility gene, causes failure of meiotic chromosome synapsis and infertility in male hybrids that are the offspring of two mouse subspecies. Within species, Prdm9 determines the sites of programmed DNA double-strand breaks (DSBs) and meiotic recombination hotspots. To investigate the relation between Prdm9-controlled meiotic arrest and asynapsis, we inserted random stretches of consubspecific homology on several autosomal pairs in sterile hybrids, and analyzed their ability to form synaptonemal complexes and to rescue male fertility. Twenty-seven or more megabases of consubspecific (belonging to the same subspecies) homology fully restored synapsis in a given autosomal pair, and we predicted that two or more DSBs within symmetric hotspots per chromosome are necessary for successful meiosis. We hypothesize that impaired recombination between evolutionarily ...
A 5'-enhancer-lacking construct of the mouse MHC class I H-2Kb gene is stimulated by interfer... more A 5'-enhancer-lacking construct of the mouse MHC class I H-2Kb gene is stimulated by interferons in a similar manner as a 5'-enhancer-containing H-2Kb gene. This ability is markedly reduced upon introducing a second deletion removing the first and second intron of the H-2Kb gene. Computational analysis of the deleted stretch reveals the presence of the interferon-stimulated response element (ISRE) in the middle of the second intron. The identified sequence exhibits typical ISRE characteristics in gel retardation experiments. A fragment containing the 5'-enhancer interferon responsive sequence competes effectively in the binding reactions. These results strongly suggest that the second intron of the H-2Kb gene participates in interferon stimulation via the identified ISRE sequence.
Transcription termination by RNA polymerase I (Pol I) is a stepwise process. First the elongating... more Transcription termination by RNA polymerase I (Pol I) is a stepwise process. First the elongating RNA polymerase is forced to pause by DNA-bound transcription termination factor (TTF-I). Then the ternary transcription complex is dissociated by PTRF, a novel factor that promotes release of both nascent transcripts and Pol I from the template. In this study we have investigated the ability
It has recently been proposed that primary mutations in genes involved in fatty acid and lipid me... more It has recently been proposed that primary mutations in genes involved in fatty acid and lipid metabolism may contribute to the pathogenesis of insulin resistance and dyslipidemia often observed in spontaneous forms of hypertension. In the current study in the spontaneously hypertensive rat (SHR), we mapped and sequenced the gene encoding a key transcription factor known as ADD1 (adipocyte determination and differentiation factor 1) or SREBP-1c (sterol regulatory element binding protein- c) that has recently been identified as a master regulator of genes involved in the hepatic control of lipid and carbohydrate metabolism. We found that (1) the gene for ADD1/SREBP-1c maps to a region of rat Chromosome 10 previously reported to contain a quantitative trait locus involved in the regulation of hepatic cholesterol levels and (2) the SHR harbors a valine-to-methionine substitution in the COOH terminal portion of the ADD1/SREBP-1 protein that is not present in 44 other strains of laboratory rats. These findings, together with previous studies showing that transgenic expression of SREBP-1 isoforms has major effects on hepatic fatty acid and cholesterol biosynthesis, suggest that naturally occurring variation in the gene encoding the SREBP-1 isoforms might contribute to inherited variation in lipid metabolism in the SHR versus other strains of rats. These results should serve to motivate future transfection studies of the effect of the SHR mutant on SREBP-1 expression and activation in vitro, as well as the development of congenic and transgenic strains of SHR to investigate the effects of different variants of SREBP-1 on carbohydrate and lipid metabolism in vivo.
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Papers by Petr Jansa