PRC2 represses transcribed genes on the imprinted inactive X chromosome in mice

Abstract Background Polycomb repressive complex 2 (PRC2) catalyzes histone H3K27me3, which marks many transcriptionally silent genes throughout the mammalian genome. Although H3K27me3 is associated with silenced gene expression broadly, it remains unclear why some but not other PRC2 target genes require PRC2 and H3K27me3 for silencing. Results Here we define the transcriptional and chromatin features that predict which PRC2 target genes require PRC2/H3K27me3 for silencing by interrogating imprinted mouse X-chromosome inactivation. H3K27me3 is enriched at promoters of silenced genes across the inactive X chromosome. To abrogate PRC2 function, we delete the core PRC2 protein EED in F1 hybrid trophoblast stem cells (TSCs), which undergo imprinted inactivation of the paternally inherited X chromosome. Eed –/– TSCs lack H3K27me3 and Xist lncRNA enrichment on the inactive X chromosome. Despite the absence of H3K27me3 and Xist RNA, only a subset of the inactivated X-linked genes is derepressed in Eed –/– TSCs. Unexpectedly, in wild-type (WT) TSCs these genes are transcribed and are enriched for active chromatin hallmarks on the inactive-X, including RNA PolII, H3K27ac, and H3K36me3, but not the bivalent mark H3K4me2. By contrast, PRC2 targets that remain repressed in Eed –/– TSCs are depleted for active chromatin characteristics in WT TSCs. Conclusions A comparative analysis of transcriptional and chromatin features of inactive X-linked genes in WT and Eed –/– TSCs suggests that PRC2 acts as a brake to prevent induction of transcribed genes on the inactive X chromosome, a mode of PRC2 function that may apply broadly.https://deepblue.lib.umich.edu/bitstream/2027.42/136651/1/13059_2017_Article_1211.pd

Differentiation-dependent Requirement of Tsix long non-coding RNA in Imprinted X-chromosome Inactivation

Imprinted X-inactivation is a paradigm of mammalian transgenerational epigenetic regulation resulting in silencing of genes on the paternally-inherited X-chromosome. The pre-programmed fate of the X-chromosomes is thought to be controlled in cis by the parent-of-origin-specific expression of two long non-coding RNAs, Tsix and Xist, in mice. Exclusive expression of Tsix from the maternal–X has implicated it as the instrument through which the maternal germline prevents inactivation of the maternal–X in the offspring. Here, we show that Tsix is dispensable for inhibiting Xist and X-inactivation in the early embryo and in cultured stem cells of extra-embryonic lineages. Tsix is instead required to prevent Xist expression as trophectodermal progenitor cells differentiate. Despite induction of wild-type Xist RNA and accumulation of histone H3-K27me3, many Tsix-mutant X-chromosomes fail to undergo ectopic X-inactivation. We propose a novel model of lncRNA function in imprinted X-inactivation that may also apply to other genomically imprinted loci

Data Throughput of Wireless Network for Fire Alarms

Import 22/07/2015Tato bakalářská práce se zabývá ostravskou hasičskou sítí, propustností, rušením a návrhem na vylepšení sítě z hlediska datové propustnosti. Analýza datové propustnosti byla provedena pomoci vlastního programu napsaného v C#. Pomocí USB tuneru Rafael Micro R820T s čipsetem RTL2832U a počítačem s operačním systémem Ubuntu 14.04, na kterém byly nainstalován software Librtlsdr, GNU radio GQRX , Teamviewer a Kazam. Těmito programy byly sledovány vstupní kmitočty převaděčů, které neodhalily žádné rušení. Dále byly vypsány možné vlivy teoretického rušení. Následně byly vymyšleny dvě teoreticky zlepšené varianty systému. První se zabývá obousměrným přenosem, kdy koncové vysílače přijímají zprávu o potvrzení přijetí z převaděče a druhá přidáním dalšího převaděče, který by se při správném umístění, které by bylo na výškové budově domova sester. Hlavní výhodou tohoto řešení je větší pokrytí oblasti. Oba tyto návrhy mají lepší vlastnosti v oblasti datové propustnosti.The bachelor thesis deals with the fire-fighting net in Ostrava, it's permeability, disturbance and improvement proposal for this net from the point of view of data permeability. Analysis of data permeability was made by own programme wrote in C#. Disturbance was watched by USB tuner Rafael Micro R820T with chipset RTL2832U and with computer with operating system Ubuntu 14.04. On Ubuntu was install a software Librtlsdr, GNU radio GQRX, Teamviewer and Kazam. But the disturbance was not found. The list of the theroretical influences on disturbance was made. Two theoretical better options were invented. The first one deals with two-way transfer and the second one proposes additional convertor. These suggestions have better properties in the field of data permeability.440 - Katedra telekomunikační technikydobř

Thorough assessment of DNA preservation from fossil bone and sediments excavated from a late Pleistocenee-Holocene cave deposit on Kangaroo Island, South Australia

Fossils and sediments preserved in caves are an excellent source of information for investigating impacts of past environmental changes on biodiversity. Until recently studies have relied on morphology-based palaeontological approaches, but recent advances in molecular analytical methods offer excellent potential for extracting a greater array of biological information from these sites. This study presents a thorough assessment of DNA preservation from late Pleistocene-Holocene vertebrate fossils and sediments from Kelly Hill Cave Kangaroo Island, South Australia. Using a combination of extraction techniques and sequencing technologies, ancient DNA was characterised from over 70 bones and 20 sediment samples from 15 stratigraphic layers ranging in age from >20 ka to ~6.8 ka. A combination of primers targeting marsupial and placental mammals, reptiles and two universal plant primers were used to reveal genetic biodiversity for comparison with the mainland and with the morphological fossil record for Kelly Hill Cave. We demonstrate that Kelly Hill Cave has excellent long-term DNA preservation, back to at least 20 ka. This contrasts with the majority of Australian cave sites thus far explored for ancient DNA preservation, and highlights the great promise Kangaroo Island caves hold for yielding the hitherto-elusive DNA of extinct Australian Pleistocene species

An Analysis of Polycomb Repressive Complex 2 Function Through Imprinted Mouse X-chromosome Inactivation.

Abstract Polycomb proteins comprise two major classes of evolutionarily conserved epigenetic transcription repressors, Polycomb repressive complex 2 and 1 (PRC2 and PRC1). PRCs are thought to catalyze epigenetic silencing via histone modifications and/or physical compaction of the surrounding chromatin. The inactive X-chromosome is a common target of PRCs. X-chromosome inactivation is a paradigmatic epigenetic phenomenon resulting in the equal expression of genes from the X-chromosome between XY male and XX female mammals. The initial form of X-inactivation during murine embryogenesis is imprinted X-inactivation, during which the paternally inherited X-chromosome is preferentially silenced. In my thesis work, I tested the hypothesis that PRC2 proteins orchestrate gene silencing on the paternal X-chromosome during imprinted X-inactivation. To test if PRC2 subunits are required to propagate the X-inactive state, I derived and investigated X-linked gene silencing in mouse trophoblast stem cells (TSCs), an ex vivo model of imprinted X-inactivation. In TSCs lacking the core PRC2 proteins EZH2 and its homologue EZH1, which catalyze trimethylation of histone H3 at lysine 27 (H3-K27me3), I found that X-inactivation was unperturbed. In TSCs lacking EED, which is required for the assembly of PRC2, I found that imprinted X-inactivation was defective. In Eed-/- TSCs, enrichment of H3-K27me3 and the Xist long non-coding RNA, which is required for stable X-inactivation, are lost from the inactive-X. Despite the absence of H3-K27me3 and Xist RNA, only a subset of the genes on the inactive X-chromosome is reactivated in Eed-/- TSCs. Lack of a silencing defect for a majority of X-linked genes in Eed-/- TSCs suggests that factors other than EED, H3-K27me3, and Xist RNA are essential for propagating X-chromosome inactivation. To assess if my findings from TSCs applied in vivo, I generated embryos lacking maternal and zygotic EZH2, or EZH2 and 1, or EED. I discovered that EED, but not EZH2/1, is necessary to trigger imprinted X-inactivation in the embryo. This comparative analysis of PRC2 components suggests a PRC2 independent role for EED in imprinted X-inactivation. Moreover, these results are the initial demonstration that maternal factors control the silencing of the X-chromosome in the embryo, an example of a transgenerational epigenetic regulation.PhDHuman GeneticsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/133519/1/mirihi_1.pd

A Primary Role for the Tsix lncRNA in Maintaining Random X-Chromosome Inactivation

Differentiating pluripotent epiblast cells in eutherians undergo random X-inactivation, which equalizes X-linked gene expression between the sexes by silencing one of the two X-chromosomes in females. Tsix RNA is believed to orchestrate the initiation of X-inactivation, influencing the choice of which X remains active by preventing expression of the antisense Xist RNA, which is required to silence the inactive-X. Here we profile X-chromosome activity in Tsix-mutant (XΔTsix) mouse embryonic epiblasts, epiblast stem cells, and embryonic stem cells. Unexpectedly, we find that Xist is stably repressed on the XΔTsix in both sexes in undifferentiated epiblast cells in vivo and in vitro, resulting in stochastic X-inactivation in females despite Tsix-heterozygosity. Tsix is instead required to silence Xist on the active-X as epiblast cells differentiate in both males and females. Thus, Tsix is not required at the onset of random X-inactivation; instead, it protects the active-X from ectopic silencing once X-inactivation has commenced