Cytogenetic analysis on Sanzinia and Acrantophis
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PROVIDER: PRJEB31505 | ENA |
REPOSITORIES: ENA
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Project description:The centromere-specific Histone H3-variant CENH3 (also known as CENP-A) is considered to be an epigenetic mark for establishment and propagation of centromere identity. Pulse-induction of CENH3 (Drosophila CID) in Schneider S2 cells incorporates into noncentromeric regions and generates CID islands that resist clearing from chromosome arms for multiple cell generations. We demonstrate that CID islands represent functional ectopic kinetochores, which are non-randomly distributed on the chromosome and display a preferential localization near telomeres and pericentric heterochromatin in transcriptionally silent, intergenic chromatin domains. Although overexpression of heterochromatin protein 1 (HP1) or increasing Histone acetylation interferes with CID islands formation on a global scale, induction of a locally defined region of synthetic heterochromatin by targeting HP1-LacI fusions to stably integrated Lac Operator arrays produces a proximal hotspot for CID islands formation. These data suggest that the characteristics of regions bordering heterochromatin promote de novo kinetochore assembly and thereby contribute to centromere identity.
2011-07-15 | E-MTAB-652 | biostudies-arrayexpress
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Project description:Long non-coding RNAs are involved in dosage compensation both in mammals and in Drosophila by inducing changes in the X-chromosome chromatin structure. In Drosophila melanogaster, roX1 and roX2 are long non-coding RNAs that together with proteins form the male-specific lethal (MSL) complex, which coats the entire male X-chromosome and mediates dosage compensation by increased transcriptional output. It has been shown that in polytene chromosomes, in absence of both roX1 and roX2, the MSL-complex is decreased on the male X-chromosome and found relocated to the chromocenter, and the 4th chromosome. Here we address the role of roX RNAs in MSL-complex targeting and in the evolution of dosage compensation in Drosophila. We performed ChIP-seq experiments and show that MSL-complex recruitment to high affinity sites (HAS) on the X-chromosome is independent on roX and that the HAS sequence motif is conserved in D. simulans. Additionally, a complete and enzymatically active MSL-complex is recruited to six specific genes on the 4th chromosome. Interestingly, our sequence analysis shows that in the absence of roX RNAs, the MSL-complex has affinity to regions enriched in Hoppel transposable elements and to repeats in general. We hypothesize that roX mutants reveal an ancient targeting of the MSL-complex and propose that the role of roX RNAs is to restrict MSL-complex from binding to heterochromatin.
2014-11-07 | GSE58768 | GEO
Project description:X chromosome inactivation (XCI) in female lymphocytes is uniquely regulated, as the inactive X (Xi) chromosome lacks localized Xist RNA and heterochromatin modifications. Epigenetic profiling reveals that Xist RNA is lost from the Xi at the pro-B cell stage and that additional heterochromatic modifications are gradually lost during B cell development. Activation of mature B cells restores Xist RNA and heterochromatin to the Xi in a dynamic two-step process that differs in timing and pattern, depending on the method of B cell stimulation. Finally, we find that DNA binding by YY1 maintains XCI in activated B cells, as ex-vivo YY1 deletion results in loss of Xi heterochromatin marks and up-regulation of X-linked genes. Ectopic expression of the YY1 zinc finger domain is sufficient for Xist RNA localization during B cell activation. Together, our results indicate that Xist RNA localization is critical for maintaining XCI in female lymphocytes, and that chromatin changes on the Xi during B cell development and the dynamic nature of YY1-dependent XCI maintenance in mature B cells predisposes X- linked immunity genes to reactivation.
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Project description:Frogs are an ecologically diverse and phylogenetically ancient group of anuran amphibians that include important vertebrate cell and developmental model systems, notably the genus Xenopus. Here we report a high-quality reference genome sequence for the western clawed frog, Xenopus tropicalis, along with draft chromosome-scale sequences of three distantly related emerging model frog species, Eleutherodactylus coqui, Engystomops pustulosus and Hymenochirus boettgeri. Frog chromosomes have remained remarkably stable since the Mesozoic Era, with limited Robertsonian (i.e., centric) translocations and end-to-end fusions found among the smaller chromosomes. Conservation of synteny includes conservation of centromere locations, marked by centromeric tandem repeats associated with Cenp-a binding, surrounded by pericentromeric LINE/L1 elements. We explored chromosome structure across frogs, using a dense meiotic linkage map for X. tropicalis and chromatin conformation capture (Hi-C) data for all species. Abundant satellite repeats occupy the unusually long (~20 megabase) terminal regions of each chromosome that coincide with high rates of recombination. Both embryonic and differentiated cells show reproducible association of centromeric chromatin, and of telomeres, reflecting a Rabl-like configuration. Our comparative analyses reveal 13 conserved ancestral anuran chromosomes from which contemporary frog genomes were constructed.
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Project description:Analyses of ancient DNA typically involve sequencing the surviving short oligonucleotides, and aligning to genome assemblies from related, modern species. Here, we report that skin from a female woolly mammoth (†Mammuthus primigenius) which died 52,000 years ago retained its ancient genome architecture. We use PaleoHi-C to map chromatin contacts and assemble its genome, yielding twenty-eight chromosome-length scaffolds. Chromosome territories, compartments, loops, Barr bodies, and inactive-X chromosome (Xi) superdomains persist. The active and inactive genome compartments in mammoth skin more closely resemble Asian elephant skin than other elephant tissues. Our analyses uncover new biology. Differences in compartmentalization reveal genes whose transcription was potentially altered in mammoths vs. elephants. Mammoth Xi has a tetradic architecture, not bipartite like human and mouse. We hypothesize that, shortly after this mammoth’s death, the sample spontaneously freeze-dried in the Siberian cold, leading to a glass transition that preserved subfossils of ancient chromosomes at nanometer scale.
2024-05-22 | GSE268050 | GEO
Project description:Linguistic and cultural evidence suggests that Madagascar was the final point of two major dispersals of Austronesian and Bantu speaking populations. Today, Mikea are described as the last known Malagasy population reported to be still practising a hunter-gatherer life-style. It is unclear, however, whether Mikea descend from a remnant population that existed before the arrival of Austronesian and Bantu agriculturalists or whether it is only their life-style that separates them from the other contemporary populations of South Madagascar. In order to address these questions we have performed a genome wide analysis of >700,000 SNP markers on 21 Mikea, 24 Vezo and 24 Temoro individuals together with 50 individuals from Bajo and Lebbo populations from Indonesia. Our analyses of these data in the context of data available from other Southeast Asian and African populations reveal that all three Malagasy populations are derived from the same admixture event involving Austronesian and Bantu sources. In contrast to the fact that most of the vocabulary of the Malagasy speakers is derived from the Barito group of the Austronesian language family we observe that only one third of their genetic ancestry is related to the populations of Java-Kalimantan-Sulawesi area. Because no additional ancestry components distinctive to for the Mikea were found, it is likely that they have adopted their hunter-gatherer way of life by through cultural reversion.
2013-12-19 | GSE53445 | GEO
Project description:The centromere-specific Histone H3-variant CENH3 (also known as CENP-A) is considered to be an epigenetic mark for establishment and propagation of centromere identity. Pulse-induction of CENH3 (Drosophila CID) in Schneider S2 cells incorporates into noncentromeric regions and generates CID islands that resist clearing from chromosome arms for multiple cell generations. We demonstrate that CID islands represent functional ectopic kinetochores, which are non-randomly distributed on the chromosome and display a preferential localization near telomeres and pericentric heterochromatin in transcriptionally silent, intergenic chromatin domains. Although overexpression of heterochromatin protein 1 (HP1) or increasing Histone acetylation interferes with CID islands formation on a global scale, induction of a locally defined region of synthetic heterochromatin by targeting HP1-LacI fusions to stably integrated Lac Operator arrays produces a proximal hotspot for CID islands formation. These data suggest that the characteristics of regions bordering heterochromatin promote de novo kinetochore assembly and thereby contribute to centromere identity. ArrayExpress Release Date: 2011-07-15 Person Roles: submitter Person Last Name: Diehl Person First Name: Sarah Person Mid Initials: Person Email: diehl@immunbio.mpg.de Person Phone: (+49) 761 5108 795 Person Address: Stuebeweg 51, 79108 Freiburg im Breisgau, Germany Person Affiliation: Max-Planck-Institute for Immunobiology and Epigenetics Person Roles: investigator Person Last Name: Heun Person First Name: Patrick Person Mid Initials: Person Email: heun@immunbio.mpg.de Person Phone: (+49) 761 5108 717 Person Address: Stuebeweg 51, 79108 Freiburg im Breisgau, Germany Person Affiliation: Max-Planck-Institute for Immunobiology and Epigenetics Publication Title: Heterochromatin boundaries are hotspots for de novo kinetochore formation. Publication Author List: Agata Olszak, Dominic van Essen, Antonio J. Pereira, Sarah Diehl, Thomas Manke, Helder Maiato, Simona Saccani and Patrick Heun
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