Ontology highlight
ABSTRACT:
PROVIDER: PRJNA556108 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR9733594_1.fastq.gz | Fastqsanger.gz | |||
| SRR9733594_2.fastq.gz | Fastqsanger.gz | |||
| SRR9733595_1.fastq.gz | Fastqsanger.gz | |||
| SRR9733595_2.fastq.gz | Fastqsanger.gz | |||
| SRR9733596_1.fastq.gz | Fastqsanger.gz |
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Similar Datasets
Project description:Transposable elements employ distinct integration strategies with respect to transcriptional landscapes in eukaryotic genomes
| PRJNA611566 | ENA
Project description:Transposable elements are entangled in a constant evolutionary arms race with their host genomes, constantly evolving ways to evade host silencing mechanisms. One silencing mechanism used by many distantly related eukaryotes is dependent on cytosine methylation, an epigenetic mark deposited by C5 cytosine methyltransferases (CMTs). Therefore, it is expected transposable elements would acquire mechanisms to escape from being targeted by cytosine methylation. Here we report how two distantly related eukaryotic lineages have incorporated CMTs into the coding regions of distinct retrotransposon classes. Three of these events have occurred in the dinoflagellates of the genus Symbiodinium, where these CMT-encoding retrotransposons show hundreds of insertions. In a case of convergent evolution, the charophyte Klebsormidium nitens shows an independent expansion of CMT encoding retrotransposons. Concomitantly, we find that Symbiodinium genomes show cytosine methylation patterns unlike any other eukaryote with most of the genome hypermethylated in CpGs, while targeted CH methylation accumulates on transposable elements. Similarly, K. nitens shows CHH and CHG targeted methylation on repressed transposable elements, while CpG methylation is concentrated in gene bodies and transposable elements. Furthermore, we demonstrate the ability of retrotransposon CMTs to de novo methylate CpGs, indicating a putative role in mimicking retrotranscribed DNA as host active genomic DNA. Our results show an unprecedented example of how retrotransposons incorporate host-derived genes involved in DNA methylation as a source of adaptation to their host epigenomic environments.
2018-04-11 | GSE104474 | GEO
Project description:In organisms ranging from vertebrates to plants, major components of centromeres are rapidly-evolving repeat sequences, such as tandem repeats (TRs) and transposable elements (TEs). These repeats harbor centromere-specific histone H3 (CENH3), which also evolves rapidly. Complete centromere structures recently determined in human and Arabidopsis suggest frequent integration and purging of retrotransposons within the TR regions of centromeres. Despite the high impact of “centrophilic” retrotransposons on the paradox of rapid centromere evolution, the mechanisms involved in centromere targeting remain poorly understood in any organism. Here we show that both Ty3 and Ty1/Copia LTR elements rapidly turnover within the centromeric TRs of Arabidopsis species. We demonstrate that the Ty1/Copia element Tal1 (Transposon of Arabidopsis lyrata 1) integrates de novo into regions occupied by CENH3 in A. thaliana, and that ectopic expansion of the CENH3 region results in spread of Tal1 integration regions. The integration spectra of chimeric TEs revealed the key structural variations responsible for the contrasting chromatin targeting specificities to centromeres versus gene-rich regions, which have recurrently converted during the evolution of these TEs. Our findings reveal the impact of centromeric chromatin on TE-mediated rapid centromere evolution, with relevance across eukaryotic genomes.
2024-08-08 | GSE263225 | GEO
Project description:In organisms ranging from vertebrates to plants, major components of centromeres are rapidly-evolving repeat sequences, such as tandem repeats (TRs) and transposable elements (TEs). These repeats harbor centromere-specific histone H3 (CENH3), which also evolves rapidly. Complete centromere structures recently determined in human and Arabidopsis suggest frequent integration and purging of retrotransposons within the TR regions of centromeres. Despite the high impact of “centrophilic” retrotransposons on the paradox of rapid centromere evolution, the mechanisms involved in centromere targeting remain poorly understood in any organism. Here we show that both Ty3 and Ty1/Copia LTR elements rapidly turnover within the centromeric TRs of Arabidopsis species. We demonstrate that the Ty1/Copia element Tal1 (Transposon of Arabidopsis lyrata 1) integrates de novo into regions occupied by CENH3 in A. thaliana, and that ectopic expansion of the CENH3 region results in spread of Tal1 integration regions. The integration spectra of chimeric TEs revealed the key structural variations responsible for the contrasting chromatin targeting specificities to centromeres versus gene-rich regions, which have recurrently converted during the evolution of these TEs. Our findings reveal the impact of centromeric chromatin on TE-mediated rapid centromere evolution, with relevance across eukaryotic genomes.
2024-08-08 | GSE263224 | GEO
Project description:Sugarcane is an important crop worldwide for sugar production and increasingly, as a renewable energy source. Modern cultivars have polyploid, large complex genomes, with highly unequal contributions from ancestral genomes. Long Terminal Repeat retrotransposons (LTR-RTs) are the single largest components of most plant genomes and can substantially impact the genome in many ways. It is therefore crucial to understand their contribution to the genome and transcriptome, however a detailed study of LTR-RTs in sugarcane has not been previously carried out. Sixty complete LTR-RT elements were classified into 35 families within four Copia and three Gypsy lineages. Structurally, within lineages elements were similar, between lineages there were large size differences. Four distinct patterns were observed in sRNA mapping, the most unusual of which was that of Ale1, with very large numbers of 24nt sRNAs in the coding region. The results presented support the conclusion that distinct small RNA-regulated pathways in sugarcane target the lineages of LTR-RT elements. Individual LTR-RT sugarcane families have distinct structures, and transcriptional and regulatory signatures. Our results indicate that in sugarcane individual LTR-RT families have distinct behaviors and can potentially impact the genome in diverse ways. For instance, these transposable elements may affect nearby genes by generating a diverse set of small RNA's that trigger gene silencing mechanisms. There is also some evidence that ancestral genomes contribute significantly different element numbers from particular LTR-RT lineages to the modern sugarcane cultivar genome. Examination of small RNA populations in the sugarcane leaves that show matches against sugarcane LTR-RTs.
2012-04-16 | E-GEOD-35143 | biostudies-arrayexpress
Project description:Transposable elements comprise a large proportion of animal genomes. Transcripts of transposable elements are a source for the synthesis of endogenous siRNAs and piRNAs. In order to determine if small RNAs mapped to expressed Tc1-like elements are present during early Xenopus tropicalis development, we used Illumina (Solexa) to sequence small RNAs from gastrula-stage embryos. We obtained about 17 million reads that mapped perfectly to the genome. Small RNAs mapped to selected transposable elements were characterized and the expression of selected small RNAs was experimentally verified during development. This is the first deep sequencing experiment for small RNAs in the Xenopus tropicalis gastrula. Analysis of small RNAs expressed in the Xenopus tropicalis gastrula.
2011-06-18 | E-GEOD-30067 | biostudies-arrayexpress
Project description:Eukaryotic cytosine methylation represses transposable elements, but also occurs in bodies of active genes. The extent to which these processes are conserved is unclear, and little is known about methylation outside of mammals, Arabidopsis thaliana, and Neurospora crassa. Utilizing deep bisulfite sequencing, we have quantified DNA methylation in five plant, seven animal, and five fungal genomes. We find that gene body methylation is conserved between plants and animals, whereas selective methylation of transposons has evolved independently in the vertebrate lineage. We show that methylation of plant transposons in the CHG context extends to green algae, and present evidence for RNA-directed DNA methylation of fungal genes. We also show that antagonism between DNA methylation and histone H2A.Z is conserved between plants and animals. Our data demonstrate that extant DNA methylation systems are mosaics of conserved and derived features, and indicate that gene body methylation is an ancient property of eukaryotic genomes. Keywords: Epigenetics Examination of DNA methylation and transcription in plant, animal, and fungal genomes, and examination of how H2A.Z deposition relates to both methylation and transcription in puffer fish. Descriptions of the Samples' raw and processed data (provided as supplementary files) can be found in GSE19824_README.txt at the foot of this record.
2010-04-15 | E-GEOD-19824 | biostudies-arrayexpress
Project description:RNAi, a gene-silencing pathway triggered by double-stranded RNA, is conserved in diverse eukaryotic species but has been lost in the model budding yeast, Saccharomyces cerevisiae. We report that RNAi is present in other budding-yeast species, including Saccharomyces castellii and Candida albicans. These species use noncanonical Dicer proteins to generate siRNAs, which mostly correspond to transposable elements and YM-BM-4 subtelomeric repeats. In S. castellii, RNAi mutants are viable but have excess YM-BM-4 mRNA levels. In S. cerevisiae, introducing Dicer and Argonaute of S. castellii restores RNAi, and the reconstituted pathway silences endogenous retrotransposons. These results identify a novel class of Dicer proteins, bring the tool of RNAi to the study of budding yeasts, and bring the tools of budding yeast to the study of RNAi. Employ high-throughput sequencing of endogenous small RNAs from the budding yeasts Saccharomyces castellii, Kluyveromyces polysporus, Candida albicans, Saccharomyces cerevisiae, and Saccharomyces bayanus.
2009-09-10 | E-GEOD-17871 | biostudies-arrayexpress
Project description:Transposable elements have the potential to act as controlling elements to influence the expression of genes. The current paradigm suggests that heterochromatic silencing can spread beyond the borders of the transposable element and influence the chromatin state of neighboring low-copy sequences. This would allow transposable elements to condition obligatory or facilitated epialleles and act as controlling elements. The maize genome contains numerous families of class I transposable elements (retrotransposons) that are present in moderate to high copy numbers and many are found in regions near genes which provides an opportunity to test whether the spreading of heterochromatin from retrotransposons is prevalent. We have investigated the extent of heterochromatin spreading into flanking DNA around each family of retrotransposons through profiling of DNA methylation and di-methylation of lysine 9 of histone 3 (H3K9me2) in low-copy regions of the maize genome. The effects of different retrotransposon families on local chromatin are highly variable. Some LTR families exhibit enrichment of heterochromatic marks within 800-1200 base pairs of the insertion site while other families have very little evidence for spreading of heterochromatic marks. The analysis of chromatin state in genotypes that lack specific insertions suggests that the adjacent heterochromatin results from spreading of silencing rather than insertion-site preferences. Genes that are located near elements that exhibit spreading of heterochromatin tend to be expressed at lower levels than other genes. Our findings suggest that a subset of LTR retrotransposon families may act as controlling elements influencing neighboring sequences while the majority of elements have little effect on flanking sequences Transposable elements comprise a substantial portion of many eukaryotic genomes. These mobile fragments of DNA can result in mutations through insertions into genes but may also affect the regulation of genes they insert near. There is evidence that the majority of transposable elements are epigenetically silenced and in some cases this silencing may affect neighboring sequences. However, evolutionary theory would predict that there would be selective pressures for transposable elements to limit their effects on neighboring genes. The maize genome has a complex organization with many genes flanked by retrotransposons. We profiled the spread of heterochromatin from the retrotransposons into nearby low copy sequences for 150 high copy retrotransposon families. While the manymajority of retrotransposons exhibit little to no spreading of heterochromatin there are a small number ofsome retrotransposon families that influence the chromatin state of surrounding regions. The families may represent bad “neighbors” that spread heterochromatin and influence nearby genes. 6 total samples: 3 replicates of B73 H3k9 and 3 replicates of Mo17 H3k9 3 total samples: mop1 mutant, b73.zmet2 (zmet2.m1 mutant in B73 background) and mo17.zmet2 (zmet2.m1 mutant in Mo17 background)
2012-11-26 | E-GEOD-39460 | biostudies-arrayexpress
Project description:The organization of chromatin in the nucleus plays an essential role in gene regulation. About half of the mammalian genome comprises transposable elements. Given their repetitive nature, reads associated with these elements are generally discarded or randomly distributed among elements of the same type in genome-wide analyses. Thus, it is challenging to identify the activities and properties of individual transposons. As a result, we only have a partial understanding of how transposons contribute to chromatin folding and how they impact gene regulation. Using adapted PCR and Capture-based chromosome conformation capture (3C) approaches, collectively called 4Tran, we take advantage of the repetitive nature of transposons to capture interactions from multiple copies of endogenous retrovirus (ERVs) in the human and mouse genomes. With 4Tran-PCR, reads are selectively mapped to unique regions in the genome. This enables the identification of transposable element interaction profiles for individual ERV families and integration events specific to particular genomes. With this approach, we demonstrate that transposons engage in long-range intra-chromosomal interactions guided by the separation of chromosomes into A and B compartments as well as topologically associated domains (TADs). In contrast to 4Tran-PCR, Capture-4Tran can uniquely identify both ends of an interaction that involve retroviral repeat sequences, providing a powerful tool for uncovering the individual transposable element insertions that interact with and potentially regulate target genes. 4Tran provides new insight into the manner in which transposons contribute to chromosome architecture and identifies target genes that transposable elements can potentially control.
2018-11-28 | GSE122976 | GEO