Transcription ciliate genome rearrangements
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ABSTRACT:
PROVIDER: PRJEB32087 | ENA |
REPOSITORIES: ENA
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Project description:Here we report that soon after mating of Oxytricha trifallax, abundant 27nt small RNAs are produced that are not present prior to mating. We performed next generation sequencing of these 27nt RNAs from various times after mating. Using sequence comparisons between macronuclear and micronuclear versions of genes, we found that this 27nt RNA class derives from the parental macronucleus, not the developing macronucleus. These small RNAs are produced equally from both strands of macronuclear nanochromosomes, but in a highly non-uniform distribution along the length of the nanochromosome, and with a particular depletion in the 30 nt telomere-proximal positions. Unlike the Tetrahymena scanRNAs, the Oxytricha macronuclear-derived 27mers are not modified by 2'O-methylation at their 3' ends. Examination of small RNAs produced in Oxytricha trifallax during vegetative growth and at various timepoints during the mating process
2012-04-19 | E-GEOD-37390 | biostudies-arrayexpress
Project description:Here we report that soon after mating of Oxytricha trifallax, abundant 27nt small RNAs are produced that are not present prior to mating. We performed next generation sequencing of these 27nt RNAs from various times after mating. Using sequence comparisons between macronuclear and micronuclear versions of genes, we found that this 27nt RNA class derives from the parental macronucleus, not the developing macronucleus. These small RNAs are produced equally from both strands of macronuclear nanochromosomes, but in a highly non-uniform distribution along the length of the nanochromosome, and with a particular depletion in the 30 nt telomere-proximal positions. Unlike the Tetrahymena scanRNAs, the Oxytricha macronuclear-derived 27mers are not modified by 2'O-methylation at their 3' ends.
2012-04-19 | GSE37390 | GEO
Project description:As part of sexual reproduction, the stichotrichous ciliate Oxytricha trifallax orchestrates a remarkable transformation of one of the newly formed germline micronuclear genomes, in which hundreds of thousands of gene pieces are stitched together, excised from chromosomes, and amplified dozens of times, to yield a functional somatic macronuclear genome composed of ~16,000 distinct DNA molecules that typically encode a single gene. Little is known about the proteins that carry out this process. We profiled mRNA expression as a functional of macronuclear development and identified hundreds of mRNAs preferentially expressed at specific times during the program. We find that a disproportionate number of these mRNAs encode proteins that are involved in DNA and RNA functions. Many mRNAs preferentially expressed during macronuclear development have paralogs that are not differentially expressed during development or are expressed at different times, including many components of RNA polymerase II and homologous recombination complexes, suggesting that gene duplication and functional specialization were a key source of evolutionary innovation. While many mRNAs preferentially expressed during macronuclear development encode proteins with no recognizable homolog, hundreds encode proteins that are well-conserved, including a disproportionate number with links to germline function or development in multicellular lineages. These analyses have thus identified scores of factors that may have ancient roles in sexual propagation, germline specialization and differentiation, in addition to dozens of novel factors with striking expression patterns, some of which likely evolved to carry out these extraordinary DNA manipulations.
2017-01-13 | GSE86081 | GEO
Project description:Dicer-dependent small non-coding RNAs play important roles in gene regulation in a wide variety of organisms. Endogenous small interfering RNAs (siRNAs) are part of an ancient pathway of transposon control in plants and animals. The ciliate, Oxytricha trifallax, has approximately 16,000 gene-sized chromosomes in its somatic nucleus. Long non-coding RNAs establish high ploidy levels at the onset of sexual development, but the factors that regulate chromosome copy numbers during cell division and growth have been a mystery. We report a novel function of a class of Dicer (Dcl-1)– and RNA-dependent RNA polymerase (RdRP)– dependent endogenous small RNAs in regulating chromosome copy number and gene dosage in O. trifallax. Asexually growing populations express an abundant class of 21nt sRNAs that map to both coding and non-coding regions of most chromosomes. These sRNAs are bound to chromatin and their levels surprisingly do not correlate with mRNA levels. Instead, the levels of these small RNAs correlate with genomic DNA copy number. Reduced sRNA levels in dcl-1 or rdrp mutants lead to concomitant reduction in chromosome copy number. Furthermore, these cells show no signs of transposon activation, but instead display irregular nuclear architecture and signs of replication stress. In conclusion, Oxytricha Dcl-1 and RdRP-dependent small RNAs that derive from the somatic nucleus contribute to the maintenance of gene dosage, possibly via a role in DNA replication, offering a novel role for these small RNAs in eukaryotes.
2017-09-21 | GSE104078 | GEO
Project description:5-methyl-cytosine DNA methylation regulates gene expression and developmental programming in a broad range of eukaryotes. However, its presence and potential roles in ciliates, complex single-celled eukaryotes with germline-somatic genome specialization via nuclear dimorphism, are largely uncharted. While canonical cytosine methyltransferases have not been discovered in published ciliate genomes, recent studies performed in the stichotrichous ciliate Oxytricha trifallax suggest de novo cytosine methylation during macronuclear development. In this study, we applied bisfulfite genome sequencing, DNA mass spectrometry and antibody-based fluorescence detection to investigate the presence of DNA methylation in Paramecium tetraurelia. While the antibody-based methods suggest cytosine methylation, DNA mass spectrometry and bisulfite sequencing reveal that levels are actually below the limit of detection. Our results suggest that Paramecium does not utilize 5-methyl-cytosine DNA methylation as an integral part of its epigenetic arsenal.
2018-04-01 | GSE111621 | GEO
Project description:Long-read sequencing of the Oxytricha trifallax macronuclear genome
| PRJNA352762 | ENA
Project description:We report the existence of both methylcytosine and hydroxymethylcytosine in the genomic DNA of the ciliate Oxytricha trifallax during its genome rearrangement process. These modifications are dynamically added, de novo, to sequences targeted for elimination and are not present after the rearrangement process (in vegetative cells). We performed methyl-DNA immunoprecipitation-sequencing (meDIP-seq) with antibodies against methylcytosine and hydroxymethylcytosine.
2012-09-26 | GSE41060 | GEO