Hi-C guided assemblies reveal conserved regulatory topologies on X and autosomes despite extensive genome shuffling
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ABSTRACT:
ORGANISM(S): Drosophila busckii Drosophila melanogaster Drosophila virilis
PROVIDER: GSE120752 | GEO | 2019/10/14
REPOSITORIES: GEO
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Project description:Genome rearrangements that occur during evolution impose major challenges on regulatory mechanisms that rely on three-dimensional genome architecture. Here, we developed a scaffolding algorithm and generated chromosome-length assemblies from Hi-C data for studying genome topology in three distantly related Drosophila species. We observe extensive genome shuffling between these species with one synteny breakpoint after approximately every six genes. A/B compartments, a set of large gene-dense topologically associating domains (TADs), and spatial contacts between high-affinity sites (HAS) located on the X chromosome are maintained over 40 million years, indicating architectural conservation at various hierarchies. Evolutionary conserved genes cluster in the vicinity of HAS, while HAS locations appear evolutionarily flexible, thus uncoupling functional requirement of dosage compensation from individual positions on the linear X chromosome. Therefore, 3D architecture is preserved even in scenarios of thousands of rearrangements highlighting its relevance for essential processes such as dosage compensation of the X chromosome.
| S-EPMC6824461 | biostudies-literature
Project description:We used an approach combining PacBio data and published Illumina reads to de novo assemble D. busckii contigs. We generated Hi-C data from D. busckii embryos to order these contigs into chromosome-length scaffolds. For D. virilis we generated Hi-C data to order and orient the published Dvir_caf1 scaffolds into chromosome-length assemblies. Furthermore, we compared Hi-C matrices from these two new assemblies with D. melanogaster with respect to synteny blocks and dosage compensation as a chromosome-wide gene-regulatory mechanism.
2019-10-14 | GSE120751 | GEO
Project description:We used an approach combining PacBio data and published Illumina reads to de novo assemble D. busckii contigs. We generated Hi-C data from D. busckii embryos to order these contigs into chromosome-length scaffolds. For D. virilis we generated Hi-C data to order and orient the published Dvir_caf1 scaffolds into chromosome-length assemblies. Furthermore, we compared Hi-C matrices from these two new assemblies with D. melanogaster with respect to synteny blocks and dosage compensation as a chromosome-wide gene-regulatory mechanism.
2019-10-14 | GSE120750 | GEO
Project description:Hi-C guided assemblies reveal conserved regulatory topologies on X and autosomes despite extensive genome shuffling
| PRJNA494393 | ENA
Project description:Hi-C guided assemblies reveal conserved regulatory topologies on X and autosomes despite extensive genome shuffling [ChIP-seq]
| PRJNA494470 | ENA
Project description:Chromosome rearrangements are arguably the most dramatic type of mutations, often leading to rapid evolution and speciation. However, chromosome dynamics have only been studied at the sequence level in a small number of model systems. In insects, Diptera and Lepidoptera have conserved genome structure at the scale of whole chromosomes or chromosome arms. Whether this reflects the diversity of insect genome evolution is questionable given that many species exhibit rapid karyotype evolution. Here, we investigate chromosome evolution in aphids-an important group of hemipteran plant pests-using newly generated chromosome-scale genome assemblies of the green peach aphid (Myzus persicae) and the pea aphid (Acyrthosiphon pisum), and a previously published assembly of the corn-leaf aphid (Rhopalosiphum maidis). We find that aphid autosomes have undergone dramatic reorganization over the last 30 My, to the extent that chromosome homology cannot be determined between aphids from the tribes Macrosiphini (Myzus persicae and Acyrthosiphon pisum) and Aphidini (Rhopalosiphum maidis). In contrast, gene content of the aphid sex (X) chromosome remained unchanged despite rapid sequence evolution, low gene expression, and high transposable element load. To test whether rapid evolution of genome structure is a hallmark of Hemiptera, we compared our aphid assemblies with chromosome-scale assemblies of two blood-feeding Hemiptera (Rhodnius prolixus and Triatoma rubrofasciata). Despite being more diverged, the blood-feeding hemipterans have conserved synteny. The exceptional rate of structural evolution of aphid autosomes renders them an important emerging model system for studying the role of large-scale genome rearrangements in evolution.
| S-EPMC7947777 | biostudies-literature
Project description:Detailed mechanistic understanding of L1 retrotransposition is sparse, particularly with respect to ORF1p, a coiled coil-mediated homotrimeric nucleic acid chaperone that can form tightly packed oligomers on nucleic acids. Although the coiled coil motif is highly conserved, it is uniquely susceptible to evolutionary change. Here we studied three ORF1 proteins: a modern human one (111p), its resuscitated primate ancestor (555p) and a mosaic modern protein (151p) wherein 9 of the 30 coiled coil substitutions retain their ancestral state. While 111p and 555p equally supported retrotransposition, 151p was inactive. Nonetheless, they were fully active in bulk assays of nucleic acid interactions including chaperone activity. However, single molecule assays showed that 151p trimers form stably bound oligomers on ssDNA at <1/10th the rate of the active proteins, revealing that oligomerization rate is a novel critical parameter of ORF1p activity in retrotransposition conserved for at least the last 25 Myr of primate evolution.
| S-EPMC4705668 | biostudies-literature
Project description:Genome-wide analysis methods, such as array comparative genomic hybridization (CGH) and whole-genome sequencing (WGS), have greatly advanced the identification of structural variants (SVs) in the human genome. However, even with standard high-throughput sequencing techniques, complex rearrangements with multiple breakpoints are often difficult to resolve, and predicting their effects on gene expression and phenotype remains a challenge. Here, we address these problems by using high-throughput chromosome conformation capture (Hi-C) generated from cultured cells of nine individuals with developmental disorders (DDs). Three individuals had previously been identified as harboring duplications at the SOX9 locus and six had been identified with translocations. Hi-C resolved the positions of the duplications and was instructive in interpreting their distinct pathogenic effects, including the formation of new topologically associating domains (neo-TADs). Hi-C was very sensitive in detecting translocations, and it revealed previously unrecognized complex rearrangements at the breakpoints. In several cases, we observed the formation of fused-TADs promoting ectopic enhancer-promoter interactions that were likely to be involved in the disease pathology. In summary, we show that Hi-C is a sensible method for the detection of complex SVs in a clinical setting. The results help interpret the possible pathogenic effects of the SVs in individuals with DDs.
| S-EPMC7273525 | biostudies-literature
Project description:BackgroundAmong three sources of evolutionary innovation in gene function - point mutations, gene duplications, and gene shuffling (recombination between dissimilar genes) - gene shuffling is the most potent one. However, surprisingly little is known about its incidence on a genome-wide scale.ResultsWe have studied shuffling in genes that are conserved between distantly related species. Specifically, we estimated the incidence of gene shuffling in ten organisms from the three domains of life: eukaryotes, eubacteria, and archaea, considering only genes showing significant sequence similarity in pairwise genome comparisons. We found that successful gene shuffling is very rare among such conserved genes. For example, we could detect only 48 successful gene-shuffling events in the genome of the fruit fly Drosophila melanogaster which have occurred since its common ancestor with the worm Caenorhabditis elegans more than half a billion years ago.ConclusionThe incidence of gene shuffling is roughly an order of magnitude smaller than the incidence of single-gene duplication in eukaryotes, but it can approach or even exceed the gene-duplication rate in prokaryotes. If true in general, this pattern suggests that gene shuffling may not be a major force in reshaping the core genomes of eukaryotes. Our results also cast doubt on the notion that introns facilitate gene shuffling, both because prokaryotes show an appreciable incidence of gene shuffling despite their lack of introns and because we find no statistical association between exon-intron boundaries and recombined domains in the two multicellular genomes we studied.
| S-EPMC1175970 | biostudies-literature
Project description:The N-terminal (NT) domain of spider silk proteins (spidroins) is crucial for their storage at high concentrations and also regulates silk assembly. NTs from the major ampullate spidroin (MaSp) and the minor ampullate spidroin are monomeric at neutral pH and confer solubility to spidroins, whereas at lower pH, they dimerize to interconnect spidroins in a fiber. This dimerization is known to result from modulation of electrostatic interactions by protonation of well-conserved glutamates, although it is undetermined if this mechanism applies to other spidroin types as well. Here, we determine the solution and crystal structures of the flagelliform spidroin NT, which shares only 35% identity with MaSp NT, and investigate the mechanisms of its dimerization. We show that flagelliform spidroin NT is structurally similar to MaSp NT and that the electrostatic intermolecular interaction between Asp 40 and Lys 65 residues is conserved. However, the protonation events involve a different set of residues than in MaSp, indicating that an overall mechanism of pH-dependent dimerization is conserved but can be mediated by different pathways in different silk types.
| S-EPMC9097459 | biostudies-literature