Project description:Venomous animals have traditionally been studied from a proteomic (but also transcriptomic) perspective, often overlooking the study of venom from a genomic point of view until recently. The rise of genomics has led to an increase in the number of reference genomes for non-model organisms, including venomous taxa, enabling new questions on venom evolution from a genomic context. Although venomous snakes are the fundamental model system in venom research, the number of high-quality reference genomes in the group remains limited. In this study, we present a high-quality chromosome-level reference genome for the Arabian horned viper (Cerastes gasperettii), a highly venomous snake native to the Arabian Peninsula. Our highly-contiguous genome allowed us to explore macrochromosomal rearrangements within the Viperidae family, as well as across squamate reptile evolution. Furthermore, we identified a total of ten different toxins conforming the venom’s core, in line with our proteomic results. We also compared microsyntenic changes in the main toxin gene clusters with those of other venomous snake species, highlighting the pivotal role of gene duplication and loss in the emergence and diversification of the two main toxin families for Cerastes gasperettii. Using Illumina data, we reconstructed the demographic history and genome-wide diversity of the species, revealing how historical aridity likely drove population expansions. Finally, this study highlights the importance of using long-read sequencing as well as chromosome-level reference genomes to disentangle the origin and diversification of toxin families in venomous species.
Project description:Venomous animals have traditionally been studied from a proteomic (but also transcriptomic) perspective, often overlooking the study of venom from a genomic point of view until recently. The rise of genomics has led to an increase in the number of reference genomes for non-model organisms, including venomous taxa, enabling new questions on venom evolution from a genomic context. Although venomous snakes are the fundamental model system in venom research, the number of high-quality reference genomes in the group remains limited. In this study, we present a high-quality chromosome-level reference genome for the Arabian horned viper (Cerastes gasperettii), a highly venomous snake native to the Arabian Peninsula. Our highly-contiguous genome allowed us to explore macrochromosomal rearrangements within the Viperidae family, as well as across squamate reptile evolution. Furthermore, we identified a total of ten different toxins conforming the venom’s core, in line with our proteomic results. We also compared microsyntenic changes in the main toxin gene clusters with those of other venomous snake species, highlighting the pivotal role of gene duplication and loss in the emergence and diversification of the two main toxin families for Cerastes gasperettii. Using Illumina data, we reconstructed the demographic history and genome-wide diversity of the species, revealing how historical aridity likely drove population expansions. Finally, this study highlights the importance of using long-read sequencing as well as chromosome-level reference genomes to disentangle the origin and diversification of toxin families in venomous species.
Project description:ChIP-seq data characterizing the occupancy of TFAM over the mitochondrial and nuclear genomes in HeLa cells. Characterization of mitochondrial and nuclear genome-wide TFAM binding in HeLa cells
Project description:Peanut (Arachis hypogaea) has a large (~2.7 Gbp) allotetraploid genome with closely related component genomes making its genome very challenging to assemble. Here we report genome sequences of its diploid ancestors (A. duranensis and A. ipaënsis). We show they are similar to the peanutâs A- and B-genomes and use them use them to identify candidate disease resistance genes, create improved tetraploid transcript assemblies, and show genetic exchange between peanutâs component genomes. Based on remarkably high DNA identity and biogeography, we conclude that A. ipaënsis may be a descendant of the very same population that contributed the B-genome to cultivated peanut. Whole Genome Bisulphite Sequencing of the peanut species Arachis duranensis and Arachis ipaensis.
Project description:Dnmt1 epigenetically propagates symmetrical CG methylation in many eukaryotes. Their genomes are typically depleted of CG dinucleotides because of imperfect repair of deaminated methylcytosines. Here, we extensively survey diverse species lacking Dnmt1 and show that, surprisingly, symmetrical CG methylation is nonetheless frequently present and catalyzed by a different DNA methyltransferase family, Dnmt5. Numerous Dnmt5-containing organisms that diverged more than a billion years ago exhibit clustered methylation, specifically in nucleosome linkers. Clustered methylation occurs at unprecedented densities and directly disfavors nucleosomes, contributing to nucleosome positioning between clusters. Dense methylation is enabled by a regime of genomic sequence evolution that enriches CG dinucleotides and drives the highest CG frequencies known. Species with linker methylation have small, transcriptionally active nuclei that approach the physical limits of chromatin compaction. These features constitute a previously unappreciated genome architecture, in which dense methylation influences nucleosome positions, likely facilitating nuclear processes under extreme spatial constraints. DNA methylation, RNA and nucleosome sequencing data for diverse eukaryotes