Project description:We sequenced at mRNA level in adult hearts of zebrafish, pamprey and sea squirt. Combined with other 11 vertebrate heart RNA-Seq data online, we conducted comprehensive evolutionary genomic analyses to address the contribution of gene/genome duplications on heart structure evolution. We observed that number of duplicate genes expressed in heart increased gradually with the increase of heart chamber number along the vertebrate phylogeny, despite that most of them were duplicated at the time near to the origin of vertebrates or more ancient. Our research provides a clear-cut example to show the relationship among gene duplication, continuous character evolution like heart structure evolution and nature selection.
Project description:Sea urchins are emblematic marine animals with a rich fossil record and represent instrumental models for developmental biology. As echinoderms, sea urchins display several characteristics that set them apart from other deuterostomes such as their highly regulative embryonic development and their unique pentaradial adult body plan. To determine whether these characteristics are linked to particular genomic rearrangement or gene regulatory rewiring, we introduce a chromosome-scale genome assembly for sea urchin Paracentrotus lividus as well as extensive transcriptomic and epigenetic profiling during its embryonic development. We found that sea urchins show opposite modalities of genome evolution as compared to those of vertebrates: they retained ancestral chromosomal linkages that otherwise underwent mixing in vertebrates, while their intrachromosomal gene order has evolved much faster between sea urchin species that split 60 Myr ago than it did in vertebrates. We further assessed the conservation of the cis-regulatory program between sea urchins and chordates and identified conserved modules despite the developmental and body plan differences. We documented regulatory events underlying processes like zygotic genome activation and transition to larval stage in sea urchins. We also identified a burst of gene duplication in the echinoid lineage and showed that some of these expanded genes are involved in organismal novelties, such as Aristotle's lantern, tube feet, or in the specification of lineages through for instance the pmar1 and pop genes. Altogether, our results suggest that gene regulatory networks controlling development can be conserved despite extensive gene order rearrangement.
