Meeting Abstract
Comparative genomic approaches applied to cnidarian genomes can provide a powerful framework for exploring fundamental questions about the evolution of complex biological processes such as embryonic development, regeneration, self-recognition, and aging. We have chosen to focus on the colonial cnidarian Hydractinia, a hydrozoan representative that has lost the medusa stage and produces gametes directly from sexual polyps known as gonozooids. Hydractinia forms colonies of clonal polyps interconnected through a stolonal network and, in nature, colonies are typically found on shells inhabited by hermit crabs. We formed an international consortium and generated high-quality, high-coverage genome assemblies for H. echinata and its sister species, H. symbiolongicarpus, using PacBio, Illumina, and Dovetail sequence data. The estimated genome size is 774 Mb for H. echinata and 514 Mb for H. symbiolongicarpus. Similar to Hydra, both genomes are AT-rich (65%) and highly repetitive (at least 47%). We are using a comparative genomics approach where we (1) assess differences in gene content when compared to a recently updated high-quality Hydra Dovetail genome assembly; (2) explore regions of possible synteny among the genomes; and (3) compare non-coding RNAs, classes of repetitive elements, and conserved gene families. Interesting themes have begun to emerge in each of these areas that will ultimately reveal both the conserved features and extensive evolutionary novelties contained within these model hydrozoan genomes.
