RT Journal Article SR Electronic T1 Polarella glacialis genomes encode tandem repeats of single-exon genes with functions critical to adaptation of dinoflagellates JF bioRxiv FD Cold Spring Harbor Laboratory SP 704437 DO 10.1101/704437 A1 Timothy G. Stephens A1 Raúl A. González-Pech A1 Yuanyuan Cheng A1 Amin R. Mohamed A1 Debashish Bhattacharya A1 Mark A. Ragan A1 Cheong Xin Chan YR 2019 UL http://biorxiv.org/content/early/2019/07/16/704437.abstract AB Dinoflagellates are diverse, ecologically important phytoplankton in marine and freshwater environments. Here, we present two draft de novo diploid genome assemblies of the free-living dinoflagellate Polarella glacialis, isolated from the Arctic and Antarctica. For each genome, we predicted >50,000 high-quality genes supported by full-length transcriptome data. About 68% of the total genome sequence is repetitive, and includes long terminal repeats that likely contribute to intra-species structural divergence and distinct genome sizes (3.0 and 2.7 Gbp). In each genome, ∼40% of genes are encoded unidirectionally and ∼25% are single exonic; these include tandemly repeated genes that encode functions related to cold adaptation and photosynthesis. Multi-genome comparison unveiled genes specific to P. glacialis and a common ancestral origin of ice-binding domains in cold-adapted dinoflagellates. Our results provide insights into how dinoflagellate genomes may enhance the transcriptional efficiency of critical genes as a mechanism of environmental adaption and niche specialisation.