RT Journal Article
SR Electronic
T1 <em>Polarella glacialis</em> 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 Stephens, Timothy G.
A1 González-Pech, Raúl A.
A1 Cheng, Yuanyuan
A1 Mohamed, Amin R.
A1 Burt, David W.
A1 Bhattacharya, Debashish
A1 Ragan, Mark A.
A1 Chan, Cheong Xin
YR 2019
UL http://biorxiv.org/content/early/2019/10/15/704437.abstract
AB Dinoflagellates are taxonomically diverse, ecologically important phytoplankton in marine and freshwater environments. Here, we present two draft diploid genome assemblies of the free-living dinoflagellate Polarella glacialis, isolated from the Arctic and Antarctica. For each genome, guided using full-length transcriptome data, we predicted &gt;50,000 high-quality genes. About 68% of the genome is repetitive sequence; long terminal repeats likely contribute to intra-species structural divergence and distinct genome sizes (3.0 and 2.7 Gbp). Of all genes, ∼40% are encoded unidirectionally, ∼25% comprised of single exons. Multi-genome comparison unveiled genes specific to P. glacialis and a common, putatively bacterial, origin of ice-binding domains in cold-adapted dinoflagellates. Our results elucidate how selection acts within the context of a complex genome structure to facilitate local adaptation. Since most dinoflagellate genes are constitutively expressed, Polarella glacialis has enhanced transcriptional responses via unidirectional, tandem duplication of single-exon genes that encode functions critical to survival in cold, low-light environments.