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Photo of Chlamydomonas priscuii UWO241
Chlamydomonas priscuii UWO241 originates from the depths of the Antarctic Lake Bonney, where it thrives in a variety of extreme conditions (top). C. priscuii can exist either as a biflagellate, motile single cell or as non-motile palmelloid colonies (bottom). Image credit: M. Cvetkovska

The Chalmydomonas priscuii UWO241 (formerly designated Chlamydomonas sp. UWO241) genome sequence and gene models have not been determined by the JGI, but were downloaded from NCBI on July 30, 2021. In order to ensure this genome is comparable to those sequenced by the JGI, we applied filters to remove if present: 1) transposable elements, 2) pseudogenes, 3) alternative transcripts and overlapping models, and 4) unsupported short models. This resulted in the removal of 1264 models from Chlamydomonas priscuii UWO241 and the generation of the FilteredModels1 gene track. All published models are available in the ExternalModels track. Please note that this copy of the genome is not maintained by NCBI and is therefore not automatically updated. In order to allow comparative analyses with other algal genomes sequenced by the JGI, a copy of this genome is incorporated into PhycoCosm. The JGI Annotation Pipeline was used to add functional annotation to this genome.

Chlamydomonas priscuii UWO241

Chlamydomonas priscuii UWO241 is a unicellular biflagellate green alga, representing a unique lineage within the Moewusinia clade of the Chlamydomonadales (Chlorophyceae). This alga resides in a narrow band of liquid water 17 m below the surface of the perennially ice-covered Lake Bonney in the McMurdo Dry Valleys, Antarctica. This is a highly stable environment characterized by permanently low temperatures (~4°C), low irradiance (<50 µmol photons m-2 s-1) enriched in blue-green wavelengths (450–550 nm), high salinities (0.7 M), low levels of phosphorus (N:P ~1000), and unusually high oxygen concentrations (200% air saturation). Furthermore, C. priscuii is exposed to seasonal extremes in photoperiod (e.g. ~24h dark during the austral winter). C. priscuii is an obligate psychrophile and can not survive at temperatures above 18°C.

The C. priscuii nuclear genome (~212 Mb) is rich in functional RNAs, noncoding DNA (~87%) and the highest average intron density yet observed from a green alga (~10 introns/gene). It also harbors hundreds of highly similar duplicate genes from diverse cellular pathways (particularly in protein translation, DNA packaging and photosynthesis), as well as a large number of ice-binding proteins (>37). With over two decades of research focused on the biochemistry and biophysics of its photosynthetic apparatus, and a close phylogenetic relationship with model algae such as Chlamydomonas reinhardtii and Dunaliella salina, C. priscuii is emerging as an attractive system for studying how green algae adapt to low temperatures.

Genome Reference(s)