title: In situ gene expression profiling of the thermoacidophilic alga Cyanidioschyzon in relation to visible and ultraviolet irradiance.
abstract: Ultraviolet and high-intensity visible radiation generate reactive intermediates that damage phototrophic microorganisms. In Yellowstone National Park, the thermoacidophilic alga Cyanidioschyzon exhibits an annual seasonal biomass fluctuation referred to as 'mat decline', where algal viability decreases as ultraviolet and visible irradiances increase during summer. We examined the role irradiance might play in mat decline using irradiance filters that uncouple ultraviolet and visible effects along with custom microarrays to study gene expression in situ. Of the 6507 genes, 88% showed no response to ultraviolet or visible, implying that at the biomolecular level, these algae inhabit a chemostat-like environment and is consistent with the near constant aqueous chemistry measured. The remaining genes exhibited expression changes linked to ultraviolet exposure, to increased visible radiation, or to the apparent combined effects of ultraviolet and visible. Expression of DNA repetitive elements was synchronized, being repressed by visible but also influenced by ultraviolet. At highest irradiance levels, these algae reduced transcription of genes encoding functions involved with DNA replication, photosynthesis and cell cycle progression but exhibited an uptick in activities related to repairing DNA damage. This corroborates known physiological responses to ultraviolet and visible radiation, and leads us to provisionally conclude that mat decline is linked to photoinhibition.
authors.affiliation: Department of Microbiology, Montana State University, Bozeman, MT, 59717, USA.
authors.forename: Dana J
authors.initials: DJ
authors.lastname: Skorupa
authors.forename: Richard W
authors.initials: RW
authors.lastname: Castenholz
authors.forename: Aurélien
authors.initials: A
authors.lastname: Mazurie
authors.forename: Charles
authors.initials: C
authors.lastname: Carey
authors.forename: Frank
authors.initials: F
authors.lastname: Rosenzweig
authors.forename: Timothy R
authors.initials: TR
authors.lastname: McDermott
mesh_terms: D004260:DNA Repair; D004261:DNA Replication; D020869:Gene Expression Profiling; D017343:Genes, Plant; D046228:Microarray Analysis; D010788:Photosynthesis / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D000461:Rhodophyta / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D012621:Seasons; D059467:Transcriptome; D014466:Ultraviolet Rays
chemical_list: D010940:Plant Proteins