title: Transcript patterns of chloroplast-encoded genes in cultured Symbiodinium spp. (Dinophyceae): testing the influence of a light shift and diel periodicity.
abstract: Microalgae possess numerous cellular mechanisms specifically employed for acclimating the photosynthetic pathways to changes in the physical environment. Despite the importance of coral-dinoflagellate symbioses, little focus has been given as to how the symbiotic algae (Symbiodinium spp.) regulate the expression of their photosynthetic genes. This study used real-time PCR to investigate the transcript abundance of the plastid-encoded genes, psbA (encoding the D1 protein of photosystem II) and psaA (encoding the P700 protein in photosystem I), within the cultured Symbiodinium ITS-2 (internal transcribed spacer region) types A20 and A13. Transcript abundance was monitored during a low to high-light shift, as well as over a full diel light cycle. In addition, psaA was characterized in three isolates (A20, A13, and D4-5) and noted as another example of a dinoflagellate plastid gene encoded on a minicircle. In general, the overall incongruence of transcript patterns for both psbA and psaA between the Symbiodinium isolates and other models of transcriptionally controlled chloroplast gene expression (e.g., Pisum sativum [pea], Sinapis alba [mustard seedling], and Synechocystis sp. PCC 6803 [cyanobacteria]) suggests that Symbiodinium is reliant on posttranscriptional mechanisms for homeostatic regulation of its photosynthetic proteins.
authors.affiliation: College of Earth, Ocean, and Environment, University of Delaware, Lewes, Deleware 19958, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: McGinley
authors.affiliation: Department of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Suggett
authors.affiliation: College of Earth, Ocean, and Environment, University of Delaware, Lewes, Deleware 19958, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Warner
keywords: Symbiodinium; dinoflagellates; minicircle; photosynthetic gene expression; photosystem; real-time PCR