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Kinetics of Photosynthetic Response to Ultraviolet and Photosynthetically Active Radiation in Synechococcus WH8102 (CYANOBACTERIA)

Kinetics of Photosynthetic Response to Ultraviolet and Photosynthetically Active Radiation in Synechococcus WH8102 (CYANOBACTERIA)
Kinetics of Photosynthetic Response to Ultraviolet and Photosynthetically Active Radiation in Synechococcus WH8102 (CYANOBACTERIA)
The picoplanktonic cyanobacteria, Synechococcus spp., (Nägeli) are important contributors to global ocean primary production that can be stressed by solar radiation, both in the photosynthetically active (PAR) and ultraviolet (UV) range. We studied the responses of PSII quantum yield (active fluorescence), carbon fixation (14C assimilation) and oxygen evolution (membrane inlet mass spectrometry) in Synechococcus WH8102 under moderate UV and PAR. PSII quantum yield decreased during exposure to moderate UV and UV+PAR, with response to the latter being faster (6.4 versus 2.8 min, respectively). Repair processes were also faster when UV+PAR exposure was followed by moderate PAR (1.68 min response time) than when UV was followed by very low PAR (10.5 min response time). For the UV+PAR treatment, the initial decrease in quantum yield was followed by a 50% increase (“rebound”) after 7 min exposure, showing an apparent photoprotection induction. While oxygen uptake increased with PAR, it did not change under UV, suggesting that this oxygen-dependent mechanism of photoprotection, which may be acting as an electron sink, is not an important strategy against UV. We used propyl gallate, an antioxidant, to test for plastid terminal oxidase (ptox) or ptox-like enzymes activity, but it caused nonspecific and toxic effects on Synechococcus WH8102.
0031-8655
522-532
Fragoso, Glaucia M.
406a23cd-79a7-430b-9dc5-9b98676b7f0f
Neale, Patrick J.
aaf3781b-6710-41ea-b1b3-697710e3ff53
Kana, Todd M.
51dd41fc-0b90-4f6c-a3eb-a513132d92b1
Pritchard, Alicia L.
f1920337-2624-43ac-a574-c084897c9399
Fragoso, Glaucia M.
406a23cd-79a7-430b-9dc5-9b98676b7f0f
Neale, Patrick J.
aaf3781b-6710-41ea-b1b3-697710e3ff53
Kana, Todd M.
51dd41fc-0b90-4f6c-a3eb-a513132d92b1
Pritchard, Alicia L.
f1920337-2624-43ac-a574-c084897c9399

Fragoso, Glaucia M., Neale, Patrick J., Kana, Todd M. and Pritchard, Alicia L. (2014) Kinetics of Photosynthetic Response to Ultraviolet and Photosynthetically Active Radiation in Synechococcus WH8102 (CYANOBACTERIA). Photochemistry and Photobiology, 90 (3), 522-532. (doi:10.1111/php.12202).

Record type: Article

Abstract

The picoplanktonic cyanobacteria, Synechococcus spp., (Nägeli) are important contributors to global ocean primary production that can be stressed by solar radiation, both in the photosynthetically active (PAR) and ultraviolet (UV) range. We studied the responses of PSII quantum yield (active fluorescence), carbon fixation (14C assimilation) and oxygen evolution (membrane inlet mass spectrometry) in Synechococcus WH8102 under moderate UV and PAR. PSII quantum yield decreased during exposure to moderate UV and UV+PAR, with response to the latter being faster (6.4 versus 2.8 min, respectively). Repair processes were also faster when UV+PAR exposure was followed by moderate PAR (1.68 min response time) than when UV was followed by very low PAR (10.5 min response time). For the UV+PAR treatment, the initial decrease in quantum yield was followed by a 50% increase (“rebound”) after 7 min exposure, showing an apparent photoprotection induction. While oxygen uptake increased with PAR, it did not change under UV, suggesting that this oxygen-dependent mechanism of photoprotection, which may be acting as an electron sink, is not an important strategy against UV. We used propyl gallate, an antioxidant, to test for plastid terminal oxidase (ptox) or ptox-like enzymes activity, but it caused nonspecific and toxic effects on Synechococcus WH8102.

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Published date: May 2014
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 365342
URI: http://eprints.soton.ac.uk/id/eprint/365342
ISSN: 0031-8655
PURE UUID: 5d9f77b4-c83f-47b4-84e9-21f104618578

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Date deposited: 02 Jun 2014 12:39
Last modified: 16 Jul 2019 21:04

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