Premium
EFFECTS OF ULTRAVIOLET RADIATION ON PHOTOSYNTHESIS IN THE SUBTROPICAL MARINE DIATOM, CHAETOCEROS GRACILIS (BACILLARIOPHYCEAE) 1
Author(s) -
Hazard Christina,
Lesser Michael P.,
Kinzie Robert A.
Publication year - 1997
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.1997.00960.x
Subject(s) - biology , acclimatization , photosynthesis , carbon fixation , diatom , botany , rubisco , chlorophyll , trichodesmium , chlorophyll a , nitrogen fixation , bacteria , diazotroph , genetics
ARSTRACT Acclimation to ambient ultraviolet radiation (UVR) was examined in a subtropical marine diatom, Chaetoceros gracilis Schutt. Short‐term exposure to UVR (<24 h) reduced the efficiency of photosynthetic energy conversion, carbon fixation, activity of 1,5‐bisphosphate carboxylase‐loxygenase (RUBISCO), and the rapid turnover of the putative Dl reaction center (32 kda) protein, whereas longer‐term exposure to ambient UVR (24–48 h) revealed a steady‐state acclimation, defined as recovery of carbon fixation and RUBISCO activity to rates equivalent to treatments without exposure to UVR. The turnover of D1 and chlorophyll a (Chl a) remained high during exposure to UVR. Efficiency of energy conversion by photosystem II, measured with double flash (pump and probe) fluorometry, increased by 24% in cells acclimated to UVR. Acclimation to UVR had no detectable effect on the functional absorption cross‐section or cellular concentrations of Chl a, Chl c, or total carotenoids. However, the maximum rate of carbon fixation was reduced by UVR on a Chl a basis but remained unaffected on a per‐cell basis. Response to UVR exposure in this subtropical diatom has two components: a short‐term inhibitory response and a longer‐term acclimation process that ameliorates the inhibition of carbon fixation.