Comparison of chlorophyll far-red and rea fluorescence excitation spectra with photo-synthetic oxygen action spectra for photo-system II in algae

Abstract

The shapes of excitation spectra for chlorophyll a fluorescence in the far-red (730 nm) were compared under physiological conditions to those for chlorophyll a fluorescence in the red (685 nm) and to action spectra for photosynthetic oxygen production in diversely pigmented algae. Species examined as representatives of the prominent oceanic light harvesting systems were Chaetoceros graciljs, Glenodinium sp., Ulva sp., Porphyrid~um cruentum and Chroomonas sp. Qualitatively, for any one alga, all 3 action spectra exhbited broadly similar spectral features, suggesting initial light harvesting for photosynthesis by the same major pigments, i.e. those commonly associated with photosystem 11. As such, measurement of fluorescence (in preference to may provide a useful and facile alternative to oxygen action spectra in assessing the full photosynthetic spectral performance (320 to 700 nm) of individua! phy!opl=nkta~ species er =ssernb!-.ges.

Bio-optical modelling of primary production in the SW Finnish coastal zone, Baltic Sea: fast repetition rate fluorometry in Case 2 waters

“…The absorption coefficient of photosynthetic pigments (a ps (λ)) was estimated from the quantum-corrected and scaled far-red excitation spectra of phytoplankton (Neori et al 1988). In vivo fluorescence excitation spectra (excitation from 380 to 700 nm, emission 730 nm) were measured on a (3-[3, 4-dichlorophenyl]-1,1-dimethylurea) (DCMU)-treated (final concentration 20 µM) suspension using a spectrofluorometer (Shimadzu RFPC-5001).…”

Evaluation of biophysical and optical determinations of light absorption by photosystem II in phytoplankton

“…Spectrofluorescence-Fluorescence excitation spectra were measured in 10 mm quartz cuvettes between 400 and 800 nm using a Perkin Elmer LS50B (ES, Perkin-Elmer) or a Shimadzu RF-5301 (HP, Shimadzu Scientific Instruments). The emission monochromator was set to 730 nm (F 730 ) because 730 nm fluorescence has been shown to correspond with O 2 evolution, and therefore PSII action spectra (Neori et al 1988), but also minimizes potential reabsorption of fluorescence (Hofstraat et al 1992). Each sample was treated with 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (DCMU, <1% ethanol, to a final concentration of 20mM) and pre-illuminated for 5 minutes to penetrate and saturate PSII reaction centres (Johnsen and Sakshaug 1993).…”

Light histories influence the impacts of solar ultraviolet radiation on photosynthesis and growth in a marine diatom, Skeletonema costatum

“…The deleterious effects of UVR include inhibition of growth and photosynthesis [3][4][5], damage of proteins and DNA [6][7][8][9] and suppression of nutrient uptake [10]. On the other hand, positive effects of UVR have also been documented, such as UV-A-aided repair of damaged DNA [6], UVR-driven photosynthetic carbon fixation in the absence of PAR [11] and UV-A-enhanced photosynthesis in the presence of it [12][13][14][15].…”