Evidence for cyclic electron flow around photosystem II in Chlorella pyrenoidosa

Journal Article · Thu May 01 00:00:00 EDT 1986 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.81.1.310· OSTI ID:6936046

Falkowski, P G; Fujita, Y; Ley, A; Mauzerall, D

Electron flow around photosystem II was investigated in Chlorella pyrenoidosa. Using a bare platinum O/sub 2/ electrode, simultaneous measurements were made of steady-state photosynthesis in continuous light, the yield of oxygen (Yo/sub 2/) produced by a superimposed saturating xenon flash, and the change in fluorescence yield of a weak flash triggered before and 70 microseconds after the saturating flash. Throughout most of the continuous photosynthesis-irradiance curve, normalized O/sub 2/ flash yields (Yo/sub 2//Yo/sub 2//sub max/) and normalized variable fluorescence yields ..delta..omega/..delta..omega' were linearly correlated with a slope of 1.0. As photosynthetic rates reached light saturation, however, the variable fluorescence yields remained relatively constant while O/sub 2/ flash yields decreased. These results strongly suggest that there is a cyclic electron flow around photosystem II in unpoisoned intact cells at light saturation and supraoptimal light intensities.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• OSTI ID: 6936046
• Journal Information: Plant Physiol.; (United States), Vol. 81:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CHLORELLA
PHOTOSYNTHESIS
PHOTOSYNTHETIC REACTION CENTERS
CHARGE EXCHANGE
EXPERIMENTAL DATA
FLUORESCENCE
FLUX DENSITY
MEASURING METHODS
PHOTONS
ALGAE
CHEMICAL REACTIONS
DATA
ELEMENTARY PARTICLES
INFORMATION
LUMINESCENCE
MASSLESS PARTICLES
MICROORGANISMS
NUMERICAL DATA
PHOTOCHEMICAL REACTIONS
PLANTS
SYNTHESIS
UNICELLULAR ALGAE
550500* - Metabolism