Evidence for cyclic electron flow around photosystem II in Chlorella pyrenoidosa

Journal Article · Thu May 01 04:00:00 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., Upton, NY
• OSTI ID: 6936046
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 81:1; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

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