Monochromatic ultraviolet light induced damage to photosystem ii efficiency and carbon fixation in the marine diatom thalassiosira pseudonana (3h)

Joe Grzymski, Cristine Orrico, Oscar M. Schofield

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

Low light adapted cultures of the marine diatom Thalassiosira pseudonana (3H) were cultured and incubated for 30 min under different ultraviolet (UV) wavelengths of near monochromatic light with and without background photosynthetically active radiation (PAR, 380-700 nm). Maximum damage to the quantum yield for stable charge separations was found in the UVB (280-320 nm) wavelengths without background PAR light while the damage under PAR was 30% less. UV induced damage to carbon fixation in the cells was described by a function similar to non-linear functions of inhibiting irradiance previously published with the exception that damage was slightly higher in the UVA (320-380). Various measurements of fluorescent transients were measured and the results indicate localised damage most likely on the acceptor side of the Photosystem II reaction center. However, dark adapted measurements of fluorescence transients with and without DCMU do not result in similar functions. This is also true for the relationships between fluorescence transients and carbon fixation for this species of marine diatom. The correlation between the weightings εH from measurements of carbon fixation and the quantum yield for stable charge separation as calculated from induction curves with DCMU and without DCMU is R2 0.44 and R2 0.78, respectively. The slopes of the two measurements are 3.8 and 1.4, respectively. The strong correlation between the weightings of the induction curves without DCMU and carbon fixation are due to a loss of electron transport from the reaction center to plastoquinone. Under these experimental conditions of constant photon flux density (PFD) this is manifested as a strong linear relationship between the decrease in the operational quantum yield of Photosystem II and carbon fixation.

Original languageEnglish (US)
Pages (from-to)181-192
Number of pages12
JournalPhotosynthesis research
Volume68
Issue number3
DOIs
StatePublished - 2001

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Plant Science
  • Cell Biology

Keywords

  • Carbon fixation
  • Fluorescence
  • Photosystem II
  • Phytoplankton
  • Ultra-violet light

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