The Effect of Decreasing the External Salinity on the Primary Processes of Photosynthesis in<i>Dunaliella tertiolecta</i>

Gilmour, D. James; Hipkins, M.F.; Boney, A. D.

doi:10.1093/jxb/35.1.28

Cited by 33 publications

(19 citation statements)

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“…Gilmour et al 1984;Greene et al 1994;Hofstraat et al 1994), in this study FJF,, had consistently lower values for all species. F,./F, ranged from 0.7 in S. protuberans to 0.4 in P. tricornutum (Table 2).…”

Section: Methodssupporting

confidence: 67%

Light dependence of quantum yields for PSII charge separation and oxygen evolution in eucaryotic algae

Flameling

Kromkamp

1998

Limnology & Oceanography

126

105

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Quantum yields of photosystcm I1 (PSII) charge separation (@& and oxygen production ((I) (,,) were determined by simultaneous measurements of oxygen production and variable fluorescence in four different aquatic microalgae representing three different taxonomic groups: the freshwater alga Scenedesmus protuberans (Chlorophyceae) and the marine algae Phneorystis globosa (Prymnesiophyceae), Emiliania huxleyi (Prymnesiophyceae), and Phaeodactylum tricornutum (Bacillariophyceae). In S. protuberans, P. tricornutum, and E. huxleyi, light-dependent variability was observed in the ratio of a(,,, to a,,, i.c. in the number of oxygen molecules produced per electron generated by PSII. The ratio ao,:@,, was highly variable at low light intensities (E < OSE,), and at higher light intensities (E > OSE,) @(,, : @,, showed a nonlinear decrease with increasing light intensity. In contrast, in P. globosa. a trend in a<,, : @,, could not be distinguished, and this species showed a decrease in @'o, : $ during the day, indicating a dependency of a(,, : a,, on light history. Additionally, considerable interspecific quantitative differences in a(,, : a,, were observed. Two possible interpretations to explain the variability in '.I+)! : a, are discussed. Assuming that 0, is a reliable measure of the quantum yield for charge separation at PSII, one interpretation is that net oxygen production is influenced by processes that consume oxygen or affect linear electron transport (e.g. cyclic electron transport around PSII, pseudocyclic electron transport in the Mehler reaction, Rubisco oxygenase activity, and lightdependent mitochondrial respiration). A second interpretation, however, suggests that at saturating light, changes in photosynthesis turnover time occur, such that $ does not predict the steady-state O2 yield.Quantum yields of phytoplankton photosynthesis are usually defined as the quantum yields for O? production (CacjL) or C fixation (@c,,,) (Kok 1948;Myers 1980;Babin et al. 1996). Because measurements of @oz and @'co, are laborious and time-consuming, much attention has been focused lately on the use of variable chlorophyll fluorescence as a tool to measure the quantum yield of charge separation in photosystem II (PSIl) reaction centers (Genty et al. 1989). This technique is rapid and noninvasive and may offer high temporal and spatial resolution when used in field measurements (Schreiber et al. 1986). Theoretically, the rate of noncyclic photosynthetic electron transport of a PSI1 (J) can be calculated from the quantum yield of PSI1 charge separation (a,,) according to J = @,J%s,,rwhere E is the incident light intensity and cr,,,, is the absorption cross section of PSII, which determines the fraction of the incident light intensity that is actually used by PSI1 (e.g. Kolber and Falkowski 1993; Kroon 1991; Hofstraat et al. 1994, Biehler andFock 1995). In order to use J as a measure for photosynthesis, the relationships between @,,, @coL, and @coz have to be well established. According to the stoichiometry of the Z-schem...

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Section: Methodssupporting

confidence: 67%

Light dependence of quantum yields for PSII charge separation and oxygen evolution in eucaryotic algae

Flameling

Kromkamp

1998

Limnology & Oceanography

126

105

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“…1) is in accordance with earlier results (Ben-Amotz and Avron 1972, Frank andWegmann 1974) but contradicts those reported by Gilmour et al (1984) and Wegmann (1977). The main reason for these discrepancies probably is that the latter authors used non-adapted cells for their measurements of salt dependent photosynthetic activity thus recording stress characteristics.…”

Section: Net Oxygen Exchange (Net)supporting

confidence: 91%

16O2/18O2 analysis of oxygen exchange in Dunaliella tertiolecta. Evidence for the inhibition of mitochondrial respiration in the light

1988

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A mass spectrometric (16)O2/(18)O2-isotope technique was used to analyse the rates of gross O2 evolution, net O2 evolution and gross O2 uptake in relation to photon fluence rate by Dunaliella tertiolecta adapted to 0.5, 1.0, 1.5, 2.0 and 2.5 M NaCl at 25°C and pH 7.0.At concentrations of dissolved inorganic carbon saturating for photosynthesis (200 μM) gross O2 evolution and net O2 evolution increased with increasing salinity as well as with photon fluence rate. Light compensation was also enhanced with increased salinities. Light saturation of net O2 evolution was reached at about 1000 μmol m(-2)s(-1) for all salt concentrations tested. Gross O2 uptake in the light was increased in relation to the NaCl concentration but it was decreased with increasing photon fluence rate for almost all salinities, although an enhanced flow of light generated electrons was simultaneously observed. In addition, a comparison between gross O2 uptake at 1000 μmol photons m(-2)s(-1), dark respiration before illumination and immediately after darkening of each experiment showed that gross O2 uptake in the light paralleled but was lower than mitochondrial O2 consumption in the dark.From these results it is suggested that O2 uptake by Dunaliella tertiolecta in the light is mainly influenced by mitochondrial O2 uptake. Therefore, it appears that the light dependent inhibition of gross O2 uptake is caused by a reduction in mitochondrial O2 consumption by light.

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“…Algae are known to adapt to altered environmental conditions due to the specific physiological and biochemical processes in their cells (Gapochka 1981). These processes include changes in fatty acid composition (Cohen et al 1988;Xu and Beardall 1997) and accumulation of different organic substances required for osmoregulation: proline Jafarova 1993), glycerol (Ahmad andHellebutt 1985;Gilmour et al 1984), taurine (Jackson et al 1992), etc. The most disruptive effect on C. hystrix was caused by the decrease in salinity to 12‰ (all microalgae died by the end of the experiment) and to 16‰ (most cells died by day 14).…”

Section: Discussionmentioning

confidence: 99%

The effect of decrease in salinity on the dynamics of abundance and the cell size of Corethron Hystrix (Bacillariophyta) in laboratory culture

Айздайчер

Markina

2010

Ocean Sci. J.

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Effect of salinity on abundance dynamics and cell size of microalga Corethron hystrix Hensen (Bacillariophyta) were studied. C. hystrix can normally grow within a rather narrow salinity range between 32 and 28‰. The viable cells of this microalga change their morphological characters at a salinity of 24‰. This salinity level probably marks the beginning of cell division restriction, because the general number of cells by the end of the experiment was lower than in the control. The decrease of salinity to 16‰ caused pronounced irreversible morphological changes: cell height increased, chloroplasts compressed, protoplasm became granular, cytoplasm retracted, and spines shortened.

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The Effect of Decreasing the External Salinity on the Primary Processes of Photosynthesis inDunaliella tertiolecta

Cited by 33 publications

References 0 publications

Light dependence of quantum yields for PSII charge separation and oxygen evolution in eucaryotic algae

Light dependence of quantum yields for PSII charge separation and oxygen evolution in eucaryotic algae

16O2/18O2 analysis of oxygen exchange in Dunaliella tertiolecta. Evidence for the inhibition of mitochondrial respiration in the light

The effect of decrease in salinity on the dynamics of abundance and the cell size of Corethron Hystrix (Bacillariophyta) in laboratory culture

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