Photosystem stoichiometry and chlorophyll antenna size in Dunaliella salina (green algae)

Guenther, Jeanne E.; Nemson, Jeff A.; Melis, Anastasios

doi:10.1016/0005-2728(88)90125-9

Cited by 56 publications

(33 citation statements)

References 40 publications

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“…Also in agreement with earlier studies (9,27), we found that photoinhibition adversely affected PSII,, whereas PSIIp appeared resistant to damage (Fig. 4) (17,18). A schematic depicting the role of this activation in the general PSII repair cycle is given in Figure 9.…”

Section: Discussionsupporting

confidence: 79%

“…Activation may include movement of the complex from the stroma-exposed region of the thylakoid membrane to the grana partition region (18,28). The process could occur rapidly during strong irradiance exposure because no additional protein complexes need be synthesized.…”

Section: Discussionmentioning

confidence: 99%

“…The absorbance difference measurements were corrected for the effect of particle flattening (40), and an extinction coefficient of 65 mm-'* cm-' was applied (12). Under these conditions, the concentration of PSII is equal to that measured by the quantitation of QA (light-minus-dark absorbance change at 320 nm) ( 12,18).…”

Section: Methodsmentioning

confidence: 99%

“…Lavergne [24]). Previous work has shown that these QB-nonreducing centers have a PSII#-type of antenna (18,29). The slow, exponential kinetics of the F0 to F,, rise (Fig.…”

Section: Heterogeneitymentioning

confidence: 99%

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Activation of a Reserve Pool of Photosystem II in Chlamydomonas reinhardtii Counteracts Photoinhibition

Neale¹,

Melis²

1990

Plant Physiol.

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The effect of strong irradiance (Q000 micromole photons per square meter per second) on PSII heterogeneity in intact cells of Chiamydomonas reinhardtii was investigated. Low light (LL,15 micromole photons per square meter per second) grown C. reinhardtii are photoinhibited upon exposure to strong irradiance, and the loss of photosynthetic functioning is due to damage to PSII. Under physiological growth conditions, PSII is distributed into two pools. The large antenna size (PSIIa) centers account for about 70% of all PSII in the thylakoid membrane and are responsible for plastoquinone reduction (OB-reducing centers). The smaller antenna (PSII) account for the remainder of PSII and exist in astate not yet able to photoreduce plastoquinone (0B-nonreducing centers). The exposure of C. reinhardtii cells to 60 minutes of strong irradiance disabled about half of the primary charge separation between P680 and pheophytin. The PSII,content remained the same or slightly increased during strong-irradiance treatment, whereas the photochemical activity of PSIIa decreased by 80%. Analysis of fluorescence induction transients displayed by intact cells indicated that strong irradiance led to a conversion of PSlI,6 from a 0.-nonreducing to a QO-reducing state. Parallel measurements of the rate of oxygen evolution revealed that photosynthetic electron transport was maintained at high rates, despite the loss of activity by a majority of PSIIa. The results suggest that PSlI, in C. reinhardtii may serve as a reserve pool of PSII that augments photosynthetic electron-transport rates during exposure to strong irradiance and partially compensates for the adverse effect of photoinhibition on PSII,.Light energy drives photosynthesis but excess light is potentially damaging to the photosynthetic apparatus. The latter phenomenon is called photoinhibition and is manifested as a loss in chloroplast electron-transport capacity (for recent reviews see 38, 39). Though plants differ greatly in their sensitivity to photoinhibition, current evidence indicates widespread occurrence of photoinhibition in both terrestrial and aquatic environments (2, 33). In most cases, the loss of PSII function is responsible for decreased electron-transport activity, though damage to the PSI complex has also been reported (39). When isolated spinach thylakoids were illuminated with strong-irradiance (2500 Amol.m-2 s-') at 0C, both the QA2 (320 nm absorbance change) and Pheo (685 nm absorbance change) signal were lowered in parallel (8,9,12), suggesting inhibition of primary photochemistry. The PSII primary charge separation was also inhibited when intact cells of the green alga, Chiamydomonas reinhardtii, were exposed to strong irradiance (12). The rapid loss of the pheophytin photoreduction during photoinhibition has also been detected using EPR difference spectroscopy (46). These results indicated that photoinhibitory damage affected the ability of PSII to form the P680+ Pheo-charge separation.An alternative proposal (22, 37) is that photoinhibition result...

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Lavergne [24]). Previous work has shown that these QB-nonreducing centers have a PSII#-type of antenna (18,29). The slow, exponential kinetics of the F0 to F,, rise (Fig.…”

Section: Heterogeneitymentioning

confidence: 99%

See 2 more Smart Citations

Activation of a Reserve Pool of Photosystem II in Chlamydomonas reinhardtii Counteracts Photoinhibition

Neale¹,

Melis²

1990

Plant Physiol.

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“…In both previous PSU analyses, conclusions were made by measuring PSU in terms of either PS I or PS 11, but not both , Falkowski & Dubinsky 1981. The notion that PS 1:PS I1 stoichiometries are variable, and that the variations are dependent on irradiance, has been firmly established for most primary producers (Falkowski et al 1981, Myers & Graham 1983, Barlow & Alberte 1985, Chow et al 1988, 1990, Guenther et al 1988.…”

Section: Consistent With Previous Observationsmentioning

confidence: 99%

Acclimation and adaptation to irradiance in symbiotic dinoflagellates. I. Responses of the photosynthetic unit to changes in photon flux density

Iglesias-Prieto¹,

Trench²

1994

Mar. Ecol. Prog. Ser.

237

201

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The photosynthetic responses to variations in photon flux density were determined for Symbiodinium microadriaticum, the symbiont of the Caribbean jellyfish Cassiopeia xamachana, S. kawagutii, the symbiont of the Indo-Pacific stony coral Montipora verrucosa, and S. pilosum, the symbiont of the Caribbean zoanthld Zoanthus sociatus. Photosynthetic responses were characterized in terms of cellular pigment content, photosynthesis versus irradiance (P-I) relationships, and number and size of the photosynthetic unit (PSU). Analyses of the responses under 2 Light regimes of 40 and 250 p 0 1 quanta m-' S-' indicate that: (1) the 3 different species cultured under identical conditions possess different photosynthetic characteristics; (2) the 3 species acclimate to low photon flux density by simultaneously increasing the number and size of their PSU; (3) PSU characteristics were not correlated with the parameters of their respechve P-lcurves; (4) the 3 species analyzed have different photoacclimatory capabilities which can be correlated with their respective ecological distribution as endosymbionts. As different species demonstrate characteristic responses, photo-acclunatory adjustment in symbiotic dinoflagellates may be under genetic constraints, and thus may represent photo-adaptation (sensu 0. Bjorkman). As a whole, the results suggest that symbiont photo-adaptation may constitute an important axis of niche diversification for the intact associations.

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Excitation Energy Transfer: Functional and Dynamic Aspects of Lhc (cab) Proteins

Melis

Oxygenic Photosynthesis: The Light Reactions

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Photosystem stoichiometry and chlorophyll antenna size in Dunaliella salina (green algae)

Cited by 56 publications

References 40 publications

Activation of a Reserve Pool of Photosystem II in Chlamydomonas reinhardtii Counteracts Photoinhibition

Activation of a Reserve Pool of Photosystem II in Chlamydomonas reinhardtii Counteracts Photoinhibition

Acclimation and adaptation to irradiance in symbiotic dinoflagellates. I. Responses of the photosynthetic unit to changes in photon flux density

Excitation Energy Transfer: Functional and Dynamic Aspects of Lhc (cab) Proteins

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