The Molecular Analysis of the Light Adaptation Reactions in the Yellow‐green Alga<i>Pleurochloris meiringensis</i>(Xanthophyceae)

Büchel, Claudia; Wilhelm, Christian; Lenartz‐Weiler, I.

doi:10.1111/j.1438-8677.1988.tb00049.x

Cited by 18 publications

(5 citation statements)

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“…A higher than expected electron transport rate could be due to a change of energy distribution in favor of PS I during the RLC recording. In Chl c-containing algae it has been postulated that the relative absorption sections of PS II and PS I are light intensity-dependent (Owens 1986;Bu¨chel et al 1988).…”

Section: Modelling Of Primary Production In Natural Phytoplanktonmentioning

confidence: 99%

Estimation of chlorophyll content and daily primary production of the major algal groups by means of multiwavelength-excitation PAM chlorophyll fluorometry: performance and methodological limits

et al. 2005

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The performance and methodological limits of the Phyto-PAM chlorophyll fluorometer were investigated with laboratory grown algae cultures and natural phytoplankton from the rivers Saar and Saale. The Phyto-PAM is a 4-wavelength chlorophyll fluorometer with the functional combination of chlorophyll (Chl) estimation and assessment of photosynthetic activity, both differentiated into the main algal groups. The reliability of fluorescence-based Chl estimation strongly depends on the group specific calibration of the instrument and the resulting chlorophyll/fluorescence (Chl/F) ratios in reference algal cultures. A very high reliability of the Chl estimation was obtained in the case of constant Chl/F-ratios. Algae grown at different light intensities showed marked differences in Chl/F-ratios, reflecting differences in pigment composition and Chl a specific absorption (a*). When the Phyto-PAM was calibrated with laboratory grown diatoms, the Chl a in river grown diatoms was underestimated, due a lower content of accessory pigments and stronger pigment packaging. While this aspect presently limits the application of PAM fluorometry in limnology, this limitation may be overcome by future technical progress in the detection of dynamic changes in Chl/F-ratio via fluorescence-based measurements of the functional PS II absorption cross-section. Practically identical Chl/F-ratios were found for the diatom-dominated waters of the rivers Saar and Saale, suggesting that the same instrument calibration parameters may be applied for hydrographically similar surface waters. For this particular case, despite of the present methodological limitations, the potential of PAM fluorometry in limnology could be demonstrated. Light response curves were measured to estimate primary production with a spectrally resolved model in daily courses at two sampling sites. Fluorescence based primary production was closely correlated with measured oxygen evolution rates until midday. In the afternoon, at the water surface the fluorescence approach gave higher rates than the measured oxygen evolution. Possible explanations for the observed differences are discussed.

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Section: Modelling Of Primary Production In Natural Phytoplanktonmentioning

confidence: 99%

Estimation of chlorophyll content and daily primary production of the major algal groups by means of multiwavelength-excitation PAM chlorophyll fluorometry: performance and methodological limits

et al. 2005

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“…Characteristic features common to the carotenoids encountered are a high proportion of epoxidic carotenoids (78-86%), allenic carotenoids (24-82%), acetylated carotenols (18-81%), and acetylenic carotenoids (61-67%; Group I only). The xanthophycean cultured alga Pleurochloris meiringensis contains heteroxanthin, diadinoxanthin, and β-carotene (279). Carotenoids extracted from freshwater red tide plankton were shown to include β-carotene (8.1%), peridinin (26.5%), dinochrome A (14.3%), dinochrome B (2.7%), dinoxanthin (1.7%), diadinochrome A (170, 2.7%), diatoxanthin (172, 6.8%), and 13′-cis-7′,8′-dihydroneoxanthin-20′-al 3′-β-lactoside (4.7%).…”

Section: Metabolites Of Macro-and Microalgal Speciesmentioning

confidence: 99%

Anticancer activity of natural and synthetic acetylenic lipids

Dembitsky¹

2006

Lipids

129

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This review is a comprehensive survey of acetylenic lipids and their derivatives, obtained from living organisms, that have anticancer activity. Acetylenic metabolites belong to a class of molecules containing triple bond(s). They are found in plants, fungi, microorganisms, and marine invertebrates. Although acetylenes are common as components of terrestrial plants, fungi, and bacteria, it is only within the last 30 years that biologically active polyacetylenes having unusual structural features have been reported from plants, cyanobacteria, algae, invertebrates, and other sources. Naturally occurring aquatic acetylenes are of particular interest since many of them display important biological activities and possess antitumor, antibacterial, antimicrobial, antifouling, antifungal, pesticidal, phototoxic, HIV-inhibitory, and immunosuppressive properties. There is no doubt that they are of great interest, especially for the medicinal and/or pharmaceutical industries. This review presents structures and describes cytotoxic and anticancer activities only for more than 300 acetylenic lipids and their derivatives isolated from living organisms.

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“…It has been postulated that the mechanism regulating PSII excitation energy density is light intensitydependent rather than light quality-dependent (Owens, 1986b). This was also observed in the Chl c-containing alga Pleurochloris meiringensis (Buchel et al, 1988), where changes in PSII absorption section occurred in response to light intensity and not wavelength.…”

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confidence: 93%

Photochemical and Nonphotochemical Fluorescence Quenching Processes in the Diatom Phaeodactylum tricornutum

1993

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Nonphotochemical fluorescence quenching was found to exist in the dark-adapted state in the diatom Pbaeodactyhm tricornutum. Pretreatment of cells with the uncoupler carbonylcyanide mchlorophenylhydrazone (CCCP) or with nigericin resulted in increases in dark-adapted minimum and maximum fluorescence yields. This suggests that a pH gradient exists across the thylakoid membrane in the dark, which serves to quench fluorescence levels nonphotochemically. The physiological processes involved in establishing this proton gradient were sensitive to anaerobiosis and antimycin A. Based on these results, it is likely that this energization of the thylakoid membrane is due in part to chlororespiration, which involves oxygen-dependent electron flow through the plastoquinone pool. Chlororespiration has been shown previously to occur in diatoms. In addition, we observed that cells treated with 3-(3,4-dichlorophenyI)-l,l-dimethylurea exhibited very strong nonphotochemical quenching when illuminated with actinic light.The rate and extent of this quenching were light-intensity dependent. This quenching was reversed upon addition of CCCP or nigericin and was thus due primarily to the establishment of a pH gradient across the thylakoid membrane. Preincubation of cells with CCCP or nigericin or antimycin A completely abolished this quenching. Cyclic electron transport processes around photosystem I may be involved in establishing this proton gradient across the thylakoid membrane under conditions where linear electron transport is inhibited. At steady state under normal physiological conditions, the qualitative changes in photochemical and nonphotochemical fluorescence quenching at increasing photon flux densities were similar to those in higher plants. However, important quantitative differences existed at limiting and saturating intensities. Dissimilarities in the factors that regulate fluorescence quenching mechanisms in these organisms may account for these differences.One process that competes directly with photochemistry for deactivation of excited-state energy is fluorescence emission from Chl a molecules of the PSII antenna. Changes in the proportion of excited states utilized for photochemistry will result in changes in fluorescence intensity. In recent years, it has been shown that both photochemical and nonphotochemical processes reduce the yield of fluorescence during photosynthesis (Krause et al., 1982). However, our current knowledge of these processes is based primarily on studies with higher plants and green algae. The components involved in qP are present in the PSII reaction center, which has been found to be highly conserved throughout evolution (Thornber, 1986). It is therefore likely that the mechanism of photochemical quenching has also been conserved. In contrast, a diverse group of underlying processes controls qN, whose primary site of action is thought to be in the lightharvesting antennae. With the extensive diversity in the composition of light-harvesting complexes among the algae, it is likely that the m...

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The Molecular Analysis of the Light Adaptation Reactions in the Yellow‐green AlgaPleurochloris meiringensis(Xanthophyceae)

Abstract: KeywordsAlgae, energy distribution, light adaptation, thylakoid structure.

Cited by 18 publications

References 18 publications

Estimation of chlorophyll content and daily primary production of the major algal groups by means of multiwavelength-excitation PAM chlorophyll fluorometry: performance and methodological limits

Estimation of chlorophyll content and daily primary production of the major algal groups by means of multiwavelength-excitation PAM chlorophyll fluorometry: performance and methodological limits

Anticancer activity of natural and synthetic acetylenic lipids

Photochemical and Nonphotochemical Fluorescence Quenching Processes in the Diatom Phaeodactylum tricornutum

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