Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

Zvezdanović, Jelena; Cvetic, Tijana; Veljović-Jovanović, Sonja; Marković, Dejan

doi:10.1016/j.radphyschem.2008.07.006

Cited by 47 publications

(33 citation statements)

References 32 publications

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“…It is likely to consider that the red shift of the pigment red maximum in liposomes is due to the polar environment in which the porphyrin macrocycle is located -the lipid-water interface in the vicinity of polar lipid heads, rather than to the presence of the pigments in aggregated forms (dimers). The concentration of pigments in liposomes is low (approximately 10 -6 M) and usually at this concentration, the monomeric form is dominant, even in non-polar solvents (Zvezdanović et al 2009). The comparison with the red band position of Chla, recorded in a native, highly-organized structure of pigment-protein complexes of isolated thylakoids -where Chls exist in aggregated form with the maximum at 679 nm (Santabarbara 2006) -is pleading also for the existence of pigments mainly in monomeric form in the lipid bilayers of liposomes.…”

Section: Discussionmentioning

confidence: 99%

“…Chlorophyll fraction (Chla with 4% traces of Chlb) was isolated by column chromatography with silica gel as the adsorbent (silica gel 60, Merck, 0.063-0.200 mm) and n-hexane/acetone mixture as the eluent (Zvezdanović et al 2009). The n-hexane/acetone ratio was changed from initial 1:0 to final 1:1 (v/v), to permit an easier elution of the polar fractions.…”

Section: Chlorophyll Extractionmentioning

confidence: 99%

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Comparative spectroscopic studies on liposomes containing chlorophyll a and chlorophyllide a

Milenković¹,

Barbinta-Patrascu²,

Baranga³

et al. 2013

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Abstract. Chlorophyll a (Chla) and chlorophyllide a (Chlida) -a derivative of Chla, have been incorporated in the lipid bilayers of two types of liposomes, small unilamellar vesicles (SUV) and multilamelar vesicles (MLV). The objective of the present work was to compare the spectral behaviour of Chla and Chlida incorporated in the lipid bilayers and their sensing behaviour at molecular level. The VIS absorption and fluorescence emission presented differences depending on the type of liposomes and inserted pigment, reflecting the different localization of porphyrin macrocycle in the lipid moieties. The temperature dependence of emission anisotropy and fluorescence intensity, for both Chla and Chlida incorporated in DPPC SUV, revealed the presence of different lipid phases. The degree of incorporation of quercetin (QCT) in liposome membrane was studied by using Chla and Chlida as molecular sensors. The fluorescence polarisation data and the fluorescence quenching process provided arguments for the insertion of the QCT at the interface lipid/water, in the vicinity of lipid polar heads and porphyrin macrocycle. The phytyl chain of Chla penetrating in the hydrophobic core of the lipid bilayers is responsible for the observed differences among Chla and Chlida in sensing the lipid phase transition and the fluorescence quenching process induced by QCT.

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Section: Discussionmentioning

confidence: 99%

Section: Chlorophyll Extractionmentioning

confidence: 99%

Comparative spectroscopic studies on liposomes containing chlorophyll a and chlorophyllide a

Milenković¹,

Barbinta-Patrascu²,

Baranga³

et al. 2013

gpb

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“…It is possible that some of these organisms represent phylogenetic lineages that recently lost phototrophy. Alternatively, these cells may be phototrophs (or mixotrophs) with pigment fluorescence below FACS detection limit due to photobleaching (Zvezdanovic et al, 2009) or other physiological suppression of fluorescence. The rarefaction analysis demonstrates that neither SAG nor clone libraries were sufficiently large to assess the complete diversity of the analyzed protist sample at an operationally defined 'species' phylogenic resolution of 99% sequence similarity (Supplementary Figure D).…”

Section: Discussionmentioning

confidence: 99%

Capturing diversity of marine heterotrophic protists: one cell at a time

et al. 2010

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Recent applications of culture-independent, molecular methods have revealed unexpectedly high diversity in a variety of functional and phylogenetic groups of microorganisms in the ocean. However, none of the existing research tools are free from significant limitations, such as PCR and cloning biases, low phylogenetic resolution and others. Here, we employed novel, single-cell sequencing techniques to assess the composition of small (o10 lm diameter), heterotrophic protists from the Gulf of Maine. Single cells were isolated by flow cytometry, their genomes amplified, and 18S rRNA marker genes were amplified and sequenced. We compared the results to traditional environmental PCR cloning of sorted cells. The diversity of heterotrophic protists was significantly higher in the library of single amplified genomes (SAGs) than in environmental PCR clone libraries of the 18S rRNA gene, obtained from the same coastal sample. Libraries of SAGs, but not clones contained several recently discovered, uncultured groups, including picobiliphytes and novel marine stramenopiles. Clone, but not SAG, libraries contained several large clusters of identical and nearly identical sequences of Dinophyceae, Cercozoa and Stramenopiles. Similar results were obtained using two alternative primer sets, suggesting that PCR biases may not be the only explanation for the observed patterns. Instead, differences in the number of 18S rRNA gene copies among the various protist taxa probably had a significant role in determining the PCR clone composition. These results show that single-cell sequencing has the potential to more accurately assess protistan community composition than previously established methods. In addition, the creation of SAG libraries opens opportunities for the analysis of multiple genes or entire genomes of the uncultured protist groups.

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“…Chloroplastic pigments are lipophilic compounds (FernandezOrozco et al, 2011) and chlorophylls as no phenolic compound (in all known forms) have two major absorption bands in the visible range, "red" and "blue" and absorption maxima (A max ) for Chlorophyll "a" and "b" in acetone are located at 662.10 and 645.50 nm, respectively (Zvezdanović et al, 2009). In this context, the INT and lipophilic HF fractions present the peaks at different retention times (between 88 and 92 min) with typical spectra of chlorophyll (Supplement Fig.1.c).…”

Section: Determination Of Phenolic Compounds Hplc Analysismentioning

confidence: 99%

HPLC-DAD profile of phenolic compounds and antioxidant activity of leaves extract of Rhamnus alaternus L.

Moussi

Nayak

Perkins

et al. 2015

Industrial Crops and Products

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Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

Cited by 47 publications

References 32 publications

Comparative spectroscopic studies on liposomes containing chlorophyll a and chlorophyllide a

Comparative spectroscopic studies on liposomes containing chlorophyll a and chlorophyllide a

Capturing diversity of marine heterotrophic protists: one cell at a time

HPLC-DAD profile of phenolic compounds and antioxidant activity of leaves extract of Rhamnus alaternus L.

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