Photosynthetic pigments in a warm core eddy of the East Australian Current were studied by In vjvo fluorometry, spectrophotometry and thin-layer chromatography. The Variosens i n sltu fluorometer gave only an approximate guide to the location and quantity of phytoplankton in the water column; spectrophotometric curve analysis revealed the presence of intact or detrital chlorophylls, and quantit...

Acclimation of the photosynthetic apparatus to light absorbed primarily by photosystem I (PSI) or by photosystem II (PSII) was studied in the unicellular red alga Porphyridium cruentum (ATCC 50161). Cultures grown under green light of 15 microeinsteins per square meter per second (PSII light; absorbed predominantly by the phycobilisomes) exhibited a PSII/PSI ratio of 0.26 +/- 0.05. Under red li...

The response regulator RpaA was examined by targeted mutagenesis under high light conditions in Synechocystis sp. PCC 6803. A significant reduction in chlorophyll fluorescence from photosystem I at 77 K was observed in the RpaA mutant cells under high light conditions. Interestingly, the chlorophyll fluorescence emission from the photosystem I trimers at 77 K are similar to that of the wild typ...

Gut fluorescence attributable to algae caten by an herbivorous zooplankter should be a function of chlorophyll consumption minus loss of pheopigments in defecation. The amount of chlorophyll ingested, as determined in a laboratory grazing experiment, minus the gut pigment content at the end in the grazers, should equal chlorophyll dcfecatcd and should also provide a calibration for the determin...

Accurate quantification of pigments in mixtures is essential in all cases in which separation of pigments by chromatography is impracticable for one reason or another. An example is the analysis of in vivo formation of heavy metal-substituted chlorophylls in heavy metal-stressed plants. We describe here a novel, accurate UV/VIS spectrophotometric method for the quantification of individual chlo...

Light absorbed in the far red limit of the absorption spectrum of green plants shows a poor yield of photosynthesis but is enhanced to much greater efficiency when it is supplemented by shorter wave length light1. These two colour effects were a first hint to suppose 20 years ago that the primary reaction of photosynthesis may perhaps be sensitized by two pigments, a long wavelength and a short...

Subpicosecond fluorescence upconversion has been used to measure the rate of chlorophyll b to chlorophyll a electronic energy transfer in situ within the LHC pigment proteins of Chlamydomonas reinhardtii mutant C2. The time scale of energy transfer is 0.5 & 0.2 ps as determined from the rise time of chlorophyll a fluorescence following chlorophyll b excitation. Estimates of the energy-transfer ...

Fine structure, pigment content and photosynthetic activity of variegated leaves of Euonymus fortunei var. radicans have been studied in detail. The middle dark-green leaf areas contain normal chloroplasts with large grana. Their chlorophyll content is high, as is their photosynthetic activity. The marginal leaf areas with mutant plastids are highly light-sensitive. When grown in the shade they...

BACKGROUND The evidence for red meat as a determinant of colorectal cancer remains equivocal, which might be explained by differences in heme content. Heme is the pro-oxidant, iron-containing porphyrin pigment of meat and its content depends on the type of meat. Chlorophyll from green vegetables might modify this association. METHODS The Netherlands Cohort Study was initiated in 1986 when a s...