Three seedling lethal mutants of Zea mays with impaired photosynthesis are described. These recessive mutants were selected on the basis of high chlorophyll fluorescence. They have normal chlorophyll pigmentation but are unable to fix CO(2) fully. Evidence is presented from fluorescence characteristics of isolated chloroplasts that both photosystem I and II mutants were isolated. Using conventi...

Stroma-freed chloroplasts were extracted with sucrose palmitate-stearate containing buffer. After the addition of dodecyl sulfate and mercaptoethanol to the extract a series of polypeptides was isolated from the mixture by gel filtration. These polypeptides were later used for immunization. Antisera to four polypeptides reacted in the Ouchterlony double diffusion test with authentic coupling fa...

Photosynthetic activities were analyzed in Chlamydomonas reinhardtii mitochondrial mutants affected in different complexes (I, III, IV, I + III, and I + IV) of the respiratory chain. Oxygen evolution curves showed a positive relationship between the apparent yield of photosynthetic linear electron transport and the number of active proton-pumping sites in mitochondria. Although no significant a...

Three polypeptide fractions with the apparent molecular weight 66 000 were isolated from stromafreed Antirrhinum chloroplasts which were solubilized with dodecyl sulfate. Antisera to these fractions affect electron transport in distinctly different ways. For the characterization of the three antisera photochemical reactions of chloroplast preparation with artificial electron donors and acceptor...

The toxic effects of cadmium on the photosynthetic apparatus of Avicennia germinans were evaluated by means of the chlorophyll fluorescence transient O-J-I-P. The chlorophyll fluorescence transients were recorded in vivo with high time resolution and analyzed according to the OJIP-test that can quantify the performance of photosystem II. Cadmium-treated plants showed a decrease in yield for pri...

Yamashita and Butler [I] have shown that extraction of chloroplasts with a high concentration of Tris (0.8 M, pH 8.0) eliminates flow of electrons from water to nicotinamide adenine dinucleotide phosphate (NADP+)* or other Hill oxidants. They suggest that washing with Tris causes a block on the water side of the electron transport chain. Addition of electron donors such as reduced phenylene dia...

Time-resolved fluorescence spectroscopy of tryptophan and two related dipeptides, tryptophylalanine and alanyltryptophan, has been carried out on the subnanosecond time scale by using picosecond exciting pulses at a wavelength of 264 nm. Detection was with an ultrafast streak camera coupled to an optical multichannel analyzer. The zwitterions of these molecules show a definite nonexponential fl...

ABSTRACT Background: accurate methods of radiation therapy dose calculation. There are different Monte Carlo codesfor simulation of photons, electrons and the coupled transport of electrons and photons. MCNPis a general purpose Monte Carlo code that can be used for electron, photon and coupledphoton-electron transport.Monte Carlo simulation of radiation transport is considered to be one of the ...

Redox changes of the flavoproteins of mung bean (Phaseolus aureus) mitochondria were measured by differential absorbance at 468 to 493 nanometers and by fluorescence emission above 500 nanometers excited at 436 nanometers. Four flavoproteins are distinguishable by the ratio of their fluorescence to absorbance changes, and by their requirement, or lack of it, for energy-linked reverse electron t...