Dichroism of bacteriochlorophyll in cells of the photosynthetic bacterium Rhodopseudomonas palustris

1. The dichroism was measured at varied wavelengths of polarized light in “intact” cells of Rhodopseudomonas palustris and in films of air-dried lamellar fragments of the bacterium.     

A simple method forin situ freezing of anchorage-dependent cells including rat liver parenchymal cells

We developed a simple method for freezing anchorage-dependent cells, including primary cultured rat liver parenchymal cells, without detaching the cells from the culture dish. The method consists of preculture of the cells to confluence, changing the growth medium to a conventional freezing medium, packaging in a container, and storage at –80°C. After thawing and changing the freezing medium to regular growth medium, cell growth was nearly identical to that of cells freshly seeded into a new dish.     

Respiratory System of Rhodotorula glutinis I. Inhibitor Tolerance and Cytochrome Components

Oxygen uptake by the carotenoid-containing yeast, Rhodotorula glutinis was not affected by concentrations of cyanide and antimycin A which completely inhibit the respiration of Saccharomyces cerevisiae. The tolerance of R. glutinis to these inhibitors was somewhat dependent on the age of the cultures. Reduced minus aerated difference spectra of cells revealed spectral changes presumably due to cytochromes and carotenoids. The kinetics of these spectral changes induced by oxygen were followed. Carotenoid deficient cells were prepared by growth in the presence of diphenylamine. Difference spectra of these cells revealed the presence of flavoprotein, and a, b, and c type cytochromes. Growth of R. glutinis was completely inhibited by concentrations of cyanide which did not affect respiration. Oxidation of reduced nicotinamide adenine dinucleotide by sub-cellular fractions was sensitive to cyanide and antimycin A. Although respiration of intact cells is tolerant to these inhibitors, studies with cell-free extracts suggest the presence of a cyanide and antimycin A-sensitive, cytochrome-linked, respiratory chain.     

Changes in Adenine Nucleotides of Intact Chromatium D Produced by Illumination

The total adenine nucleotide content of suspensions of Chromatium D averaged 14 nmoles/mg of dry weight. Of this, one-third to one-half was adenosine triphosphate (ATP), even in suspensions incubated in darkness. Illumination with high intensities caused a rise in ATP and a drop mainly in adenosine diphosphate, the new steady state being reached in 5 to 15 sec at room temperature. The dark steady state was re-established 15 to 30 sec after returning the suspensions to darkness. The rates of these changes were little affected by the presence of electron donors or CO(2), though their magnitude was reduced when substrates were added to starved suspensions. At limiting light intensities, complex kinetics characterized the transition from both dark to light and light to dark, and, at lower light intensities, more ATP was produced in suspensions supplemented with electron donors than in starved cells. The results show that photophosphorylation accompanying cyclic electron flow occurred in intact cells, and suggest that noncyclic phosphorylation can also occur.     

Average distance between bacteriochlorophyll molecules on chromatophore membranes of Rhodopseudomonas sphaeroides

The average distance betweeen bacteriochlorophyll moleculeson the chromatophore membrane of Rhodopseudomonas sphaeroideswas estimated by two methods: measurement of the ratio of thenumber of chromatophores to the number of polystyrene-latexparticles mixed in a chromatophore suspension and measurementof the packed volume of chromatophores in the suspension. Theaverage distance was obtained under the assumption that bacteriochlorophyllmolecules are positioned at hexagonal lattice points. The valuewas 34 A{ring} when the bacteriochlorophyll molecules were assumedto be on one side of the membranes and 48 A{ring} when theywere assumed to be on both sides. (Received February 20, 1978; )