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P Rowell

Publications and source records attributed to P Rowell.

29 records · Page 2Linked to original sources
PubMed1976

A mutant strain of Scenedesmus obliquus deficient in ribulose diphosphate carboxylase, cytochrome f and photosystem II activity.

The partial reactions of photosynthesis shown by strain F208, a non-photosynthetic mutant strain of Scenedesmus obliquus, have been compared with those performed by other mutant strains which lacked; Photosystem II activity (strains 11 and F131), cytochrome f (strain 50), P-700 and cytochrome f (strain F 119), and P-700 (strains F139 and 199). In this respect the properties of strain F208 were those that would be expected if Photosystem II activity and cytochrome f were not present in this strain. Examination of the composition of strain F208 has shown the absence of cytochrome f in both the soluble and the membrane-bound form. The considerably lower level of plastoquinone compared to that found in the wild type is characteristic of the strains which lack Photosystem II activities. Fraction 1 protein could not be detected in extracts of strain F208 by sedimentation velocity experiments in the ultracentrifuge, and only 7% of the wild type ribulose diphosphate carboxylase activity was found after chromatography of these extracts on DEAE-cellulose. The properties of strain F208 are compared with those of the ac-20 and cr-1 strains of Chlamydomanas rheinhardi, both of which have a deficiency of ribulose diphosphate carboxylase which is considered to result from a deficiency of chloroplast ribosomes. Strain F208 resembles these strains in its abnormal chloroplast ultrastructure and its decreased levels of the RNA forms derived from the chloroplast ribosomes when compared with the wild type. Chloroplast fragments isolated from strains of S. obliquus which lacked cytochrome f (strains 50 and F208) were able to use diaminodurene and ascorbate as an electron donor to Photosynstem I. Since this reaction was inhibited by mercuric salts it would appear that plastocyanin, but not cytochrome f, was involved in this electron transfer.

Ascorbic Acid↗
PubMed1975

Alanine dehydrogenase of the N2-fixing blue-green alga, Anabaena cylindrica.

The L-alanine dehydrogenase (ADH) of Anabaena cylindrica has been purified 700-fold. It has a molecular weight of approximately 270,000, has 6 sub-units, each of molecular weight approximately 43,000, and shows activity both in the aminating and deaminating directions. The enzyme is NADH/NAD+ specific and oxaloacetate can partially substitute for pyruvate. The Kampp for NAD+ is 14 muM and 60 muM at low and high NAD concentrations respectively.

Alanine↗
PubMedDate not supplied

Cyanobacteria-eukaryotic plant symbioses.

N2-fixing heterocystous cyanobacteria develop in symbiotic association with a small number of eukaryotic plant species belonging to the algae, fungi, liverworts, ferns, gymnosperms and angiosperm. When the free-living cyanobacteria develop in symbiosis, they become modified morphologically, physiologically and biochemically. The symbiosis are relatively specific, and among the changes which occur in the endophytic cyanobacteria are increases in the size of the vegetative cells, changes in the ultrastructure of the vegetative cells, a tendency for a reduction in the filamentous habit, an increased heterocyst frequency when another photosynthetic partner is present, reduced activities of glutamine synthetase and glutamate synthase, and NH4+ release by; the endophytic cyanobacteria. These and other aspects are considered, emphasizing, in particular, work carried out in the authors' laboratory.

Cyanobacteria↗