Intracellular location of carbonate dehydratase (carbonic anhydrase) in leaf tissue

Two proteins which have carbonate dehydratase (carbonic anhydrase, EC 4.2.1.1) activity were shown to be in the chloroplasts and in the cytosol of leaves of Brassica chinensis, Spinacia oleracea, and in variegated leaves of Tradescantia albiflora and Hedera canariensis. The chloroplastic enzyme is smaller than the one in the cytosol, as it runs farther on gradient polyacrylamide gels. It was separated from the other by isolation of chloroplasts of Brassica and Spinacia on sucrose density gradients; approximately half of the total activity was in the chloroplasts.     

Isometric virus-like particles from citrus red mites, Panonychus citri

Virus-like spherical particles found in laboratory-reared citrus red mites but not in field populations were independent of the pathogenic virus affecting this species. Three sizes of particles are present: 18-nm spheres occuring in crystalline array, and 30- and 37-nm spheres. The particles possess antigenic properties and contain RNA.     

Magnetic resonance studies on manganese-nucleotide complexes of phosphoglycerate kinase.

Measurements of the relaxation rate of water protons (PRR) have been used to study the interaction of yeast phosphoglycerate kinase with the manganous complexes of a number of nucleotides. The results indicate that phosphoglycerate kinase belongs to the same class of enzymes as creatine kinase, adenylate kinase, formyltetrahydrofolate synthetase, and arginine kinase, with maximal binding of metal ion to tne enzyme in the presence of the nucleotide substrate. However, an analysis of titration curves for a number of nucleoside diphosphates (ADP, IDP, GDP) showed that there is a substantial synergism in binding of the metal ion and nucleotide to the enzyme in the ternary complex. The metal-substrate binds to the enzyme approximately two orders of magnitude more tightly than the free nucleotide; Other evidence for an atypical binding scheme for Mn(II)-nucleoside diphosphates was obtained by electron paramagnetic resonance (EPR) studies; the EPR spectrum for the bound Mn(II) in the enzyme-MnADP complex differed substantially from those obtained for other kinases. An identical EPR spectrum is observed with the MnADP complex with the rabbit muscle enzyme as with the yeast enzyme. In contrast, the dissociation constant for the enzyme-MnATP complex is approximately fourfold lower than that for enzyme-ATP, and there are no substantial changes in the electron paramagnetic resonance spectrum of MnATP2- when the complex is bound to phosphoglycerate kinase. A small but significant change in the PRR of water is observed on addition of 3-phosphoglycerate (but not 2-phosphoglycerate) to the MnADP-enzyme complex. However, addition of 3-phosphoglycerate to enzyme-MnADP did not influence the EPR spectrum of the enzyme-bound Mn(II).     

Binding of thiamin thiazolone pyrophosphate to mammalian pyruvate dehydrogenase and its effects of kinase and phosphatase activities.

The pyruvate dehydrogenase component of the bovine kidney pyruvate dehydrogenase complex has two thiamin-PP binding sites per α₂β₂ tetramer. Titration of these binding sites with the transition state analog, thiamin thiazolone pyrophosphate, strongly inhibits phosphorylation of pyruvate dehydrogenase by pyruvate dehydrogenase kinase and ATP. The analog has little effect, if any, on dephosphorylation of phosphorylated pyruvate dehydrogenase by pyruvate dehydrogenase phosphatase. Phosphorylation of pyruvate dehydrogenase inactivates the enzyme, but does not significantly affect the thiamin-PP binding sites. It appears that phosphorylation produces a conformational change in pyruvate dehydrogenase that displaces a catalytic group (or groups) at the active center.     

Comparisons of dermatoglyphic patterns in monochorionic and dichorionic monozygotic twins

The data presented here indicate that different influences affect dermatoglyphic pattern development in MC-MZ and DC-MZ twins. Only five of 84 variables had significant mean differences but their clustering suggested a real difference in mean placement of the atd angle. Nineteen of 84 variables had significantly different within-pair mean squares for the two twin types. Larger numbers of twins will be required to obtain accurate estimates of the magnitude of the dermatoglyphic differences between MC-MZ and DC-MZ twins. Studies of dermatoglyphics in MC-MZ and DC-MZ twins are important to the understanding of factors which influence early embryonic development and when better documented may provide a mechanism for retrospectively diagnosing placental type of MZ twins.     

Distribution of Methylomonas methanica and Methylosinus trichosporium in Cleveland Harbor as Determined by an Indirect Fluorescent Antibody-Membrane Filter Technique

An indirect fluorescent antibody-membrane filter staining technique, which permitted the autecological study of Methylomonas methanica and Methylosinus trichosporium, was developed. This technique was used to assay the numbers of these two organisms in Cleveland Harbor. The concentrations of M. methanica and M. trichosporium were found to be inversely proportional to the sampling depth, with the highest cell counts observed in the sediments. M. methanica was observed at every sampling station, whereas M. trichosporium was found at only two of the stations.     

A haptoglobin radioassay based on binding to solid-phase hemoglobin.

A specific and sensitive assay for haptoglobin based on binding to an easily prepared Sepharose-bound hemoglobin reagent is described. The assay is suitable for directly determining radiolabeled amino acid incorporation into haptoglobin in several liver cell systems in vitro and can be adapted to measure unlabeled free haptoglobin in plasma samples regardless of the presence of the haptoglobin-hemoglobin complex.     

Study of Developmental Stages of Methylosinus trichosporium with the Aid of Fluorescent-Antibody Staining Techniques

When stained by using an indirect fluorescent-antibody technique, Methylosinus trichosporium displayed an uneven fluorescence. Exospores and the polar tips of some vegetative cells displayed a more intense fluorescence than the other cells. Cross-absorption of the specific anti-M. trichosporium immunoglobulin G with exospores resulted in no fluorescence of exospores or exospore regions of sporulating vegetative cells. This demonstrated that antigens were present on exospores and exospore regions of vegetative cells that are different from vegetative cell antigens. Taking advantage of this phenomenon, three fluorescentantibody staining techniques were developed which were used to study the life cycle of M. trichosporium.     

Plant-herbivore interactions

Summary Plants with the C₄ dicarboxylic acid pathway of photosynthetic CO₂ fixation are generally nutritionally inferior to C₃ (Calvin cycle) plants as foodstuff for herbivores. A possible contributing factor to this nutritional inferiority is the concentration, in C₄ plants, of large quantities of nutritional material in very tough, thick-walled vascular bundle sheath cells which herbivores may not be able to break down. Experiments with 10 species of grass-hoppers from different areas in the United States revealed large numbers of unbroken bundle sheath cells, contents intact, in fecal pellets produced when the grasshoppers were fed C₄ vegetation. We conclude that the material stored in C₄ bundle sheath cells is at least partially unavailable to herbivores, and that this may contribute to the observed nutritional inferiority of C₄ vegetation.