Reductive alkylation of ribosomes as a probe to the topography of ribosomal proteins

Escherichia coli ribosomes were treated with a number of different aldehydes of various sizes in the presence of NaBH(4). After incorporation of either (3)H or (14)C, the ribosomal proteins were separated by two-dimensional polyacrylamide-gel electrophoresis and the extent of alkylation of the lysine residues in each protein was measured. The same pattern of alkylation was observed with the four reagents used, namely formaldehyde, acetone, benzaldehyde and 3,4,5-trimethoxybenzaldehyde. Every protein in 30S and 50S subunits was modified, although there was considerable variation in the degree of alkylation of individual proteins. A topographical classification of ribosomal proteins is presented, based on the degree of exposure of lysine residues. The data indicate that every protein of the ribosome has at least one lysine residue exposed at or near the surface of the ribonucleo-protein complex.     

Inhibition of enzymes by metal ion-chelating reagents. Theory and new graphical methods of study

1. The mechanism of inhibition of enzymes by metal ion-chelating reagents is discussed and equations derived. 2. Two distinct mechanisms are postulated and graphical methods are given for differentiating between them. 3. Where the metal ion is actually removed from the enzyme to form a co-ordination complex in solution, a procedure is described for obtaining the stability constant for metal-enzyme interaction, the number of metal ions involved and the stoicheiometry of metal ion-ligand interaction.     

Alkaline phosphatase of Drosophila melanogaster. II. Biochemical comparison among four allelic forms

Biochemical analyses of partially purified preparations of APH-4 and -6 (common allelic forms) and APH-2 and -10 (rare allelic forms) of D. melanogaster reveal that the two common forms are similar in all properties investigated except for pH optimum (8.0 vs. 8.5). The common and rare forms share certain properties in common but differ in that the common forms are more stable to heat and more sensitive to inhibition by inorganic phosphate. With respect to such properties as substrate preferences and K _i values for inorganic phosphate, the common forms and APH-2 are similar to one another, whereas APH-10 is distinctly different. All four activities show preference for a phosphoaromatic compound as substrate, with O-phosphotyrosine being the best substrate of biological origin. Transphosphorylation, as related to these allelic forms of APH, is discussed.Paper No. 3892 of the Journal Series of the North Carolina State University Agricultural Experiment Station, Raleigh, North Carolina. This study was supported by Atomic Energy Commission Contract AT-(40-1-)-3980.     

Effect of Gibberellic Acid on the Elongation Rate of Agrostis alba Root Hairs

The influence of gibberellic acid over a wide range of concentrations on the rate of elongation of root hairs of redtop grass was investigated. The rate of root hair elongation was increased by GA over the concentration range of 10^?7 to 10^?12 M inclusive, with peak stimulation occurring at 10^?6 M. Although root hair growth was slightly accelerated by 10^?6 M GA, this concentration damaged many root hairs and caused some to stop growing altogether. Rate of root hair elongation was reduced to less than 84% of the control by 10^?5 M GA.     

Wall-softening enzymes in the gynoecium and pollen of Hemerocallis fulva

Summary Variations in extractable cellulase and pectinase were followed during development of Hemerocallis (day lily) flowers. A peak in cellulase activity occurs in the pistil just prior to anthesis, followed by a 62% diminution in the enzyme activity at the time of anthesis. Cellulase activity, per mg protein, is about twice as high in the upper (stigma) portion as in the middle and lower one-third of the pistil tissues. No pectinase activity was detected in the pistil at all stages of development. Extractable pectinase is present at a maximum level in the very young ovary; it decreases rapidly as the ovary develops. Cellulase remains at a moderate level of activity throughout the development of the ovary, except for an increase of about 50% at pollination. Soluble cellulase and pectinase are found in mature pollen. The changes in the cell-wall hydrolytic enzymes in the pistil were pollen-tube growth. It may also promote changes in the cell walls of the pistil cells, although metabolism of the middle lamella during pollen germination is primarily controlled by pollen pectinases.A contribution of the Florida Agricultural Experiment Station, Journal Series No. 3070.     

Electron microscopy of crystalline micelles in cellulose elementary fibrils of Dictyostelium discoideum

Summary In negatively stained preparations the cellulose of Dictyostelium discoideum appears in the form of 35 Å wide fibrils of undetermined length. Upon mild acid hydrolysis a periodic pattern may be observed along the fibrils, in the form of fine, electron-dense bands across the full diameter of the fibril spaced apart from each other by electron-transparent segments approximately 100 Å long. We propose that the electron-transparent segments represent the crystalline micelles of the elementary cellulose fibril, whereas the electron-opaque bands represent the amorphous regions.Part of a thesis submitted by the senior author in partial fulfillment of the requirements for the Ph.D. degree, University of Hawaii.     

Recherches sur l'utilisation deVagoiavirus melolonthae pour la lutte microbiologique contre les vers blancs

Résumé Les résultats des infections au laboratoire des larves deM. melolontha par le virus de la ≪sphéro?dose≫ ont fait l'objet d'essais sur le terrain dans la Sarthe. Cette expérimentation, en parcelles, préliminaire à des applications à une échelle plus agricole, a mis en évidence la possibilité d'implantation de la maladie dans un sol non contaminé naturellement et le développement de cell-ci avec le temps. D'après cet exemple les possibilités d'emploi de ce type de virus en lutte microbiologique contre les insectes sont discutées.

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Summary The results of laboratory infections ofMelolontha melolontha larvae by the virus of ≪sphero?dosis≫ have been tested in the field in Sarthe. These plot experiments were made preliminary to applications on a larger agricultural scale, and have shown the possibility to implant the disease in a naturally non-infected soil, and the further development of this disease. By this example, the possibilities to use this type of virus in microbial control against insects are discussed.