Conversion of squalene-2(3)epoxide by enzymes of Alnus glutinosa

The incubation of [1-¹⁴C]-squalene-2(3)epoxide ([1-¹⁴C]-SO) with a cell-free extract of Alnus glutinosa gave only cycloartenol in 1% yield.     

Occurrence and accumulation of the granulosis virus of Pieris rapae in treated field plots

The granulosis virus of Pieris rapae, the imported cabbageworm (P. rapae GV), persisted in soil after application. Virus produced by epizootics of the disease in populations of the host accumulated in soil in nontreated plots with concentrations of the virus in soil and on foliage, being similar at harvest to concentrations in virus-treated plots. Also P. rapae GV produced in epizootics of the disease increased concentrations in soil of virus-treated plots and maintained substantial residues of the virus on the foliage. Little virus accumulated in plots treated with some chemical insecticides and Bacillus thuringiensis because few host larvae survived to support late-season epizootics. Small quantities of P. rapae GV were found in heads of cabbage harvested from plots in October, but these residues were not related to plot treatment.A study in which nontreated and virus-treated plots were replanted for 2 years after treatment indicated an increase in concentrations of P. rapae GV in surface soil in years following treatment. Concentrations of P. rapae GV in soil in virus-treated and nontreated plots were similar in the autumn of the year of treatment and in subsequent years of the study. Concentrations were nearly unchanged during the winter, were reduced by cultivation preparatory to planting in the spring, and increased with epizootics of the disease in host populations in summer and autumn.P. rapae GV disease was prevalent during September and October in populations of P. rapae larvae in plots in which substantial concentrations of the virus were found and contributed to late-season control of the pest insect.     

Quasi-elastic light scattering study of salt induced conformational transitions of chromatin subunit

The translational diffusion coefficient D_T of monodisperse solutions of 146 base pairs (bp) core particles was studied by the quasi-elastic light scattering technique. When the salinity was raised a change of D_T from 1.9 × 10^?7 cm² s^?1 to 3.2 × 10^?7 cm² s^?1 was detected at about 2 mM NaCl, followed by a smooth decrease of D_T beyond 0.6 M NaCl. The measurements of particle concentration and scattering vector effects on the D_T showed that the influence of interactions between particles can be disregarded. The interaction between particles and counterions is also discussed and does not appear to be the origin of the actual changes in D_T. These transitions of D_T are hence related to changes of shape and size of the particles. It is shown that the single transition at low salinity corresponds to a conformational change while the variation of D_T at high salinity can be interpreted by a destabilization of the edifice. In different regions of salinities, the observed values of D_T can lead to reasonable hydrodynamic models.     

Identification and quantitation of heparins by microelectrophoresis on agarose gel

The microelectrophoresis procedure on agarose devised by Jaques, Ballieux, Dietrich, and Kavanagh (1) for the identification and measurement of heparin provides a quick, versatile, and adaptable procedure. Differentiation of heparin and related polyanions can be accomplished at various stages of the procedure—migration, fixation, staining, destaining, evaluation. Tests such as solubility in solvents, precipitation by chemical reagents, action of enzymes, may be applied to minute amounts of materials.A linear relationship was observed between absorbance and heparin concentration applied and between log of spot area and log concentration so that total optical density of spots can be used to estimate heparin. Visual comparison of microelectrophoresis slides with a series of reference slides with 0.02 to 0.6 units of heparin gave a coefficient of variation of 15.5%. Difficulty was found in providing a densitometer with sufficient sensitivity and reproducibility. Special slide holders were designed to hold the microelectrophoresis slide in the Chromoscan densitometer and in the Beckman DK-2 spectrophotometer. By specifying carriage position for the slide, slit size in the optical system, baseline adjustment, background correction, light filter, reproducibility of measurement could be achieved with the Chromoscan densitometer with 10% maximum error with low counts. The Coefficient of Variation was 6.2% when all precautions were taken.     

Isoprostanes in fetal and neonatal health and disease

Isoprostanes are prostaglandin-like bioactive molecules generated via nonenzymatic peroxidation of lipid membrane-derived arachidonic acid by free radicals and reactive oxygen species. Their cognate receptors, biological actions, and signaling pathways are poorly understood. Aside from being sensitive and specific biomarkers of oxidative stress, E- and F-ring isoprostanes have important biological functions and likely mediate many of the disease-related pathological changes for which they are used as indicators. The biochemical pathways involved in isoprostane formation, their pathogenetic relevance to adult disease states, and their biological function are addressed. Developmentally, plasma and tissue content data show that isoprostane levels are highest during fetal and early neonatal life, when compared with adults. As such, the available data suggesting that isoprostanes play an important biological role, as well as possibly actively participate in the regulation of pulmonary vascular tone and the transition from fetal to postnatal life, are here reviewed. Lastly, the association between isoprostanes and certain neonatal clinical conditions is addressed. Although its existence has been recognized for almost 20 years, little is known about the critical importance of isoprostanes during fetal life and immediate neonatal period. This review is an attempt to bridge this knowledge gap.     

Rat liver nuclear protein kinases NI and NII. Purification, subunit composition, substrate specificity, possible levels of regulation

Rat liver nuclear protein kinases NI and NII have been purified to homogeneity by an improved method. This method includes a casein-phosvitin-Sepharose column step, which separates the enzymes from the other chromosomal non-histone proteins, and a gel filtration at high ionic strength in the presence of a high concentration of protease inhibitors to separate the two enzymes from each other. NI has an apparent molecular mass of approximately 50 kDa and is composed of a single subunit. NII has an apparent molecular mass of 133 kDa and is composed of two subunits of identical molecular mass. The V and the Km of the two enzymes were determined for several substrates. Both enzymes phosphorylate chromosomal non-histone proteins with partly different specificities as shown by two-dimensional electrophoreses. When incubated in the absence of protease inhibitors, the enzymes were degraded into discrete polypeptides. Autophosphorylation of a polypeptide derived from NII was observed after incubation of the enzyme with ATP. This phosphorylation stimulated the enzyme activity. Several chromosomal proteins coeluted with NII from the casein-phosvitin-Sepharose column. They remained associated with the enzyme in sucrose gradients, during gel filtration performed at physiological ionic strength, and are dissociated at high ionic strength. These proteins were highly phosphorylated when the protein-NII complex was incubated with ATP.     

Stimulation of human lymphocytes by phorbol acetate and a calcium ionophore induces an early transient expression of the c-fos oncogene followed by c-myc

After stimulation of human lymphocytes by 12-0 tetradecanoyl phorbol acetate (TPA) and by the calcium ionophore A23187 an early transient expression of proto-oncogene fos followed by an expression of c-myc is observed, as has been described in rodent fibroblast stimulated by growth factors. This observation suggests a direct role of protein Kinase C and of calcium flux an the induction of cellular oncogenes fos and myc that may be associated with the early steps of activation and proliferation of lymphocytes.