The biosynthetic pathway of new polyamines in Caldariella acidophila

A spontaneous mutant of Escherichia coli (strain AB2847), selected for resistance to the aminoglycoside antibiotic neamine, shows severe restriction of amber suppressors in vivo. Ribosomes isolated from the mutant exhibit only low misreading in vitro in the presence of the antibiotic. Genetic and biochemical analyses indicate that the neamine-resistant phenotype is the result of two distinct mutations. The first, res3128, appears to affect the gene (strA) coding for the ribosomal protein S12. Although it leads to a restrictive phenotype it does not, however, confer resistance to streptomycin. The second mutation, X3128, is located between the sirA and AROB loci and is lethal when segregated from the res3128 mutation. It may affect the ribosome at the level of a post-translational modification.     

Localization of acid phosphatase activity in the liver of pregnant rats

Synopsis In the liver of pregnant rats, fedad libitum, there was an increase in acid phosphatase specific activity which occurred in two peaks, one at the 15th day and the other at the end of gestation. By light and electron microscopic histochemistry, the activity was found to be localized in parenchymal cell peribiliary dense bodies and also in phagosomes present in macrophages and parenchymal cells. There was an increase in liver weight which reached a peak at the 17th day of gestation. Total DNA also rose to the 17th day; there was a high rate of cell division in the hepatic parenchyma at the 17th and 18th days of gestation. During this period single cell deletion by apoptosis was relatively frequent and in late pregnancy there was evidence of cell deletion by lysis.During pregnancy there was a slight increase in sinusoidal macrophages as a proportion of the total cell population but there did not appear to be significant changes in macrophage enzymic activity. It is suggested that the acid phosphatase activity present in macrophages makes a minor contribution to total liver activity, most of which is present in parenchymal cells. Acid phosphatase activity associated with single cell deletion appears to be quantitatively negligible.There was a direct relationship between total hepatic acid phosphatase activity and the numbers of peribiliary dense bodies, which were most numerous at the 15th day and at the end of gestation. It is suggested that these residual bodies contain products of detoxification processes and also cell structural elements resulting from enhanced liver metabolism and intracellular turnover during pregnancy.     

ON THE MECHANISM OF ELECTROSHOCK-INDUCED INHIBITION OF PROTEIN SYNTHESIS IN RABBIT CEREBRAL CORTEX

Abstract— The mechanism of electroshock (ES)-induced inhibition of protein synthesis in rabbit cerebral cortex has been investigated by using a cell-free system. The protein biosynthetic activity of the post-mitochondrial supernatant (PMS) obtained from the cerebral cortex of ES-treated animals was found to be markedly lower than in controls (C). This inhibition was accompanied by a decrease of polysomes and an increase of monomers. In addition, a relative increase in light polysomes was evident at short intervals after ES treatment. No difference was found in the total soluble activity and in the activity of the elongation factors and ribonuclease present in the cell sap of C and ES animals. The biosynthetic activity of ES-total. free and membrane-bound ribosomes was approx 45% lower than that of the corresponding C fractions: polysome/monomer ratios were similarly reduced. The total content of cortical ribosomes was not affected by ES. Following ES treatment there was no change in the ribo-somal ability to elongate, terminate and release polypeptide chains, nor a decrease in the polysomal content of poly(A)-containing mRNA. These data strongly suggest that the ES-induced inhibition of protein synthesis results from a defect in the initiation process. The possible mechanisms mediating this defect have been discussed.     

The action of cyclic somatostatin on hypoglycemia due to prolonged fasting in normal animals]

The authors have examined the action of cyclic Somatostatin on blood glucose levels in normal rats and in rats starved for 36 and 50 hours. The infusion of 0,235 gamma/min. of Somatostatin for thirty minutes in the normals induced a slight increase in blood glucose levels that was statistically non significative. Under the same condition, the cyclic Somatostatin increased, in a statistically significant way, the levels of plasma glucose in both starved groups of rats.     

Banding patterns of the chromosomes ofCercopithecus neglectus: Comparison withMiopithecus talapoin andErythrocebus patas

The G, Q, and C bands and the location of the nucleolar organizing regions (NORs) of the chromosomes of two male Cercopithecus neglectusare described. The diploid number of the species is 2n =62. Comparison with the karyotypes of Miopithecus talapoin (2n =54), and Erythrocebus patas (2n =54)showed the presence of total banding homeology for only 10 chromosome pairs.     

Gene dose effect: intraband mapping of the LDH A locus using cells from four individuals with different interstitial deletions of 11p

The quantitative expression of LDH A was studied in hemolysates from four patients with different but overlapping interstitial deletions of the short arm of chromosome 11. Deficiency of LDH A was demonstrated in one patient, and the LDH A locus has been assigned to that segment of 11p for which this patient alone was deficient, i.e., to band 11p12 (region 11p1203 leads to 11p1208).     

Effect of papulacandin B on β-glucan synthesis in Schizosaccharomyces pombe

Abstract The antifungal antibiotic papulacandin β inhibited B(1,3)glucan-synthase activity, in vitro, from Schizosaccharomyces pombe . Levels of β(1,3)glucan-synthase from antibiotic-treated cultures were lower than the control cultures whereas mannan-synthase and β(1,3)glucanase activities were almost unaffected. The presence of an osmotic stabilizer reduced the inhibition of growth caused by the antibiotic. Addition of papulacandin β to a culture of S. pombe specifically inhibited incorporation of glucose into the β-glucan cell wall fraction. The fatty acids as well as the hydroxyl groups on the phenol residue of the papulacandin β molecule were essential for the inhibitory activity.     

Mutants of Saccharomyces cerevisiae cell division cycle defective in cytokinesis. Biosynthesis of the cell wall and morphology

The four temperature-sensitive mutants of Saccharomyces cerevisiae in the cell division cycle defective in cytokinesis (cdc, 3, 10, 11 and 12), have been analyzed with respect to the biosynthesis of the cell wall polymers. After 3 hours of incubation at the non-permissive temperature (37°C) these strains stop growing. The synthesis of glucan, mannan and chitin (wall polymers) level off in a similar time, but glucan, mannan and chitin synthases remained active for at least 4 hours.If the mutants are analyzed by transmission and scanning electron microscopy different pictures emerge. Two of the mutants cdc 10 and cdc 12, after 3 hours of incubation at 37°C present apparently normal cytoplasms and cell wall surfaces with multiple elongated buds. The other two mutants, cdc 3 and cdc 11, present a completely disarranged cytoplasmic content and damage at the level of the plasma membrane is evident.These and other observations, suggest that between the execution points of cdc 3 (0.27) and cdc 10 (0.58), essential processes in the assembly of cell membrane occur.This work was supported in part by a grant from la Comisión de Investigación Científica y Técnica of the Spanish Ministerio de Educación y Ciencia (Project no. 4593-1980).     

The granin (chromogranin/secretogranin) family

The chromogranins/secretogranins, referred to in abbreviated form as granins, are a family of acidic secretory proteins that are found in the secretory granules of a wide variety of endocrine cells and neurons, being stored together with many different peptide hormones and neuropeptides. The recent elucidation of their primary structure has provided insights into possible functions of these proteins. Moreover, the granins have been successfully used as markers for normal and neoplastic endocrine and neuronal cells, as well as model proteins to understand the sorting mechanism involved in the formation of secretory granules.