Nitrate reductase activity in the course of cucumber leaf ontogenesis

Nitrate reductase activity in the leaves of young plants of cucumber.Cucumis sativus L. cv. Bílská, as determined bothin vitro andin vivo and expressed in terms of fresh weight, gradually changes in dependence on the ontogenetic development of the plants, reaching its maximum before full expansion of the leaves.     

Unit cell and space group of catalase from Micrococcus luteus.

Octahedral shaped crystals of about 1 mm were grown from catalase of Micrococcus luteus. The space group was determined as P4₂2₁2₁ with $\text{a = b = 106.6}\text{A}\text{?}\text{and}\text{c = 106.3}\text{A}\text{?}$. In contrast to mammalian catalase, the bacterial catalase contains only one subunit per asymmetric unit. This proves that the four subunits of bacterial catalase are identical.     

The mitochondrially encoded "phantom ATPase" of S. cerevisiae. II. A heterogeneous mitochondrial ATPase population in situ.

Summary The mitochondrial ATPase from a PHO 1 mutant (OLI 2, PHO 1, OLI 4 region on mit DNA of S. cerevisiae) was further examined. A new purification method using Lysolecithin instead of Triton allowed us to solubilize and separate a heterogeneous ATPase population from PHO 1-mitochondria: the major abnormal fraction had extremely low oligomycin-sensitivity (but normal specific immunological reactivity), while a minor normal fraction (representing about 20% of the initial mitochondrial ATPase activity) had high sensitivity and affinity for oligomycin.Moderate urea treatment of PHO 1-mitochondria leads to partial loss of ATPase activity and a concomitant increase of oligomycin-sensitivity, suggesting that a heterogeneous ATPase population exists in situ in the mitochondrial membrane: part of the major abnormal ATPase fraction is selectively inactivated by urea, producing a concomitant enrichment in the initially minor normal ATPase fraction.If the minor normal ATPase fraction is the only one capable of in vivo ATP synthesis, the deficient but oligomycin-sensitive cell growth and oxidative phosphorylation in vitro are readily explained.Further structural studies are under way to ascertain whether the minor normal ATPase fraction is strictly identical to the wild type, in which case PHO 1 is a regulatory gene, or not, in which case PHO 1 is a structural gene.     

Hemotypes and genetic structure of Camargue horses

The nature and distribution of hemotypes constituted by electrophoretic phenotypes in six loci, in a group of 183 Camargue horses, have been compared with those of five breeds of horses and ponies. The genetic similarities have been observed mainly with New Forest and Haflinger ponies, less with Barbs and Thoroughbreds, and the least with Arab horses.     

Search for a relationship between molecular anomalies of the mutant erythrocyte pyruvate kinase variants and their pathological expression

Summary Anomalies of the mutant pyruvate kinase variants and clinical symptoms have been compared in 22 unrelated patients with congenital red cell pyruvate kinase deficiency. This study suggests that some characteristics of the mutant enzymes could play a role in the intensity of haemolysis, namely residual activity, affinity for the substrate phosphoenolpyruvate and for the allosteric activator fructose 1,6 diphosphate and inhibition by ATP.     

Heparin-inhibitable lectins: Marked similarities in chicken and rat

Extracts of young rat lung contain a heparin-inhibitable lectin that closely resembles one recently purified from chicken liver. Both lectins interact with heparin and N-acetyl-D-galactosamine, and were purified by gel filtration on Sepharose CL-2B followed by affinity chromatography on heparin-Sepharose. They both behave as high molecular weight aggregates that can be dissociated into two peptides with apparent molecular weights of 13,000 and 16,000 by gel electrophoresis in SDS. Samples of purified lectin contained up to 20% DNA by weight, and the degree of lectin aggregation and hemagglutination activity was greatly reduced by treatment with micrococcal nuclease without inhibiting heparin-binding activity. Association of lectin with DNA is an artifact of homogenization in high salt, since only 2% of the lectin is found associated with a purified nuclear fraction.     

Mosaic trisomy 9: Two additional cases

Summary Two unrelated patients were found to be mosaic for an extra chromosome 9 (46,XX/47,XX,+9). The first patient showed a prominent nose, deep set eyes, carp shaped mouth and complex congenital cardiac anomalies. She died of congestive cardiac failure at the age of 10 days. The second patient, was a 7 1/2 year old female who had persistent alacrimia and mental retardation.     

Involvement of IS1 in the dissociation of the r-determinant and RTF components of the plasmid R100.1

Summary Detailed mapping localized the PHO 1 mutation between the OLI 2 and OLI 4 loci on mitochondrial DNA of Saccharomyces cerevisiae.In its mitochondrially integrated form, the PHO 1-ATPase³ was difficult to identify either immunologically or by specific inhibitors like oligomycin and DCCD. Solubilization by Triton X-100 allowed unambiguuous identification of this enzyme as an authentic mitochondrial ATPase. However, Triton extraction produced a 2 to 3 fold enhancement of the PHO 1-ATPase activity which also became drastically cold-sensitive. The wild type ATPase was neither activated nor made cold-labile by solubilization, and retained full sensitivity to oligomycin and DCCD.Sucrose gradient analysis of the Triton-extracted ATPase from wild type, PHO 1 mutant and rho ^- strains showed a density difference between the solubilized PHO 1-and wild type ATPase, and similarity between solubilized PHO 1-and rho ^- ATPase (F₁).Whole cells of the PHO 1 mutant present considerably increased respiration rates.Comparison of oligomycin-sensitivity in whole cells, coupled isolated mitochondria and membrane-bound ATPase indicates a contrast between oligomycin-resistance of the ATPase and oligomycin-sensitivity of in vivo or in vitro coupling systems, which might characterize the products of this region of mitochondrial DNA.     

Reactions of 4β,5-epoxy-5β-androstan-3-ones with hydrogen fluoride in pyridine

4β,5-Epoxy-5β-androstane-3,17-dione ($\text{1a}$), 17β-hydroxy-4β,5-epoxy-5β-androstan-3-one ($\text{1b}$) and 17β-acetoxy-4β,5-epoxy-5β-androstan-3-one ($\text{1c}$) were treated with anhydrous hydrogen fluoride in pyridine (70% solution) at 55° and yielded the corresponding 4-en-4-ols e.g. 4-hydroxy-4-androstene-3, 17-dione ($\text{2a}$).As the reaction temperature was lowered each epoxide formed a second product which, at ?75°, was the major component of the reaction mixture and was identified as the 5α-fluoro-4α-ol derivative of the parent enone, e.g. 4α-hydroxy-5-fluoro-5α-androstane-3,17-dione ($\text{3a}$). These fluorohydrins are thermally unstable, losing hydrogen fluoride.The acetates of the fluorohydrins were also prepared, characterized, and shown to be more stable than the parent alcohols.     

Excretion of citric and isocitric acids by the yeast Saccharomycopsis lipolytica

Summary We investigated the excretion of citric and isocitric acids in a strain of Saccharomycopsis lipolytica grown on either n-paraffins, glucose, or glycerol. These acids were excreted in the ratio of 67:33 on n-paraffins and roughly 92:8 on either glucose or glycerol. However, with all the carbon sources used, the relative amount of isocitric acid in the intracellular pool remained below 10%. The assimilation of citric and isocitric acids was prevented when glucose or glycerol were the carbon sources, but not when n-paraffins were used. Citric acid stopped isocitric acid assimilation. These phenomena of selective assimilation and/or uptake might explain the variations observed in the ratio of citric to isocitric acids excreted on different carbon sources.