Studies on purine transport and on purine content in vacuoles isolated from Saccharomyces cerevisiae

The transport of purine derivatives into vacuoles isolated from Saccharomyces cerevisiae was studied. Vacuoles which conserved their ability to take up purine compounds were prepared by a modification of the method of polybase-induced lysis of spheroplasts.Guanosine > inosine = hypoxanthine > adenosine were taken up with decreasing initial velocities, respectively; adenine was not transported.Guanosine and adenosine transporting systems were saturable, with apparent K_m values 0.63 mM and 0.15 mM respectively, while uptake rates of inosine and of hypoxanthine were linear functions of their concentrations.Adenosine transport in vacuoles appeared strongly dependent on the growth phase of the cell culture.The system transporting adenosine was further characterized by its pH dependency optimum of 7.1 and its sensitivity to inhibition by $\text{S-}\text{adenosyl-}\text{l}\text{-methionine}$.In the absence of adenosine in the external medium, [¹⁴C]adenosine did not flow out from preloaded vacuoles. However, in the presence of external adenosine, a very rapid efflux of radioactivity was observed, indicating an exchange mechanism for the observed adenosine transport in the vacuoles.In isolated vacuoles the only purine derivative accumulated was found to be $\text{S-}\text{adenosyl-}\text{l}\text{-homocysteine}$.     

Linear oligopeptides: 65′. Conformational analysis of the N-protected aromatic α-amino acid N-tert-butyloxycarbonyl-l-phenylalanine by X-ray diffraction and infrared absorption

The X-ray diffraction and i.r. absorption conformational analysis of $\text{N}\text{-tert-butyloxycarbonyl-}\text{l}\text{-phenylalanine}$ has showed the absence of intramolecularly hydrogen-bonded peptide conformations in the solid state. The molecules are held together in rows of ‘cyclic dimer’ motifs through intermolecular NH … OC (acid) and OH … OC {urethane} hydrogen bonds, the secondary amide-like group of the urethane moiety being in the unusual cis conformation, whereas the carboxylic acid group in the common syn conformation. The two molecules in the unit cell present a centrosymmetric set of ?, ψ¹, and ψ² values. In polar solvents solvated species largely predominate. In saturated hydrocarbon solution non-associated and associated (mostly involving the carboxylic acid CO as the proton acceptor) species simultaneously occur. The extent of association decreases with dilution. The amount of intramolecularly hydrogen-bonded oxy-C₇ and C₅ forms if any, should be extremely small. The type of association at saturation seems to differ from that found in the crystalline compound obtained by precipitation with saturated aliphatic hydrocarbons (from a diethyl ether solution).     

Sialyl-transferase mitochondriale

A sialyl transferase activity is found in purified mitochondria. It is not due to residual contamination and this enzymatic system is located in the outer mitochondrial membrane. This proves mitochondrial autonomy in regard to glycoconjugate sialylation.     

Biosynthetic approach to the structure of F1-ATPase (BF1 factor) from Micrococcus lysodeikticus membranes: in vivo labeling of the polypeptides and study of their relationship

The F₁-ATPase or BF₁ factor was purified from Micrococcus lysodeikticus substrain B grown in a synthetic medium in the presence of tritiated amino acids. When analyzed in sodium dodecyl sulfate-7% polyacrylamide gels, the fresh purified preparation contained α, β, γ subunits (referred as the intrinsic subunits) and two other polypeptides (designated as X and component of relative mobility 1.0) whose status as subunits remains to be established. This overall polypeptide composition was similar to that of the F₁-ATPase isolated from the same strain grown in complex medium (J. Carreira, J. M. Andreu, M. Nieto, and E. Muñoz., 1976 Mol. Cell. Biochem.10, 67–76). The distribution of ³H-labeled amino acids into purified F₁-ATPase and its constituent polypeptides under different stages of growth was used to investigate the biosynthetic relationship between the different polypeptides. The incorporation of amino acids into purified BF₁ factor was slower than that of cytoplasmic and other membrane proteins. In isotope-dilution and chase experiments, F₁-ATPase showed one of the slowest rates of decay of the incorporated label. These results point out that F₁-ATPase of M. lysodeikticus undergoes slower turnover than the overall cytoplasmic and membrane proteins. Pulse and chase experiments allowed us to conclude that the α, β, γ subunits and the components of relative mobility 1.0 are independent with differences in their turnover and therefore do not bear any apparent relation as precursors-products. The two major subunits represent seemingly the “core” of ATPase, the β subunit behaving like the most stable component. On the other hand, the γ subunit appears to be synthesized independently from this α + β complex.     

Occurrence of subcutaneous zygomycosis (Entomophthoromycosis Basidiobolae) caused by Basidiobolus haptosporus with pulmonary involvement

A case of a two-year-old boy with multiple subcutaneous lesions caused by Basidiobolus haptosporus is presented.The child had also a non-toxic familial goiter and clinical and radiological features of a pulmonary illness. The pulmonary manifestations only disappeared with the treatment with potassium iodide. The authors think that the pulmonary lesions must have arisen by direct spread of the fungus from the subcutaneous lesions of the chest.     

Triplex gene dosage effect for β-glucronidase and possible assignment to band q22 in a partial duplication 7q

Summary A 2-year-old girl had a de novo duplication in the long arm of one chromosome 7 and an increased level of the enzyme -glucuronidase in cultured fibroblasts. The phenotype of the girl partly overlaps those of two presumptive syndromes due to secondary partial trisomies 7q. The ratio of the enzyme activity was 1.43 to the controls, and 1.37 to her parent's values. We could not define the abnormality but suggest two alternatives: either the patient is trisomic for region q112 to q22 or for the region q22 to q34. If the second alternative is correct the locus for -glucuronidase is possibly assigned to band 7q22.     

A Romanian-American dialogue

Conclusion These American anthropological studies both reflect and distort our own Romanian-conceptions. Paradoxically, this gives both Romanian and American researchers an opportunity to verify their validity and reliability. The studies are notable for their multiplicity of theoretical approaches to Romanian reality: each author brings in something new by way of interpretation and, at the same time, maintains a dialectical conception as a methodological frame of reference.The authors are certainly conversant with present and future strategies of development in Romania. But their main problem is that they do not always understand the spirit of the latter and consequently fail to interpret contemporary Romanian realities in a deeply humanistic way.And now, some proposals. For a more active dialogue between Romanian and American scientists I suggest a more comprehensive use of the Romanian sources of information, including historical, beletristic, sociological, and political works. With reference to their reflections on history, the American anthropologists could have discussions with Romanian historians, and could use Romanian historical periodization, especially for the contemporary period. For us, the following sequence is basic: the moment of the armed insurrection as the beginning of the popular democratic revolution (August 23, 1944); proclamation of a Peoples' Republic of Romania (December 30, 1947); unification of Social Democratic Party with the Communist Party to form the Romanian Workers Party (Spring 1948); at this time it is possible to speak of a socialist revolution. The analysis of the Americans should take into consideration these important dates in Romanian history and structure their studies accordingly. Sometimes they must pay more attention to the affective connotation of words, especially for a Romanian reader. Such words would be, for example, their use of elite, rather than leaders, bureaucracy rather than administration, pressure rather than social necessities with the consciousness of development, patronclient instead of using interpersonal relations with mutual benefit, etc.I would also urge that substantive discussions between Romanians and Americans begin, built around specific topics of mutual interest, rather than ceremonial meetings which occur when the parties have neither the language skills, data nor social conceptions to interact fruitfully.I suggest to the American researchers that they maintain and strengthen their contacts with Romanian administrators at local, regional and national levels, so that their studies may contribute to our social praxis.Finally, the Americans should always take into account the economic constraints that shape political, juridical, moral, and philosophical phenomena, and try also to grasp more fully the interaction between elements of the superstructure and between superstructure and base in contemporary Romanian socialist society.Above all, along with Professor Cole , I hope that the scientific effort at interpreting Romanian reality, with its lights and shadows, will be used only for reciprocal knowledge and cooperation.Maria Cobianu-Bacanu is Scientific Researcher at the Center for Sociology, Academy of Social and Political Sciences, Bucharest, Romania.

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Effects of Chlorine Concentration on the Structure of Poliovirus

Chlorine concentrations below 0.8 mg/liter inactivated poliovirus without causing separation of the viral components. These results indicate that the release of RNA from the capsids is the result, not the cause, of virus inactivation by chlorine.