Effects of 3,5,3'-triiodothyroacetic acid (TRIAC) on protein metabolism of genetically obese or non-obese Zucker rats

Genetically obese female rats (fa/fa) and their lean littermates (Fa/-) were given oral administration of 3,5,3-triiodothyroacetic acid (TRIAC) (20 micrograms/ 100 g of body weight/ day) during 4 weeks. Metabolism of proteins was evaluated in several organs and in skeletal muscle after intraperitoneal injection of 14C and 3H-leucine 6 days and 16 hrs respectively before the sacrifice of animals. We have determined radioactivity of 14C and 3H and the 3H/14C ratio. No significant differences were found in lean and obese rats except in skeletal muscle. The relative protein turnover in skeletal muscle is significantly higher in the obese rats than in the lean rats. Treatment by TRIAC decreases the body weight gain in obese rats compared with controls but it has no statistically significant effect on the relative protein turnover in either obese or lean rats.     

Substitution of the flavin chromophore with lipophilic side chains: A novel membrane redox label

Summary The synthesis of amphiphilic flavins substituted with C₁₈-hydrocarbon sidechains in positions 3, 5, 7, 8 and 10 is described. 3-, 7-, and 10-amphiflavins were obtained by new total syntheses. Furthermore, 3-amphiflavin was obtained by C₁₈-alkylation of natural flavin in the oxidized state, whereas 5-amphi(dihydro)flavin was obtained by alkylation under reducing conditions.In the course of these studies, a novel, selective oxidation reaction was found taking place with the 8-methyl group of natural flavins. In this way lumiflavin and riboflavin derivatives could be converted directly to flavin-8-nor-8-carboxylic acids or the corresponding alkyl esters.The new flavin derivatives lend themselves for incorporation into lipid vesicles, thus yielding the basis for model studies of anisotropic flavin chemistry and redox transfer through membranes, as described in the concomitant paper (Schmidt, W., Hemmerich, P. 1981).J. Membrane Biol. 59:129. The new flavins are characterized by means of absorption, fluorescence, and proton nuclear magnetic resonance spectroscopy.     

Characteristics of synaptosomal tyrosine uptake in various brain regions: Effect of other amino acids

Tyrosine uptake by rat synaptosomes was maximal after 5–10 min of incubation and at 30°C; uptake was inhibited by dinitrophenol (10^?4 M) or ATP (10^?3 M) and increased by reducing sodium concentrations or increasing calcium or potassium. The best model for uptake is a two-carrier system, in which one carrier shows high-affinity uptake and the other may be diffusional. Both uptake mechanisms are more concentrated in catecholamine-rich brain areas, and are inhibited $\text{in vitro}$ by other large, neutral amino acids. At physiologic amino acid brain concentrations, each system probably carries about half of the tyrosine into the nerve terminal.     

Deoxyribonucleic acid relatedness inYersinia enterocolitica andYersinia enterocolitica-like organisms

Yersinia enterocolitica andY. enterocolitica-like strains were characterized by DNA relatedness. These strains formed four distinct DNA relatedness groups: (i) the 5 classical biotypes ofY. enterocolitica sensu stricto as designated by Wauters; (ii) strains that are rhamnose positive and also positive in tests for melibiose, α-methyl-d-glucoside, raffinose, and Simmons' citrate; (iii) strains that are rhamnose positive but negative in tests for melibiose, α-methyl-d-glucoside, and raffinose; (iv) sucrose-negative, Voges-Proskauer-negative, trehalose-positive strains.     

Influence du traitement sylvicole sur la flore forestiere: Cas de la futaie et du taillis-sous-futaie

Summary In a previous study, 772 floristics relevés, made in a large forest on calcareous soils (north-east France), had been treated by factorial analysis of correspondences in order to establish a site typology. The third axis separated chiefly Fagus and Quercus, which are very common in the forest, and various other ligneous or herbaceous species (see fig. 1). Two groups of relevés, homogeneous as for edaphic conditions, were choosen, having a significant position on this axis (with either positive or negative values). From this, floristic tables have been elaborated; they show clearly the influence of silvi culture (here high forest or coppice-with-standards) on part of both ligneous and herbaceous flora. Considering plant sociology, it appears that treating a stand as a coppice-with-standards can convert a Melico-Fagetum typicum (Eu-Fagion) into a Querceto Carpinetum typicum (Fraxino-Carpinion), and a Carici-Fagetum (Cephalanthero-Fagion) into a Querceto-Carpinetum primuletosum (Fraxino-Carpinion). Fortunately a large number of species are not influenced by the silviculture; this allows the identification of isopotential sites. Possible ecological causes are briefly discussed.

Nomenclature suivant: P. Fournier, 1961. Les quatre flores de France. Edition P. Le Chevalier, Paris. 1154 p.     

Electrogenic proton ejection coupled to electron transport through the energy-conserving site 2 and K+/H+ exchange in yeast mitochondria

The proton ejection coupled to electron flow from succinate and/or endogenous substrate(s) to cytochrome c using the impermeable electron acceptor ferricyanide is studied in tightly coupled mitochondria isolated from two strains of the yeast Saccharomyces cerevisiae. (1) The observed H⁺ ejection/2e^? ratio approaches an average value of 3 when K⁺ (in the presence of valinomycin) is used as charge-compensating cation. (2) In the presence of the proton-conducting agent carbonyl cyanide m-chlorophenylhydrazone, an H⁺ ejection/2e^? ratio of 2 is observed. (3) The low stoichiometry of 3H⁺ ejected (instead of 4) per 2e^? and the high rate of H⁺ back-decay (0.1615 $\text{ln}\text{δ-}\text{(}\text{ngatom}\text{)}\text{H}{}^{\mathrm{+}}\text{s}$ and a half-time of 4.6 s for 10 mg protein) into the mitochondrial matrix are related to the presence of an electroneutral K⁺/H⁺ antiporter which is demonstrated by passive swelling experiments in isotonic potassium acetate medium.     

The effects of membrane lipid order and cholesterol on the internal and external cationic sites of the Na+−K+ pump in erythrocytes

Cholesterol depletion alters the apparent affinity of the internal cationic sites and the maximal translocation rate but not the affinity of the external cationic sites of the $\text{Na}{}^{\mathrm{+}}\text{?K}{}^{\mathrm{+}}$ pump in human erythrocytes. To test whether these effects were mediated by a direct cholesterol-internal site interaction or by a change in membrane lipid order, the effects of five fluidizing amphiphiles (chlorpromazine, imipramine, benzyl alcohol, sodium oleate and sodium benzenesulphonate) on the kinetic parameters of the $\text{Na}{}^{\mathrm{+}}\text{?K}{}^{\mathrm{+}}$ pump were determined. The cholesterol removal and all the agents used induced dose-response decreases in membrane lipid order as measured by fluorescence polarization or ESR. Positive and neutral amphiphiles mimicked the effects of cholesterol removal on the affinity of the internal sites of the pump and to a lesser extent on the maximal translocation rate. Anionic amphiphiles had no effect on internal sites, probably because they distributed preferentially within the outer leaflet on the membrane. These results indicate that cholesterol controls the affinity of the internal sites of the $\text{Na}{}^{\mathrm{+}}\text{?K}{}^{\mathrm{+}}$ pump by altering the membrane lipid order. In contrast, neither cholesterol depletion nor the agents used altered the affinity of the external sites of the $\text{Na}{}^{\mathrm{+}}\text{?K}{}^{\mathrm{+}}$ pump. This difference in sensitivity to membrane lipid order suggests that internal and external cationic sites, although borne by the same protein, are in different lipid environments.     

Interaction between macrophages and Schistosoma mansoni schistosomula: Role of IgG peptides and aggregates on the modulation of β-glucuronidase release and the cytotoxicity against schistosomula

Discharge of lysosomal enzymes, measured by release of β-glucuronidase and cytotoxicity against Schistosoma mansoni schistosomula, was studied when rat macrophages were incubated in the presence of either IgG peptides, resulting from the cleavage of nonimmune IgG by parasitic proteases, or nonimmune aggregated IgG. With peptides, the macrophage activity showed a dramatic decrease while they were stimulated by IgG aggregates. In contrast, the synthesis of lymphocyte activating factor by macrophages was unaffected. The hydrolysis of IgG is carried out by two distinct enzymatic molecules released into the medium by the larvae. The mechanism by which nonimmune IgG peptides or aggregates inhibit or stimulate macrophage activity, regulated by both parameters indicated above, is discussed and is suggested as a general regulation mechanism for the macrophage activity required for parasite survival in the host.