Study of the binding of jatrophone to Escherichia coli s-ribonucleic acid

The interaction of jatrophone with sRNA from Escherichia coli has been investigated through UV, CD, and 1H NMR measurements. The results obtained show that the interaction with jatrophone increases the stability of the polynucleotide. It appears that the optical properties of jatrophone depend upon the jatrophone/nucleotide ratio. The observed behaviour can only be explained by the existence of different types of interaction between jatrophone and sRNA. Even for a jatrophone/nucleotide ratio as low as 0.17 the 1H NMR spectra show a multiplicity of resonances that can only be explained by the simultaneous existence of two different binding modes involving the jatrophone molecules.     

Free amino acids from pollens

Pollens from Pinus canariensis, P. nigra, P. pinaster, P. pinea, Castanea sativa, Magnolia grandiflora, Olea sativa cv frantoio, cv itrana, cv pisciottana were examined for their free amino acid composition. A large amount of proline was found in all species; pollens of Olea also contain a large amount of serine.     

Inhibition of cardiolipin synthesis by end-products and other complex lipids in membrane preparations of Micrococcus lysodeikticus.

Using membrane preparations of Micrococcus lysodeikticus, the end-products of cardiolipin synthesis, cardiolipin and glycerol, were shown to inhibit cardiolipin synthetase at several concentrations. Other phospholipids tested for inhibitory effects, phosphatidyl-ethanolamine, phosphatidylinositol, and phosphatidic acid were also shown to inhibit cardiolipin synthesis. Phosphatidic acid was considerably more inhibitory than cardiolipin, phosphatidylethanolamine was similar to cardiolipin, and phosphatidylinositol less inhibitory at the same concentrations. A non-phosphate-containing glycolipid was also inhibitory. In contrast, glycerophosphate had no effect on cardiolipin synthesis.     

Spectroscopic study of monosubstituted amides. II. Rotation isomers in amides substituted by aliphatic side-chain models

The influence of the substituents upon the Amide I and νNH frequencies has been analyzed for ten amides substituted by aliphatic side chains. By considering the aliphatic chain field effect, some data are obtained as to the conformation of the N? C_α bond. In two amides, the presence of an equilibrium between two conformers is shown and a semiquantitative estimation of the energies involved is obtained. The consequences for polypeptides conformation, especially for poly-L -valine, are discussed.     

Exopolysaccharide-producing strains of thermophilic lactic acid bacteria cluster into groups according to their EPS structure

AIMS: To compare galactose-negative strains of Streptococcus thermophilus and Lactobacillus delbrueckii subspecies bulgaricus isolated from fermented milk products and known to produce exopolysaccharides (EPSs). METHODS AND RESULTS: The structures of the EPSs were determined using nuclear magnetic resonance (NMR) and their genetic relationships determined using restriction endonuclease analysis (REA) and random amplification of polymorphic DNA (RAPD). Similar groupings were apparent by REA and RAPD, and each group produced an EPS with a particular subunit structure. CONCLUSION: Although none of the strains assimilated galactose, all inserted a high proportion of galactose into their EPS when grown in skimmed milk, and fell into three distinct groups. Significance and Impact of the Study: This information should help in an understanding of genetic exchanges in lactic acid bacteria.     

Bounding fluid viscosity and translational diffusion in a fluid lipid bilayer

Fluorescence recovery after photobleaching was used to investigate the translational diffusion of a fluorescent derivative of a membrane-spanning lipid in L phase multibilayers of 1-palmitoyl-2-oleoylphosphatidylcholine prepared in water and in glycerol. The translational diffusion coefficient in hydrated bilayers (D _w) ranged between 2 and 5x10^–8 cm²/s and in glycerinated bilayers (D _g) the range was between 3 and 24×10^–10 cm²/s between 10° and 40°C. These results are discussed in terms of models for diffusion in membranes.     

Biphasic fluence-response curves for phytochrome-mediated kalanchoë seed germination : sensitization by gibberellic Acid

The fluence-response curves for the effect of two red pulses separated by 24 hours on the germination of Kalanchoe blossfeldiana Poelln. cv Vesuv seeds, incubated on gibberellic acid (GA₃) are biphasic for suboptimal concentrations. The response in the low fluence range corresponds with a classical red/far-red reversible phytochrome mediated reaction. GA₃ induces an additional response in the very low fluence range, which is also phytochrome mediated. The sensitivity to phytochrome-far-red absorbing form (Pfr), however, is increased about 20,000-fold, so that even far-red fluences become saturating. Both in the very low and low fluence response range, the maximal responses induced by saturating fluences are modulated by the GA₃ concentration. GA₃ having no direct influence on the phytochrome phototransformations, alters the Pfr requirement and determines the responding seed population fraction in the very low and low fluence range. The effet of GA₃ appears to be on the transduction chain of the phytochrome signal.     

Relative biological effectiveness (RBE) of neutrons produced by 50 MeV deuterons and by 34, 45, 65 and 75 MeV protons

RBE of p(34) + Be, p(45) + Be, p(65), + Be, p(75) + Be and d(50) + Be neutron beams produced at the cyclotron "Cyclone" of Louvain-la-Neuve were measured. The biological criterion was the regeneration of the crypts of the intestinal mucosa (50 regenerated crypts per circumference) after abdominal irradiation in mice. Taking the p(65) + Be neutrons as reference, RBE values were found equal to 1.12, 1.07, 1.00 (Ref.), 0.96 and 1.02 respectively. These results are consistent with those published for cell lethality in vitro. However, the RBE variation is smaller than this previously obtained in the laboratory for growth inhibition in Vicia faba.     

Synergism between eosinophil cationic protein and oxygen metabolites in killing of schistosomula of Schistosoma mansoni

To study the cytotoxic reactions responsible for mediating eosinophil damage to schistosomula of Schistosoma mansoni, we have used cytoplasts (eosinophil or neutrophil vesicles devoid of granules and nuclei, with an intact oxidase in their plasma membrane) in combination with purified eosinophil cationic protein (ECP) or major basic protein (MBP) in a cytotoxicity test toward schistosomula. Suboptimal concentrations of ECP (10(-6) M) or MBP (10(-6) M) resulting in less than 10% killing were used in combination with cytoplasts. Cytoplasts alone in the presence of immune serum tested over a wide range of cytoplast:schistosomula ratios generated superoxide and hydrogen peroxide, but were unable to damage schistosomula. However, when a suboptimal ECP concentration (10(-6) M) was combined with neutroplasts or eosinoplasts, 43.9% +/- 8.5 (n = 7) and 24.7% +/- 9.8 (n = 3), respectively, of the schistosomula were killed. Oxygen metabolites were responsible for the synergism, because cytoplasts from a patient with chronic granulomatous disease were unable to act in synergy with ECP. In contrast to ECP, no synergism was found between cytoplasts and MBP (10(-6) to 2 X 10(-5)M). These results show that oxygen metabolites are important for the killing of schistosomula by lowering the concentration of ECP needed to inflict damage.