Chemical composition and ultrastructure of cellular and extracellular Moraxella glucidolytica lipopolysaccharides

A cellular (LPS I) and extracellular (LPS II) lipopolysaccharide were isolated from Moraxella glucidolytica cells grown on ethanol and from the culture fluid, respectively. Both LPS were toxic when injected to mice and chick embryos. These LPS contained glucose, galactose, glucosamine, galactosamine, 2-keto-3-deoxyoctonate and lipids. By permethylation studies, glucose was found to be linked (16) and (13) in LPS I and only (16) in LPS II. Galactose was the terminal non-reducing sugar. Branching occurred at positions 3 and 4 of galactose residues. LPS I was rich in - and -hydroxylauric and -hydroxymyristic acids and LPS II contained mainly stearic and -hydroxymyristic acids. LPS I was detoxified by mild acid and alkaline treatments. It was also dissociated by sodium deoxycholate and chromatographed on Sephadex G-75. The main fraction was reassociated by removing the surfactant by dialysis. The morphology of LPS I and LPS II was examined by electron microscopy. LPS I (original and reassociated fractions) consisted exclusively of ribbons while LPS II contained ribbons and vesicles.Non-Standard Abbreviations KDO 2-Keto-3-deoxyoctonic acids - LPS Lipopolysaccharide - NaD Sodium deoxycholate     

13C NMR structural investigation of scleroglucan

This paper concerns the ¹³C NMR signal assignment in the DMSO of a neutral polysaccharide, scleroglucan. The previously proposed chemical structure is confirmed. The ¹³C NMR spectrum shows that scleroglucan is a regular poly (A, B, C, D) type glucan. The relaxation times of the different series of carbon atoms demonstrate that a single, pendant glucose group is attached to each third monomer along the main chain of what is a β(1 → 3)-glucan. Partial acid hydrolysis gives a spectrum analogous to that of the β(1 → 3)-d-glucan, curdlan, and confirms the structure of the polymer backbone.In aqueous solution, no signal has been obtained due to the existence of a rigid, ordered conformation as demonstrated by optical rotation; in the presence of sodium hydroxide, a conformational transition is produced just as with curdlan. The conclusion is that the behaviour of scleroglucan in solution is similar to that of other β(1 → 3)-d-glucans even though it is more soluble.     

Synthèse et étude conformationelle par r.m.n.-13c de β-nucléosides pyrimidiques contenant une ou deux sous-unités hexopyranosyles: Application à la conformation de l'anthelmycine

Several new peracetylated pyrimidine N-1 nucleosides containing one or two β-d-hexopyranosyl residues have been synthesized and their physical characteristics are reported. The conformation of these nucleosides has been investigated by high-resolution ¹³C-n.m.r. analysis after deblocking. It was possible to distinguish between the syn and anti rotamers of 3-β-d-glucopyranosyluracil, and to establish the favored anti conformation in solution of the nucleoside disaccharide, antibiotic anthelmycin.     

Selective expression of murine lymphocyte alloantigens controlled by the X-chromosome

Alloantisera specific to X-chromosome linked lymphocyte membrane antigens (Ly-X) were prepared by immunizing F1 male mice with identical F1 female lymphocytes. Independent B cell specific (anti Lyb-X) and T cell specific (anti Lyt-X) antibodies were detected. The Lyt-X antigen was expressed on Lyt-2⁺, 3⁺, and on Tla^–, Lyt-1⁺, 2⁺, 3⁺ T cell subpopulations. The problem of X-chromosome inactivation and the relationship ofH-2-linkedIr genes and Ia antigens, with X-linkedIr genes and lymphocyte alloantigens are discussed.     

Basal level of human platelet prostaglandins: PGE1 is more elevated than PGE2

Radioimmunoassays of platelet prostaglandins E₁ and F_1α in platelet rich plasma or platelet suspension, demonstrate that both PGE₁ and PGF_1α are present at higher concentrations than prostaglandins E₂ and F_2α. Gas chromatography — mass spectrometry determinations of prostaglandins E₁ and E₂ in resting washed platelets confirm this difference. Lastly, there is a greater incorporation of [1-¹⁴C] acetate into prostaglandins E₁ and F_1α compared to that into prostaglandins E₂ and F_2α.     

On the state of carotenoids bound to reaction centers of photosynthetic bacteria: A resonance raman study

The carotenoids bound to reaction centers of wild, Ga and GlC strains of Rhodopseudomonas spheroides, of Rhodospirillum rubrum, strain S1 and of Rhodopseudomonas viridis, yield very similar, but unusual resonance Raman spectra. Through a comparison with resonance Raman spectra of 15,15′-cis-β-carotene, these carotenoids are shown to assume cis conformations, while the corresponding chromatophores contain all-trans forms only. These cis conformations likely are identical for all the carotenoids studied. They remain unaffected by variations of temperature from 20 to 300 K as well as by the redox state of $\text{P-870}$. They are unstable, being rapidly isomerised towards the all-trans forms when extracted from the reaction centers. The possible nature of these conformers is discussed on the basis of their electronic and vibrational spectra.     

H-2 antigens,on mast cell membrane,as target antigens for anaphylactic degranulation

When single mast cells were isolated by micromanipulation, specific H-2 antigen-bearing mast cells were degranulated upon incubation with alloimmune sera (DAAD). When specific alloantigens were presented by lymphoid cells only, no degranulation occurred. Only antigen-bearing mast cells were degranulated, irrespectively of the presence of antigen-bearing lymphoid cells. Therefore, in DAAD, anaphylactic alloantibodies can and must recognize specific H-2 antigens on the mast cell membrane and simultaneously deliver the degranulation signal, through an Fc-Fc receptor interaction on the surface of the same mast cell.