Chemical and Physical Characterization of Interfacial-Active Lipids from Rhodococcus erythropolis Grown on n-Alkanes

Lipophilic compounds of the culture suspension containing Rhodococcus erythropolis DSM43215 had surfactant properties when the bacteria were cultivated with n-alkanes as the sole carbon source. Thirteen main components from a dichloromethane-methanol extract of the R. erythropolis cultures were isolated and characterized to specify quantitatively their surfactant properties, e.g., minimum surface and interfacial tensions and critical micelle concentrations. The interfacial activity of the organic extract was dominated by α,α-trehalose-6,6′-dicorynomycolates which reduced interfacial tension from 44 to 18 mN/m. Phosphatidylethanolamines which were also present in the organic extract reduced the interfacial tension below 1 mN/m. The trehalose corynomycolates had extremely low critical micelle concentrations in high-salinity solutions, and the interfacial properties were stabile in solutions with a wide range of pH and ionic strength.     

Separation of urine proteins on the anion-exchange resin mono QTM

Proteins excreted in urine due to renal failure were separated on Mono Q^TM, a new strong anion exchanger designed for fast high-resolution protein separations. The separation procedure was divided into two steps. The first step involved removal of low-molecular- weight substances by rapid desalting on a Sephadex G-25 Superfine column. In the second step, the total protein fraction (3–6 ml) was loaded onto the Mono Q column with the aid of a superloop. The proteins were adsorbed onto the top of the ion-exchanger column and gradually displaced by a combined pH and salt gradient in 40 min. The choice of ion exchanger and initial operating conditions were based on data obtained from electrophoretic titration curve experiments. Identification of separated proteins was achieved by fused rocket electrophoresis and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, respectively.     

Structure of adsorbed fibrinogen obtained by scanning force microscopy

It is shown that scanning force microscopy (SFM), operated in the attractive mode, can be used to obtain high resolution pictures of adsorbed fibrinogen molecules on solid surfaces, without the need for staining or special microscope grids. SFM also reveals the three-dimensional structure of the adsorbed molecules. Two forms of adsorbed fibrinogen are demonstrated on hydrophobic silicone dioxide surfaces; a trinodular about 60 nm long and a globular with about a 40 nm diameter. Polymeric networks formed after storage of the surface with adsorbed fibrinogen in PBS for 11 days are also shown. The SFM-results for the trinodular structure suggest the existence of loops or peptide chains extending outside the basic structure of the fibrinogen molecule.     

The organization of the gene for the human cerebroside sulfate activator protein

The organization of 14 exons covering 97% of the cDNA sequence of human cerebroside sulfate activator protein precursor has been determined from two overlapping EMBL-4 human genomic clones extending over 17kb. All exons and exon/intron splice junctions and five introns were sequenced. Exon 8 consists of only 9 bp and is involved in alternative splicing which generates three different mRNAs of cerebroside sulfate activator precursor.     

Oxidative fermentation of calcium-magnesium lactate to calcium-magnesium acetate deicing salt

Summary The oxidation of Ca–Mg lactate to Ca–Mg acetate (CMA) deicing salt was studied in pure cultures ofAcetobacter pasteurianus, Gluconobacter cerinus orG. oxydans. Gluconobacter sp., which maintained a practically self-controlled pH reaction and did not overoxidize acetate, appear to be potentially important for CMA production.     

HALDANE'S RULE AND SEX BIASSED GENE FLOW BETWEEN TWO HYBRIDIZING FLYCATCHER SPECIES (FICEDULA ALBICOLLIS AND F. HYPOLEUCA,AVES: MUSCICAPIDAE)

The collared flycatcher (Ficedula albicollis) and the pied flycatcher (F. hypoleuca) hybridize where their geographic ranges overlap. Restriction fragment comparison of 5% of the mitochondrial genome showed a sequence divergence of 10% between these flycatcher species. This degree of sequence divergence between a closely related pair of bird species is unusually high and contrasts with the low level of divergence between F. albicollis and F. hypoleuca in nuclear genes (Nei's D = 0.0006) revealed by enzyme electrophoresis. The low nuclear differentiation is explained by sex biassed gene flow and introgression in nuclear genes (via fertile male hybrids), while the high mitochondrial DNA sequence divergence is preserved by sterility of female hybrids, which prevents mitochondrial introgression. This pattern is in accordance with Haldane's rule and is supported by field data on hybrid fertility. The high mtDNA differentiation could be explained by transfer of mitochondrial DNA from a third species during a past period of hybridization.     

Effect of canine surfactant protein (SP-A) on the respiratory burst of phagocytic cells

Cells obtained from bronchoalveolar lavage, or neutrophils of peripheral blood of dog, were incubated with the canine surfactant-associated protein A (SP-A). A significant decrease of the production of Superoxide anion was observed after subsequent stimulation with phorbol-12-myristate-13-acetate (PMA) as measured by the lucigenin-dependent chemiluminesence (CL). Several other proteins used for control experiments did not decrease lucigenin-dependent CL, indicating a specific effect of SP-A on phagocytes. Treatment of SP-A with collagenase prior to incubation with neutrophils destroyed the depleting effect on oxygen radical production of PMA-stimulated cells. We propose that SP-A acts as a regulatory factor of the respitatory burst of alveolar macrophages and neutrophils in the lungs. The inhibitory effect of SP-A is down-regulated by collagenase released from stimulated alveolar macrophages.