Determination of duodenogastric reflux by quantification of bile acids in the gastric juice

The existence of duodeno-gastric reflux was evaluated in a group of 15 healthy subjects, in fasting and for 24 hours. The assessment of duodeno-gastric reflux was made by quantitation of the bile acids (BA) present in the gastric juice. The individual free and conjugated BA were separated and quantified by means of thin-layer chromatography and in situ spectrofluorometry. In 7 of the subjects studied no BA were detected, and in the other 8 subjects the BA levels were below 6 mumol reflux/hour. There were no free BA detected in any of the subjects. The levels of BA in gastric juice increased progressively with age, but there were no differences between sex. The chromatographic technique used is highly sensitive for the analysis of BA in biological samples. The study of BA in the gastric juice provides a quantitative and reliable assessment of the degree of duodeno-gastric reflux.     

A mutant of Halobacterium halobium with constitutive production of bacteriorhodopsin

Abstract A purple mutant of Halobacterium halobium was isolated in a previous study. The 'in vitro' absorption spectra of the cells gave a broad shoulder around 570 nm. The amounts of bacteriorhodopsin were high under any growth condition (including aerobic) inhibitory for the wild-type strain. The mutant grew faster under illuminated microaerophilic conditions and showed faster proton extrusion than the wild-type strain. This evidence shows that the mutant has a constitutive bacteriorhodopsin production not influenced by the oxygen concentration in the medium. However, some stimulation by light was found.     

Multilocus and morphological analysis of south-eastern Iberian Wall lizards (Squamata,Podarcis)

The phylogenetic relationships among the wall lizards of the Podarcis hispanicus complex that inhabit the south-east (SE) of the Iberian Peninsula and other lineages of the complex remain unclear. In this study, four mitochondrial and two nuclear markers were used to study genetic relationships within this complex. The phylogenetic analyses based on mtDNA gene trees constructed with ML and BI, and a species tree using *BEAST support three divergent clades in this region: the Valencia, Galera and Albacete/Murcia lineages. These three lineages were also corroborated in species delimitation analyses based on mtDNA using bPTP, mPTP, GMYC, ABGD and BAPS. Bayesian inference species delimitation method (BPP) based on both nuclear data and a combined data set (mtDNA + nuclear) showed high posterior probabilities for these three SE lineages (≥0.94) and another Bayesian analysis (STACEY) based on combined data set recovered the same three groups in this region. Divergence time dating of the species tree provided an estimated divergence of the Galera lineage from the other SE group (Podarcis vaucheri, (Albacete/Murcia, Valencia)) at 12.48 Ma. During this period, the Betic–Rifian arc was isolated, which could have caused the isolation of the Galera form distributed to the south of the Betic Corridor. Although lizards from the Albacete/Murcia and Galera lineage are morphologically similar, they clearly represent distinct genetic lineages. The noteworthy separation of the Galera lineage enables us to conclude that this lineage must be considered as a new full species.     

The use of a bacteriophage cocktail as a biocontrol measure to reduce Salmonella enterica serovar Enteritidis contamination in ground meat and goat cheese

We evaluated the effectiveness of phages on meats and goat cheese contaminated with Salmonella Enteritidis (SE). In meats, reductions of SE were observed during the whole experiment, while in goat cheese a reduction was only observed at day 3. We discuss the relevance of phages as a biocontrol in food.     

Reconstitution of the rat liver vasopressin receptor coupled to guanine nucleotide-binding proteins

The V1 vasopressin receptor has been solubilized from rat liver membranes with the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammoniol]-1-propanesulfonate (CHAPS) and reconstituted into phospholipid vesicles. There is essentially complete solubilization of the receptor by 3% CHAPS at a protein concentration of 15 mg/ml. Reconstitution into soybean phospholipid vesicles is readily achieved either by gel filtration chromatography or by membrane dialysis. The binding of [3H]vasopressin to proteoliposomes is specific, saturable, reversible, and magnesium-dependent. In contrast, the detergent-soluble vasopressin receptor does not display specific binding. The apparent affinity of the reconstituted receptor for [3H]vasopressin is approximately 4-fold lower than that of the receptor in native membranes. In addition, the binding of [3H]vasopressin to reconstituted vesicles is not sensitive to 100 microM guanosine 5'-O-thiotriphosphate (GTP gamma S) as it is in native membranes. However, the apparent affinity of the reconstituted receptor for ligand approximates that of native membranes when membranes are prebound with vasopressin prior to solubilization and reconstitution into vesicles. Furthermore, vesicles reconstituted from membranes prebound with vasopressin show GTP gamma S sensitivity of [3H] vasopressin binding. This finding strongly suggests that vasopressin stabilizes a receptor-G-protein complex during solubilization. The rat liver vasopressin receptor is a glycoprotein, as shown by its specific binding to the lectin "wheat germ agglutinin." The vasopressin receptor can be reconstituted from the N-acetylglucosamine-eluted peak of a wheat germ agglutinin-Sepharose column, and [3H] vasopressin binding activity is purified 5-6-fold from membranes by this chromatographic procedure. The functionality of the partially purified receptor is indicated by its ability to bind ligand with high affinity and by its ability to functionally interact with a G-protein when vasopressin is bound prior to solubilization.