PACAP, VIP and their receptors in the metazoa: insights about the origin and evolution of the ligand-receptor pair

The evolution, function and interaction of ligand-receptor pairs are of major pharmaceutical interest. Comparative sequence analysis approaches using data from phylogenetically distant organisms can provide insights into their origin and possible physiological roles. The present review focuses on the pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal polypeptide (VIP) and their receptors in the metazoa. A PACAP-like peptide is present in tunicates and chordates while VIP- and PACAP/VIP-specific receptors have only been isolated in the latter phyla. The apparently disparate evolution of the ligands and their specific receptors raises questions about their evolution during the metazoan radiation and also about how the ligands may have acquired new functions.     

Prediction of the anomeric configuration, type of linkage, and residues in disaccharides from 1D C NMR data

A machine learning approach was explored for the prediction of the anomeric configuration, residues, and type of linkages of disaccharides using ¹³C NMR chemical shifts. For this study, 154 pyranosyl disaccharides were used that are dimers of the α or β anomers of d-glucose, d-galactose or d-mannose residues bonded through α or β glycosidic linkages of types 1→2, 1→3, 1→4, or 1→6, as well as methoxylated disaccharides. The ¹³C NMR chemical shifts of the training set were calculated using the casper (Computer Assisted SPectrum Evaluation of Regular polysaccharides) program, and chemical shifts of the test set were experimental values obtained from the literature. Experiments were performed for (1) classification of the anomeric configuration, (2) classification of the type of linkage, and (3) classification of the residues. Classification trees could correctly classify 67%, 74%, and 38% of the test set for the three tasks, respectively, on the basis of unassigned chemical shifts. The results for the same experiments using Random Forests were 93%, 90%, and 68%, respectively.     

Kinetic modeling of brewery's spent grain autohydrolysis

Isothermal autohydrolysis treatments of brewery's spent grain were used as a method for hemicellulose solubilization and xylo-oligosaccharides production. The time course of the concentrations of residual hemicelluloses (made up of xylan and arabinan) and reaction products were determined in experiments carried out at temperatures in the range from 150 to 190 degrees C using liquid-to-solid ratios of 8 and 10 g/g. To model the experimental findings concerning to brewery's spent grain autohydrolysis several kinetic models based on sequential pseudo-homogeneous first-order reactions were tested. Xylan and arabinan were assumed to yield oligosaccharides, monosaccharides (xylose or arabinose), furfural, and other decomposition products in consecutive reaction steps. The models proposed provide a satisfactory interpretation of the hydrolytic conversion of xylan and arabinan. An additional model merging the two proposed models for xylan and arabinan degradation assuming that furfural was formed from both pentoses was developed and the results obtained are discussed. The dependence of the calculated kinetic coefficients on temperature was established using Arrhenius-type equations.     

Mannitol production by lactic acid bacteria grown in supplemented carob syrup

Detailed kinetic and physiological characterisation of eight mannitol-producing lactic acid bacteria, Leuconostoc citreum ATCC 49370, L. mesenteroides subsp. cremoris ATCC19254, L. mesenteroides subsp. dextranicum ATCC 19255, L. ficulneum NRRL B-23447, L. fructosum NRRL B-2041, L. lactis ATCC 19256, Lactobacillus intermedius NRRL 3692 and Lb. reuteri DSM 20016, was performed using a carob-based culture medium, to evaluate their different metabolic capabilities. Cultures were thoroughly followed for 30 h to evaluate consumption of sugars, as well as production of biomass and metabolites. All strains produced mannitol at high yields (>0.70 g mannitol/g fructose) and volumetric productivities (>1.31 g/l h), and consumed fructose and glucose simultaneously, but fructose assimilation rate was always higher. The results obtained enable the studied strains to be divided mainly into two groups: one for which glucose assimilation rates were below 0.78 g/l h (strains ATCC 49370, ATCC 19256 and ATCC 19254) and the other for which they ranged between 1.41 and 1.89 g/l h (strains NRRL B-3692, NRRL B-2041, NRRL B-23447 and DSM 20016). These groups also exhibited different mannitol production rates and yields, being higher for the strains with faster glucose assimilation. Besides mannitol, all strains also produced lactic acid and acetic acid. The best performance was obtained for L. fructosum NRRL B-2041, with maximum volumetric productivity of 2.36 g/l h and the highest yield, stoichiometric conversion of fructose to mannitol.     

Response to oxidative stress induced by cadmium and copper in tobacco plants (Nicotiana tabacum) engineered with the trehalose-6-phosphate synthase gene (AtTPS1)

The response of tobacco plants genetically engineered with the AtTPS1 gene to stress induced by excess Cu and Cd was evaluated in hydroponic solution (100 and 400 μM Cu and 50 and 200 μM Cd) after a 48 h exposure. Two transgenic lines, transformed with the AtTPS1 (trehalose-6-phosphate synthase) gene from Arabidopsis, with different levels of trehalose-6-phosphate synthase expression (B5H, higher and B1F, lower), and a wild type (WT) were investigated. Protein content, antioxidative enzymes (CAT, POD, SOD, and APX), glucose, fructose, lipid peroxidation, hydrogen peroxide and Cd and Cu contents were determined in leaves. The two transgenic lines were differently influenced by Cd and Cu exposure as they induced a different antioxidant enzymatic defense response. B1F and B5H plants showed a better acclimation to Cd and excess Cu compared to WT. Furthermore B1F was more tolerant than B5H to Cd and excess Cu. B1F accumulated less Cd and Cu in leaves, probably due to a more efficient exclusion mechanism. Catalase was shown to be the most important enzyme in the antioxidative system of these plants.     

Xylitol production by <Emphasis Type="Italic">Debaryomyces hansenii</Emphasis> in brewery spent grain dilute-acid hydrolysate: effect of supplementation

A brewery spent-grain hemicellulosic hydrolysate was used for xylitol production by Debaryomyces hansenii. Addition of 6 g yeast extract/l increased the xylitol yield to 0.57 g/g, and productivity to 0.51 g/l h that were, respectively, 1.4 -and 1.8-times higher than the values obtained with non-supplemented hydrolysate. When corn steep liquor was combined with 3 g yeast extract/l, the highest xylitol yield, 0.58 g/g, was obtained with a similar productivity.     

Intra-clade metabolomic profiling of MAR4 Streptomyces from the Macaronesia Atlantic region reveals a source of anti-biofilm metabolites

The search for new and effective strategies to reduce bacterial biofilm formation is of utmost importance as bacterial resistance to antibiotics continues to emerge. The use of anti-biofilm agents that can disrupt recalcitrant bacterial communities can be an advantageous alternative to antimicrobials, as their use does not lead to the development of resistance mechanisms. Six MAR4 Streptomyces strains isolated from the Madeira Archipelago, at the unexplored Macaronesia Atlantic ecoregion, were used to study the chemical diversity of produced hybrid isoprenoids. These marine actinomycetes were investigated by analysing their crude extracts using LC–MS/MS and their metabolomic profiles were compared using multivariate statistical analysis (principal component analysis), showing a separation trend closely related to their phylogeny. Molecular networking unveiled the presence of a class of metabolites not previously described from MAR4 strains and new chemical derivatives belonging to the napyradiomycin and marinone classes. Furthermore, these MAR4 strains produce metabolites that inhibit biofilm formation of Staphylococcus aureus and Marinobacter hydrocarbonoclasticus. The anti-biofilm activity of napyradiomycin SF2415B3 ( 1 ) against S. aureus was confirmed.     

The serendipitous origin of chordate secretin peptide family members

Background  

The secretin family is a pleotropic group of brain-gut peptides with affinity for class 2 G-protein coupled receptors (secretin family GPCRs) proposed to have emerged early in the metazoan radiation via gene or genome duplications. In human, 10 members exist and sequence and functional homologues and ligand-receptor pairs have been characterised in representatives of most vertebrate classes. Secretin-like family GPCR homologues have also been isolated in non-vertebrate genomes however their corresponding ligands have not been convincingly identified and their evolution remains enigmatic.