Role of aldehydic derivatives in the condensation of phenolic compounds with emphasis on the sensorial properties of fruit-derived foods

The reactions between (epi)catechin, mavidin 3-O-glucoside, and some aldehydes were investigated by LC/DAD and LC/ESI-MS analysis. The obtained results showed that the acetaldehyde-mediated condensation occurred more generally and glyoxylic acid, furfural, and 5-(hydroxymethyl)furfural (HMF) react in the same way in the first stages of the reactions. In terms of reactivity, reactions were faster with acetaldehyde than with glyoxylic acid, furfural, or HMF, where the reactions were slower. In the case of acetaldehyde, the obtained purple derivatives were more predominant and stable than the colorless adducts and no xanthylium salt was detected. Interactions involving glyoxylic acid yield purple adducts, which were obtained in small amount compared to the colorless ones. The latter were shown to proceed to more polymerized and yellowish derivatives. Finally, in the case of furfural and HMF, purple compounds involving flavanol and anthocyanin units were detected, and colorless compounds were shown to be predominant and to yield yellowish xanthylium salts.     

Synthesis and stable isotope dilution assay of ethanethiol and diethyl disulfide in wine using solid phase microextraction. Effect of aging on their levels in wine

Ethanethiol and diethyl disulfide (DEDS) most often occurred at levels above their olfactive threshold in wines with nauseous sulfur-linked smells. As ethanethiol is very oxidizable and chemically reactive, a stable isotopic dilution analysis of both ethanethiol and its disulfide in wines using solid phase microextraction and GC-MS was developed. The latter involved the determination of the proportion of DEDS formed by oxidation of the thiol during the analysis conditions, which was obtained by the use of two differently labeled disulfide standards. An original synthesis of labeled ethanethiol standards in conditions minimizing oxidation was developed, and the corresponding labeled diethyl disulfides were obtained from these thiols. This analytical method was used to follow the levels of these sulfur compounds during aging in a young red wine spiked with ethanethiol and added with enological tannins, with or without oxygen addition. The total levels of these two sulfur compounds were shown to decrease steadily after 60 days of aging, up to 83%. The effect of oxygen sped this decrease, but the effect of enological tannins was very slight. Residual ethanethiol was detected in its disulfide form from approximately 36% in the nonoxygenated wines to 69% in the oxygenated samples.     

Heavy Metal Contamination in Sediments of Lake Nahuel Huapi,Nahuel Huapi National Park,Northern Patagonia,Argentina

Trace metals (Sb, As, Br, Cs, Co, Cr, Ag and Hg), rare earth elements (Ce, Eu, La, Lu, Sm, Tb and Yb), and Sc. were analysed in suspended load and in two sediment cores from Lake Nahuel Huapi, Nahuel Huapi National Park, Patagonia, Argentina, by using Instrumental Neutron Activation Analysis. The core activity profiles of ²¹⁰Pb and ¹³⁷Cs were measured to estimate the age of the sediments. Silver was enriched in the upper layers of both cores, and correlated with the strong growthof the population of Bariloche City in the last 50 yr. Concentrations are higher in the core sampled near Bariloche, andindicate some transport in the water body. Silver concentrationsmeasured in the suspended load were 4.58±0.36 and 3.46±0.40 μg g^-1 in the southern margin of the lake, near San Carlos de Bariloche City, whereas in the northern margin the concentrations were 1.68±0.18 and 1.88±0.23 μg g^-1. Concentration ratio for silver in suspended load and upper core layers were equal in both sampling points. These facts suggest that Ag contents correspond to inputs associated with human activities. Bromine concentrations show a strong increase abovebase line values, similar to silver. In contrast, caesium, chromium, and cobalt concentrations do not differ from base linevalues. The metalloids antimony and arsenic show little variationwith regard to base line concentration. Noticeable, the mercurycontents found in the suspended load.     

Genetic differentiation in the olive complex (Olea europaea) revealed by RAPDs and RFLPs in the rRNA genes

We assessed the genetic differentiation of the Mediterranean olive from its wild relatives found in different geographic areas (Mediterranean, Asia, Africa) using eighty RAPDs revealed with eight primers. Variance analysis (AMOVA) enabled us to estimate the overall genetic differentiation parameters between wild populations. Oleasters from the Near East and Turkey were discriminated from the other Mediterranean populations. Olea laperrinei, O. maroccana and O. cerasiformis were the taxa the most related to the Mediterranean olive. In contrast, O. africana was shown to be the most genetically distant taxa from the Mediterranean olive. However, we characterised hybrid trees between these two taxa. Significant trends between genetic and geographic distances were met within the subspecies cuspidata and within the Mediterranean olive. A genetic diversity gradient was observed in both subspecies europaea and cuspidata. These results are in agreement with a mechanism of differentiation by distance in the O. europaea complex, but another non-exclusive mechanism could also be gene flow between differentiated taxa. Furthermore, we characterised the discriminating power of each RAPD to recognise the different taxa using intraclass correlation coefficients. Lastly, IGS-RFLPs enabled us to assess rDNA polymorphisms on a sub-sample of individuals. On the basis of these data, a low interspecifc differentiation was found. This suggests a recent genetic divergence between the different taxa of the O. europaea complex or the occurrence of gene flow during favourable periods or because human displacements. All the olive cultivars were genetically related to the oleaster populations supporting that Mediterranean is the olive domestication area.     

Allele mining and haplotype discovery in barley candidate genes for drought tolerance

In the present study, allele mining was conducted on a panel of drought related candidate genes in a set of 96 barley genotypes using EcoTILLING, which is a variant of the targeting induced local lesions in genomes (TILLING) technology. Analyzing approximately 1.5 million basepairs in barley a total number of 94 verified unique haplotypes were identified in 18 amplicons designed for 9 genes. Overall, 185 single nucleotide polymorphisms (SNPs) and 46 insertions/deletions (INDELs) were detected with a mean of 1SNP/92 bp and 1INDEL/372 bp genomic sequence. Based on overlapping haplotype sequences, markers were developed for four candidate genes (HvARH1, HvSRG6, HvDRF1, HVA1), which allows distinguishing between the main haplotypes showing either differences in amino acid sequence or which have larger INDELs in the promoter region. As “proof of concept”, the HvARH1 and HvSRG6 haplotypes were tested for the level of abscisic acid-induced gene expression in subsets of genotypes belonging to different haplotype categories. An integrated database was developed to contain information about the genes, genotypes, and haplotypes analyzed in this study. The database supplies profound information about the natural variation in the tested drought related candidate genes providing a significant asset for further mapping studies dealing with this highly polygenic trait.     

Deflection of the interstellar neutral hydrogen flow across the heliospheric interface

Using an absorption cell, we measured the Doppler shifts of the interstellar hydrogen resonance glow to show the direction of the neutral hydrogen flow as it enters the inner heliosphere. The neutral hydrogen flow is found to be deflected relative to the helium flow by about 4 degrees . The most likely explanation of this deflection is a distortion of the heliosphere under the action of an ambient interstellar magnetic field. In this case, the helium flow vector and the hydrogen flow vector constrain the direction of the magnetic field and act as an interstellar magnetic compass.     

Inhibition of cell motility by interferon

Interferon derived from human leukocytes, human fibroblasts, and mouse fibroblasts was found to inhibit the motility of cultured cells. It inhibits the tumor-induced motility of capillary endothelial cells as well as the spontaneous migration of other cell types. The ability of a given preparation of interferon to inhibit the motility of a given cell type is proportional to its antiviral activity in that particular cell type. Antiserum to human leukocyte interferon neutralizes both the motility-inhibitory activity and the antiviral activity of this preparation.     

Mammary carcinoma: enzymatic block in disialoganglioside biosynthesis

The sialyl transferase of disialoganglioside formation is depressed in mammary tumors induced in the rat by 7,12-dimethylbenz[a]anthracene. Specific activities of other glycosyltransferases of the pathway ceramide to monosialo-ganglioside are unchanged or elevated so that the ganglioside GM(1) accumulates and higher gangliosides are depressed. These findings with a solid tumor are critical to an involvement of gangliosides in the cell-surface changes of tumorigenesis.     

Thymic origin of intestinal alphabeta T cells revealed by fate mapping of RORgammat+ cells

Intestinal intraepithelial T lymphocytes (IELs) are likely to play a key role in host mucosal immunity and, unlike other T cells, have been proposed to differentiate from local precursors rather than from thymocytes. We show here that IELs expressing the alphabeta T cell receptor are derived from precursors that express RORgammat, an orphan nuclear hormone receptor detected only in immature CD4+CD8+ thymocytes, fetal lymphoid tissue-inducer (LTi) cells, and LTi-like cells in cryptopatches within the adult intestinal lamina propria. Using cell fate mapping, we found that all intestinal alphabeta T cells are progeny of CD4+CD8+ thymocytes, indicating that the adult intestine is not a significant site for alphabeta T cell development. Our results suggest that intestinal RORgammat+ cells are local organizers of mucosal lymphoid tissue.     

The roles of subsurface carbon and hydrogen in palladium-catalyzed alkyne hydrogenation

Alkynes can be selectively hydrogenated into alkenes on solid palladium catalysts. This process requires a strong modification of the near-surface region of palladium, in which carbon (from fragmented feed molecules) occupies interstitial lattice sites. In situ x-ray photoelectron spectroscopic measurements under reaction conditions indicated that much less carbon was dissolved in palladium during unselective, total hydrogenation. Additional studies of hydrogen content using in situ prompt gamma activation analysis, which allowed us to follow the hydrogen content of palladium during catalysis, indicated that unselective hydrogenation proceeds on hydrogen-saturated beta-hydride, whereas selective hydrogenation was only possible after decoupling bulk properties from the surface events. Thus, the population of subsurface sites of palladium, by either hydrogen or carbon, governs the hydrogenation events on the surface.