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C Salles

Publications and source records attributed to C Salles.

At least 19 recordsLinked to original sources
PubMed2001

Determination of taste-active compounds of a bitter Camembert cheese by omission tests.

The taste-active compounds of a Camembert cheese selected for its intense bitterness defect were investigated. The water-soluble fraction (WSE) was extracted with pure water and fractionated by successive tangential ultrafiltrations and nanofiltration. The physicochemical assessment of these fractions led to the construction of a model WSE which was compared by sensory evaluation to the crude water-soluble extract, using a panel of 16 trained tasters. As no significant difference was perceived, this model WSE was then used directly or mixed with other cheese components for omission tests. Among the main taste characteristics of the WSE (salty, sour, umami and bitter), bitterness was found to be due to small peptides whose mass distribution was obtained by RPHPLC-MS (400-3000 Da) and whose taste properties are discussed.

Amino Acids↗
PubMed2001

Isolation of oligopeptides from the water-soluble extract of goat cheese and their identification by mass spectrometry.

A procedure for the separation and identification of small peptides from the water-soluble fraction of a goat cheese was developed. The water-soluble extract was ultrafiltered (1000 Da membrane cutoff), and peptides were isolated by sequential chromatography: size exclusion chromatography (HPLC-grade water), anion exchange chromatography (phosphate buffer gradient), and semipreparative reverse-phase high-performance liquid chromatography (water/acetonitrile gradient). The fractions obtained were analyzed by combined mass spectrometry methods including electrospray ionization, liquid secondary ionization, and tandem mass spectrometry to identify and to confirm the sequences of 28 tri- to octapeptides naturally appearing in goat cheese during ripening. Among these peptides, 26 are produced by degradation of caseins but do not correspond to the known specific cleavages due to chymosin. Only low correlation was found between hydrophobicity of peptides and HPLC elution time with acetonitrile gradient.

Amino Acid Sequence↗
PubMed2001

Evolution of the composition of a selected bitter Camembert cheese during ripening: release and migration of taste-active compounds.

The aim of this study was to add to the understanding of changes in taste that occur during the ripening of a bitter Camembert cheese by the evolution of its composition. Physicochemical analyses were performed on rind, under-rind, and center portions of a Camembert cheese selected for its intense bitterness. At each of the six steps of ripening studied organic acids, sugars, total nitrogen, soluble nitrogen, phosphotungstic acid soluble nitrogen, non-protein nitrogen, Na, K, Ca, Mg, Pi, Cl, and biogenic amines were quantified in each portion. Changes in cheese composition seemed to mainly result from the development of Penicillium camemberti on the cheese outer layer. Migration phenomena and the release of potentially taste-active compounds allowed for the evolution of saltiness, sourness, and bitterness throughout ripening to be better understood. Apart from taste-active compounds, the impact of the cheese matrix on its taste development is discussed.

Carbohydrates↗
PubMed2001

Evolution of the taste of a bitter Camembert cheese during ripening: characterization of a matrix effect.

The objective of this study was to characterize the effect of ripening on the taste of a typically bitter Camembert cheese. The first step was to select a typically bitter cheese among several products obtained by different processes supposed to enhance this taste defect. Second, the evolution of cheese taste during ripening was characterized from a sensory point of view. Finally, the relative impact of fat, proteins, and water-soluble molecules on cheese taste was determined by using omission tests performed on a reconstituted cheese. These omission tests showed that cheese taste resulted mainly from the gustatory properties of water-soluble molecules but was modulated by a matrix effect due to fat, proteins, and cheese structure. The evolution of this matrix effect during ripening was discussed for each taste characteristic.

Cheese↗
PubMed2001

From first base: the sequence of the tip of the X chromosome of Drosophila melanogaster, a comparison of two sequencing strategies.

We present the sequence of a contiguous 2.63 Mb of DNA extending from the tip of the X chromosome of Drosophila melanogaster. Within this sequence, we predict 277 protein coding genes, of which 94 had been sequenced already in the course of studying the biology of their gene products, and examples of 12 different transposable elements. We show that an interval between bands 3A2 and 3C2, believed in the 1970s to show a correlation between the number of bands on the polytene chromosomes and the 20 genes identified by conventional genetics, is predicted to contain 45 genes from its DNA sequence. We have determined the insertion sites of P-elements from 111 mutant lines, about half of which are in a position likely to affect the expression of novel predicted genes, thus representing a resource for subsequent functional genomic analysis. We compare the European Drosophila Genome Project sequence with the corresponding part of the independently assembled and annotated Joint Sequence determined through "shotgun" sequencing. Discounting differences in the distribution of known transposable elements between the strains sequenced in the two projects, we detected three major sequence differences, two of which are probably explained by errors in assembly; the origin of the third major difference is unclear. In addition there are eight sequence gaps within the Joint Sequence. At least six of these eight gaps are likely to be sites of transposable elements; the other two are complex. Of the 275 genes in common to both projects, 60% are identical within 1% of their predicted amino-acid sequence and 31% show minor differences such as in choice of translation initiation or termination codons; the remaining 9% show major differences in interpretation.

Animals↗
PubMed2000

From sequence to chromosome: the tip of the X chromosome of D. melanogaster.

One of the rewards of having a Drosophila melanogaster whole-genome sequence will be the potential to understand the molecular bases for structural features of chromosomes that have been a long-standing puzzle. Analysis of 2.6 megabases of sequence from the tip of the X chromosome of Drosophila identifies 273 genes. Cloned DNAs from the characteristic bulbous structure at the tip of the X chromosome in the region of the broad complex display an unusual pattern of in situ hybridization. Sequence analysis revealed that this region comprises 154 kilobases of DNA flanked by 1.2-kilobases of inverted repeats, each composed of a 350-base pair satellite related element. Thus, some aspects of chromosome structure appear to be revealed directly within the DNA sequence itself.

Animals↗
PubMed2000

Taste active compounds in a goat cheese water-soluble extract. 1. Development and sensory validation of a model water-soluble extract.

The aim of this study was to evaluate the impact of the components of a goat cheese water-soluble extract (WSE) on its flavor by both physicochemical and sensory techniques with special emphasis on taste. After characterization of the organoleptic properties of the cheese, the WSE was extracted with pure water and submitted to successive tangential ultrafiltrations and nanofiltration. The physicochemical assessment of these fractions led to the constitution of a model mixture (MWSE) compared by sensory evaluation to the crude WSE, using a panel of 16 trained members. The results of both sensory profile and triangular tests indicate no significant difference, therefore proving that the reconstitution of the WSE was correct, thereby showing the sensory neutrality of lipids and peptides smaller than 500 Da, which had not been included in the MWSE. Moreover, the cheese gustatory characteristics are comparable to those of the WSE despite weaker levels of sharpness and astringency in the extract, the respective origins of which are discussed.

Animals↗
PubMed2000

Taste active compounds in a goat cheese water-soluble extract. 2. Determination of the relative impact of water-soluble extract components on its taste using omission tests.

The aim of this work was to determine the relative impact of water-soluble compounds on the gustatory properties of a goat cheese water-soluble extract (WSE). Using a semisynthetic model mixture (MWSE) previously elaborated in physicochemical and gustatory accordance with the cheese WSE (see part 1, Engel et al. J. Agric. Food Chem. 2000, 48, 4252-4259), omission tests were performed. Among the main taste characteristics of the WSE (salty, sour, and bitter), saltiness was explained by an additive contribution of sodium, potassium, calcium, and magnesium cations, whereas sourness was mainly due to a synergistic effect involving sodium chloride, phosphates, and lactic acid and bitterness was found to result from calcium and magnesium chlorides, the impact of which was partially masked by sodium chloride. In contrast, amino acids, lactose, and peptides did not have any significant impact on WSE taste properties. To quantify the contribution of the taste active compounds to bitterness and saltiness, stepwise multiple linear regressions were performed. Those contributions were expressed as a percentage of the considered taste characteristic intensity in the WSE. The model obtained allowed up to 97.4% of the perceived saltiness to be described and approximately 85% of the bitterness.

Animals↗
PubMed1996

Concurrent validity study of the Slosson Intelligence Test-Revised in mental retardation testing.

The new Slosson Intelligence Test-Revised and the recommended abbreviated battery of the Stanford-Binet Intelligence Scale: Fourth Edition were given to individuals whose Stanford-Binet IQs ranged from 36 to 110. The Slosson-R correlated highly with the Stanford-Binet, r = .92. However, except for the moderately retarded category, the Slosson-R unsatisfactorily matched the Stanford-Binet's assignment of individuals to IQ categories. In contrast, when all individuals were classified as either having or not having mental retardation, the match rate was much better. The Slosson-R can adequately screen for mental retardation, but its ability to accurately assign individuals to specific IQ categories appears to be limited.

Adolescent↗
PubMed1995

ovo, a Drosophila gene required for ovarian development, is specifically expressed in the germline and shares most of its coding sequences with shavenbaby, a gene involved in embryo patterning.

Genetic analyses of Drosophila oogenesis have revealed the central role of ovo, a gene required for differentiation of the female germline. A number of recessive ovo mutations also affect the shavenbaby (svb) function required for late embryo patterning, suggesting a tight structural link between ovo and svb. By using various genomic probes for in situ hybridization to wild type and mutant embryos, we show that ovo indeed shares most of its coding sequences with svb. svb expression is detected early in the presumptive head region and later in each segment. It requires control elements located upstream of the ovo genomic region. ovo expresses abundant maternal RNAs which are uniformly distributed in early cleavage embryos. A fraction that lacks an alternative ovo-specific protein coding region (ORF 2b) is detected in pole cells. Expression of an ovo-specific lacZ reporter gene (ovoB) shows that ovo encodes a nuclear protein present in the germline of both sexes. Zygotic ovoB expression is first detected in embryos at around stage 17 and persists up to the adult stage. Our data show that the germline specific expression of ovo in females correlates with its function in oogenesis. This expression, however, is also observed in males in which ovo is not required.

Amino Acid Sequence↗
PubMed1994

Interspecific comparison of Drosophila serendipity delta and beta: multimodular structure of these C2H2 zinc finger proteins.

The Drosophila serendipity (sry) beta and delta genes, which resulted from a gene duplication event, provide an interesting model for the evolutionary diversification in structure and function of C2H2 zinc finger proteins. We examined here the divergence of the sry beta and delta proteins over an estimated period of 45 million years by comparing their predicted sequences in D. melanogaster, D. pseudoobscura, and D. subobscura. Between orthologs, i.e., pairs of either sry beta or sry delta, the NH2-proximal region delineated by pairs of C-X2-C motifs and the DNA-binding finger domain are highly conserved. Sequence conservation operates over the entire finger domain, including the links separating adjacent fingers, even though each has a unique sequence different from the widespread TGEKP motif. In contrast, the sequence of the central acidic region has extensively diverged and differs between species in the number of amino acids, probably because of slippage-driven mutations. The NH2-terminal region and fingers 1, 5, and 6 differentiate the sry beta and delta proteins while zinc fingers 2, 3, and 4 are virtually identical in these two paralogs. A nuclear localization signal of the SV40T antigen type, preceded by a potential CKII phosphorylation regulatory site, is conserved in sry delta but not found in sry beta. The interspecific conserved regions correlate well with the positions of zygotic lethal mutations in the D. melanogaster sry delta protein. Furthermore, P-element transformation experiments show that a transgenic copy of the D. pseudoobscura sry delta gene rescues the sry delta mutant phenotype. Convergence of genetic and structural data on the sry proteins supports a multimodular function and mode of evolution of these C2H2 finger proteins.

Amino Acid Sequence↗
PubMed1994

Characterization of the mutX gene of Streptococcus pneumoniae as a homologue of Escherichia coli mutT, and tentative definition of a catalytic domain of the dGTP pyrophosphohydrolases.

We show that deletion of a gene of Streptococcus pneumoniae, which we call mutX, confers a mutator phenotype to resistance to streptomycin. Analysis of the DNA sequence changes that occurred in several streptomycin-resistant mutants showed that mutations are unidirectional AT to CG transversions. The mutX gene is located immediately downstream of the previously identified ung gene and genetic evidence suggests that the two genes are co-ordinately regulated. Nucleotide sequence determination reveals that the mutX gene encodes a 17,870 Da protein (154 residues) which exhibits significant homology with the MutT protein of Escherichia coli, a nucleoside triphosphatase (dGTP pyrophosphohydrolase). The mutX gene complements the E. coli mutT mutator phenotype when introduced on a plasmid. Site-directed mutagenesis and analysis of nitrosoguanidine-induced mutT mutants suggest that a small region of high homology between the two proteins (61% identity over 23 residues) is part of the catalytic site of the nucleoside triphosphatase. Computer searching for sequence homology to MutX uncovered a second E. coli protein, the product of orf17, a gene of unknown function located near the ruvC gene. The region of high homology between MutX and MutT is also conserved in this protein, which raises the interesting possibility that the orf17 gene plays some role in determining mutation rates in E. coli. Finally, a small set of proteins, including a family of virus-encoded proteins and two evolutionarily conserved proteins encoded by an antisense transcript from the Xenopus laevis and human bFGF genes, were also found to harbour significant homology to this highly conserved region.

Amino Acid Sequence↗
PubMed1990

A compensatory mechanism improving red cell membrane fluidity in hemodialysed patients.

A fluorescence polarization technique with 1,6-diphenyl 1,3,5-hexatriene as a fluorescent probe was used to determine the fluidity of red cell membranes from hemodialysed patients before and after dialysis. After dialysis, there was a decrease in fluidity and activation energy values revealed a significantly changed distribution. The membrane lipid composition showed a significant increase in cholesterol after dialysis (p less than 0.001) and a significant reduction in saturated fatty acids (p less than 0.01) with an increase in unsaturated fatty acids (p less than 0.05). A compensatory mechanism could be suggested involving a reduction of saturated fatty acids in response to the increase in the cholesterol/phospholipid ratio. This could lead to an optimization of membrane fluidity.

Adult↗
PubMed1989

One-step extraction of human erythrocyte lipids allowing rapid determination of fatty acid composition.

A one-step extraction procedure to directly quantify cholesterol, phospholipids, and fatty acids in red blood cell membranes has been developed. The method uses a single solvent, isopropanol, which extracts lipids and allows the rapid formation of isopropylic esters of fatty acids by acid catalysis. The efficiency of this new technique has been confirmed by comparing yields of cholesterol and total and individual phospholipids with yields obtained following conventional extraction procedures. Moreover, in comparison to the formation of methyl esters, we demonstrate that directly obtained isopropylic esters immediately allow the quantitative determination of fatty acids, without involving the hydrolytic degradation of fatty acids and the oxidation of unsaturated fatty acids.

Chloroform↗