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M Ragot

Publications and source records attributed to M Ragot.

15 recordsLinked to original sources
PubMed1996

A generalization of the mixture model in the mapping of quantitative trait loci for progeny from a biparental cross of inbred lines.

The recent advent of molecular markers has created a great potential for the understanding of quantitative inheritance. In parallel to rapid developments and improvements in molecular marker technologies, biometrical models have been constructed, refined and generalized for the mapping of quantitative trait loci (QTL). However, current models present restrictions in terms of breeding designs to which they apply. In this paper, we develop an approach for the generalization of the mixture model for progeny from a single bi-parental cross of inbred lines. Detailed derivations are given for genetic designs involving populations developed by selfing, i.e., where marker genotypes are obtained from Fx (x > or = 2) individuals and where phenotypes are measured on Fy (y > or = x) individuals or families. Extensions to designs involving doubled-haploids, backcross-derived individuals and random matings are outlined. The derivations presented here can easily be combined with current QTL mapping approaches.

Crosses, Genetic↗
PubMed1995

Isolation and characterization of a thermophilic sulfate-reducing bacterium, Desulfotomaculum thermosapovorans sp. nov.

Strain MLFT (T = type strain), a new thermophilic, spore-forming sulfate-reducing bacterium, was characterized and was found to be phenotypically, genotypically, and phylogenetically related to the genus Desulfotomaculum. This organism was isolated from a butyrate enrichment culture that had been inoculated with a mixed compost containing rice hulls and peanut shells. The optimum temperature for growth was 50 degrees C. The G+C content of the DNA was 51.2 mol%. Strain MLFT incompletely oxidized pyruvate, butyrate, and butanol to acetate and presumably CO2. It used long-chain fatty acids and propanediols. We observed phenotypic and phylogenetic differences between strain MLFT and other thermophilic Desulfotomaculum species that also oxidize long-chain fatty acids. On the basis of our results, we propose that strain MLFT is a member of a new species, Desulfotomaculum thermosapovorans.

DNA, Bacterial↗
PubMed1980

Thermodynamic studies of binding proteins: effects of temperature variations on substrate binding and conformation of the leucine-isoleucine-valine binding protein of Escherichia coli.

The behaviour of the Leucine isoleucine Valine binding protein of Escherichia coli as a function of temperature has been examined. Substrate binding measurements showed a temperature dependence of the leucine-isoleucine-valine binding protein leucine complex formation constants. The protein-substrate complex was completely dissociated beyond 70 degrees C. In the range 5-65 degrees C the protein remained active but Van't Hoff's plots indicated changes of the reaction thermodynamic parameters. Large negative delta Cp values (--2.25 kJ mole-1 K-1 between 5 and 40 degrees C and--9.40 above 40 degrees C) indicate important substrate induced modifications of the protein conformation. Scanning calorimetry of the leucine isoleucine valine binding protein before and after addition of leucine was also performed. Two thermal events were recorded when the protein was substratefree and only one, at a higher temperature and more important, when the substrate was added. The results of these two approaches were in agreement in that both methods suggested a binding dependent conformational change of the protein which resulted in a greater stability of its structure.

Bacterial Proteins↗
PubMed1978

Biphasic saturations of binding proteins can be the result of a competitive inhibition of substrate fixation.

A mathematical model is proposed which explains some biphasic saturations of Binding Proteins by their substrates through an effect of a competitive inhibition. The inhibitor can be the substrate itself especially when the retention phenomenon is occuring. This model has been verified with two periplasmic Binding Proteins of Escherichia coli: the Glutamine Binding Protein and the Leucine-Isoleucine-Valine Binding Protein. A significant connection is found between experimental results and the hypothesis.

Binding, Competitive↗
PubMed1978

[Immersion: From mental anorexia to behavioral therapeutics].

The flooding is an extinction process of an emotion or a pulsion through a mechanism of Pavlov of conditioned inhibition. The author does here an experimental study of this process. This study allows to explain the exact flooding mechanism. So we can better understand and better introduce the practical flooding applications in therapeutic as well as in psychopathology.

Animals↗
PubMed1977

Thermodynamic study of the formation of adenine nucleotide-manganese complexes. I. "pH stat" titration method results.

The thermodynamics associated with the Mn2- -ATP, Mn-ADP- and Mn-AMP complex formation reactions determined from K potentiometric measurements at I = 0.2 are reported for the temperature range 1--45 degrees C. The K values increase with the length of the phosphate chain and with temperature. The limits and the best conditions for use of the "pH stat" titration method are discussed. Comparison with the results obtained by potentiometric and calorimetric methods in the case of Mg-nucleotide complexes is made.

Adenine Nucleotides↗
PubMed1977

Thermodynamic study of the formation of adenine nucleotide-manganese complexes. II. Calorimetric results.

Enthalpic variations in the formation of adenine nucleotide-manganese complexes, as measured by microcalorimetry, are reported. All the results are obtained in the temperature range 6--30 degrees C at I =0.2 and pH values 7.00 or 7.50. All the reactions are endothermic and the deltaH values increase with the length of the phosphate chain and with temperature. The deltaH values are compared with those previously obtained for adenine nucleotide-manganesium complexes. The comparison between calorimetric and potentiometric deltaH values is made. The divergence observed between these results at low temperature leads us to assume the formation of nucleotide aggregates induced by the presence of manganese ions. This hypothesis is confirmed by differential ultraviolet spectra.

Adenine Nucleotides↗