Biomedical subjects

M Sasseville

Publications and source records attributed to M Sasseville.

4 recordsLinked to original sources

PubMed2004

Alcohol-mediated error-prone PCR.

The effect of urea, isopropanol, propan-1-ol, and butan-1-ol on PCR using three different DNA polymerases was investigated. In the presence of these agents, polymerases were active as expected up to a critical concentration where they became progressively inhibited. Critical concentrations of alcohols generally increased with thermoresistance of the polymerases and decreased with the hydrophobicity of the alcohols. These results indicate that an important aspect of the inhibition involved conformational loosening due to a decrease in the hydrophobic effect. A mutagenic effect occurred with Vent(r) (exo-) DNA polymerase in the presence of 7.0 to 8.0% v/v propan-1-ol, affording mutation frequencies of up to 9.8 x 10(-3) mutation/bp/PCR. Under these conditions the preferential replacement of Gs and Cs was observed, in opposition to standard error-prone PCR that favors replacement of As and Ts. Comparison of various PCR conditions indicates that propanol and MnCl2 have different modes of action, and that the decrease in fidelity promoted by propanol is due to a finely tuned partial destabilization of the polymerase. The PCR conditions developed in this study provide a useful alternative for targeting different sequence space for directed evolution experiments.

1-Propanol↗

PubMed2004

Single-point mutations at the surface of MB-1Trp lead to important changes in its conformational properties.

Protein design is currently used for the creation of new proteins with desirable traits. In our lab we focus on the synthesis of proteins with high essential amino acid content having potential applications in animal nutrition. One of the limitations we face in this endeavour is achieving stable proteins despite a highly biased amino acid content. We report here the synthesis and the characterization of three variants of MB-1Trp in which two solvent-exposed Leu have been replaced by Glu allowing for the formation of new salt bridges at the surface of the protein. Although both mutations were expected to be similar (i.e. same mutation in a comparable local environment), they appear to have different effects on MB-1Trp as shown by far-UV circular dichroism, thermal denaturation, fluorescence and proteolytic resistance measurements. For the mutation Leu68Glu, an increase in the protein melting temperature of 6 degrees C was observed. Surprisingly, the mutation in position Leu19Glu led to a decrease in melting temperature and a modification of tertiary structure.

Amino Acid Substitution↗

PubMed1988

Evolutionary conservation of the chromosomal configuration and regulation of amylase genes among eight species of the Drosophila melanogaster species subgroup.

Nuclear DNA was extracted from each of the eight species comprising the Drosophila melanogaster species subgroup. Southern hybridization of this DNA by using a molecular probe specific for the alpha-amylase coding region showed that the duplicated structure of the amylase locus, first found in D. melanogaster, is conserved among all species of the melanogaster subgroup. Evidence is also presented for the concerted evolution of the duplicated genes within each species. In addition, it is shown that the glucose repression of amylase gene expression, which has been extensively studied in D. melanogaster, is not confined to this species but occurs in all eight members of the species subgroup. Thus, both the duplicated gene structure and the glucose repression of Drosophila amylase gene activity are stable over extended periods of evolutionary time.

Amylases↗

PubMed1987

[Unemployment and mental health].

Evidence linking unemployment with psychiatric morbidity is available since the thirties, but it is only in the seventies that a renewed research interest on this subject took place. Two research strategies seem to be emerging: an "ecological" approach establishing correlations between economical and health indicators for a given population. Another approach focuses on the psychiatric morbidity of samples of individuals who have lost their job compared to matched control groups of individuals still employed. Many of those studies did not limit themselves on the mental health of the unemployed but on the "rippling" effect of unemployment on the family and community. Many aspects of the consequences of unemployment on mental health remain to be explored such as the effects of long-term unemployment, unemployment among women. Methods of emotional supportive interventions for the unemployed need also to be explored. Furthermore the effects of a high level of unemployment on the programs of deinstitutionalization of the chronic mentally ill as well as the mentally handicapped should be evaluated.

Economics↗