Biomedical subjects

M Fèvre

Publications and source records attributed to M Fèvre.

At least 37 records · Page 2Linked to original sources

PubMed1995

Characterization of the "promoter region" of the enolase-encoding gene enol from the anaerobic fungus Neocallimastix frontalis: sequence and promoter analysis.

The sequence of the Neocallimastix frontalis enolase gene promoter was determined up to 1800 nucleotides 5' to the major transcriptional start point. The base composition of the enolase upstream sequence revealed a very A + T-rich profile (13.5% G + C) leading to many putative hairpin structures. The functional organization of the N. frontalis enolase promoter was investigated by heterologous transient-expression assays. DNA fragments obtained by the sequential removal of sequences upstream of the translation start codon were fused to the Escherichia coli lacZ gene and the resulting plasmids were used to transform the ascomycetes Aspergillus nidulans and Penicillium roqueforti and the oomycete Saprolegnia monoica. Transient expression of the lacZ reporter gene was observed in regenerating proteoplasts of S. monoica when using the 0.3 kb or 1 kb upstream of the enolase coding region. In contrast no beta-galactosidase activity was detected in ascomycete protoplasts. DNA hybridization analysis revealed the integration of vector DNA in the genomic DNA of S. monoica and the presence of free copies of the transformation plasmid which could be rescued in E. coli. Our results indicate that the transcriptional machinery of the anaerobic chytrid N. frontalis may differ significantly from that of ascomycetes but that enough conservation exists within the lower fungi to allow a transient-driven expression of a reporter gene in an oomycete fungus.

Base Sequence↗

PubMed1995

Characterization of a multigene family encoding an endopolygalacturonase in Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum produces several polygalacturonases which together with other pectinolytic enzymes are involved in the degradation of pectin. A number of different genomic clones were isolated by screening a genomic DNA library in phage EMBL3. Southern-blot and restriction mapping indicate that seven genes constitute two subfamilies of a multigene family encoding endopolygalactutonase. Using pulsed-field gel electrophoresis to separate S. sclerotiorum chromosomes each subfamily was found to hybridize to a different chromosome. A comparison of the nucleotide sequence for the coding region of three members of the gene family reveals surprisingly few base substitutions suggesting that this gene family arose from recent multiple duplication events.

Amino Acids↗

PubMed1994

Cloning and sequence analysis of a polygalacturonase-encoding gene from the phytopathogenic fungus Sclerotinia sclerotiorum.

The phytopathogenic fungus Sclerotinia sclerotiorum produces a number of extra-cellular pectin-degrading enzymes. We have cloned and determined the complete sequence of a gene (pg1) encoding an endopolygalacturonase (PG1). The coding region consists of a non-interrupted 1143-bp open reading frame. S. sclerotiorum pg1 was compared to other fungal PG-encoding genes. Basic transcription control sequences were identified in the 5' non-coding region. The deduced amino acid (aa) sequence (380 aa) of the enzyme is compared to seven fungal PG sequences and shows a high level of identity (41.5 to 59.8%). Predicted secondary structures were compared, revealing a similar protein organization most probably in antiparallel beta sheets. Hybridization analysis using a pg1 0.65-kb BamHI fragment as a probe allowed the identification of seven different recombinant phages from a genomic library. Analysis of the hybridizing restriction fragments suggests that PG-encoding genes are organized as a family.

Amino Acid Sequence↗

PubMed1993

Randomly amplified polymorphic DNAs assess recombination following an induced parasexual cycle in Penicillium roqueforti.

Random amplified polymorphic DNAs (RAPDs) were used as a genetic marker system to characterize recombinant strains following the parasexual cycle of Penicillium roqueforti. After protoplast fusion and haploidization of diploid hybrids, segregants characterized by a reassortment of the parental genetic markers displayed specific RAPD fingerprints. The appearance or the loss of RAPD fragments demonstrate that these markers provide an efficient method to analyze recombination and to characterize somatic hybrids.

Base Sequence↗

PubMed1990

Separation and Partial Purification of 1,3-beta-Glucan and 1,4-beta-Glucan Synthases from Saprolegnia.

Enriched 1,3-beta-glucan and 1,4-beta-glucan synthase fractions from the fungus Saprolegnia were isolated by rate zonal centrifugation on glycerol gradient. Purification was improved by entrapment of the enzymes in their reaction product, i.e. microfibrillar glucans. 1,3-beta-Glucan synthases were separated from 1,4-beta-glucan synthases following resuspension of entrapped enzymes. Sodium dodecylsulfate-polyacrylamide gel electrophoresis indicated that 1,3-beta-glucan and 1,4-beta-glucan synthases may have a different polypeptide composition because they were enriched for different protein subunits (34, 48, and 50 kD for the 1,3-beta-glucan synthase and 60 kD for the 1,4-beta-glucan synthase).

Journal Article↗

PubMed1984

Patterns of plasma melatonin with ageing and mental condition: stability of nyctohemeral rhythms and differences in seasonal variations.

Effects of ageing and mental condition on the nyctohemeral and seasonal rhythms of plasma melatonin in human subjects were investigated. Four groups of subjects were formed for a transverse study: 7 healthy young men (24 years), 6 elderly women, 6 elderly men and 6 elderly patients (2 men and 4 women) suffering from senile dementia (70-80 years). The subjects were synchronized. Blood samples were taken every 4 h during 24 h in January, March, June and October. In comparison to young men, the plasma levels of melatonin were markedly decreased (by about one half) in elderly subjects without any difference according to sex or mental condition. Nyctohemeral rhythms of the hormone were validated in all groups and at all sampling sessions. The nyctohemeral acrophases were remarkably stable (around 03.00 h) whatever the season, age or sex. A seasonal variation was found in all groups (except elderly women) with differences between young and elderly subjects: plasma melatonin levels were significantly lower in January than in June in young men, whereas in elderly subjects they were significantly lower in October than in January/March. No significant difference was observed in mesor, amplitude or acrophase of nyctohemeral and seasonal rhythms of plasma melatonin in patients with senile dementia when compared with healthy elderly subjects. The stability of the nyctohemeral peak time whatever the age group or season as opposed to the differences in the seasonal pattern of plasma melatonin according to the age groups raises the problems of both outdoor photoperiod and ageing in ruling the secretion of melatonin in man.

Adult↗

PubMed1981

Age- and mental health-related circadian rhythms of plasma levels of melatonin, prolactin, luteinizing hormone and follicle-stimulating hormone in man.

Circadian changes in plasma levels of melatonin, prolactin, LH and FSH were studied in four groups: seven healthy young men, six elderly men, six elderly women and six elderly demented patients (two men and four women). The daily activities of the subjects were synchronous and blood samples were taken every 4 h. The 24-h mean concentrations of prolactin in plasma were the same in all groups, whereas those of LH and FSh were twice as high in the elderly as in the young men and eight and 23 times higher respectively in the elderly women. The 24-h mean plasma levels of melatonin in the elderly were half those in the young, but were not influenced by the sex or mental condition of the subjects. A statistically significant circadian rhythm for melatonin was defined in the four groups, for prolactin in all groups except the elderly men and for LH only in the demented patients and in the young men. No circadian rhythm could be detected for FSH in any of the four groups. The acrophases of melatonin and prolactin ranged between 02.30 and 04.00 h, those of LH (when a rhythm was validated) clustered around 01.00 h. The circadian rhythms of plasma levels of melatonin, prolactin and LH are not modified in old age nor in dementia. A positive correlation has been demonstrated in young men between melatonin and LH and between melatonin and prolactin, but no such correlation could be found in the elderly.

Adult↗

PubMed1977

[Plasma LH response to LHRH in hypothyroid and thyroxin-treated rats (author's transl)].

Plasma LH response after intravenous injection of synthetic LHRH (50 ng) was studied in male rats (normal, after thyroidectomy, after treatment by dl thyroxin 50 microgram/a day, 10 days). LH response was significantly elevated in hypothyroid animals although it was not influenced by thyroxin injections. Prolonged plasma LH half-life in hypothyroid rats can account in this result.

Animals↗

PubMed1975

[Prolactin adenoma. Study of gonadotrophic function by the sassoles G LHRH test].

An intravenous injection of synthetic LHRH (50mug) was given in 10 patients with prolactin secreting pituitary adenomas. Variations in circulating levels of gonadotrophic hormones were measured by radioimmunological estimation. The increase in blood level of luteinizing hormone was constant, low in three cases, normal in 3 and high in 4. An increase in follicle stimulating hormone (FSH) was absent in only two cases. The data obtained indicates the absence of any characteristic value of the LHRH test in the aetiological diagnosis of amenorrhoea/galactorrhoea syndromes. They represent an argument in favour of the relative character and of the functional nature of the gonadotrophic insufficiency of prolactin adenomas.

Adenoma↗

PubMed1970