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Biomedical subjects

M Masselot

Publications and source records attributed to M Masselot.

15 recordsLinked to original sources
PubMed2001

Spoligotype diversity of Mycobacterium bovis strains isolated in France from 1979 to 2000.

The molecular fingerprints of 1,349 isolates of Mycobacterium bovis received between 1979 and August 2000 at Agence Française de Sécurité Sanitaire des Aliments (Afssa) have been obtained by spoligotyping. The majority of the isolates (1,266) were obtained from cattle living in France. An apparently high level of heterogeneity was observed between isolates. One hundred sixty-one spoligotypes were observed in total, of which 153 were from French isolates. The two predominant spoligotypes, designated BCG-like and GB54, accounted for 26 and 12% of the isolates, respectively. In addition, 84% of the spoligotypes were found fewer than 10 times. Analysis of the results by clustering and parsimony-based algorithms revealed that the majority of the spoligotypes were closely related. The predominant spoligotype was identical to that of the vaccine strain Mycobacterium bovis BCG, which was isolated in France at the end of the 19th century. Some spoligotypes were closely associated with restricted geographical areas. Interestingly, some spoligotypes, which were frequently observed in France, were also observed in neighboring countries. Conversely, few spoligotypes were common to France and England, and those that were shared were observed at very different frequencies. This last point illustrates the potential role for an international data bank, which could help trace the spread of M. bovis across national borders.

Animals↗
PubMed2000

Molecular adaptation to an extreme environment: origin of the thermal stability of the pompeii worm collagen.

The annelid Alvinella pompejana is probably the most heat-tolerant metazoan organism known. Previous results have shown that the level of thermal stability of its interstitial collagen is significantly greater than that of coastal annelids and of vent organisms, such as the vestimentiferan Riftia pachyptila, living in colder parts of the deep-sea hydrothermal environment. In order to investigate the molecular basis of this thermal behavior, we cloned and sequenced a large cDNA molecule coding the fibrillar collagen of Alvinella, including one half of the helical domain and the entire C-propeptide domain. For comparison, we also cloned the 3' part of the homologous cDNA from Riftia. Comparison of the corresponding helical domains of these two species, together with that of the previously sequenced domain of the coastal lugworm Arenicola marina, showed that the increase in proline content and in the number of stabilizing triplets correlate with the outstanding thermostability of the interstitial collagen of A. pompejana. Phylogenetic analysis showed that triple helical and the C-propeptide parts of the same collagen molecule evolve at different rates, in favor of an adaptive mechanism at the molecular level.

Adaptation, Physiological↗
PubMed2000

Cirripede phylogeny using a novel approach: molecular morphometrics.

We present a new method using nucleic acid secondary structure to assess phylogenetic relationships among species. In this method, which we term "molecular morphometrics," the measurable structural parameters of the molecules (geometrical features, bond energies, base composition, etc.) are used as specific characters to construct a phylogenetic tree. This method relies both on traditional morphological comparison and on molecular sequence comparison. Applied to the phylogenetic analysis of Cirripedia, molecular morphometrics supports the most recent morphological analyses arguing for the monophyly of Cirripedia sensu stricto (Thoracica + Rhizocephala + Acrothoracica). As a proof, a classical multiple alignment was also performed, either using or not using the structural information to realign the sequence segments considered in the molecular morphometrics analysis. These methods yielded the same tree topology as the direct use of structural characters as a phylogenetic signal. By taking into account the secondary structure of nucleic acids, the new method allows investigators to use the regions in which multiple alignments are barely reliable because of a large number of insertions and deletions. It thus appears to be complementary to classical primary sequence analysis in phylogenetic studies.

Animals↗
PubMed1997

Cloning of an annelid fibrillar-collagen gene and phylogenetic analysis of vertebrate and invertebrate collagens.

Arenicola marina possesses cuticular and interstitial collagens, which are mostly synthesised by its epidermis. A cDNA library was constructed from the body wall. This annelid cDNA library was screened with a sea-urchin-collagen cDNA probe, and several overlapping clones were isolated. Nucleotide sequencing of these clones revealed an open reading frame of 2052 nucleotides. The translation product exhibits a triple helical domain of 138 Gly-Xaa-Yaa repeats followed by a 269-residue-long C-terminal non-collagenous domain (C-propeptide). The triple helical domain exhibits an imperfection that has been previously described in a peptide produced by cyanogen bromide digestion (CNBr peptide) of A. marina interstitial collagen. This imperfection occurs at the same place in the interstitial collagen of the vestimentiferan Riftia pachyptila. This identifies the clone as coding for the C-terminal part of a fibrillar collagen chain. It was called FAm1alpha, for fibrillar collagen 1alpha chain of A. marina. The non-collagenous domain possesses a structure similar to carboxy-terminal propeptides of fibrillar pro-alpha chains. Only six conserved cysteine residues are observed in A. marina compared with seven or eight in all other known C-propeptides. This provides information on the importance of disulfide bonds in C-propeptide interactions and in the collagen-assembly process. Phylogenetic studies indicate that the fibrillar collagen 1alpha chain of A. marina is homologous to the R. pachyptila interstitial collagen and that the FAm1alpha gene evolved independently from the other alpha-chain genes. Complementary analyses indicate that the vertebrate fibrillar collagen family is composed of two monophyletic subgroups with a specific position of the collagen type-V chains.

Amino Acid Sequence↗
PubMed1993

[Selective bronchial occlusion in the treatment of unilateral interstitial emphysema in respiratory distress in premature infants].

A case of right unilateral pulmonary interstitial emphysema in a compromised premature infant was managed by right selective bronchial occlusion with a favorable outcome. Occlusion with a Rashkind catheter occurred on day 8 and was well-tolerated. The balloon was deflated 10 hours later and no recurrence was observed. Right occlusion is easier than left selective intubation and seems to be the best method for treatment of unilateral interstitial emphysema in infants in extremely poor conditions.

Bronchi↗
PubMed1992

Combined radiotherapy and surgery: local control and complications in early carcinoma of the uterine cervix--the Villejuif experience, 1975-1984.

From January 1975 to December 1984, 441 patients were treated by combined radiotherapy and surgery at the Institut Gustave Roussy (IGR) for Stage IB (288) and II (proximal) (103) carcinoma of the uterine cervix. Standard treatment consisted of pre-operative utero-vaginal brachytherapy (60 Gy) using a mould technique followed by a colpo-hysterectomy and external iliac lymphadenectomy. Overall 5 year actuarial survival for the whole population was 87% and disease-free survival 85%. Loco-regional relapse occurred in 23 patients (5%). Of these, 12 were central pelvic failures, 8 regional failures and 3 combined central and regional failures. There were 36 systemic relapses (8%) of which 12 relapsed concurrently in the pelvis. Five year actuarial pelvic disease-free, disease-free and overall survival was 87, 85 and 87%, respectively, for the whole population. 340 patients developed one or more complications [Grade 1: 198/441 (44%), Grade 2: 121/441 (27%) and Grade 3 or 4: 21/441 (4.7%)]. Five year actuarial survival for the whole population was poorer for histologically node positive than for node negative (89 vs. 55%, p less than 0.0001). Pre-operative brachytherapy followed by surgery can provide good local control with acceptable morbidity in early cervical cancer.

Combined Modality Therapy↗
PubMed1977

Methionine biosynthesis in Saccharomyces cerevisiae. II. Gene-enzyme relationships in the sulfate assimilation pathway.

In Saccharomyces cerevisiae, the products of eleven different genes are needed for a functional sulfate assimilation pathway. Only five enzymatic steps are known in this pathway. The study of the gene-enzyme relationships has shown that the enzymes catalysing two of these steps are probably heteropolymeric. Moreover, mutations in three unlinked genes lead to multiple enzymatic losses. Different hypotheses are made to account for these results.

Genes, Regulator↗
PubMed1975

Methionine biosynthesis in Saccharomyces cerevisiae. I. Genetical analysis of auxotrophic mutants.

In order to analyse how many structural genes are implicated in the specific steps of the biosynthesis of methionine in Sacch. cerevisiae, a hundred mutants were studied by complementation. 21 groups were defined named MET1 to MET25. Neither recombination between independent mutants of the same complementation group nor linkage between different groups was found. Preliminary to biochemical studies, mutants of each complementation group were tested for their capacity to utilize various precursors of methionine.

Genes↗
PubMed1972

Nonsense mutation in the regulatory gene ETH2 involved in methionine biosynthesis in Saccharomyces cervisiae.

Ethionine-resistant mutants, mapping at the locus eth2-the product of which is involved in pleiotropic regulation of methionine biosynthesis-have been isolated in a strain carrying five ochre nonsense mutations. Selection for nonsense suppressors in such a strain led to characterization of several allele-specific but gene non-specific suppressors which are active on the recessive heteroallele eth2-2 (resulting in partial recovery of sensitivity toward ethionine) as well as on the five other suppressible alleles. Two of these suppressors are unlinked to the eth2 gene and either dominant or semi-dominant. It is concluded that the mutation eth2-2 resulted in a nonsense codon. Enzyme studies indicate that this mutation results in a complete absence of an active product of gene eth2, in contrast with the effect of a former mutation eth2-1 which was interpreted as leading to a modified product of this gene (Cherest, Surdin-Kerjan and de Robichon-Szulmajster 1971). This conclusion is based on the absence of repressibility of methionine group I enzymes and the observation that in a heteroallelic diploid, eth2-1 expression is not masked by eth2-2. The nonsense suppressors studied lead to at least partial recovery of repressibility of methionine group I enzymes. All these results support the idea that the product of gene ETH2 is an aporepressor protein.

Adenosine Triphosphate↗