Jean-Claude Salvado | Université De Pau Et Des Pays De L'adour (original) (raw)

Papers by Jean-Claude Salvado

John Wiley & Sons, Inc. eBooks, Nov 10, 2011

Aims: The aim of the present study was to reveal the microbial genetic diversity of epilithic bio... more Aims: The aim of the present study was to reveal the microbial genetic diversity of epilithic biofilms using a DNA-based procedure. Methods and Results: A DNA extraction protocol was first selected to obtain PCR-amplifiable metagenomic DNA from a limestone biofilm. Extracted DNA was used to amplify either 16S rRNA genes or ITS regions from prokaryotic and eukaryotic genomes, respectively. Amplified DNAs were subsequently cloned, amplified by colony PCR and screened by restriction analysis [restriction analyses of amplified ribosomal DNA (ARDRA)] for DNA sequencing. Phylogenetic analysis using 16S rDNA sequences showed that predominating bacteria were Alphaproteobacteria belonging to the genera Sphingomonas, Erythrobacter, Porphyrobacter, Rhodopila and Jannashia; Cyanobacteria and Actinobacteria were also identified. Analysis of ITS rDNA sequences revealed the presence of algae of the Chlorophyceae family and fungi related either to Rhinocladiella or to a melanized ascomycete. Statistical analysis showed that the specific richness evidenced was representative of the original sampled biofilm. Conclusions: The molecular methodology developed here constitutes a valuable tool to investigate the genetic diversity of microbial biofilms from building stone. Significance and Impact of the Study: The easy-to-run molecular method described here has practical importance to establish microbiological diagnosis and to define strategies for protection and restoration of stone surfaces.

Current Genetics, Aug 1, 1991

An Agrocybe aegerita cDNA library, constructed from fruit body primordia poly(A) + RNAs, was scre... more An Agrocybe aegerita cDNA library, constructed from fruit body primordia poly(A) + RNAs, was screened by differential colony hybridization. Clones which preferentially hybridized to poly(A) + RNA sequences from fruit body primordia, versus poly(A) + RNAs from mycelium, were isolated. Eight of these clones (EMAa-I to EMAa-8) encoded eight different poly(A) + RNAs which were demonstrated to be undetectable in the four stages preceding primordia formation and to be concomitantly accumulated when primordia differentiate, suggesting that EMAa gene products are closely involved in the morphogenesis of primordia. The eight EMAa cDNAs hybridize to at least seven unique regions distributed randomly in the A. aegerita genome. The expression of two EMAa cDNA sequences in E. coli led to the isolation of their gene products as fusion proteins.

HAL (Le Centre pour la Communication Scientifique Directe), Jun 28, 2004

The fate of mercury species in the environment strongly depends on microbial activities and envir... more The fate of mercury species in the environment strongly depends on microbial activities and environmental conditions. Methylation esp. is one of the major processes, which transform the inorg. forms of the metal into toxic and easily bioaccumulated org. forms. Thus, we designed an exptl. setup to study mercury biotransformation in estuarine ecosystems. Sediments were incubated in slurries and polluted with inorg. mercury (HgCl2). Mercury methylation was obsd. only in slurries maintained under anoxic conditions. The main microbial populations were isolated and identified by partial sequencing of 16S rDNA. The methylation, studied by gas chromatog.-inductively coupled plasma mass spectrometry, demonstrated that only sulfate-reducing bacteria were the methylators among this community, which also comprise denitrifiers and fermentative bacteria.

Plasmid, Sep 1, 1989

An erythromycin-resistant strain (M4 Er-I) was selected from Spiroplasmu citri M4+. The transfer ... more An erythromycin-resistant strain (M4 Er-I) was selected from Spiroplasmu citri M4+. The transfer by transformation of the erythromycin-resistance character to the erythromycin-sensitive S. citri strain R8A2+ was studied. Transfer became effective and reproducible when cells were treated with alkali cations plus polyethylene glycol. Comparison of the efficiency of transformation of the erythromycin-sensitive strain S. citri R8A2+ by total and extrachromosomal DNA purified from the erythromycin-resistant strain M4 Er-1 showed that the plasmid pM42 was able to transfer the erythromycin-resistance. pM42 was mapped with restriction endonucleases and found to be related to the pMH1 plasmid previously isolated from S. citri MH. Hybridization analysis of DNA from sensitive and resistant strains has shown that a sequence from pM42, analogous to a sequence from pMH 1, was integrated at a specific locus in the chromosome of the erythromycinresi ,tant cells, i.e., of the transformed R8A2 cells and of the spontaneous mutant M4 Er-1 strain.

HAL (Le Centre pour la Communication Scientifique Directe), Jul 3, 2017

Current Microbiology, 1990

Gene transfer-recombination involving three different chromosomal markers (Ars R, Van R, and Xyl ... more Gene transfer-recombination involving three different chromosomal markers (Ars R, Van R, and Xyl R) and influence of the fusing agent PEG on transfer efficiency were investigated in matings between single=resistant or single and double-resistant strains of Spiroplasma citri. Efficiency and kinetics vary, in S. citri, with the markers involved in the crosses and are not enhanced by the membrane fusion effect of PEG. These features allow one to distinguish the chromosomal gene transfer in S. citri from the closely related transfer by protoplast fusion in Gram-positive bacteria. However, the results may be explained by a spontaneous high frequency of the membrane fusion events of S. citri cells and the existence of variations in the recombination frequency of the markers. Indeed, in S. citri, the formation of the heterozygotic polyploid structure formed after membrane fusion may be considered as a nonlimiting step of the mechanism and allows one, accordingly, to point out differences in recombination frequencies of the markers.

Letters in Applied Microbiology, Sep 1, 2009

Environmental Pollution, Dec 1, 2008

Role of oxic/anoxic cycles and microbial activities on the methylmercury formation in Adour (Fran... more Role of oxic/anoxic cycles and microbial activities on the methylmercury formation in Adour (France) estuarine sediments.

Applied and Environmental Microbiology, Sep 1, 1991

The total proteins and concanavalin A-binding glycoproteins of the cultivated mushroom Agrocybe a... more The total proteins and concanavalin A-binding glycoproteins of the cultivated mushroom Agrocybe aegerita were studied in homokaryotic siblings and in dikaryotic strains. The glycoproteins exhibited considerable variability compared with the proteins; the genetic diversity detected in homokaryons in the glycoprotein analysis was 30-fold higher than the genetic diversity revealed by protein analysis, and the glycoprotein patterns could be used to characterize individual genotypes. We found that the expression of glycoproteins in haploid nuclei was significantly asymmetric when the nuclei were paired in dikaryons. The expression levels of the two component nuclei depended on their genotypes, and each haploid nucleus was characterized by its level of expression. Furthermore, some specific glycoproteins that were not detected in all of the homokaryons were newly synthesized in the dikaryotic strains. Among these was a glycoprotein designated gpAa-65, which was identified in all of the dikaryotic strains and appeared to be a good molecular marker of the dikaryotic state.

Theoretical and Applied Genetics, Oct 1, 1989

A procedure suitable for the extraction and mapping of total proteins from the basidiomycete, Agr... more A procedure suitable for the extraction and mapping of total proteins from the basidiomycete, Agrocybe aegerita, was developed. A. aegerita mycelia were fragmented either with a Dangoumeau grinder, an X-press bomb or a sonicator and the efficiency of these three disruption methods were compared. The extraction buffer composition was optimized to avoid proteolytic activities. 2D-SDS-PAGE analysis of protein extracts showed that the rate of reproducibility depending on extractions and electrophoretic separations was always greater than 96% for all strains. The differences in efficiency observed between the breaking procedures indicate that the A. aegerita cell wall is more mechanically resistant than that of other basidiomycetes. The efficient action of protease inhibitors (PMSF and SDS) showed that A. aegerita mycelia contains numerous and/or highly active proteases. Reproducibility of protein extraction and separation methods allowed the establishment and the comparison of standard maps. Qualitative and quantitative variations in gene products between a wild dikaryotic strain and 11 homokaryotic strains from its progeny were examined. The genetic diversity, determined by comparing the distribution of proteic variations in 11 homokaryons from the same progeny, was comparable to that observed between co-isogenic homokaryons of another basidiomycete.

Conservation Genetics, Apr 5, 2014

The restoration and maintenance of habitat connectivity are major challenges in conservation biol... more The restoration and maintenance of habitat connectivity are major challenges in conservation biology. These aims are especially critical for migratory species using corridors that can be obstructed by anthropogenic barriers. Here, we explored the origins and genetic diversity of Atlantic salmon (Salmo salar) recolonizing upstream areas of the largest South European Atlantic salmon population (Adour drainage, France) following restoration of connectivity and stocking. We genotyped 1,009 juvenile individuals, sampled either in continuously inhabited downstream sites or in recently reconnected and recolonized upstream locations, at 12 microsatellite loci. We found significant fine scale genetic structure, with three main genetic clusters corresponding to the Nive, Nivelle and Gaves rivers. Within each of these clusters, samples collected in continuously inhabited and recently recolonized sites had comparable allelic richness and effective population sizes and were only weakly differentiated. Genetic structure among basins was also similar among continuously inhabited and recently recolonized sites. The majority of the individuals sampled from recently recolonized sites were assigned to neighboring continuously inhabited downstream sites, but noticeable proportions of fish were assigned to samples collected in more distant sites or identified as putative hybrids. Overall, this study suggests that the restoration of accessibility to upstream areas can allow for the recolonization and effective reproduction of Atlantic salmon from proximate downstream refugia, which does not decrease local diversity or disrupt existing genetic structure.

Plant Science, Nov 1, 2003

Genetica, 1994

Most of the transposons so far characterized from mosquito genomes are retroelements which seem t... more Most of the transposons so far characterized from mosquito genomes are retroelements which seem to be distributed worldwide. The Juan transposons constitute a family of non-LTR retroelements, or LINE-retroposons, which are dispersed in the genomes of several mosquito species. Three different Juan subfamilies have been characterized, each being amplified in the genomes of many strains, if not all, of a given mosquito species. These subfamilies have been designated respectively Juan-C in Culex pipiens, Juan-Ct in Culex tarsalis and Juan-A in Aedes aegypti. A large number of the Juan retroposons which are amplified in the mosquito genomes are apparently full-length copies and potentially encode the enzymes necessary for their transposition, a nucleic acid binding protein and a reverse transcriptase. However, these complete Juan copies seem to be most frequently transcriptionally silent in insects reared under laboratory conditions. A few of them are transcribed in C. pipiens cells grown in vitro, but from an external promoter, the Juan-C specific RNA being fused to an upstream RNA sequence. Therefore, the transcription of Juan retroposons seems to depend on external promoters which are most frequently inactive. The occurrence and distribution of Juan retroposon subfamilies among mosquito species do not reflect the phylogeny of these species. Furthermore, complete Juan-C and Juan-A copies which are reiterated in strains collected from regions covering different continents are nearly identical. Juan-C copies belonging to geographically different C. pipiens strains display low levels of divergence between their nucleotide sequences and many of the mutations which have occurred among these copies do not alter their coding potential. These results indicate that the Juan retroposons occur as homogeneous subfamilies distributed worldwide and that selective constraints against amino acid change have been acting recently on these elements, despite the fact that they are now highly repeated through mosquito genomes. Therefore, Juan transposons have most probably been recently amplified in mosquito genomes. Each subfamily may have been amplified from one master element present in a unique population which has since spread worldwide. Alternatively, this amplification may have arisen in many mosquito populations, but from highly conserved master elements submitted to selection pressures. Horizontal transfers between species may also have contributed to the spread of these transposons.

Applied and Environmental Microbiology, 1991

Le but de cette étude, était de développer un nouveau biomarqueur afin d'évaluer l'impact... more Le but de cette étude, était de développer un nouveau biomarqueur afin d'évaluer l'impact de trois polluants atmosphériques préoccupants : l'ozone, le formaldéhyde et le benzène. Pour cela, nous avons mesuré le niveau d'activation du promoteur de Tnt1A sur des plantes exposées à ces trois polluants. Le rétrotransposon de tabac Tnt1A est un des seuls rétrotransposons de plantes connu pour transcriptionnellement activé par divers stress biotiques et abiotiques, chez son espèce hôte le tabac et chez des espèces hétérologues. Les expériences ont été réalisées dans le but de déterminer si le promoteur de Tnt1A pouvait être activé chez le tabac et la tomate par des polluants atmosphériques représentatifs, comme l'ozone, le formaldéhyde et le benzène. En pratique, les plantes ont était cultivées et exposées aux polluants dans des chambres à ciel ouverts (OTC). Les feuilles ont ensuite été récoltées et le niveau d'activation du promoteur de Tnt1A mésuré en utilisant ...

Fisheries Society of the British Isles Annual Symposium, Jul 3, 2017

Geomicrobiology Journal, 2009

... R. Duran a , D. Amouroux b , JC Salvado a & R. Guyoneaud a pages 1-8. ... The extraction ... more ... R. Duran a , D. Amouroux b , JC Salvado a & R. Guyoneaud a pages 1-8. ... The extraction procedure used for sediments (Rodriguez Martin-Doimeadios et al. 200436. Rodriguez Martin-Doimeadios, RC, Tessier, E, Guyoneaud, R, Duran, R, Caumette, P and Donard, O FX. 2004. ...

Environmental Pollution, 2008

Theoretical and Applied Genetics, 1989