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Biomedical subjects

J Sanjuan

Publications and source records attributed to J Sanjuan.

At least 19 recordsLinked to original sources
PubMed2006

Persistent auditory hallucinations.

BACKGROUND: There is still a significant proportion of psychotic patients who suffer from persistent auditory hallucinations (PAH) in spite of treatment. The objective of our study was to analyze those clinical dimensions that characterize persistent hallucinators in comparison with episodic hallucinators. SAMPLING AND METHODS: Ninety-one outpatients with AH were assessed through semistructured interviews. The interviews included the Psychotic Symptom Rating Scales for AH and the Krawiecka scale. They elicited descriptions about the persistence of AH, existence of pleasurable hallucinations and other types of hallucinations. RESULTS: Forty-five patients fulfilled criteria for reported PAH. Persistent hallucinators showed greater scores in frequency and duration of hallucinations, Krawiecka total score and incoherence of speech. Moreover, pleasurable experiences were more frequent in this group of patients. Logistic regression analysis rendered a model with the following variables: duration of voices, degree of control and pleasurable hallucinations. CONCLUSION: Specific dimensions of AH can predict the possibility of treatment resistance.

Adult↗
PubMed2004

A possible association between the CCK-AR gene and persistent auditory hallucinations in schizophrenia.

Recent studies have suggested that DNA variations in the CCK-AR gene might predispose individuals to schizophrenia and particularly to auditory hallucinations (AH). The aim of this study is to assess the association between AH, using a specific scale for AH in schizophrenia (PSYRATS), and the CCK-AR polymorphism at 779 in a Spanish sample. A total of 105 DSM-IV schizophrenic patients with AH and 93 unrelated controls were studied. Twenty-two patients were considered as persistent auditory hallucinators, which showed similar clinical and demographic characteristic than patients with episodic AH, but with the exception of the PSYRATS values. The persistent AH group showed an excess of the A1 allele when was compared with episodic or control groups. Our data support the possible role of the CCK-AR gene in the development of persistent AH in schizophrenic patients.

Adult↗
PubMed2004

Pleasurable auditory hallucinations.

OBJECTIVE: The focus in auditory hallucination (AH) research is usually on the negative impact of the experience itself. There are practically no studies on whether voices can be perceived as pleasurable. The aim of the present study was to assess the frequency of voices as a pleasurable experience in a psychotic patient population. METHOD: A total of 160 patients with AHs (89 schizophrenia and 17 other psychoses) were assessed with the psychotic symptom rating scale (PSYRATS) for AHs, including an added item on whether the experience was pleasurable. RESULTS: Twenty-eight patients (26%) reported the voices as a pleasurable experience and 10 of them did so frequently. Pleasurable hallucinations showed negative associations with amount and intensity of distress, degree of negative content and loudness. Positive associations were apparent with chronicity and perceived control over the voices. CONCLUSION: Pleasurable hallucinations can be detected in a substantial proportion of patients, and cross validated with existing instruments.

Adult↗
PubMed2002

Phenotypic and molecular characterization of chickpea rhizobia isolated from different areas of Morocco.

AIMS: To determine the biodiversity of rhizobial strains nodulating Cicer arietinum L. in representative soils from various areas of Morocco. METHODS AND RESULTS: Symbiotic traits, utilization of 49 carbohydrate sources, resistance to antibiotics and heavy metals, tolerance to salinity, to extreme temperatures and pH were studied as phenotypic markers. In addition, restriction fragment length polymorphism (RFLP) of PCR-amplified 16S rDNAs were compared with those of reference strains. Numerical analysis of the phenotypic characteristics showed that the 48 strains studied fell into three distinct groups. RFLP analysis of 16S rRNA genes revealed an additional heterogeneity and four ribotypes were identified. CONCLUSIONS: Chickpea rhizobia isolated from Moroccan soils are both phenotypically and genetically diverse. Most of these rhizobia belong to the Mesorhizobium genus. However, some strains originating from a particular soil appeared to have 16S rRNA genes similar to Sinorhizobium as well as very distinct auxanographic characteristics compared with Mesorhizo- bium isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: A well characterized collection of chickpea-nodulating rhizobia in representative soils of Morocco has been generated, which can be used to develop efficient inoculants for this crop. This is the first report evidencing that chickpeas may be nodulated by bacteria from the Sinorhizobium genus.

Alphaproteobacteria↗
PubMed2001

The disruption of a gene encoding a putative arylesterase impairs pyruvate dehydrogenase complex activity and nitrogen fixation in Sinorhizobium meliloti.

Nitrogen-fixing Sinorhizobium meliloti cells depend upon dicarboxylic acids as carbon and energy sources. The metabolism of these intermediate compounds of the trichloroacetic acid cycle is dependent upon the availability of acetyl-coenzyme A (CoA). In bacteroids, the combined activities of malic enzymes and pyruvate dehydrogenase (PDH) have been proposed to be responsible for the anaplerotic synthesis of acetyl-CoA. We obtained a S. meliloti mutant strain, PD3, in which a Tn5 insertion led to a significant decrease in the overall PDH activity. The genetic characterization of this mutant revealed that the transposon is located at the 3' end of a gene (ada) encoding a putative arylesterase. The mutant PD3 is deficient in nitrogen fixation, which strengthens the physiological importance of PDH activity in the symbiosis of S. meliloti with alfalfa plants.

Acetyl Coenzyme A↗
PubMed1998

Mercury in water and sediments of the southern Baltic sea.

Total mercury concentrations [HgT] were measured in samples of water and sediments collected from the southern Baltic Sea from the period 1993-1995. Picomolar concentrations of HgT were found in offshore surface water. Higher levels were measured in samples from the plum of the Vistula. An exceptionally high concentration of mercury (25 pM HgT, 5 pM methylmercury) was measured in the near bottom, quasi-anoxic water of the Gdañsk Deep and explained by the release of mercury from fine grained sediments covering the bottom. In the sediments, the largest contents of HgT were found in fine grained, organic rich deposits of the Baltic deeps. The increase in mercury contents in the upper layers of sediments deposited within the last 100-150 years was attributed to the anthropogenic load of mercury and its increased scavenging to sediments with organic matter.

Atlantic Ocean↗
PubMed1998

Characterization of Bradyrhizobium japonicum pcaBDC genes involved in 4-hydroxybenzoate degradation.

The pca structural genes encode enzymes that participate in the conversion of protocatechuate to succinate and acetylcoenzyme A. A 3. 05-kb region of the Bradyrhizobium japonicum strain USDA110 genome has been characterized, which contains the pcaB, pcaD and pcaC genes. The predicted protein sequences of the three genes have extensive homologies with beta-carboxy-cis,cis-muconate cycloisomerase (PcaB), beta-ketodiapate enol-lactone hydrolase (PcaD), and gamma-carboxymuconolactone decarboxylase (PcaC), respectively, from Acinetobacter calcoaceticus and Pseudomonas putida. The DNA sequence revealed that the pca genes are probably arranged in a single transcriptional unit, pcaBDC, similar to that described in P. putida. A pcaB deletion mutant constructed by marker exchange mutagenesis lost the ability to use 4-hydroxybenzoate or protocatechuate as the only carbon source, demonstrating functionality of the characterized genes in catabolism of hydroxyaromatics by B. japonicum. Furthermore, 4-hydroxybenzoate and protocatechuate became toxic for the pcaB mutant, indicating that hydroxyaromatics catabolism serves both nutritional and detoxifying purposes.

Amino Acid Sequence↗
PubMed1998

Cloning and identification of conjugative transfer origins in the Rhizobium meliloti genome.

A simple approach was used to identify Rhizobium meliloti DNA regions with the ability to convert a nontransmissible vector into a mobilizable plasmid, i.e., to contain origins of conjugative transfer (oriT, mob). RecA-defective R. meliloti merodiploid populations, where each individual contained a hybrid cosmid from an R. meliloti GR4 gene library, were used as donors en masse in conjugation with another R. meliloti recipient strain, selecting transconjugants for vector-encoded antibiotic resistance. Restriction analysis of cosmids isolated from individual transconjugants resulted in the identification of 11 nonoverlapping DNA regions containing potential oriTs. Individual hybrid cosmids were confirmed to be mobilized from the original recA donors at frequencies ranging from 10(-2) to 10(-5) per recipient cell. DNA hybridization experiments showed that seven mob DNA regions correspond to plasmid replicons: four on symbiotic megaplasmid 1 (pSym1), one on pSym2, and another two on each of the two cryptic plasmids harbored by R. meliloti GR4. Another three mob clones could not be located to any plasmid and were therefore preliminarily assigned to the chromosome. With this strategy, we were able to characterize the oriT of the conjugative plasmid pRmeGR4a, which confirmed the reliability of the approach to select for oriTs. Moreover, transfer of the 11 mob cosmids from R. meliloti into Escherichia coli occurred at frequencies as high as 10(-1), demonstrating the R. meliloti gene transfer capacity is not limited to the family Rhizobiaceae. Our results show that the R. meliloti genome contains multiple oriTs that allow efficient DNA mobilization to rhizobia as well as to phylogenetically distant gram-negative bacteria.

Base Sequence↗
PubMed1996

Ammonia Inhibition of Plasmid pRmeGR4a Conjugal Transfer between Rhizobium meliloti Strains.

We have examined nutritional factors influencing conjugal transfer of the two nonsymbiotic large plasmids, pRmeGR4a and pRmeGR4b, of Rhizobium meliloti GR4. To monitor transfer, each plasmid was tagged with a different antibiotic resistance marker. Transfer of plasmid pRmeGR4b was dependent upon the presence of plasmid pRmeGR4a on the same donor cell. Transconjugants for pRmeGR4b were obtained at frequencies 5-to 10-fold higher than transconjugants carrying both plasmids, indicating that mobilization of pRmeGR4b by pRmeGR4a probably occurred in trans. Conjugal transfer of the tagged plasmids between R. meliloti strains was tested on minimal medium supplemented with single amino acids, nitrate, or ammonium as the single nitrogen source. A higher number of transconjugants was obtained when glutamate was the only nitrogen source, whereas conjugation was virtually undetectable on ammonium. No relationship was found between donor or recipient growth rate and plasmid transfer rate on a given nitrogen source. Furthermore, in media containing both glutamate and ammonium as nitrogen sources, transfer was reduced almost 100-fold compared with that in media containing glutamate alone. Inhibition was readily detected at 2.5 mM or higher concentrations of either ammonium chloride or ammonium sulfate and appeared to be specific for exogenously supplied ammonium. Inhibition of conjugal transfer between R. meliloti strains by ammonium was only observed for rhizobial plasmids, not for a heterologous plasmid such as RP4. Apparently, ammonium did not affect the plasmid-encoded transfer machinery, as it had no influence on rhizobial plasmid transfer from R. meliloti to Agrobacterium tumefaciens. The effect of ammonium seemed to take place on R. meliloti recipient cells, thereby reducing the efficiency of plasmid conjugation, probably by affecting mating pair formation or stabilization.

Journal Article↗
PubMed1994

nodZ, a unique host-specific nodulation gene, is involved in the fucosylation of the lipooligosaccharide nodulation signal of Bradyrhizobium japonicum.

The nodulation genes of rhizobia are regulated by the nodD gene product in response to host-produced flavonoids and appear to encode enzymes involved in the production of a lipo-chitose signal molecule required for infection and nodule formation. We have identified the nodZ gene of Bradyrhizobium japonicum, whose product is required for the addition of a 2-O-methylfucose residue to the terminal reducing N-acetylglucosamine of the nodulation signal. This substitution is essential for the biological activity of this molecule. Mutations in nodZ result in defective nodulation of siratro. Surprisingly, although nodZ clearly codes for nodulation function, it is not regulated by NodD and, indeed, shows elevated expression in planta. Therefore, nodZ represents a unique nodulation gene that is not under the control of NodD and yet is essential for the synthesis of an active nodulation signal.

Amino Acid Sequence↗
PubMed1993

nolMNO genes of Bradyrhizobium japonicum are co-transcribed with nodYABCSUIJ, and nolO is involved in the synthesis of the lipo-oligosaccharide nodulation signals.

A host-inducible lacZ fusion was mapped down-stream of the nodYABCSUIJ operon in Bradyrhizobium japonicum strain USDA110. Sequencing of this region identified three novel genes, nolMNO. RNA dot blot analysis showed that nolO transcription is nodD1-dependent and that a polar mutation in nodS, located 5 kilobases upstream of nolO, blocks the transcription of nolO. Coupled with the host-inducible nature of nolO expression, these results indicate that nolMNO are part of a 9-kilobase operon, nodYABCSUIJnolMNO. The lipo-oligosaccharide nodulation signals produced by strains SL67 (nolO-) and SL65(nolNO-) were purified, and their chemical structures were determined. In addition to the wild-type signal molecules, both mutants produced modified compounds that are not produced by the parent strain USDA110. The most prevalent difference observed was the absence of the 2-O-methylfucosyl residue from the mutant structures. In addition, metabolites were found in which the N-acetylglucosamine residue at the reducing end was glycosidically linked to glycerol. These alterations in the profiles of nodulation signals produced by strains SL67 and SL65 were accompanied by reduced nodulation efficiency on all hosts tested.

Amino Acid Sequence↗
PubMed1993

The structures and biological activities of the lipo-oligosaccharide nodulation signals produced by type I and II strains of Bradyrhizobium japonicum.

Bradyrhizobium japonicum produces lipo-oligosaccharide signal molecules that induce deformation of root hairs and meristematic activity on soybeans. B. japonicum USDA135 (a Type I strain) produces modified chitin pentasaccharide molecules with either a terminal N-C16:0- or N-C18:1-glucosamine with and without an O-acetyl group at C-6 and with 2-O-methylfucose linked to C-6 of the reducing N-acetylglucosamine. An additional molecule has N-C16:1-glucosamine and no O-acetyl group. All of these molecules cause root hair deformation on Vicia sativa and Glycine soja. The C18:1-containing molecules were tested and found to induce meristem formation on G. soja. USDA61 (a Type II strain) produces eight additional molecules. Five have a carbamoyl group on the terminal N-acylglucosamine. Six have chitin tetrasaccharide backbones. Three have a terminal N-acyl-N-methylglucosaminosyl residue. In four molecules, the reducing-end N-acetylglucosamine is glycosidically linked to glycerol and has a branching fucosyl, rather than a 2-O-methylfucosyl, residue. One molecule has a terminal N-acylglucosamine that has both acetyl and carbamoyl groups (one each).

Antigens, Bacterial↗
PubMed1993

Use of a promoter-probe vector system in the cloning of a new NifA-dependent promoter (ndp) from Bradyrhizobium japonicum.

Many of the symbiotic nitrogen-fixation genes in the soybean root nodule bacterium, Bradyrhizobium japonicum, are transcribed from -24/-12 promoters that are recognized by the sigma 54-RNA polymerase and activated by the transcriptional regulator protein, NifA. Several lines of evidence suggest that the B. japonicum genome has more than those seven NifA-regulated promoters which were characterized previously. Here, we present a strategy aimed at the cloning of new NifA-activated promoters. It makes use of (i) a promoter-probe vector into which random B. japonicum genomic fragments were cloned in front of a promoterless reporter gene and (ii) a screening procedure that allowed us to distinguish constitutive promoters from promoters that were specifically activated by NifA under microaerobic or anaerobic conditions. With certain modifications, the system may be generally applicable to clone positively regulated, anaerobically induced genes. A novel NifA-dependent promoter region (ndp) of B. japonicum was found by these means. The transcription start point was mapped, and its 5'-flanking DNA carried a -24/-12-type promoter sequence plus potential binding sites for NifA and integration host factor. Further transcript analyses confirmed that maximal transcription from this promoter occurred only in the presence of NifA and sigma 54 during anaerobic growth of B. japonicum. In Escherichia coli, expression of beta-galactosidase derived from a transcriptional ndp::lacZ fusion was activated 11-fold by B. japonicum NifA, and this activation also required sigma 54 but was independent of NtrC. The DNA around ndp shared no similarity with known sequences in databases.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Proteins↗
PubMed1992

A 2-O-methylfucose moiety is present in the lipo-oligosaccharide nodulation signal of Bradyrhizobium japonicum.

Bradyrhizobium japonicum is a soil bacterium that forms nitrogen-fixing nodules on the roots of the agronomically important legume soybean. Microscopic observation of plant roots showed that butanol extract of B. japonicum strain USDA110 cultures induced for nod gene expression elicited root hair deformation, an early event in the nodulation process. The metabolite produced by B. japonicum responsible for root hair deformation activity was purified. Chemical analysis of the compound revealed it to be a pentasaccharide of N-acetylglucosamine modified by a C18:1 fatty acyl chain at the nonreducing end. In these respects, the B. japonicum metabolite is similar to the lipo-oligosaccharide signals described from Rhizobium species. However, the B. japonicum compound is unique in that an additional sugar, 2-O-methylfucose, is linked to the reducing end. Comparative analysis of the B. japonicum Nod metabolite and those characterized from Rhizobium species suggests that the presence of the fucosyl residue plays an important role in the specificity of the B. japonicum-soybean symbiosis. The availability of the purified B. japonicum nodulation signal should greatly facilitate further studies of soybean nodulation.

Carbohydrate Sequence↗
PubMed1991

NifA-NtrA regulatory system activates transcription of nfe, a gene locus involved in nodulation competitiveness of Rhizobium meliloti.

We have previously demonstrated that the Rhizobium meliloti large plasmid pRmeGR4b carries the gene locus nodule formation efficiency (nfe) which is responsible for nodulation efficiency and competitive ability of strain GR4 on alfalfa roots. In this study we report that expression of nfe-lacZ fusions in Escherichia coli is activated in the presence of the cloned nifA gene of R. meliloti. This activation was found to be oxygen sensitive and to require the E. coli ntrA gene product. In contrast to the R. meliloti nifA, the cloned nifA gene of Klebsiella pneumoniae was able to activate expression of nfe in aerobically grown cells of both E. coli and R. meliloti. Hybridization experiments did not show homology to nfe in four R. meliloti wild-type strains tested. These strains were uncompetitive when coinoculated with a GR4 derivative carrying plasmid pRmeGR4b, but were competitive when coinoculated with a GR4 derivative carrying a single transposon mutation into the nfe region. When nfe DNA was introduced into the four wild-type strains, a significant increase in the competitive ability of two of them was observed, as deduced from their respective percentages of alfalfa root nodule occupancy in two-strains coinoculation experiments.

Gene Expression Regulation, Bacterial↗
PubMed1991

Bradyrhizobium japonicum has two differentially regulated, functional homologs of the sigma 54 gene (rpoN).

Recognition of -24/-12-type promoters by RNA polymerase requires a special sigma factor, sigma 54 (RpoN NtrA GlnF). In the nitrogen-fixing soybean symbiont Bradyrhizobium japonicum, two functional, highly conserved rpoN genes (rpoN1 and rpoN2) were identified and sequenced. The two predicted B. japonicum RpoN protein sequences were 87% identical, and both showed different levels of homology to the RpoN proteins of other bacteria. Downstream of rpoN2 (but not of rpoN1), two additional open reading frames were identified that corresponded to open reading frames located at similar positions in Klebsiella pneumoniae and Pseudomonas putida. Both B. japonicum rpoN genes complemented the succinate- and nitrate-negative phenotypes of a Rhizobium meliloti rpoN mutant. B. japonicum strains carrying single or double rpoN mutations were still able to utilize C4-dicarboxylates as a carbon source and histidine, proline, or arginine as a nitrogen source, whereas the ability to assimilate nitrate required expression of at least one of the two rpN genes. In symbiosis both rpoN genes could replace each other functionally. The rpoN1/2 double mutant induced about twice as many nodules on soybeans as did the wild type, and these nodules lacked nitrogen fixation activity completely. Transcription of a nifH'-'lacZ fusion was not activated in the rpoN1/2 mutant background, whereas expression of a fixR'-'lacZ fusion in this mutant was affected only marginally. By using rpoN'-'lacZ fusions, rpoN1 expression was shown to be activated at least sevenfold in microaerobiosis as compared with that in aerobiosis, and this type of regulation involved fixLJ. Expression of rpoN2 was observed under all conditions tested and was increased fivefold in an rpoN2 mutant. The data suggested that the rpoN1 gene was regulated in response to oxygen, whereas the rpoN2 gene was negatively autoregulated.

Amino Acid Sequence↗
PubMed1989

Implication of nifA in regulation of genes located on a Rhizobium meliloti cryptic plasmid that affect nodulation efficiency.

We examined the contribution of a cryptic plasmid, pRmeGR4b, to the nodulation of Medicago sativa by strain GR4 of Rhizobium meliloti. A 905-base-pair PstI DNA fragment in pRmeGR4b was found to hybridize DNA of the R. meliloti fixA promoter region as a probe. Sequence analysis of the PstI fragment showed a 206-base-pair region displaying high homology with the DNA upstream of the RNA start points of the P1 and P2 symbiotic promoters. Putative nif promoter consensus sequences were conserved in this DNA segment. Expression of DNA downstream of the nif promoterlike sequence, monitored by beta-galactosidase activity of different lacZ fusions, was demonstrated to depend on a functional nifA gene, both in microaerobically free-living cells and in nodules. Individual transposon Tn3-HoHo1 insertions in this DNA region caused a reduced nodulation competitiveness. This new symbiotic region, occupying approximately 5 kilobases of pRmeGR4b DNA, was called nfe (nodule formation efficiency).

Base Sequence↗