A thiotrophic microbial community in an acidic brine lake in Northern Chile.

The endorheic basins of the Northern Chilean Altiplano contain saline lakes and salt flats. Two of the salt flats, Gorbea and Ignorado, have high acidic brines. The causes of the local acidity have been attributed to the occurrence of volcanic native sulfur, the release of sulfuric acid by oxidation, and the low buffering capacity of the rocks in the area. Understanding the microbial community composition and available energy in this pristine ecosystem is relevant in determining the origin of the acidity and in supporting the rationale of conservation policies. Besides, a comparison between similar systems in Australia highlights key microbial components and specific ones associated with geological settings and environmental conditions. Sediment and water samples from the Salar de Gorbea were collected, physicochemical parameters measured and geochemical and molecular biological analyses performed. A low diversity microbial community was observed in brines and sediments dominated by Actinobacteria, Algae, Firmicutes and Proteobacteria. Most of the constituent genera have been reported to be either sulfur oxidizing microorganisms or ones having the potential for sulfur oxidation given available genomic data and information drawn from the literature on cultured relatives. In addition, a link between sulfur oxidation and carbon fixation was observed. In contrast, to acid mine drainage communities, Gorbea microbial diversity is mainly supported by chemolithoheterotrophic, facultative chemolithoautotrophic and oligotrophic sulfur oxidizing populations indicating that microbial activity should also be considered as a causative agent of local acidity.

Correction to: A thiotrophic microbial community in an acidic brine lake in Northern Chile.

In Table 1 of the original article, the unit mg/L was incorrectly published as ng/L in the aluminum, chloride, sulphate and OM columns.

Flavodoxin overexpression confers tolerance to oxidative stress in beneficial soil bacteria and improves survival in the presence of the herbicides paraquat and atrazine.

AIM: To determine whether expression of a cyanobacterial flavodoxin in soil bacteria of agronomic interest confers protection against the widely used herbicides paraquat and atrazine. METHODS AND RESULTS: The model bacterium Escherichia coli, the symbiotic nitrogen-fixing bacterium Ensifer meliloti and the plant growth-promoting rhizobacterium Pseudomonas fluorescens Aur6 were transformed with expression vectors containing the flavodoxin gene of Anabaena variabilis. Expression of the cyanobacterial protein was confirmed by Western blot. Bacterial tolerance to oxidative stress was tested in solid medium supplemented with hydrogen peroxide, paraquat or atrazine. In all three bacterial strains, flavodoxin expression enhanced tolerance to the oxidative stress provoked by hydrogen peroxide and by the reactive oxygen species-inducing herbicides, witnessed by the enhanced survival of the transformed bacteria in the presence of these oxidizing agents. CONCLUSIONS: Flavodoxin overexpression in beneficial soil bacteria confers tolerance to oxidative stress and improves their survival in the presence of the herbicides paraquat and atrazine. Flavodoxin could be considered as a general antioxidant resource to face oxidative challenges in different micro-organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of plant growth-promoting rhizobacteria or nitrogen-fixing bacteria with enhanced tolerance to oxidative stress in contaminated soils is of significant agronomic interest. The enhanced tolerance of flavodoxin-expressing bacteria to atrazine and paraquat points to potential applications in herbicide-treated soils.

Laser flash-induced photoreduction of photosynthetic ferredoxins and flavodoxin by 5-deazariboflavin and by a viologen analogue.

Laser flash photolysis has been used to compare the kinetics of reduction of ferredoxin isoforms from the green alga Monoraphidium braunii, and the ferredoxin and flavodoxin from the cyanobacterium Anabaena PCC 7119, by 5-deazariboflavin semiquinone (dRfH.) and the viologen analogue 1,1'-propylene-2,2'-bipyridyl (PDQ.+). Similar ionic strength-independent second-order rate constants (1.4 x 10(8) M-1 s-1) were obtained for the reduction of both algal ferredoxin isoforms by dRfH.. For the reduction of oxidized flavodoxin by dRfH., a more complex behavior was observed, with a second-order rate constant for dRfH. decay of 1.8 x 10(8) M-1 s-1, and a first-order (i.e. protein concentration independent) rate constant of 450 s-1, that probably corresponds to the protonation of the FMN semiquinone cofactor, which occurs subsequent to electron transfer. A value of 5 x 10(7) M-1 s-1 was obtained for the second-order rate constant of flavodoxin semiquinone reduction by dRfH.. The reduction of ferredoxins and flavodoxin semiquinone by PDQ.+ showed nonlinear protein concentration dependencies, consistent with a minimal two-step mechanism involving complex formation followed by intracomplex electron transfer. A negative ionic strength effect on the kinetic constants was obtained, indicating the existence of attractive electrostatic interactions during electron transfer. With all the ferredoxins the k infinity values (rate constants extrapolated to infinite ionic strength) for the second-order step of the reduction process (complex formation) are smaller than previously reported for spinach ferredoxin, although Anabaena ferredoxin is somewhat more reactive than are the algal ferredoxins with the viologen.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermoluminescence response of calcic bentonite subjected to conditions of high nuclear waste underground storage.

Bentonite is regarded as a backfilling material for underground storage facilities of highly radioactive nuclear waste built on granite formations. In these facilities, bentonite will be subjected to a gradient of temperature and dose rate, achieving a very high integrated dose and, therefore, changes in its structure and physical properties may take place. Two experiments to discriminate between the thermal and the irradiation effect were performed. In the first (named BIC 2A), samples were subjected to temperature while in the second (named BIC-2B) the combined effect of temperature and irradiation was studied. The experimental conditions were: a thermal gradient between 130 degrees C and 90 degrees C, a maximum dose rate of 3.5 kGy.h(-1) and a gradient of the integrated dose between 1.75 MGy and 10 MGy. Both experiments lasted a total of 124 days. An irradiation source of 60Co with an activity close to 300,000 Ci, and bentonite samples of 200 mm in length and 50 mm in diameter were used. After the experiment, the samples were ground and two fractions were obtained: a fine fraction (<2 microm) enriched in montmorillonite clay mineral and a coarse fraction (>80 microm). The results are described of thermoluminescence analyses on the two fractions obtained which showed that the coarse fraction can be 100 times more sensitive to radiation than the fine fraction. On the other hand, the heated and irradiated samples showed a thermoluminescence response around 50 times greater than the samples that were only heated. In addition to this, the temperature and dose rate conditions are relevant parameters in the generation and stabilisation of radiation induced defects. Finally, the response of samples heated and irradiated for two months was quite similar to that obtained on samples heated and irradiated for four months, indicating a saturation phenomenon.

[Neuroendocrine tumor of the submandibular gland. Report of one case and review of literature]. / Tumor neuroendocrino de glándula submaxilar. Presentación de un caso y revisión de literatura.

Report on one case of primary neuroendocrine tumor of the submandibularis gland, early detected without initial spread. Immunohistochemistry and electron microscopy were realized in order to determine the presence of intracytoplasmatic hypersecretory thick granules, these being the laboratory trials to differentiate between neuroendocrine tumors and undifferentiate carcinomata. Bibliographic review and proposal of classification of this sort of tumors.

[Sjögren syndrome in ORL. Diagnostic considerations]. / Síndrome de Sjögren en O.R.L. Consideraciones diagnósticas.

A presentation the history of a 51-year-old woman with xerostomia and keratoconjunctivitis sicca (KCS), developed in 10 months, investigations revealed the presence in serum of antibodies against cytoplasmic antigens SS-A (Ac anti-Ro/SS-A), antinuclear antibodies (ANAs) and rheumatoid factor (RF). The Rose Bengal test was positive and in the salivary gammagraphy, made with pertecnate 99 mTc, it was observed a decrease of the captation and excretion of the designer for salivary glands. The histopathology and immunohistochemical study of minor salivary glands showed the presence of a focal lymphocitic sialadenitis (fsa) and a predominance of lymphocites CD4+. It was diagnosed as primary Sjögren's syndrome (PSS) and the patient treated with salivary substitutes, artificial tears and corticoids. We analyse the current diagnostic criteria of the group of study of the European Community for the Sjögren's syndrome (SS) and emphasize the importance of histologic and immunochemical studies, that together with the rest of complementary tests will led us to distinguish not only the different forms of the presentation of the illness but also those of all patients with pathologies which are nowadays very prevalent in our environment, such as the hepatitis C (HCV) an the human immune deficiency (HIV) virus infections.

[Vernet's syndrome as an early manifestation of systemic erythematous lupus]. / Síndrome de Vernet como manifestación precoz de un lupus eritematoso sistemico.

Report of one case of Vernet's syndrome (involving the IX, X and XIth cranial nerves) in a young woman, as early sing of SEL. The patient presented the 4 criteria suggested by the American Society in order to diagnose SEL: arthritis, serositis, positive anti-nuclear antibodies and anemia. The AA. carry out a study in search of other cases sitting in the larynx and a perusal about etiopathogenical theories as well. Hinting, for the clinical picture, of being it due to a localised vasculitis of vasa nervorum, a treatment with corticoids and pentoxifylline was ordered, being the outcome, after 3 weeks, the eradication of ENT syndrome.

[Cervical emphysema caused by Forestier's disease]. / Enfisema cervical por enfermedad de forestier.

Diffuse idiopathic skeletal hyperostosis is a rare cause of dysphagia, preferentially affecting older men. This condition is also known as Forestier's malady, being characterized by a paravertebral ossification of 4 contiguous vertebrae at least. Seldom is the last etiology evoked for high dysphagia after other possible diagnosis exclusion. The diagnosis is confirmed by standard or contrast radiography. Introductory treatment is medical, being the surgery indicated for serious or resisting cases. One case is reported with dysphagia as primary sign of Forestier's malady, and review of possible diagnostic exams and treatments.

[Granular cell tumor of the larynx]. / Tumor de células granulomatosas de laringe.

Granular cell tumor is an unusual growth of probably neuroectodermal histogenesis, first reported by Abrikossoff in 1926 with the name of myoblastoma. Of the about 1200 cases reported since, the 50 percent were found in the head and neck. Of second mentioned 10 percent had a laryngeal sitting. A case of glottic granular cell tumor surgically removed with free borders is presented. Bibliographical review.

[Deep neck infections: complications of acute pharyngitis]. / Infección cervical profunda: complicación de faringitis aguda.

Deep neck infections develop as aftermath of spreading infections from an initial focus to the neighbourhood and soft tissues of the neck, through routes offering lesser resistance as fascial sheets. These cervical pictures are not numerous and generally after infective focus bad treated, linked with concomitant factors easing the rapid spread. The presence of complications as the involvement of great blood vessels, mediastin or jeopardizing the air-way may darken the prognosis, for which reason its precocious diagnosis and correct behaviour are very decisive. The paper deals with one case of neck infect, following an acute banal pharyngitis without predisposing circumstances. Follows a review of the published bibliography.

[Biopsy cannula as diagnostic alternative to puncture-aspiration biopsy with fine needle in head and neck tumors]. / La cánula de biopsia: alternativa diagnóstica de la punción-aspiración con aguja fina en tumores de cabeza y cuello.

Biopsy cannula is a diagnostic tool allowing anatomopathological examination of tissue samples, achieved through a percutaneous perforation. Unlike puncture-aspiration with fine needle method that only permits a cytologic study, this technique eases the removal of pieces big enough to provide the knowledge of the whole architecture of the lesion. At length in other specialities in our has been forgotten perhaps for the great efficiency of PAFN on neck masses or as complement of traditional surgery. We present one case in which the biopsy-cannula showed its diagnostic usefulness. We also discuss on the technique and made a bibliographic perusal about the published literature.

[Sarcoidosis in otorhinolaryngology]. / Sarcoidosis en O.R.L.

Sarcoidosis is a disease affecting the reticulo-histiocytary system and characterized by its several manifestations, always linked to the same lesion: the epithelioid granuloma without caseous necrosis. We make a review of this disease so scarce in our consulting rooms, and consider all patients diagnosed in our Hospital during one year-term, with their manifestations in ENT-area as well in other specialties and compare our inventory with other published series.

[Neurinoma of the cervical hypoglossal nerve. A clinical case and review of the literature]. / Neurinoma del hipogloso cervical. Caso clínico y revisión de literatura.

Neurilemmomas are relatively rare tumors derived from Schwann cells that may occur at any part of the body. Many are encapsulated and they are more frequently encountered in adults. A neurilemmoma of the hypoglossal cervical nerve, an unusual site, is reported. Submaxillary angioma was initially suspected.

[Jugular-tympanic paraganglioma: our experience in 2 years]. / Paraganglioma yugulotimpánico: nuestra experiencia en dos años.

The paper is a review of the jugulotympanic paragangliomata seen in our Hospital in a 2 years term. The AA. discuss every case and achieve a checking of several therapeutics procedures accepted for these growths.

[Long-term course of laryngeal verrucous carcinoma]. / Carcinoma verrucoso laríngeo de larga evolución.

Verrucous carcinoma is an odd kind from squamous or epidermoid carcinoma, amounting between 1 and 3.5% percent of the whole number of laryngeal growths. Its predominant sitting is glottic and are characterized through the pathological anatomy and its good prognosis. We report one case treated in our Department which evolved during 14 years and we point out its good prognosis and other particularities regarding its etiology, pathologic anatomy and diagnosis.

Effects of salt stress and rhizobial inoculation on growth and nitrogen fixation of three peanut cultivars.

Increasing soil salinity represents a major constraint for agriculture in arid and semi-arid lands, where mineral nitrogen (N) deficiency is also a frequent characteristic of soils. Biological N fixation by legumes may constitute a sustainable alternative to chemical fertilisation in salinity-affected areas, provided that adapted cultivars and inoculants are available. Here, the performance of three peanut cultivars nodulated with two different rhizobial strains that differ in their salt tolerance was evaluated under moderately saline water irrigation and compared with that of N-fertilised plants. Shoot weight was used as an indicator of yield. Under non-saline conditions, higher yields were obtained using N fertilisation rather than inoculation for all the varieties tested. However, under salt stress, the yield of inoculated plants became comparable to that of N-fertilised plants, with minor differences depending on the peanut cultivar and rhizobial strain. Our results indicate that N fixation might represent an economical, competitive and environmentally friendly choice with respect to mineral N fertilisation for peanut cultivation under moderate saline conditions.

Diversity of rhizobial bacteria isolated from nodules of the Gypsophyte Ononis tridentata L. growing in Spanish soils.

The aim of this work is to describe the diversity and phylogeny of rhizobial bacteria associated to nodules of Ononis tridentata L. in different geographical regions of Spain. Twenty-two bacterial isolates were characterized using several molecular techniques (16S amplified ribosomal deoxyribonucleic acid restriction analysis, fingerprinting, and sequencing) and phylogenies were inferred from their 16S and nodC gene sequences. Phylogenetically, the isolates grouped with the genera Rhizobium, Mesorhizobium, Phylobacterium, and Bosea. The nodC gene, essential for nodulation, was detected for the first time in isolates close to the genera Bosea and Phyllobacterium. The bacteria isolated showed a high diversity at the genus, species, and strain level regardless of the geographical origin of the host plant. This is the first report describing bacteria associated to nodules of O. tridentata. This shrub legume is highly prized for the revegetation of gypsum soils in semiarid Mediterranean areas. Our molecular description of bacteria associated to this legume improves the current understanding of the ecology of this plant species. Our findings have implications for formulating suitable bacterial inocula to recover gypsum ecosystems.

Transgenic Medicago truncatula plants that accumulate proline display nitrogen-fixing activity with enhanced tolerance to osmotic stress.

Legume root nodule nitrogen-fixing activity is severely affected by osmotic stress. Proline accumulation has been shown to induce tolerance to salt stress, and transgenic plants over-expressing Delta(1)-pyrroline-5-carboxylate synthetase (P5CS), which accumulates high levels of proline, display enhanced osmotolerance. Here, we transformed the model legume Medicago truncatula with the P5CS gene from Vigna aconitifolia, and nodule activity was evaluated under osmotic stress in transgenic plants that showed high proline accumulation levels. Nitrogen fixation was significantly less affected by salt treatment compared to wild-type (WT) plants. To our knowledge, this is the first time that transgenic legumes have been produced that display nitrogen-fixing activity with enhanced tolerance to osmotic stress. We studied the expression of M. truncatula proline-related endogenous genes M. truncatulaDelta(1)-pyrroline-5-carboxylate synthetase 1 (MtP5CS1), M. truncatulaDelta(1)-pyrroline-5-carboxylate synthetase 2 (MtP5CS2), M. truncatula ornithine delta-aminotransferase (MtOAT), M. truncatula proline dehydrogenase (MtProDH) and a proline transporter gene in both WT and transgenic plants. Our results indicate that proline metabolism is finely regulated in response to osmotic stress in an organ-specific manner. The transgenic model allowed us to analyse some of the biochemical and molecular mechanisms that are activated in the nodule in response to high salt conditions, and to ascertain the essential role of proline in the maintenance of nitrogen-fixing activity under osmotic stress.

Purification of ferredoxin-NADP+ reductase, flavodoxin and ferredoxin from a single batch of the cyanobacterium Anabaena PCC 7119.

Methods are described for the simultaneous isolation of ferredoxin-NADP+ reductase, ferredoxin and flavodoxin from large quantities of the cyanobacterium Anabaena PCC 7119 allowing the use of a single batch of cells. The ultraviolet-visible spectra and the extinction coefficients of ferredoxin-NADP+ reductase and ferredoxin were determined. The purification procedure also yields enriched fractions of phycobiliproteins and cytochrome c553.