Mancha3D Code: Multipurpose Advanced Nonideal MHD Code for High-Resolution Simulations in Astrophysics.

The Mancha3D code is a versatile tool for numerical simulations of magnetohydrodynamic (MHD) processes in solar/stellar atmospheres. The code includes nonideal physics derived from plasma partial ionization, a realistic equation of state and radiative transfer, which allows performing high-quality realistic simulations of magnetoconvection, as well as idealized simulations of particular processes, such as wave propagation, instabilities or energetic events. The paper summarizes the equations and methods used in the Mancha3D (Multifluid (-purpose -physics -dimensional) Advanced Non-ideal MHD Code for High resolution simulations in Astrophysics 3D) code. It also describes its numerical stability and parallel performance and efficiency. The code is based on a finite difference discretization and a memory-saving Runge-Kutta (RK) scheme. It handles nonideal effects through super-time-stepping and Hall diffusion schemes, and takes into account thermal conduction by solving an additional hyperbolic equation for the heat flux. The code is easily configurable to perform different kinds of simulations. Several examples of the code usage are given. It is demonstrated that splitting variables into equilibrium and perturbation parts is essential for simulations of wave propagation in a static background. A perfectly matched layer (PML) boundary condition built into the code greatly facilitates a nonreflective open boundary implementation. Spatial filtering is an important numerical remedy to eliminate grid-size perturbations enhancing the code stability. Parallel performance analysis reveals that the code is strongly memory bound, which is a natural consequence of the numerical techniques used, such as split variables and PML boundary conditions. Both strong and weak scalings show adequate performance up to several thousands of processors (CPUs).

Bacillus subtilis biofilm matrix components target seed oil bodies to promote growth and anti-fungal resistance in melon.

Beneficial microorganisms are used to stimulate the germination of seeds; however, their growth-promoting mechanisms remain largely unexplored. Bacillus subtilis is commonly found in association with different plant organs, providing protection against pathogens or stimulating plant growth. We report that application of B. subtilis to melon seeds results in genetic and physiological responses in seeds that alter the metabolic and developmental status in 5-d and 1-month-old plants upon germination. We analysed mutants in different components of the extracellular matrix of B. subtilis biofilms in interaction with seeds and found cooperation in bacterial colonization of seed storage tissues and growth promotion. Combining confocal microscopy with fluorogenic probes, we found that two specific components of the extracellular matrix, amyloid protein TasA and fengycin, differentially increased the concentrations of reactive oxygen species inside seeds. Further, using electron and fluorescence microscopy and metabolomics, we showed that both TasA and fengycin targeted the oil bodies in the seed endosperm, resulting in specific changes in lipid metabolism and accumulation of glutathione-related molecules. In turn, this results in two different plant growth developmental programmes: TasA and fengycin stimulate the development of radicles, and fengycin alone stimulate the growth of adult plants and resistance in the phylloplane to the fungus Botrytis cinerea. Understanding mechanisms of bacterial growth promotion will enable the design of bespoke growth promotion strains.

Intraoral anastomosis in maxillary microvascular reconstruction after oncological excision.

Microvascular anastomosis using an intraoral approach can avoid unnecessary external incisions thus improving patient satisfaction. Furthermore, in case of short pedicle flaps, the lack of proximity of the recipient vessels can be a problem in microvascular reconstruction of the midface. We present our experience in six patients treated for tumours affecting the midface and reconstructed with microvascular flaps through anastomosis to the intraoral aspect of the facial vessels, with the aim of reviewing the use of this technique. Our results showed that intraoral anastomosis is a feasible technique that can be used in the reconstruction after tumours resection, avoiding additional external incisions in patients with no previous cervicotomy incisions. In two cases, a vein graft was interposed to perform the intraoral arterial anastomosis in a tension-free situation without increasing morbidity. The technical features and advantages of intraoral anastomosis were reviewed.

Detection of White Root Rot in Avocado Trees by Remote Sensing.

White root rot, caused by the soilborne fungus Rosellinia necatrix, is an important constraint to production for a wide range of woody crop plants such as avocado trees. The current methods of detection of white root rot are based on microbial and molecular techniques, and their application at orchard scale is limited. In this study, physiological parameters provided by imaging techniques were analyzed by machine learning methods. Normalized difference vegetation index (NDVI) and normalized canopy temperature (canopy temperature - air temperature) were tested as predictors of disease by several algorithms. Among them, logistic regression analysis (LRA) trained on NDVI data showed the highest sensitivity and lowest rate of false negatives. This algorithm based on NDVI could be a quick and feasible method to detect trees potentially affected by white root rot in avocado orchards.

Analysis of Genetic Diversity of Fusarium tupiense, the Main Causal Agent of Mango Malformation Disease in Southern Spain.

Mango malformation disease (MMD) has become an important global disease affecting this crop. The aim of this study was to identify the main causal agents of MMD in the Axarquía region of southern Spain and determine their genetic diversity. Fusarium mangiferae was previously described in the Axarquía region but it represented only one-third of the fusaria recovered from malformed trees. In the present work, fusaria associated with MMD were analyzed by arbitrary primed polymerase chain reaction (ap-PCR), random amplified polymorphic DNA (RAPD), vegetative compatibility grouping (VCG), a PCR screen for mating type idiomorph, and phylogenetic analyses of multilocus DNA sequence data to identify and characterize the genetic diversity of the MMD pathogens. These analyses confirmed that 92 of the isolates were F. tupiense, which was previously only known from Brazil and Senegal. In addition, two isolates of a putatively novel MMD pathogen were discovered, nested within the African clade of the Fusarium fujikuroi species complex. The F. tupiense isolates all belonged to VCG I, which was first described in Brazil, and the 11 isolates tested showed pathogenicity on mango seedlings. Including the prior discovery of F. mangiferae, three exotic MMD pathogenic species have been found in southern Spain, which suggests multiple independent introductions of MMD pathogens in the Axarquía region.

Comparative Genomics Within the Bacillus Genus Reveal the Singularities of Two Robust Bacillus amyloliquefaciens Biocontrol Strains.

Bacillus amyloliquefaciens CECT 8237 and CECT 8238, formerly known as Bacillus subtilis UMAF6639 and UMAF6614, respectively, contribute to plant health by facing microbial pathogens or inducing the plant's defense mechanisms. We sequenced their genomes and developed a set of ad hoc scripts that allowed us to search for the features implicated in their beneficial interaction with plants. We define a core set of genes that should ideally be found in any beneficial Bacillus strain, including the production of secondary metabolites, volatile compounds, metabolic plasticity, cell-to-cell communication systems, and biofilm formation. We experimentally prove that some of these genetic elements are active, such as i) the production of known secondary metabolites or ii) acetoin and 2-3-butanediol, compounds that stimulate plant growth and host defense responses. A comparison with other Bacillus genomes permits us to find differences in the cell-to-cell communication system and biofilm formation and to hypothesize variations in their persistence and resistance ability in diverse environmental conditions. In addition, the major protection provided by CECT 8237 and CECT 8238, which is different from other Bacillus strains against bacterial and fungal melon diseases, permits us to propose a correlation with their singular genetic background and determine the need to search for additional blind biocontrol-related features.

First Report of Mango Malformation Disease Caused by Fusarium mangiferae in Spain.

Mango (Mangifera indica L.) malformation disease (MMD) is one of the most important diseases affecting this crop worldwide, which causes severe economic losses because of the reduction of productivity. Symptoms of MMD in Spain were observed for the first time in April of 2006 in three mango orchards in the Axarquia Region (southern Spain). Symptoms included an abnormal development of vegetative shoots with shortened internodes and dwarfed leaves and hypertrophied short and thickened panicles. In the years of 2006, 2009, and 2010, isolates of Fusarium were obtained from vegetative shoots and floral tissue of symptomatic mango trees from 21 different orchards of cvs. Keitt, Kent, Osteen, Tommy Atkins, and a variety of minor commercial cultivars, all showing typical symptoms of MMD. Different Fusarium-like strains were isolated from infected tissues. Colonies from single-spored isolates possessed dark purple-to-salmon-colored mycelium when grown on potato dextrose agar medium. On fresh carnation leaf agar medium, mycelium contained aerial conidiophores possessing three- to five-celled macroconidia and abundant microconidia in false heads from mono- and polyphialides; while cream-orange-colored sporodochia were produced on the surface of the medium, typical for Fusarium mangiferae. The identification of 37 isolates was confirmed as F. mangiferae by species-specific PCR analysis with the primer pair 1-3 F/R that amplified a 608-bp DNA fragment from all Spanish isolates as well as a representative Israeli control strain, Fus 34, also designated as MRC7560 (2). Pathogenicity using four representative isolates, UMAF F02, UMAF F10, UMAF F17, and UMAF F38 of F. mangiferae from Spain as well as isolate MRC7560, was tested on 2-year-old healthy mango seedlings cv. Keitt by inoculating 15 buds from three different trees with a 20-µl conidial suspension (5 × 107 conidia per ml) per isolate (1). This experiment was conducted twice with two independent sets of plants and at different times (March and November 2010). Typical mango malformation symptoms were detected after bud break in March 2011, 5 and 12 months after inoculation. Symptoms were observed for 60% of the inoculated buds with the four F. mangiferae Spanish isolates and 75% with the MRC7560 control strain, but not with water-inoculated control plants. Recovered isolates from the infected floral and vegetative malformed buds were identical morphologically to those inoculated, and the specific 608-bp fragment described for F. mangiferae was amplified with specific-PCR, thus fulfilling Koch's postulates. To our knowledge, this is the first report of mango malformation disease caused by F. mangiferae in Spain and Europe. References: (1) S. Freeman et al. Phytopathology 89:456, 1999. (2) Q. I. Zheng and R. C. Ploetz. Plant Pathol. 51:208, 2002.

Biocontrol bacteria selected by a direct plant protection strategy against avocado white root rot show antagonism as a prevalent trait.

AIM: This study was undertaken to study bacterial strains obtained directly for their efficient direct control of the avocado white root rot, thus avoiding prescreening by any other possible mechanism of biocontrol which could bias the selection. METHODS AND RESULTS: A collection of 330 bacterial isolates was obtained from the roots and soil of healthy avocado trees. One hundred and forty-three representative bacterial isolates were tested in an avocado/Rosellinia test system, resulting in 22 presumptive protective strains, all of them identified mainly as Pseudomonas and Bacillus species. These 22 candidate strains were screened in a more accurate biocontrol trial, confirming protection of some strains (4 out of the 22). Analyses of the potential bacterial traits involved in the biocontrol activity suggest that different traits could act jointly in the final biocontrol response, but any of these traits were neither sufficient nor generalized for all the active bacteria. All the protective strains selected were antagonistic against some fungal root pathogens. CONCLUSIONS: Diverse bacteria with biocontrol activity could be obtained by a direct plant protection strategy of selection. All the biocontrol strains finally selected in this work were antagonistic, showing that antagonism is a prevalent trait in the biocontrol bacteria selected by a direct plant protection strategy. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the isolation of biocontrol bacterial strains using direct plant protection strategy in the system avocado/Rosellinia. Characterization of selected biocontrol bacterial strains obtained by a direct plant protection strategy showed that antagonism is a prevalent trait in the selected strains in this experimental system. This suggests that antagonism could be used as useful strategy to select biocontrol strains.

GFP sheds light on the infection process of avocado roots by Rosellinia necatrix.

In order to monitor Rosellinia necatrix infection of avocado roots, we generated a plasmid vector (pCPXHY1eGFP) constitutively expressing EGFP and developed a protoplast transformation protocol. Using this protocol, four R. necatrix isolates were efficiently transformed and were shown to stably express EGFP homogeneously while not having any observable effect on pathogenicity. Confocal laser scanning microscopy (CLSM) images of avocado roots infected with the highly virulent isolate CH53-GFP demonstrated that fungal penetration of avocado roots occurs simultaneously at several random sites, but it occurs preferentially in the crown region as well as throughout the lenticels and in the junctions between epidermal cells. Not only were R. necatrix hyphae observed invading the epidermal and cortical root cells, but they were also able to penetrate the primary and secondary xylem. Scanning electron microscopy (SEM) images allowed detailed visualisation of the hyphal network generated by invasion of R. necatrix through the epidermal, cortical and vascular cells, including hyphal anastomosis and branching points. To our knowledge, this is the first report describing the construction of GFP-tagged strains belonging to the genus Rosellinia for monitoring white root rot using CLSM and SEM.

First Occurrence of Cucurbit Powdery Mildew Caused by Race 3-5 of Podosphaera fusca in Spain.

A new race of cucurbit powdery mildew was observed for the first time on melon (Cucumis melo) in three research greenhouses in the Axarquia area of southern Spain during the spring of 2008. Fungal growth appeared as white powdery colonies initially restricted to the upper leaf surfaces. Morphological characteristics of colonies, conidiophores, conidia, germ tubes, and appressoria indicated that the powdery mildew fungus was Podosphaera fusca (also known as P. xanthii) (3), a fungal pathogen extensively reported in the area (1). However, the fungus developed on plants of melon cv. PMR 6, which is resistant to races 1 and 2 of P. fusca, suggesting that the fungus could belong to race 3, a race of P. fusca not yet reported in Spain. Race determination was carried out by inoculating the third true leaf of a set of differential melon genotypes that were maintained in a greenhouse. Symptoms and colonization observed on cvs. Rochet, PMR 45, PMR 6, and Edisto 47 indicated that the isolates belonged to race 3-5 of P. fusca. Fungal strains of races 1, 2, and 5 of P. fusca (all present in Spain) were used as controls. Pathotype designation was determined by inoculating different cucurbit genera and species (2). In addition to melon, the isolates were pathogenic on zucchini (Cucurbita pepo) cv. Diamant F1, but failed to infect cucumber (C. sativus) cv. Marketer and watermelon (Citrullus lanatus) cv. Sugar Baby; therefore, the isolates were pathotype BC (2). Races 1, 2, 4, and 5 of P. fusca have been previously reported in the area (1). The occurrence of race 3-5 represents another challenge in the management of cucurbit powdery mildew in Spain. References: (1) D. del Pino et al. Phytoparasitica 30:459, 2002. (2) E. Krístková et al. Sci. Hortic. 99:257, 2004. (3) A. Pérez-García et al. Mol. Plant Pathol. 10:153, 2009.

Enantiomeric resolution of bupivacaine by high-performance liquid chromatography and chiroptical detection.

This work reports a new analytical procedure for the separation and determination of the enantiomers of bupivacaine and the determination of the enantiomeric purity. The isomers were separated using a Chirex 3020 (250 mm x 4.6 mm) with a mobile phase of n-hexane:dichloroethane:ethanol (82:9:9, v/v/v) at a flow-rate of 1 ml min(-1) and UV, polarimetric and circular dichroism (CD) detection. Obtained retention times were 5.93 and 7.53 min (R and S) with a resolution of Rs=2.36. Precisions (RSD) were 1.83 and 2.02% (CD detection) and 3.07 and 1.26% (UV detection) for R- and S-enantiomers, respectively (at 10 microg level). Detection limits were 0.5 and 0.5 microg (R and S) with CD detection, and 0.9 and 0.3 microg with UV detection. Polarimetric detection was inadequate to perform a quantitative method at similar concentration ranges as UV and CD because of poor sensitivity. A procedure for determination of enantiomeric purity using a conventional chromatographic column (RP18, Luna) coupled to a CD detector and anisotropy factor (CD/UV) as analytical signal was also developed. Obtained results show that RSDs of 6.7-1.6% were obtained in the range of 0-100% enantiomeric purity.

62-kb plasmids harboring rulAB homologues confer UV-tolerance and epiphytic fitness to Pseudomonas syringae pv. syringae mango isolates.

The presence of genetic determinants homologous to rulAB genes for ultraviolet (UV) radiation resistance was determined in a collection of Pseudomonas syringae pv. syringae strains isolated from mango. The potential role of these plasmids in UV tolerance and ecological fitness in the mango phyllosphere was also evaluated. Nearly all of the 62-kb plasmids present in the P. syringae pv. syringae strains hybridized with a rulAB probe, but these 62-kb plasmids showed differences in restriction patterns. In vitro assays of tolerance to UV radiation of P. syringae pv. syringae strains showed a higher survival of the strains harboring the 62-kb plasmids compared to strains lacking plasmids when exposed to UVC or UVA+B fractions. Similar results were observed when transconjugants harboring the 62-kb plasmid were tested. Survival assays were carried out under field conditions, and a higher survival of P. syringae pv. syringae strains harboring 62-kb plasmids under direct solar radiation on the adaxial surface of leaves was also observed. When the assays were carried out in shady areas or on the abaxial surface of leaves, survival time was comparable for all the assayed strains, whether or not they contained a 62-kb plasmid hybridizing to rulAB. Our results indicate that P. syringae pv. syringae strains harboring 62-kb plasmids show an increase in ecological fitness when colonizing the mango phyllosphere.

Effect of lipopeptides of antagonistic strains of Bacillus subtilis on the morphology and ultrastructure of the cucurbit fungal pathogen Podosphaera fusca.

AIMS: To analyse the morphological and ultrastructural effects of lipopeptides of cell-free liquid cultures from the antagonistic Bacillus subtilis strains, UMAF6614 and UMAF6639, on the cucurbit powdery mildew fungus, Podosphaera fusca, conidial germination. METHODS AND RESULTS: Butanolic extracts from cell-free supernatants of B. subtilis cultures were tested for their ability to arrest P. fusca conidial germination using the zucchini cotyledon disc method. Previously, the occurrence of lipopeptide antibiotics fengycin, iturin/bacillomycin and surfactin in the extracts was verified by diverse chromatographic approaches. Conidial germination was strongly reduced by antifungal extracts obtained from liquid cultures of both B. subtilis strains. Scanning electron microscopy analysis showed morphological damage in conidia characterized by the presence of large depressions and loss of turgidness. Transmission electron microscopy analysis revealed severe modifications in the plasma membrane and disorganization of the P. fusca cell cytoplasm. CONCLUSIONS: The lipopeptides produced by the two strains of B. subtilis are able to reduce cucurbit powdery mildew disease by arresting conidial germination, which seems to result from the induction of important cytological alterations. SIGNIFICANCE AND IMPACT OF THE STUDY: We elucidated the mechanisms employed by these antagonistic strains of B. subtilis to suppress cucurbit powdery mildew disease and delineate the ultrastructural damages responsible for their suppressive effect.

Estudio de los efectos psicológicos a corto plazo de los atentados del 11-M en población general de la zona afectada / No disponible

El objetivo del presente estudio es identificar los efectos psicológicos a corto plazo de los atentados del 11-M en la población general de la comunidad de Madrid y del área del Corredor del Henares de la provincia de Guadalajara. En el estudio participaron 1.179 personas mayores de 18 años, que fueron evaluadas en la segunda semana tras los atentados (entre el 18 y el 24 de marzo). La muestra incluía un tercio de personas que viven o trabajan en la zona más directamente afectada. Los datos indican que una semana después de los atentados, cerca de la mitad de los participantes afirmaba que se había implicado emocionalmente hasta el punto de ver afectada su vida cotidiana. Así mismo, los porcentajes de personas con síntomas depresivos o de estrés agudo se sitúan entorno al 50% y el 47% respectivamente, llegando a producir un deterioro del funcionamiento cotidiano en un 17% de los casos para ambos tipos de síntomas. Cabe destacar que un 13,5% de los participantes mostraban simultáneamente síntomas depresivos y de estrés agudo que interferían en su vida cotidiana. Los resultados se discuten desde el punto de vista de la planificación de servicios ajustados a las necesidades identificadas en la población (AU)

The aim of the present study is to analyze the short-term psychological effects of the March 11th terrorist attack on the general population of Madrid and the Corredor del Henares area in Guadalajara. 1.179 subjects aged over 18 participated in the study and were assessed in the second week after the attack (that is, between March 18th and 24th). The sample included a third of subject that live or work in the area most directly affected. Results show that, a week after the terrorist attack, about a half of the participants showed emotional involvement that had a negative effect on their daily life. Furthermore, the percentages of people with depressive or acute stress symptoms reach about 50% and 47% respectively; these symptoms cause functional impairment for 17% of the subjects. It is worth mentioning that a 13,5% of the participants showed simultaneously depressive and acute stress symptoms that affected their daily life. Results are discussed considering the planning of services fitting the actual needs of the population (AU)

Powdery Mildew of Dill (Anethum graveolens): A New Disease Caused by Erysiphe heraclei Detected in Spain.

Powdery mildew was observed for the first time on dill (Anethum graveolens L.) in several commercial greenhouses in Almería (southern Spain) during the spring and summer of 2002. Fungal growth appeared as typical white, dense, persistent powdery mildew colonies on leaves, inflorescences, and stems. Hyphae were 6 to 10 µm wide (mean = 6.88, standard deviation [SD] = 1.22, and n = 50). Conidia were produced singly on unbranched three-celled conidiophores, were cylindrical to ovate, and ranged in length from 26 to 42 µm (mean = 33.7, SD = 4.33, n = 55) and width from 12 to 18 µm (mean = 14.4, SD = 1.46). No fibrosin bodies were observed. Germ tubes were formed from the ends of conidia. Appressoria from mycelia were lobed. Conidiophores were 64 to 154 µm long (mean = 110, SD = 19.86, n = 30) with straight foot cells 24 to 42 µm long (mean = 33.8, SD = 6.17) and 6 to 10 µm wide (mean = 8.4, SD = 1). No cleistothecia were found so an accurate identification of the species was not possible. However, on the basis of morphological characteristics of the imperfect state, this powdery mildew corresponds with Erysiphe heraclei, the powdery mildew of umbelliferous crops (1) that was previously reported on dill from France and Portugal (2) and recently from Turkey (3). In Spain, the disease has been previously reported in other umbelliferous plants, such as carrot and celery (2), which are common crops in southern Spain. When infected with E. heraclei, these plants can serve as potential sources of inoculum. References: (1) U. Braun. Page 216 in: A Monograph of Erysiphales (Powdery Mildew). Nova Hedwigia. J. Cramer Berlin-Stuttgart, 1987. (2) U. Braun. Pages 116-117 in: The Powdery Mildew (Erysiphales) of Europe. Gustav Fischer-Verlag, Jena, Germany, 1995. (3) E. M. Soylu and S. Soylu. Plant Pathol. 52:423, 2003.

Isolation and evaluation of antagonistic bacteria towards the cucurbit powdery mildew fungus Podosphaera fusca.

Powdery mildew is one of the most important limiting factors for cucurbits production in Spain, its management being strongly dependent on chemicals. The aim of this work was to evaluate the possibility of exploiting antagonistic bacteria in the biological control of the cucurbit powdery mildew fungus Podosphaera fusca (syn. Sphaerotheca fusca). Among a collection of bacterial strains isolated from distinct cucurbit powdery mildew diseased plants and rhizospheric soils, four isolates were selected, by means of a screening method based on antibiotic production, and identified as Bacillus spp. These isolates proved to be efficacious in the control of cucurbit powdery mildew in in vitro detached leaves and seedling biocontrol assays, where reductions of disease severity of up to 80% were obtained. Furthermore, bacterial populations on melon leaves remained at similar levels (10(5) cfu cm(-2)) over the 16-day period studied and, as observed by scanning electron microscopy analysis, they were able to establish microcolonies associated with an extracellular matrix, which reveals that these isolates efficiently colonize melon phylloplane. These results indicate that the bacterial isolates selected are promising candidates for biological control agents of cucurbit powdery mildew in southern Spain.

Bacterial Apical Necrosis of Mango in Southern Spain: A Disease Caused by Pseudomonas syringae pv. syringae.

ABSTRACT A necrotic bacterial disease of mango trees (Mangifera indica) in Spain affecting buds, leaves, and stems is described for the first time. Necrosis of flower and vegetative buds on commercial trees during winter dormancy was the most destructive symptom of the disease. The apical necrosis is caused by Pseudomonas syringae, which was always isolated from mango trees with disease symptoms. Of 95 bacterial strains isolated from symptomatic tissues and characterized from 1992 to 1997, over 90% were identified as P. syringae pv. syringae. Additional strains were isolated from healthy mango trees, and they were identical to the isolates from diseased tissues. Pathogenicity tests on mango plants showed that P. syringae pv. syringae incited the apical necrosis, but that climatic conditions determined the onset of disease development. Populations of total bacteria and of P. syringae and the number of active ice nuclei were monitored over a 3-year period. The largest populations of P. syringae were associated with cool, wet periods that coincided with the highest disease severity, whereas P. syringae was only occasionally detected on healthy trees. The median effective dose was estimated from infectivity titration assays.

Comparison of microbial tests for the detection of heavy metal genotoxicity.

Heavy metal genotoxicity was evaluated by using different microbial tests. Four genotoxicity assays were employed: the Ames test, the E. coli WP2 test, the Mutatox test detecting mutagenicity, and the SOS assay with E. coli-detecting enzyme induction. All the metals tested (cadmium, chromium, copper, mercury, nickel, and zinc) were detected as genotoxic by the Mutatox and the SOS tests. The Ames test and the E. coli WP2 assay only detected chromium as genotoxic, causing a mutagenic effect. The sensitivity to metals of all the assays used was maintained when they were dissolved in sewage, although there was a slight increase in the sensitivity thresholds.

A comparison of microbial bioassays for the detection of metal toxicity.

Heavy metal toxicity was studied by assaying six microbiological toxicity tests, both in solution and wastewater. Pseudomonas fluorescens and baker's yeast (Saccharomyces cerevisiae) were used; growth and respirometric determinations were performed. In addition, the Microtox test was employed as a reference method. The Microtox test is the most sensitive assay for detecting toxicity of zinc, copper, and mercury but not for cadmium, chromium, and nickel. Wastewater increases the sensitivity threshold (EC20) and EC50 values of the metals in most of the assays, which is correlated to the presence of organic and inorganic compounds that can reduce the bioavailability of the metals, leading to a general loss of sensitivity. All the above-mentioned assays are potentially useful in the detection of chemical toxicity of metals. However, each test shows different sensitivities to each metal, which is related to different sensitivities of the organisms used in the assays, as well as to other factors. Therefore, it would be advisable to use a battery of tests for biological evaluation of metal toxicity.

Molecular characterization of a cDNA clone encoding glutamine synthetase from a gymnosperm, Pinus sylvestris.

A full-length cDNA clone (pGSP114) encoding glutamine synthetase was isolated from a lambda gt11 library of the gymnosperm Pinus sylvestris. Nucleotide sequence analysis showed that pGSP114 contains an open reading frame encoding a protein of 357 amino acid residues with a calculated molecular mass of 39.5 kDa. The derived amino acid sequence was more homologous to cytosolic (GS1) (78-82%) than to chloroplastic (GS2) (71-75%) glutamine synthetase in angiosperms. The lack of N-terminal presequence and C-terminal extension which define the primary structure of GS2, also supports that the isolated cDNA encodes cytosolic GS. Southern blot analysis of genomic DNA from P. sylvestris and P. pinaster suggests that GS may be encoded by a small gene family in pine. GS mRNA was more abundant in cotyledons and stems than in roots of both Scots and maritime pines. Western blot analysis in P. sylvestris seedlings showed that only one GS polypeptide, similar in size to GS1 in P. pinaster, could be detected in several different tissues. Our results suggest that cytosolic GS is mainly responsible for glutamine biosynthesis in pine seedlings.