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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).
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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.
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Agricultura , Persea , Tecnología de Sensores Remotos , Xylariales , Agricultura/métodos , Algoritmos , Aprendizaje Automático , Persea/microbiología , Temperatura , Xylariales/fisiologíaRESUMEN
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.
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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.
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Bacillus/genética , Cucurbitaceae/microbiología , Genoma Bacteriano/genética , Genómica , Enfermedades de las Plantas/prevención & control , Bacillus/química , Bacillus/fisiología , Proteínas Bacterianas/genética , Secuencia de Bases , Datos de Secuencia Molecular , Familia de Multigenes , Control Biológico de Vectores , Fenotipo , Filogenia , Enfermedades de las Plantas/microbiología , Hojas de la Planta/microbiología , Semillas/microbiología , Análisis de Secuencia de ADNRESUMEN
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.
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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.
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Bacillus subtilis , Cucurbitaceae , Bacillus subtilis/metabolismo , Cucurbitaceae/microbiología , Matriz Extracelular de Sustancias Poliméricas , Gotas Lipídicas , Semillas/microbiologíaRESUMEN
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.
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Colgajos Tisulares Libres , Procedimientos de Cirugía Plástica , Anastomosis Quirúrgica , Cara/cirugía , Humanos , Maxilar/cirugía , Microcirugia , Colgajos QuirúrgicosRESUMEN
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.
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Antibiosis , Bacillus/aislamiento & purificación , Persea/microbiología , Enfermedades de las Plantas/prevención & control , Pseudomonas/aislamiento & purificación , Bacillus/crecimiento & desarrollo , Biopelículas , Productos Agrícolas/microbiología , Enfermedades de las Plantas/microbiología , Raíces de Plantas/microbiología , Pseudomonas/crecimiento & desarrollo , Rizosfera , Microbiología del Suelo , Xylariales/patogenicidadRESUMEN
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.
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Ascomicetos/patogenicidad , Proteínas Fluorescentes Verdes/metabolismo , Persea/microbiología , Enfermedades de las Plantas/microbiología , Raíces de Plantas/microbiología , Ascomicetos/citología , Ascomicetos/genética , Ascomicetos/metabolismo , Proteínas Fluorescentes Verdes/genética , Transformación Genética , VirulenciaRESUMEN
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.
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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.
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Bupivacaína/química , Bupivacaína/aislamiento & purificación , Dicroismo Circular/métodos , Anisotropía , Cromatografía Líquida de Alta Presión , Espectrofotometría Ultravioleta , EstereoisomerismoRESUMEN
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.
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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.
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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.
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Proteínas Bacterianas/genética , Mangifera/microbiología , Plásmidos/genética , Pseudomonas syringae/efectos de la radiación , Tolerancia a Radiación/genética , Rayos Ultravioleta , Recuento de Colonia Microbiana , Conjugación Genética , Electroporación , Hojas de la Planta/microbiología , Pseudomonas syringae/genética , Pseudomonas syringae/crecimiento & desarrollo , Pseudomonas syringae/aislamiento & purificación , Luz SolarRESUMEN
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.
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Antibiosis/fisiología , Ascomicetos/efectos de los fármacos , Bacillus subtilis/metabolismo , Proteínas Bacterianas/farmacología , Lipoproteínas/farmacología , Antifúngicos/farmacología , Ascomicetos/crecimiento & desarrollo , Ascomicetos/ultraestructura , Bacillus subtilis/clasificación , Bacillus subtilis/fisiología , Medios de Cultivo Condicionados/farmacología , Microscopía Electrónica , Microscopía Electrónica de Rastreo , Control Biológico de Vectores/métodos , Esporas Fúngicas/efectos de los fármacos , Esporas Fúngicas/crecimiento & desarrollo , Esporas Fúngicas/ultraestructuraRESUMEN
The resistance patterns of Pseudomonas aeruginosa strains isolated from freshwater and seawater to different antimicrobial agents and heavy metals were studied. It was found that resistance in these environments is linked to the level of faecal pollution. All strains were resistant to ampicillin and tetracycline but sensitive to carbenicillin, amikacin, tobramycin, and colistin, and to the assayed concentrations of silver, cadmium, lead, and molybdenum. Resistance to gentamicin, sulphadiazine, mercury, arsenic, and chromium was variable, so their use as epidemiological markers was considered. There was a close relationship between the degree of pollution and the frequency of heavy metal resistant strains of Ps. aeruginosa. The highest frequencies of resistance to mercury and arsenic were obtained from marine environments with little faecal pollution, where the highest incidence of multi-resistant strains was also observed.
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Antibacterianos/farmacología , Metales/farmacología , Pseudomonas aeruginosa/efectos de los fármacos , Microbiología del Agua , Farmacorresistencia Microbiana , Heces/microbiología , Agua Dulce , Agua de Mar , Aguas del AlcantarilladoRESUMEN
Seedlings of Pinus pinaster Alton accumulated chlorophyll (Chl) when grown in complete darkness. Contents of Chl a and Chl b increased during germination, reaching similar levels in light- and dark-grown plants. Glutamine-synthetase (GS; EC 6.3.1.2) activity was detected in the embryo and its level increased markedly in cotyledons of dark-germinated seedlings. Similar levels of GS activity were observed when the seeds were germinated in the presence of white light. Only one GS form, which eluted at about 0.1 M KCl, was found by ion-exchange chromatography. A predominant GS polypeptide of 43 kDa was detected in cotyledons, and its steady-state level increased with development in a lightindependent fashion. In roots and needles, a related GS polypeptide of 43 kDa was the unique species detectable by western blot analysis. Immunoblots of soluble proteins from isolated chloroplasts showed low abundance of GS protein, indicating that glutamine synthesis in pine cotyledons occurs mainly in the cytosol. Nitrogen-feeding experiments carried out with detached shoots indicated that neither NO 3 (-) nor NH 4 (+) regulate GS levels and the polypeptide pattern. Our results indicate that environmental factors, such as light and nitrogen supply, have a limited role in GS accumulation during pine development.
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The survival of Pseudomonas aeruginosa in the marine environment and in the laboratory under controlled conditions was investigated. The in situ studies show that the die-off of P. aeruginosa in seawater is very similar to those of Fecal Streptococci, and slower than those of Coliforms. Besides the physical processes, the action of some environmental factors on the survival of P. aeruginosa in seawater must be considered. The most important inactivating effects are produced by the visible light and the non-filtrable biotic factors.
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Pseudomonas aeruginosa/crecimiento & desarrollo , Agua de Mar , Microbiología del Agua , Enterobacteriaceae/crecimiento & desarrollo , Aguas del Alcantarillado , Streptococcus/crecimiento & desarrolloRESUMEN
Studies of the survival of Pseudomonas aeruginosa in freshwater, in situ and in the laboratory, were carried out. A die-off of P. aeruginosa very similar to those of the microbial indicators of fecal pollution, especially to the coliforms, was observed from the results obtained by in situ experiments. The laboratory studies show that the factors tested which exert the greatest effect on the survival of P. aeruginosa in freshwater are the luminous radiations and non-filtrable biotic factors. Furthermore, a negative effect on the viability of this microorganism in freshwater is observed when sewage is added.
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Pseudomonas aeruginosa/crecimiento & desarrollo , Microbiología del Agua , Enterobacteriaceae/crecimiento & desarrollo , Heces/microbiología , Agua Dulce , Luz , Aguas del Alcantarillado , Streptococcus/crecimiento & desarrollo , TemperaturaRESUMEN
Eleven media were studied for their suitability in the selective isolation of Aeromonas hydrophila. Preliminary results showed that five of them (inositol-brilliant green-bile salts agar, bile salts-brilliant green agar, Rimler-Shotts agar, xylose-sodium deoxycholate-citrate agar, and dextrin-fuchsin-sulfite agar) allowed the growth of several microorganisms that are usually present in the same samples in which A. hydrophila is found. Six media (mA agar, modified Rimler-Shotts agar, DNase-toluidine blue-ampicillin agar, Pril-xylose-ampicillin agar, MacConkey-trehalose agar, and starch-bile salts agar) were selected for evaluation as recovery selective media on the basis of their efficiency in the isolation of A. hydrophila from natural water samples. mA agar showed the best recovery rate and also an acceptable specificity, but its selectivity was low. Another medium that can be considered is DNase-toluidine blue-ampicillin agar, which showed good accuracy, but its specificity was low.