Origin, accumulation and fate of dissolved organic matter in an extreme hypersaline shallow lake.

Hypersaline endorheic aquatic systems (H-SEAS) are lakes/shallow playas in arid and semiarid regions that undergo extreme oscillations in salinity and severe drought episodes. Although their geochemical uniqueness and microbiome have been deeply studied, very little is known about the availability and quality of dissolved organic matter (DOM) in the water column.. A H-SEAS from the Monegros Desert (Zaragoza, NE Spain) was studied during a hydrological wetting-drying-rewetting cycle. DOM analysis included: (i) a dissolved organic carbon (DOC) mass balance; (ii) spectroscopy (absorbance and fluorescence) and (iii) a molecular characterization with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The studied system stored a large amount of DOC and under the highest salinity conditions, salt-saturated waters (i.e., brines with salinity > 30%) accumulated a disproportionate quantity of DOC, indicating a significant in-situ net DOM production. Simultaneously, during the hydrological transition from wet to dry, the DOM pool showed strong alterations of it molecular composition. Spectroscopic methods indicated that aromatic and degraded DOM was rapidly replaced by fresher, relatively small, microbial-derived moieties with a large C/N ratio. FT-ICR-MS highlighted the accumulation of small, saturated and oxidized molecules (molecular O/C > 0.5), with a remarkable increase in the relative contribution of highly oxygenated (molecular O/C>0.9) compounds and a decrease of aliphatic and carboxyl-rich alicyclic moleculesThese results indicated that H-SEAS are extremely active in accumulating and processing DOM, with the notable release of organic solutes probably originated from decaying microplankton under large osmotic stress at extremely high salinities.

Réplica a: "Visibilidad de los institutos de investigación sanitaria a través de la base de datos Web of Science2 / Reply to "Visibility of healthcare research institutes through the Web of Science2 database"

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Multiscale imaging characterization of dopamine transporter knockout mice reveals regional alterations in spine density of medium spiny neurons.

The dopamine transporter knockout (DAT KO) mouse is a model of chronic hyperdopaminergia used to study a wide range of neuropsychiatric disorders such as schizophrenia, attention deficit hyperactivity disorder (ADHD), drug abuse, depression, and Parkinson's disease (PD). Early studies characterizing this mouse model revealed a subtle, but significant, decrease in the anterior striatal volume of DAT KO mice accompanied by a decrease in neuronal cell body numbers (Cyr et al., 2005). The present studies were conducted to examine medium spiny neuron (MSN) morphology by extending these earlier reports to include multiscale imaging studies using correlated light microscopy (LM) and electron microscopy (EM) techniques. Specifically, we set out to determine if chronic hyperdopaminergia results in quantifiable or qualitative changes in DAT KO mouse MSNs relative to wild-type (WT) littermates. Using Neurolucida Explorer's morphometric analysis, we measured spine density, dendritic length and synapse number at ages that correspond with the previously reported changes in striatal volume and progressive cell loss. Light microscopic analysis using Neurolucida tracings of photoconverted striatal MSNs revealed a highly localized loss of dendritic spines on the proximal portion of the dendrite (30 µm from the soma) in the DAT KO group. Next, thick sections containing MSN dendritic segments located at a distance of 20-60 µm from the cell soma, a region of the dendrite where spine density is reported to be the highest, were analyzed using electron microscope tomography (EMT). Because of the resolution limits of LM, the EM analysis was an extra measure taken to assure that our analysis included nearly all spines. Spine density measurements collected from the EMT data revealed only a modest decrease in the DAT KO group (n=3 mice) compared to age-matched WT controls (n=3 mice), a trend that supports the LM findings. Finally, a synaptic quantification using unbiased stereology did not detect a difference between DAT KO mice (n=6 mice) and WT controls (n=7 mice) at the EM level, supporting the focal nature of the early synaptic loss. These findings suggest that DAT KO mice have MSNs with highly localized spine loss and not an overall morphologically distinct cell shape. The characterization of morphological changes in DAT KO mice may provide information about the neural substrates underlying altered behaviors in these mice, with relevance for human neurological disorders thought to involve altered dopaminergic homeostasis. Results from this study also indicate the difficulty in correlating structural changes across scales, as the results on fine structure revealed thus far are subtle and non-uniform across striatal MSNs. The complexities associated with multiscale studies are driving the development of shared online informatics resources by gaining access to data where it is being analyzed.

The taxophysiological paradox: changes in theintestinal microbiota of the xylophagouscockroach Cryptocercus punctulatus dependingon the physiological state of the host

The phylogenetic relationships of symbiotic bacteria from the xylophagous cockroach Cryptocercus (Cryptocercidae, Blattaria) were compared to those described in previous reports in lower termites. The 16S rDNA bacterial genes were PCR-amplified from DNA isolated from the entire hindgut using Bacteria-selective primers, and the 16S rDNA amplicons were cloned into Escherichia coli. The changes in the gut microbiota of Cryptocercus under three physiological conditions, «active», «fasting», and «dead», were studied. Analysis of the active-clone library revealed 45 new phylotypes (clones sharing >97% sequence identity were grouped into the same phylotype) from 54 analyzed clones. The clones were affiliated with the phyla Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, Spirochaetes, Synergistetes, Verrucomicrobia, and candidate phylum Termite Group 1 (TG1). Clones belonging to Spirochaetes, Bacteroidetes, and TG1 phyla clustered with previously reported sequences obtained from the guts of several termites, suggesting that these clones are common constituents of the intestinal microbiota of lower termites and Cryptocercus. In the fasting-clone library, 19 new phylotypes, from 49 clones studied, were distinguished. The new phylotypes were affiliated with the phyla Bacteroidetes, Firmicutes, Actinobacteria, Proteobacteria, Spirochaetes, Synergistetes, and the candidate phylum TM7. Finally, in the dead-clone library, 24 new phylotypes from 50 studied clones were found. The new phylotypes were affiliated with the phyla Firmicutes, Actinobacteria, and Proteobacteria. Thus, from active, to fasting, to dead physiological states, a decrease in the number of phyla present in the whole microbial gut was evident. However, in the dead physiological state, each phylum conserved contained more new phylotypes. This poses a taxophysiological paradox, because a stable, active physiological state of Cryptocercus-due to a continuous input of wood-supports a higher diversity of bacterial phyla, probably necessary to maintain a sharp O(2)-H(2) gradient in the gut. By contrast, in the dead state, nutrient input is limited to the residual gut microbiota that is killed by the newly oxic environment, thus providing a food source for other, aerobic or facultative anaerobic bacteria. This results in an increase in the internal diversity of the few remaining phyla (AU)

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[Measurement of minimum disposable volume in the extraction of an analysis through an arterial catheter]. / Determinación del volumen mínimo desechable en laextracción de una analítica a través de un catéter arterial.

OBJECTIVE: Arterial catheters are used to extract blood samples. To maintain its permeability we use heparin solution, which may contaminate and alter the desired results. Our aim was to determine the volume of the minimum discards during blood extractions to avoid results that might be altered in the analysis of biochemistry. MATERIAL AND METHODS: A prospective study was carried out in 18 beds intensive care unit. Patients with arterial catheter (Seldicath) were included, maintaining 500 UI of heparin in saline of 500 ml, at a pressure of 300 mmHg through pressurizer (Tycos). The dead space (DS) in the radial arterial system is 0.8 ml and 1 ml in the femoral. We analyzed the reliability of different discards comparing the following: 3 ml + DS, 7.5 ml + DS, 12 ml + DS and 16.5 ml + DS. The statistical analysis was carried out through ANOVA and t Student. RESULTS: In biochemistry, significant differences were not found except for potasium (p< 0.001) with 3 ml+DS during control, although it is not clinically relevant [difference through = 0.1 mEq/l (DS 0.2)]. Significant differences in prothrombina (p = 0.004) were found in coagulation, comparing 3 ml+DS and 16.5 ml + DS and in cefaline, comparing 7.5 ml + DS (p< 0.0001) and 16.5 ml + DS. There were not significant differences in the studies of gases. CONCLUSIONS: Our study shows that to reach a reliable analytical results, it is not necessary to discard more than 3 ml+DS in biochemistry and in blood gases, and to determine cefalina time would necessary to discard a minimum of 7.5 ml+DS.

Cholinergic interneurons of the nucleus accumbens and dorsal striatum are activated by the self-administration of cocaine.

The nucleus accumbens, a major component of the ventral striatum, and the dorsal striatum are primary targets of the mesolimbic dopamine pathway, which is a pathway that plays a critical role in reward and addiction. The shell compartment of the nucleus accumbens and the ventromedial striatum, in particular, receive extensive afferent projections from the ventral tegmental area, which is the major afferent source of the mesolimbic pathway [Prog Brain Res 99 (1993) 209; J Neurosci 7 (1987) 3915]. The present study focused on striatal cholinergic interneurons as potential key neurons involved in the neural basis of drug reinforcement. The main finding of this study is that cholinergic interneurons located in the shell compartment of the nucleus accumbens and the ventromedial striatum were activated, as measured by Fos labeling, following a 1 h session of the self-administration of cocaine in rats. A direct correlation existed between the percent of cholinergic interneurons that were activated and the amount of cocaine that was self-administered. The greatest amount of administered cocaine (approximately 10 mg/kg) resulted in the activation of approximately 80% of the cholinergic neurons. No such correlation existed in the group of animals that self-administered saline. In addition, activation was not found in the core compartment of the nucleus accumbens or the dorsolateral striatum, which receive extensive innervation from the substantia nigra and thus are more closely tied to the motor effects of the drug. In conclusion, cocaine-driven neuronal activation was specific to the shell compartment of the nucleus accumbens (R(2)=0.9365) and the ventromedial striatum (R(2)=0.9059). These findings demonstrate that cholinergic interneurons are involved in the initial stage of cocaine intake and that these neurons are located in areas of the nucleus accumbens and dorsal striatum that are more closely tied to the rewarding and hedonic effects rather than the motor effects of cocaine intake.

Microbial mats and the search for minimal ecosystems.

This article reviews some ecological concepts common to all kinds of ecosystems, describes the characteristics of microbial mats, and focuses on the description of the Ebro Delta microbial mats, to assess whether they fit the concept of a minimal ecosystem. First, microorganisms as components of ecosystems are considered, and some features of microbial life, including ubiquity, size and metabolism, genetic versatility, and strategies to overcome unfavorable conditions, are discussed. Models for ecosystems, regardless of their size, have the same basic components; tropical forests, multilayered planktonic microbial communities, and benthic microbial mats are analogous ecosystems at different scales. The structure--in terms of populations and communities--and ecophysiology of microbial mats are also discussed. The linear distribution of microbial populations along steep gradients of light and hydrogen sulfide allows for the simultaneous presence of different microbial populations. Defining the minimal ecosystem requirements necessary for the survival and proliferation of organisms is crucial in the search for extraterrestrial life and for establishing ecosystems beyond the Earth.

Microbial mats and the search for minimal ecosystems / Los tapetes microbianos y la búsqueda de los ecosistemas mínimos

This article reviews some ecological concepts common to all kinds of ecosystems, describes the characteristics of microbial mats, and focuses on the description of the Ebro Delta microbial mats, to assess whether they fit the concept of a minimal ecosystem. First, microorganisms as components of ecosystems are considered, and some features of microbial life, including ubiquity, size and metabolism, genetic versatility, and strategies to overcome unfavorable conditions, are discussed. Models for ecosystems, regardless of their size, have the same basic components; tropical forests, multilayered planktonic microbial communities, and benthic microbial mats are analogous ecosystems at different scales. The structure--in terms of populations and communities--and ecophysiology of microbial mats are also discussed. The linear distribution of microbial populations along steep gradients of light and hydrogen sulfide allows for the simultaneous presence of different microbial populations. Defining the minimal ecosystem requirements necessary for the survival and proliferation of organisms is crucial in the search for extraterrestrial life and for establishing ecosystems beyond the Earth (AU)

Este artículo revisa algunos conceptos ecológicos que son comunes a todo tipo de ecosistemas y describe las características de los tapetes microbianos, centrándose en la descripción de los tapetes microbianos del delta del Ebro para ver si se ajustan al concepto de ecosistema mínimo. En primer lugar se consideran los microorganismos como componentes del ecosistema y se describen algunas características de la vida microbiana como la ubicuidad, el tamaño y metabolismo, la variabilidada genética y las estrategias para superar las condiciones desfavorables. Independientemente de su tamaño, cualquier modelo de ecosistema tiene los mismos componentes básicos; los bosques tropicales, las comunidades microbianas planctónicas estratificadas y los tapetes microbianos bénticos son ecosistemas análogos a diferente escala. También se describen la estructura —en términos de población y comunidad— y la ecofisiología de los tapetes microbianos. La distribución lineal de las poblaciones microbianas a lo largo de gradientes acusados de luz y de sulfuro de hidrógeno permite la presencia simultánea de poblaciones microbianas distintas. Para la búsqueda de vida extraterrestre y para el establecimiento de ecosistemas más allá de la Tierra, es fundamental definir las características de los ecosistemas mínimos. (AU)

Vaginal microbiota in healthy pregnant women and prenatal screening of group B streptococci (GBS).

The microbiota of the lower female genital tract was evaluated from vaginal swabs obtained from 623 healthy pregnant women at gestation periods of 35-40 weeks. Isolated and identified microorganisms were expressed as percentages of total samples. As expected, lactobacilli made up the dominant vaginal microbiota (70%). Enterobacteriaceae, mainly Escherichia coli, Klebsiella spp. and Proteus, were present in 38% of the samples, which might reflect the possible contamination of vaginal tract with rectal microorganisms. Candida albicans was present in 10% of healthy pregnant woman assayed. Streptoccocci (Streptococcus sp. and Enterococcus faecalis with 3% and 4%, respectively) and other gram-positive cocci (Staphylococcus sp., 5%), along with other microorgansisms such as Gardnerella vaginalis (5%) and Pseudomonas aeruginosa (2%) may represent a potential infection risk. Streptococcus agalactiae (group B streptococci beta-hemolytic, GBS) was detected in 7% of the samples. GBS infection is a leading cause of neonatal morbidity and mortality in the developed world. Furthermore, GBS was often co-isolated with C. albicans (54.5%) in the samples. A complete and detailed evaluation of the vaginal biota swab, with particular attention to the presence of potential pathogens such as GBS, is a preventive strategy that can provide useful information to obstetricians and gynecologist in managing the last days of pregnancy and delivery.

Vaginal microbiota in healthy pregnant women and prenatal screening of group B streptococci (GBS) / Microbiota vaginal durante la gestación en mujeres sanas y diagnóstico prenatal de estreptococos del grupo B (GBS)

The microbiota of the lower female genital tract was evaluated from vaginal swabs obtained from 623 healthy pregnant women at gestation periods of 35-40 weeks. Isolated and identified microorganisms were expressed as percentages of total samples. As expected, lactobacilli made up the dominant vaginal microbiota (70%). Enterobacteriaceae, mainly Escherichia coli, Klebsiella spp. and Proteus, were present in 38% of the samples, which might reflect the possible contamination of vaginal tract with rectal microorganisms. Candida albicans was present in 10% of healthy pregnant woman assayed. Streptoccocci (Streptococcus sp. and Enterococcus faecalis with 3% and 4%, respectively) and other gram-positive cocci (Staphylococcus sp., 5%), along with other microorgansisms such as Gardnerella vaginalis (5%) and Pseudomonas aeruginosa (2%) may represent a potential infection risk. Streptococcus agalactiae (group B streptococci beta-hemolytic, GBS) was detected in 7% of the samples. GBS infection is a leading cause of neonatal morbidity and mortality in the developed world. Furthermore, GBS was often co-isolated with C. albicans (54.5%) in the samples. A complete and detailed evaluation of the vaginal biota swab, with particular attention to the presence of potential pathogens such as GBS, is a preventive strategy that can provide useful information to obstetricians and gynecologist in managing the last days of pregnancy and delivery (AU)

Se evaluó la microbiota del tracto genital inferior femenino a partir de raspados vaginales obtenidos de 623 mujeres embarazadas en períodos de gestación de 35-40 semanas. Las cantitades de microorganismos aislados e identificados se expresan en porcentaje sobre la muestra total. Como se esperaba, los lactobacilos constituían la mayor parte de la microbiota vaginal (70 por ciento). En el 38 por ciento de las muestras se encontraron enterobacteriáceas, principalmente Escherichia coli, Klebsiella spp. y Proteus spp., lo cual refleja una posible contaminación del tracto vaginal con microorganismos rectales. Candida albicans estaba presente en el 10 por ciento de las mujeres sanas de la muestra. Los estreptococos (Streptococcus sp. y Enterococcus faecalis con un 3 por ciento y un 4 por ciento, respectivamente), junto con otros microorganismos tales como Gardnerella vaginalis (5 por ciento) y Pseudomonas aeruginosa (2 por ciento) representan un riesgo potencial de infección. Se detectó Streptococcus agalactiae (estreptococo del grupo B b-hemolítico, GBS) en el 7 por ciento de las muestras. La infección por GBS es una de las causas principales de morbidez neonatal y de mortalidad en el mundo desarrollado. Además, GBS suele ser co-aislado con C. albicans (54.5 por ciento) en las muestras. La evaluación e identificación de toda la biota en el raspado vaginal, con especial atención a patógenos como GBS, es una estrategia de prevención que proporciona información útil a los obstétricos y ginecólogos para controlar los últimos días del embarazo y el parto (AU)

Determination of the partition coefficients of a homologous series of ciprofloxacin: influence of the N-4 piperazinyl alkylation on the antimicrobial activity.

Partitioning of a fluoroquinolone antibiotic, ciprofloxacin, and its N-piperazinyl alkyl derivatives, between octanol or Escherichia coli lipid membrane extract and aqueous buffer pH 7.4, was studied. The experimental partition coefficients (Pexp) were corrected at this pH using an expression that includes the microconstant values of each compound. The relationship between the corrected partition coefficients expressed as logP (thermodynamic partition coefficient) and the diffusion through the lipid bilayers ('hydrophobic pathway') of entry has been considered here. In this work, we have explored the possibility of using our model to provide physicochemical evidences to support such a via. The correlation between logP values and antibacterial activities (expressed as minimal inhibitory concentration (MIC) values) of the homologous series of antibiotics against different bacteria were studied. A parabolic behaviour was observed which evidenced that the only increase in lipophilicity does not result in an enhanced antimicrobial activity for the homologous family studied.

Determination by fluorimetric titration of the ionization constants of ciprofloxacin in solution and in the presence of liposomes.

A fluorescence titration method was applied for the determination of pKa of ciprofloxacin (CPX) in solution. Values of 6.18 +/- 0.05 and 8.76 +/- 0.03 were obtained for pKa1 and pKa2, respectively. The method was used to determine the ionization constants in the presence of liposomes of dipalmitoylphosphatidylcholine (DPPC) and DPPC with 10 mol% of dipalmitoylphosphatidylglycerol. A dependence on the surface charge of liposomes was found which supported the existence of a basic electrostatic interaction between CPX and the phospholipid bilayer. Both pK values for the N-4 butyl-piperazinyl derivative (BCPX) of the parent compound were also determined in solution and in the presence of liposomes. The competition of both drugs for the same binding site as 1-anilino-8-naphtalene sulfonate demonstrate that the interaction is governed by electrostatic forces.

Evidence of an efflux pump in Serratia marcescens.

Spontaneous mutants resistant to fluoroquinolones were obtained by exposing Serratia marcescens NIMA (wild-type strain) to increasing concentrations of ciprofloxacin both in liquid and on solid media. Frequencies of mutation ranged from 10(-7) to 10(-9). Active expulsion of antibiotic was explored as a possible mechanism of resistance in mutants as well as changes in topoisomerase target genes. The role of extrusion mechanisms in determining the emergence of multidrug-resistant bacteria was also examined. Mutants resistant to high concentrations of fluoroquinolones had a single mutation in their gyrA QRDR sequences, whereas the moderate resistance in the rest of mutants was due to extrusion of the drug.

Role of the outer membrane in the accumulation of quinolones by Serratia marcescens.

Accumulation of four quinolones by Serratia marcescens was measured fluorometrically. The passage of quinolones through the outer membrane was studied in both lipopolysaccharide-deficient and porin-deficient mutants. The lipopolysaccharide (LPS) layer formed a partially effective barrier for highly hydrophobic quinolones such as nalidixic acid. Quinolones with a low relative hydrophobicity coefficient seemed to pass preferentially through the water-filled Omp3 porin channels. Results were confirmed when Omp3 was cloned in a porin-defective Escherichia coli.

Salicylate induction of phenotypic resistance to quinolones in Serratia marcescens.

The influence of salicylic acid on the permeability and susceptibility of Serratia marcescens to both nalidixic acid and ciprofloxacin was studied, as well as the effect of salicylate on outer membrane proteins and lipopolysaccharide. As salicylic acid concentration increased, ciprofloxacin accumulation decreased with a concomitant, previously observed, reduction in the porin content of the outer membrane. Resistance to ciprofloxacin and nalidixic acid was enhanced when bacteria grew in the presence of salicylic acid.

New fimbrial adhesins of Serratia marcescens isolated from urinary tract infections: description and properties.

Fimbriation, hemagglutination and adherence properties were studied in two strains of S. marcescens (ATCC 43820 and 43821) isolated from the urine of two hospitalized patients in two different hospitals. Studies were performed using electron microscopy (EM), fimbrial purification, recombinant DNA and hemagglutination techniques, hydrophobicity and tests of adherence to uroepithelial cells, catheters and glass. In EM, fimbriae of these two strains showed an inner channel and were 11 nm. thick and 0.76-1.08 microns long. Original strains and the clone GH42-pSF192 (recombinant DNA prepared using E. coli GH42 as recipient and the cosmid SuperCos 1 as a vector) versus negative control (E. coli GH42-SuperCos 1) showed mannose-resistant hemagglutination of tanned erythrocytes and yeast, high hydrophobicity (55.4 and 49.6% at 37C versus 22.8%) and high adherence to borosilicate glass (313,000 and 168,000 CFU/cm.2 versus 17,000 CFU/cm.2), catheters (4.7 x 10(6) and 1.0 x 10(6) CFU/cm.2 versus 3.9 x 10(4) CFU/cm.2) and uroepithelial cells (adherence indexes of 3.82 and 3.29 versus 1.25). The properties of the fimbriae studied were different from those previously described in the genus Serratia, and they were designated as MR/T.

Postnatal alteration in hematocrit and viscosity in normal and polycythemic infants.

This study was done to document postnatal alterations in hematocrit and viscosity in the first 18 hours of life in 99 full-term infants, to better understand the age-dependent variations in these measurements that may have a bearing on the diagnosis of neonatal polycythemia. The peripheral venous Hct was highest at 2 hours of age, and dropped to cord blood levels by 18 hours. The whole blood viscosity of peripheral venous samples did not change significantly with age. In infants with peripheral venous Hct greater than or equal to 64%, and therefore considered to have polycythemia, a similar postnatal variation in Hct level was seen. Only 38% of infants with Hct greater than or equal to 64% at 2 hours of age continued to have a high level beyond 12 hours of age. The viscosity level in these infants tended to follow that of the Hct. The mean +/- 2 SD viscosity values obtained from peripheral venous samples was much higher than the upper limits of viscosity used in previous studies in which cord blood viscosity was used as the norm. Cord blood Hct correlated better with peripheral venous Hct than with capillary hematocrit, and provided a noninvasive method for screening. These findings suggest that the postnatal variations in Hct should be taken into consideration in the diagnosis of neonatal polycythemia.