Infection of J774A.1 with different Mycobacterium species induces differential immune and miRNA‐related responses

Macrophages act as a reservoir for Mycobacterium tuberculosis, producing latent infection in approximately 90% of infected people. In this study, J774A.1 mouse macrophage cell line response and microRNA (miRNA) expression during infection with the most relevant mycobacterial strains for humans (M. tuberculosis, M. bovis and M. bovis BCG) was explored. No significant differences in bacillary loads were observed between activate and naive macrophages infected with M. tuberculosis and M. bovis. Nitrite production inhibition and infection control were in accordance with the virulence of the strain. Expression of let‐7e, miR‐21, miR‐155, miR‐210 and miR‐223 was opposite in the two species and miR‐146b* and miR‐1224 expression seemed to be part of the general response to infection.     

Potential of three-Way randomly amplified polymorphic DNA analysis as a typing method for twelve Salmonella serotypes.

The potential of a three-way randomly amplified polymorphic DNA (RAPD) procedure (RAPD typing) for typing Salmonella enterica strains assigned to 12 serotypes was analyzed. The series of organisms used included 235 strains (326 isolates) collected mainly from clinical samples in the Principality of Asturias and 9 reference strains. RAPD typing was performed directly with broth cultures of bacteria by using three selected primers and optimized PCR conditions. The profiles obtained with the three primers were used to define RAPD types and to evaluate the procedure as a typing method at the species and serotype levels. The typeability was 100%; the reproducibility and in vitro stability could be considered good. The concordance of RAPD typing methods with serotyping methods was 100%, but some profiles obtained with two of the three primers were obtained with strains assigned to different serotypes. The discrimination index (DI) within the series of organisms was 0.94, and the DI within serotypes Typhimurium, Enteritidis, and Virchow were 0.72, 0.52, and 0.66, respectively. Within these serotypes the most common RAPD types were differentiated into phage types and vice versa; combining the types identified by the two procedures (RAPD typing and phage typing) resulted in further discrimination (DI, 0. 96, 0.74, and 0.87, respectively). The efficiency, rapidity, and flexibility of the RAPD typing method support the conclusion that it can be used as a tool for identifying Salmonella organisms and as a typing method that is complementary to serotyping and phage typing methods.     

Antilisterial Activity of Peptide AS-48 and Study of Changes Induced in the Cell Envelope Properties of an AS-48-Adapted Strain of Listeria monocytogenes

The peptide AS-48 is highly active on all Listeria species. It has a bactericidal and bacteriolytic mode of action on Listeria monocytogenes CECT 4032, causing depletion of the membrane electrical potential and pH gradient. The producer strain Enterococcus faecalis A-48-32, releases sufficient amounts of AS-48 into the growth medium to suppress L. monocytogenes in cocultures at enterococcus-to-listeria ratios above 1 at 37°C or above 10 at 15°C. As the temperature decreases, the bactericidal effects of AS-48 are less pronounced, but at 2.5 μg/ml it still can inhibit the growth of listeria at 6°C. AS-48 is highly active on liquid cultures, although concentrations above 0.2 μg/ml are required to avoid adaptation of listeria. AS-48-adapted cells can be selected at low (but still inhibitory) concentrations, and they can be inhibited completely by AS-48 at 0.5 μg/ml. The adaptation is lost gradually upon repeated subcultivation. AS48^ad cells are cross-resistant to nisin and show an increased resistance to muramidases. Their fatty acid composition is modified: they show a much higher proportion of branched fatty acids as well as a higher C_{15:0 An}-to-C_{17:0 An} ratio. Resistance to AS-48 is also maintained by protoplasts from AS48^ad cells. Electron microscopy observations show that the cell wall of AS48^ad cells is thicker and less dense. The structure of wild-type cells is severely modified after AS-48 treatment: the cell wall and the cytoplasmic membrane are disorganized, and the cytoplasmic content is lost. Intracytoplasmic membrane vesicles are also observed when the wild-type strain is treated with high AS-48 concentrations.     

Chemical Analysis of the Lamella Walls of Agaricus bisporus Fruit Bodies

Purified lamella wall fragments of Agaricus bisporus fruit bodies were analyzed and shown to consist of neutral sugars (46.5%), hexosamines (31.7%), proteins (9.5%), some lipid material (10.0%), and ash (1.4%). The cell walls were fractionated on the basis of their polysaccharide solubility in water and alkaline solutions. The isolated fractions, using methylation analysis, exhibited striking chemical structural differences compared with the same fractions obtained from the corresponding vegetative cells and fruit bodies (stipe and pileus) walls. The structural differences detected in the wall seem to correspond to the ultimate differentiation of the mycelium inside the fruit body of A. bisporus. Received: 30 November 1998 / Accepted: 29 January 1999     

Reactions of adult and immature squirrel monkeys to intergroup exposure

Initial encounters between unfamiliar animals raise the practical problem of controlling aggression and provide the opportunity to examine changes in social structure that may occur as groups merge. Social interactions and spatial grouping patterns were examined in newly formed squirrel monkey groups, in which a subgroup of familiar adults was introduced to a subgroup of familiar immature squirrel monkeys. Yearlings (10–11 months) and subadults (20–50 months) generally remained spatially distinct from adults, and intergroup interactions often consisted of adult-initiated antagonism. Adults exhibited sexual segregation in their spatial grouping patterns and interactions, whereas yearlings and subadults generally showed sexual integration. These data suggest that there is considerable adult resistance to integration of unfamiliar immatures into established adult social groups. Zoo Biol 17:519–524, 1998. © 1998 Wiley-Liss, Inc.     

Bayesian Inference for the Ratio of the Means of Two Normal Populations with Unequal Variances

The problem of making inferences about the ratio of two normal means has been addressed, both from the frequentist and Bayesian perspectives, by several authors. Most of this work is concerned with the homoscedastic case. In contrast, the situation where the variances are not equal has received little attention. Cox (1985) deals, within the frequentist framework, with a model where the variances are related to the means. His results are mainly based on Fieller's theorem whose drawbacks are well known. In this paper we present a Bayesian analysis of this model and discuss some related problems. An agronomical example is used throughout to illustrate the methods.     

Importance of advective mass transfer and sediment surface area for streambed microbial communities

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Food availability and reproduction affects lipid and fatty acid composition of the brown mussel, Perna perna, raised in suspension culture

We examined the influence of the reproductive cycle and environmental factors on variations of the condition index (CI), tissue dry mass, shell size, total lipid content, and relative percent of fatty acids in the mussel, Perna perna. Spat or juveniles were reared to commercial size (70 mm) in suspension culture in the Golfo de Cariaco, Venezuela between May and October 2004. The dry mass of soft tissues and shell, a visual assessment of gonadal status and the organism lipid profile were established every fortnight. In parallel, we measured the environmental conditions, following chlorophyll a, salinity, temperature and seston levels. After an initial decrease, the CI rose and remained high until August after which it decreased continuously until October. Total lipid values also decreased initially, after which they showed two periods of rapid recuperation and depletion, the first between May and August and the second between August and October. Similar tendencies were noted in the fatty acids, C18:3n-3, C18:4n-3 and C22:6n-3. Correlation analysis found no significant relationships between environmental parameters and the variations in total lipids. However, significant correlations were noted between fatty acids and specific environmental parameters. In particular, temperature was inversely correlated with C14:0, C16:1n-7, C18:0, C18:1n-9 and 20:5n-3. Chlorophyll a was positively correlated with C14:0, C16:1n-7, C18:1n-7, C18:4n-3 and 20:4n-6. On the other hand, gametogenesis had an effect on C14:0, C16:1n-7, C18:1n-9 and C18:1n-7, while spawned and gonadal regression states had an effect on fatty acid 20:4n-6. Temperature and chlorophyll a levels strongly influenced the proportion of mussels spawning, suggesting that their influence upon lipid composition may be secondary to their impact upon reproduction. Despite the thermal stability of this tropical system, the lipid composition of mussels changed markedly during the study, reflecting the central role of diet and reproductive investment upon lipid composition.     

Distribution and antifungal susceptibility of Candida clinical isolations coming from six health care centers in the metropolitan area of Caracas, Venezuela (years 2003-2005)

The aim of this study was to investigate the frequency and antifungal susceptibility of Candida clinical isolations coming from patients with candidiasis in six health care centers of Caracas, Venezuela metropolitan area. The laboratory reports were retrospectively revised from January 2003 through August 2005. The isolated yeasts identification was carried out by conventional methods and antifungal susceptibility was evaluated by ATB-fungus (bioMérieux, France) and Etest (AB Biodisk, Solna, Sweden). One thousand nine hundred seventy seven (1.977) yeasts were studied and their susceptibility testing were carried out only in 1,414 of them. C. albicans was the most isolated yeast (46.7%) and none-albicans Candida-species represented more than half of the isolations (53.4%). All the isolated yeasts evaluated presented CMIs<1 microg/ml to anfotericina B and showed variable susceptibility percentages to fluconazole (91.5%), itraconazole (80%) and voriconazole (98.6%).