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Kruk C.,Institute Investigaciones Biolo Gicas Clemente Estable | Kruk C.,University of the Republic of Uruguay | Kruk C.,Institute Investigaciones Biologicas Clemente Estable | Segura A.M.,University of the Republic of Uruguay | And 7 more authors.
Limnology and Oceanography | Year: 2012

We explored systematic patterns in predictability of phytoplankton species from 83 lakes over a gradient ranging from subpolar to tropical regions in South America. We estimated the explained variance (proxy of predictability) of the presence and biomass (estimated as biovolume) of species using multiple regressions from commonly measured environmental variables such as nutrient levels, light, mixing depth, temperature, and zooplankton biomass. Both the presence and biomass of species occurring at least in 10 lakes were quite well predicted from the environmental variables, with average values of 35% and 58%, respectively. Predictability was not systematically related to phylogenetic affiliation or particular functional groups as defined by morphology. However, biomass predictability decreased with increasing occurrence, and improved with larger species size (maximum linear dimension). Species that were predictable in terms of biomass (R2 ≥ 0.5, p ≤ 0.05) had, on average, a larger volume, and were relatively more frequent in lakes from warmer regions, with high water temperature, low chlorophyll a, low nutrient concentrations, and low total zooplankton biomass. Although we cannot diagnose the mechanisms involved, our finding that the number of predictable species increases towards warmer regions resembles situations where competition for nutrients and grazing are likely to be less severe, and may imply that in a future warmer world phytoplankton will be easier to predict. © 2012, by the Association for the Sciences of Limnology and Oceanography, Inc. Source


Palacios F.,Institute Pasteur Of Montevideo | Palacios F.,University of Montevideo | Abreu C.,Institute Pasteur Of Montevideo | Prieto D.,Institute Pasteur Of Montevideo | And 11 more authors.
Leukemia | Year: 2015

Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal B cells arrested in G0/G1 stages that coexist, in different proportions, with proliferative B cells. Understanding the crosstalk between the proliferative subsets and their milieu could provide clues on CLL biology. We previously identified one of these subpopulations in the peripheral blood from unmutated patients that appears to be a hallmark of a progressive disease. Aiming to characterize the molecular mechanism underlying this proliferative behavior, we performed gene expression analysis comparing the global mRNA and microRNA expression of this leukemic subpopulation, and compared it with their quiescent counterparts. Our results suggest that proliferation of this fraction depend on microRNA-22 overexpression that induces phosphatase and tensin homolog downregulation and phosphoinositide 3-kinase (PI3K)/AKT pathway activation. Transfection experiments demonstrated that miR-22 overexpression in CLL B cells switches on PI3K/AKT, leading to downregulation of p27-Kip1 and overexpression of Survivin and Ki-67 proteins. We also demonstrated that this pathway could be triggered by microenvironment signals like CD40 ligand/interleukin-4 and, more importantly, that this regulatory loop is also present in lymph nodes from progressive unmutated patients. Altogether, these results underline the key role of PI3K/AKT pathway in the generation of the CLL proliferative pool and provide additional rationale for the usage of PI3K inhibitors. © 2015 Macmillan Publishers Limited. Source


Aisenberg A.,Institute Investigaciones Biolo Gicas Clemente Estable | Gonzalez M.,Institute Investigaciones Biolo Gicas Clemente Estable | Gonzalez M.,CONICET
Journal of Arachnology | Year: 2011

When males have high reproductive investment and female quality is variable, male assessment of sexual partners is expected. Allocosa alticeps (Mello-Leitão 1944) is a nocturnal wolf spider that shows a reversal in the sex roles and sexual size dimorphism usual in spiders. Females are the smaller, mobile sex, and they initiate courtship. Males construct burrows that serve as mating refuges and nests for female oviposition and cocoon care. In sex role reversed systems, male mate assessment is expected. Our objective was to test the occurrence of sequential male mate assessment based on female reproductive status and/or body characteristics in A. alticeps, discussing the results under sex role reversal hypotheses. We exposed males consecutively to virgin females and mated females and then recorded both courtship performance and mating occurrences relative to individuals' body characteristics. Virgin and mated females detected and entered male burrows in all the cases, and they were courted by males. However, copulations were more frequent with virgin females. The results suggest male mate selectivity in A. alticeps is based on female reproductive status. We discuss possible mechanisms underlying male mate choice in this species. © 2011 The American Arachnological Society. Source


Di Giorgio M.,Autoridad Regulatoria Nuclear ARN | Vallerga M.B.,Autoridad Regulatoria Nuclear ARN | Radl A.,Autoridad Regulatoria Nuclear ARN | Taja M.R.,Autoridad Regulatoria Nuclear ARN | And 16 more authors.
Radiation Protection Dosimetry | Year: 2013

The bottleneck in data acquisition during biological dosimetry based on a dicentric assay is the need to score dicentrics in a large number of lymphocytes. One way to increase the capacity of a given laboratory is to use the ability of skilled operators from other laboratories. This can be done using image analysis systems and distributing images all around the world. Two exercises were conducted to test the efficiency of such an approach involving 10 laboratories. During the first exercise (E1), the participant laboratories analysed the same images derived from cells exposed to 0.5 and 3 Gy; 100 images were sent to all participants for both doses. Whatever the dose, only about half of the cells were complete with well-spread metaphases suitable for analysis. A coefficient of variation (CV) on the standard deviation of ̃15 % was obtained for both doses. The trueness was better for 3 Gy (0.6 %) than for 0.5 Gy (37.8 %). The number of estimated doses classified as satisfactory according to the z-score was 3 at 0.5 Gy and 8 at 3 Gy for 10 dose estimations. In the second exercise, an emergency situation was tested, each laboratory was required to score a different set of 50 images in 2 d extracted from 500 downloaded images derived from cells exposed to 0.5 Gy. Then the remaining 450 images had to be scored within a week. Using 50 different images, the CVon the estimated doses (79.2 %) was not as good as in E1, probably associated to a lower number of cells analysed (50 vs. 100) or from the fact that laboratories analysed a different set of images. The trueness for the dose was better after scoring 500 cells (22.5 %) than after 50 cells (26.8 %). For the 10 dose estimations, the number of doses classified as satisfactory according to the z-score was 9, for both 50 and 500 cells. Overall, the results obtained support the feasibility of networking using electronically transmitted images. However, before its implementation some issues should be elucidated, such as the number and resolution of the images to be sent, and the harmonisation of the scoring criteria. Additionally, a global website able to be used for the different regional networks, like Share Points, will be desirable to facilitate worldwide communication © The Author 2012. Published by Oxford University Press. All rights reserved. Source


D'Alessandro B.,Institute Investigaciones Biolo Gicas Clemente Estable | Lery L.M.S.,Federal University of Rio de Janeiro | Von Kruger W.M.A.,Federal University of Rio de Janeiro | Lima A.,Institute Pasteur Of Montevideo Institute Investigaciones Biologicas Clemente Estable | And 2 more authors.
FEMS Immunology and Medical Microbiology | Year: 2011

Proteus mirabilis is an opportunistic pathogen that frequently causes complicated urinary tract infections. Among a wide spectrum of potential virulence factors, outer membrane proteins (OMPs) are critical for bacterial interactions and survival in different environments. In this work, we used a proteomic approach to assess P. mirabilis in vivo OMPs expression compared to in vitro, including iron replete and iron-restricted conditions. Three putative iron receptors, IreA, PMI0842, and PMI2596, were detected both in bacterium grown in vivo and in vitro under iron-restricted conditions. A prophage gene product, PMI1721, was detected only on in vivo growing bacterium, suggesting a potential role yet to be disclosed on the surface of P. mirabilis. Plasminogen, a host protein, was co-purified with OMPs of in vivo grown bacteria, which is in accordance with previous observations and suggests that plasminogen bound to P. mirabilis surface may be associated to virulence as seen in other bacterial pathogens. Western blots using sera of experimentally challenged mice showed that iron-regulated proteins are expressed and highly immunogenic during infection. This work confirms observations made by others for P. mirabilis and reveals details not yet described, suggesting new aspects of the bacterium pathogenesis that remain unknown. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved. Source

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