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Romina Schiaffino M.,National University of Central Buenos Aires | Laura Sanchez M.,University of Buenos Aires | Gerea M.,CONICET | Unrein F.,IIB INTECH | And 3 more authors.
Gynecologic Oncology | Year: 2015

We explored the distribution patterns of bacterial and archaeal abundances at the phylum and class level using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH), examining the among (across 35 water bodies) and within-lake (intra-Annual seasonality) patterns in Patagonia (Argentina). Alphaproteobacteria, Betaproteobacteria and Actinobacteria globally dominated the bacterioplankton, whereas Gammaproteobacteria and Archaea never exceeded 3 and 6% of the community, respectively. The different groups showed seasonality, with simultaneous peaks of all bacterial group absolute abundances during late winter or spring, and with peaks of Archaea during winter, late spring and summer. The bacterial groups presented roughly similar relative abundances in all seasons, whereas Archaea varied in their relative contribution to community structure. Multivariate analyses showed that dissolved organic carbon was an important variable structuring the community at the studied taxonomic resolution (using absolute and relative abundances), in both among and within-lake patterns. The absolute abundance of most bacterial groups was significantly higher in mesotrophic and eutrophic systems than in oligotrophic ones (except Actinobacteria), whereas their relative abundances did not change among trophic states (except Bacteroidetes). The lake grouping obtained from CARD-FISH was consistent with previous work using polymerase chain reaction-denaturing gradient gel electrophoresis data: deep oligotrophic lakes clustered together, whereas small and shallow water bodies grouped separately. Source


Kraiselburd I.,National University of Rosario | Alet A.I.,National University of Rosario | Tondo M.L.,National University of Rosario | Petrocelli S.,National University of Rosario | And 5 more authors.
PLoS ONE | Year: 2012

Recent studies have demonstrated that an appropriate light environment is required for the establishment of efficient vegetal resistance responses in several plant-pathogen interactions. The photoreceptors implicated in such responses are mainly those belonging to the phytochrome family. Data obtained from bacterial genome sequences revealed the presence of photosensory proteins of the BLUF (Blue Light sensing Using FAD), LOV (Light, Oxygen, Voltage) and phytochrome families with no known functions. Xanthomonas axonopodis pv. citri is a Gram-negative bacterium responsible for citrus canker. The in silico analysis of the X. axonopodis pv. citri genome sequence revealed the presence of a gene encoding a putative LOV photoreceptor, in addition to two genes encoding BLUF proteins. This suggests that blue light sensing could play a role in X. axonopodis pv. citri physiology. We obtained the recombinant Xac-LOV protein by expression in Escherichia coli and performed a spectroscopic analysis of the purified protein, which demonstrated that it has a canonical LOV photochemistry. We also constructed a mutant strain of X. axonopodis pv. citri lacking the LOV protein and found that the loss of this protein altered bacterial motility, exopolysaccharide production and biofilm formation. Moreover, we observed that the adhesion of the mutant strain to abiotic and biotic surfaces was significantly diminished compared to the wild-type. Finally, inoculation of orange (Citrus sinensis) leaves with the mutant strain of X. axonopodis pv. citri resulted in marked differences in the development of symptoms in plant tissues relative to the wild-type, suggesting a role for the Xac-LOV protein in the pathogenic process. Altogether, these results suggest the novel involvement of a photosensory system in the regulation of physiological attributes of a phytopathogenic bacterium. A functional blue light receptor in Xanthomonas spp. has been described for the first time, showing an important role in virulence during citrus canker disease. © 2012 Kraiselburd et al. Source


Schiaffino M.R.,National University of Central Buenos Aires | Sanchez M.L.,University of Buenos Aires | Gerea M.,National University of Comahue | Unrein F.,IIB INTECH | And 3 more authors.
Journal of Plankton Research | Year: 2015

We explored the distribution patterns of bacterial and archaeal abundances at the phylum and class level using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH), examining the among (across 35 water bodies) and within-lake (intra-annual seasonality) patterns in Patagonia (Argentina). Alphaproteobacteria, Betaproteobacteria and Actinobacteria globally dominated the bacterioplankton, whereas Gammaproteobacteria and Archaea never exceeded 3 and 6% of the community, respectively. The different groups showed seasonality, with simultaneous peaks of all bacterial group absolute abundances during late winter or spring, and with peaks of Archaea during winter, late spring and summer. The bacterial groups presented roughly similar relative abundances in all seasons, whereas Archaea varied in their relative contribution to community structure. Multivariate analyses showed that dissolved organic carbon was an important variable structuring the community at the studied taxonomic resolution (using absolute and relative abundances), in both among and within-lake patterns. The absolute abundance of most bacterial groups was significantly higher in mesotrophic and eutrophic systems than in oligotrophic ones (except Actinobacteria), whereas their relative abundances did not change among trophic states (except Bacteroidetes). The lake grouping obtained from CARD-FISH was consistent with previous work using polymerase chain reaction-denaturing gradient gel electrophoresis data: deep oligotrophic lakes clustered together, whereas small and shallow water bodies grouped separately. © The Author 2015. Published by Oxford University Press. All rights reserved. Source


Nestler J.M.,IIHR Hydroscience | Pompeu P.S.,Federal University of Lavras | Goodwin R.A.,U.S. Army | Smith D.L.,U.S. Army | And 3 more authors.
River Research and Applications | Year: 2012

The dynamics of many large floodplain rivers are dominated by the flood pulse. The high kinetic energy of the erosive flows associated with the flood pulse forms and reforms the river channel. In general, the flood pulse supports the immense abundance and diversity of river life by transporting nutrients and organic matter into backwaters in spring, supporting primary and secondary production during the summer and redistributing these products to channels as water levels recede. Both North American and South American fluvial-dependent large river fishes exhibit complex, system-level longitudinal and/or lateral movements across life stages that allow them to exploit flood pulse-driven spatial heterogeneity and seasonal connectivity to feed, reproduce and avoid harsh conditions. We argue that two hydraulic variables, the magnitudes of velocity and the spatial velocity gradient, are necessary and sufficient to both understand fish 'hydro-navigation' as well as explain patterns in biogeochemistry and fluvial geomorphology and thereby create a new conceptual framework for large floodplain rivers integrating fluid dynamics, channel morphology, biogeochemical cycling and important elements of fish ecology. We illustrate the framework using summary data from the São Francisco River, Brazil that contains sub-basins possessing different levels of impact and also from the lower Paraná River (Argentina) where natural processes can still be studied. We believe the framework is an important element of large river restoration because it directly links the unique physical and chemical processes of large floodplain rivers to life requirements important to fishes and other biota. © 2011 John Wiley & Sons, Ltd. Source


Bayona J.C.,IIB INTECH | Nakayasu E.S.,University of Texas at El Paso | Nakayasu E.S.,Pacific Northwest National Laboratory | Laverriere M.,IIB INTECH | And 8 more authors.
Molecular and Cellular Proteomics | Year: 2011

SUMOylation is a relevant protein post-translational modification in eukaryotes. The C terminus of proteolytically activated small ubiquitin-like modifier (SUMO) is covalently linked to a lysine residue of the target protein by an isopeptide bond, through a mechanism that includes an E1-activating enzyme, an E2-conjugating enzyme, and transfer to the target, sometimes with the assistance of a ligase. The modification is reversed by a protease, also responsible for SUMO maturation. A number of proteins have been identified as SUMO targets, participating in the regulation of cell cycle progression, transcription, translation, ubiquitination, and DNA repair. In this study, we report that orthologous genes corresponding to the SUMOylation pathway are present in the etiological agent of Chagas disease, Trypanosoma cruzi. Furthermore, the SUMOylation system is functionally active in this protozoan parasite, having the requirements for SUMO maturation and conjugation. Immunofluorescence analysis showed that T. cruzi SUMO (TcSUMO) is predominantly found in the nucleus. To identify SUMOylation targets and get an insight into their physiological roles we generated transfectant T. cruzi epimastigote lines expressing a double- tagged T. cruzi SUMO, and SUMOylated proteins were enriched by tandem affinity chromatography. By two-dimensional liquid chromatography-mass spectrometry a total of 236 proteins with diverse biological functions were identified as potential T. cruzi SUMO targets. Of these, metacaspase-3 was biochemically validated as a bona fide SUMOylation substrate. Proteomic studies in other organisms have reported that orthologs of putative T. cruzi SUMOylated proteins are similarly modified, indicating conserved functions for protein SUMOylation in this early divergent eukaryote. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc. Source

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