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1.
Castagno LN Estrella MJ Sannazzaro AI Grassano AE Ruiz OA 《Journal of applied microbiology》2011,110(5):1151-1165
Aims: To isolate and characterize phosphate‐solubilizing strains from a constrained environment such as the Salado River Basin and to assess their phosphate‐solubilizing mechanisms, to further selection of the most promising strains to inoculate and improve the implantation and persistence of Lotus tenuis in the most important area devoted to meat‐cow production in Argentina. Methods and Results: Fifty isolates were obtained and through BOX‐PCR analysis, 17 non‐redundant strains were identified. Subsequently, they were found to be related to Pantoea, Erwinia, Pseudomonas, Rhizobium and Enterobacter genera, via 16S rRNA gene sequence analysis. This was in agreement with the clusters obtained by antibiotic resistance analysis. All isolates were tested for their phosphate‐solubilizing activity and selected strains were inoculated onto L. tenuis plants. The most efficient isolate, was identified as Pantoea eucalypti, a novel species in terms of plant growth‐promoting rhizobacteria. Conclusions: The isolates obtained in this study showed a significant in vitro plant‐growth promoting activity onto Lotus tenuis and the best of them solubilizes phosphate mainly via induction of the metabolism through secretion and oxidation of gluconic acid. Singnificance and Impact of the Study: The use of these bacteria as bioinoculants, alone or in combination with nitrogen‐fixing micro‐organisms, could be a sustainable practice to facilitate the nutrient supply to Lotus tenuis plants and preventing negative side‐effects such as eutrophication. 相似文献
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Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4° C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample. 相似文献
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Danielle B Rodrigues Roger Chammas Natália V Malavasi Patrícia LN da Costa Rosa M Chura-Chambi Keli N Balduino Ligia Morganti 《BMC biotechnology》2010,10(1):19
Background
Theracyte is a polytetrafluoroethylene membrane macroencapsulation system designed to induce neovascularization at the tissue interface, protecting the cells from host's immune rejection, thereby circumventing the problem of limited half-life and variation in circulating levels. Endostatin is a potent inhibitor of angiogenesis and tumor growth. Continuous delivery of endostatin improves the efficacy and potency of the antitumoral therapy. The purpose of this study was to determine whether recombinant fibroblasts expressing endostatin encapsulated in Theracyte immunoisolation devices can be used for delivery of this therapeutic protein for treatment of mice bearing B16F10 melanoma and Ehrlich tumors. 相似文献5.
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Andrew P. Castagno Till J. W. Wagner Mattias R. Cape Conner W. Lester Elizabeth Bailey Catharina Alves-de-Souza Robert A. York Alyson H. Fleming 《Global Change Biology》2023,29(17):5087-5098
Phytoplankton primary production in the Arctic Ocean has been increasing over the last two decades. In 2019, a record spring bloom occurred in Fram Strait, characterized by a peak in chlorophyll that was reached weeks earlier than in other years and was larger than any previously recorded May bloom. Here, we consider the conditions that led to this event and examine drivers of spring phytoplankton blooms in Fram Strait using in situ, remote sensing, and data assimilation methods. From samples collected during the May 2019 bloom, we observe a direct relationship between sea ice meltwater in the upper water column and chlorophyll a pigment concentrations. We place the 2019 spring dynamics in context of the past 20 years, a period marked by rapid change in climatic conditions. Our findings suggest that increased advection of sea ice into the region and warmer surface temperatures led to a rise in meltwater input and stronger near-surface stratification. Over this time period, we identify large-scale spatial correlations in Fram Strait between increased chlorophyll a concentrations and increased freshwater flux from sea ice melt. 相似文献
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Analía Inés Sannazzaro Verónica Mariel Bergottini Rosalía Cristina Paz Luis Nazareno Castagno Ana Bernardina Menéndez Oscar Adolfo Ruiz Fernando Luis Pieckenstain María Julia Estrella 《Antonie van Leeuwenhoek》2011,99(2):371-379
The Flooding Pampa (FP) is the most important area for cattle breeding in Argentina. In this region, persistence and yield
of typical forage legumes are strongly limited by soil salinity and alkalinity, which affect around 30% of the total area.
Instead, naturalized Lotus tenuis is the main forage legume in this region. Rhizobial strains currently used for inoculating L. tenuis in the FP are exotic or native from non-saline soils of this region, their taxonomic identity being unknown. Assuming that
rhizobia native from the most restrictive environments are well adapted to adverse conditions, the use of such isolates could
improve the productivity of L. tenuis in the FP. Hence, the goal of this study was to evaluate the symbiotic efficiency of selected L. tenuis rhizobia native from the FP, as compared with strains currently used for field inoculation of this legume. Under non-stressing
conditions, the symbiotic performance of native strains of FP exceeded those ones currently used for L. tenuis. Moreover, the symbiotic performance of the native strain ML103 was considerably high under salt stress, compared with strains
currently used as inoculants. Analysis of 16S rRNA gene sequencing revealed that unclassified rhizobia currently used for
field inoculation of L. tenuis and native strains grouped with the genus Mesorhizobium. As a whole, results obtained demonstrate that soils of the FP are a source of efficient and diverse rhizobia that could
be used as a sustainable agronomic tool to formulate inoculants that improve forage yield of L. tenuis in this region. 相似文献
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Pamela Orjuela-Sánchez Nadira D Karunaweera Mônica da Silva-Nunes Natal S da Silva Kézia KG Scopel Raquel M Gonçalves Chanaki Amaratunga Juliana M Sá Duong Socheat Rick M Fairhust Sharmini Gunawardena Thuraisamy Thavakodirasah Gawrie LN Galapaththy Rabindra Abeysinghe Fumihiko Kawamoto Dyann F Wirth Marcelo U Ferreira 《BMC genetics》2010,11(1):65
Background
The ideal malaria parasite populations for initial mapping of genomic regions contributing to phenotypes such as drug resistance and virulence, through genome-wide association studies, are those with high genetic diversity, allowing for numerous informative markers, and rare meiotic recombination, allowing for strong linkage disequilibrium (LD) between markers and phenotype-determining loci. However, levels of genetic diversity and LD in field populations of the major human malaria parasite P. vivax remain little characterized.Results
We examined single-nucleotide polymorphisms (SNPs) and LD patterns across a 100-kb chromosome segment of P. vivax in 238 field isolates from areas of low to moderate malaria endemicity in South America and Asia, where LD tends to be more extensive than in holoendemic populations, and in two monkey-adapted strains (Salvador-I, from El Salvador, and Belem, from Brazil). We found varying levels of SNP diversity and LD across populations, with the highest diversity and strongest LD in the area of lowest malaria transmission. We found several clusters of contiguous markers with rare meiotic recombination and characterized a relatively conserved haplotype structure among populations, suggesting the existence of recombination hotspots in the genome region analyzed. Both silent and nonsynonymous SNPs revealed substantial between-population differentiation, which accounted for ~40% of the overall genetic diversity observed. Although parasites clustered according to their continental origin, we found evidence for substructure within the Brazilian population of P. vivax. We also explored between-population differentiation patterns revealed by loci putatively affected by natural selection and found marked geographic variation in frequencies of nucleotide substitutions at the pvmdr-1 locus, putatively associated with drug resistance.Conclusion
These findings support the feasibility of genome-wide association studies in carefully selected populations of P. vivax, using relatively low densities of markers, but underscore the risk of false positives caused by population structure at both local and regional levels.See commentary: http://www.biomedcentral.com/1741-7007/8/9010.
Pauly M; Andersen LN; Kauppinen S; Kofod LV; York WS; Albersheim P; Darvill A 《Glycobiology》1999,9(1):93-100
A full-length c-DNA encoding a xyloglucan-specific endo -beta-1, 4-
glucanase (XEG) has been isolated from the filamentous fungus Aspergillus
aculeatus by expression cloning in yeast. The colonies expressing
functional XEG were identified on agar plates containing azurine-dyed
cross-linked xyloglucan. The cDNA encoding XEG was isolated, sequenced,
cloned into an Aspergillus expression vector, and transformed into
Aspergillus oryzae for heterologous expression. The recombinant enzyme was
purified to apparent homogeneity by anion- exchange and gel permeation
chromatography. The recombinant XEG has a molecular mass of 23,600, an
isoelectric point of 3.4, and is optimally stable at a pH of 3.4 and
temperature below 30 degreesC. The enzyme hydrolyzes structurally diverse
xyloglucans from various sources, but hydrolyzes no other cell wall
component and can therefore be considered a xyloglucan-specific endo
-beta-1, 4-glucanohydrolase. XEG hydrolyzes its substrates with retention
of the anomeric configuration. The Kmof the recombinant enzyme is 3.6
mg/ml, and its specific activity is 260 micromol/min per mg protein. The
enzyme was tested for its ability to solubilize xyloglucan oligosaccharides
from plant cell walls. It was shown that treatment of plant cell walls with
XEG yields only xyloglucan oligosaccharides, indicating that this enzyme
can be a powerful tool in the structural elucidation of xyloglucans.
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