Influence of the Freeze-Drying Process on the Physicochemical and Biological Properties of Pre-heated Amphotericin B Micellar Systems

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Crystal structure of an acidic platelet aggregation inhibitor and hypotensive phospholipase A(2) in the monomeric and dimeric states: insights into its oligomeric state

Phospholipases A(2) belong to the superfamily of proteins which hydrolyzes the sn-2 acyl groups of membrane phospholipids to release arachidonic acid and lysophospholipids. An acidic phospholipase A(2) isolated from Bothrops juraracussu snake venom presents a high catalytic, platelet aggregation inhibition and hypotensive activities. This protein was crystallized in two oligomeric states: monomeric and dimeric. The crystal structures were solved at 1.79 and 1.90 Angstrom resolution, respectively, for the two states. It was identified a Na+ ion at the center of Ca2+-binding site of the monomeric form. A novel dimeric conformation with the active sites exposed to the solvent was observed. Conformational states of the molecule may be due to the physicochemical conditions used in the crystallization experiments. We suggest dimeric state is one found in vivo. (C) 2004 Elsevier B.V. All rights reserved.

Arbuscular mycorrhizal fungal communities and soil aggregation as affected by cultivation of various crops during the sugarcane fallow period

Management systems involving crop rotation, ground cover species and reduced soil tillage can improve the soil physical and biological properties and reduce degradation. The primary purpose of this study was to assess the effect of various crops grown during the sugarcane fallow period on the production of glomalin and arbuscular mycorrhizal fungi in two Latosols, as well as their influence on soil aggregation. The experiment was conducted on an eutroferric Red Latosol with high-clay texture (680 g clay kg-1) and an acric Red Latosol with clayey texture (440 g kg-1 clay) in Jaboticabal (São Paulo State, Brazil). A randomized block design involving five blocks and four crops [soybean (S), soybean/fallow/soybean (SFS), soybean/millet/soybean (SMS) and soybean/sunn hemp/soybean (SHS)] was used to this end. Soil samples for analysis were collected in June 2011. No significant differences in total glomalin production were detected between the soils after the different crops. However, total external mycelium length was greater in the soils under SMS and SHS. Also, there were differences in easily extractable glomalin, total glomalin and aggregate stability, which were all greater in the eutroferric Red Latosol than in the acric Red Latosol. None of the cover crops planted in the fallow period of sugarcane improved aggregate stability in either Latosol.

Unsupervised manifold learning using Reciprocal kNN Graphs in image re-ranking and rank aggregation tasks

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

State of the art on animal embryonic chimeras

Embryonic chimerism is generally used in basic research and in vivo diagnosis of undifferentiated embryonic stem cells (ESC), mostly using mice embryos, although there have been reports in the literature on using rat, rabbit, sheep, chicken, primate, bovine, goat and pig embryos. Several techniques can currently be used to produce chimeric embryos, including microinjection, co-culture with ESC, fusion and aggregation. Although microinjection is the most commonly used method in mice, the mere aggregation of embryos with ESC may result in viable chimeras and be as efficient as microinjection. In mice, this chimerism technique has been shown to have the advantage of aggregating embryos in different stages of development with different ploidy, in addition to using ESC in the tetraploid complementation assay. Compared to other techniques for producing chimeras, the aggregation technique is a cheaper, faster and easier methodology to be performed. Moreover, aggregation can be simplified by chemically removing the zona pellucida with pronase or acidic Tyrode’s solution and be enhanced by using the Well of the Well culture system in combination with adhesion molecules, such as phytohemagglutinin. The most commonly used stages for chimerism by aggregation are those that precede the full compaction of the morula. In these stages, embryos have low-tension adherent junctions at the tangential point between two blastomeres. During the embryonic development of mice, the inner cell mass differentiates into epiblast and hypoblast. These layers will originate the fetal tissues and a portion of the extraembryonic tissues (yolk sac, allantois and amnion), whereas the trophectoderm (TE) gives rise to the chorion. A functional TE is essential for the complex molecular communications that occur between the embryo and the uterus. Embryos produced by somatic cell nuclear transfer, such as commercial cattle clones or endangered species, are subject to large fetal and neonatal losses. Hence embryo complementation with heterologous TE could be of assistance to decrease these losses and might as well assist development of high-value embryos in other approaches.