The biochemical basis for the essentiality of copper, the adequacy of the dietary copper supply, factors that condition deficiency, and the special conditions of copper nutriture in early infancy are reviewed. New biochemical and crystallographic evidence define copper as being necessary for structural and catalytic properties of cuproenzymes. Mechanisms responsible for the control of cuproprotein gene expression are not known in mammals; however, studies using yeast as a eukaryote model support the existence of a copper-dependent gene regulatory element. Diets in Western countries provide copper below or in the low range of the estimated safe and adequate daily dietary intake. Copper deficiency is usually the consequence of decreased copper stores at birth, inadequate dietary copper intake, poor absorption, elevated requirements induced by rapid growth, or increased copper losses. The most frequent clinical manifestations of copper deficiency are anemia, neutropenia, and bone abnormalities. Recommendations for dietary copper intake and total copper exposure, including that from potable water, should consider that copper is an essential nutrient with potential toxicity if the load exceeds tolerance. A range of safe intakes should be defined for the general population, including a lower safe intake and an upper safe intake, to prevent deficiency as well as toxicity for most of the population.
Prunus persica has been proposed as a genomic model for deciduous trees and the Rosaceae family. Optimized protocols for RNA isolation are necessary to further advance studies in this model species such that functional genomics analyses may be performed. Here we present an optimized protocol to rapidly and efficiently purify high quality total RNA from peach fruits (Prunus persica). Isolating high-quality RNA from fruit tissue is often difficult due to large quantities of polysaccharides and polyphenolic compounds that accumulate in this tissue and co-purify with the RNA. Here we demonstrate that a modified version of the method used to isolate RNA from pine trees and the woody plant Cinnamomun tenuipilum is ideal for isolating high quality RNA from the fruits of Prunus persica. This RNA may be used for many functional genomic based experiments such as RT-PCR and the construction of large-insert cDNA libraries.
Human MSCs have been studied to define the mechanisms involved in normal bone remodeling and the regulation of osteogenesis. During osteogenic differentiation, MSCs change from their characteristic fibroblast-like phenotype to near spherical shape. In this study, we analyzed the correlation between the organization of cytoskeleton of MSCs, changes in cell morphology, and the expression of specific markers (alkaline phosphatase activity and calcium deposition) of osteogenic differentiation. For osteoblastic differentiation, cells were cultured in a culture medium supplemented with 100 nM dexamethasone, 10 mM beta- glycerophosphate, and 50 microg/ml ascorbic acid. The organization of microfilaments and microtubules was examined by inmunofluorescence using Alexa fluor 594 phalloidin and anti alpha-tubulin monoclonal antibody. Cytochalasin D and nocodazole were used to alter reversibly the cytoskeleton dynamic. A remarkable change in cytoskeleton organization was observed in human MSCs during osteogenic differentiation. Actin cytoskeleton changed from a large number of thin, parallel microfilament bundles extending across the entire cytoplasm in undifferentiated MSCs to a few thick actin filament bundles located at the outermost periphery in differentiated cells. Under osteogenic culture conditions, a reversible reorganization of microfilaments induced by an initial treatment with cytochalasin D but not with nocodazole reduced the expression of differentiation markers, without affecting the final morphology of the cells. The results indicate that changes in the assembly and disassembly kinetics of microfilaments dynamic of actin network formation may be critical in supporting the osteogenic differentiation of human MSCs; also indicated that the organization of microtubules appears to have a regulatory role on the kinetic of this process.
Understanding the factors that modulate bacterial community assembly in natural soils is a longstanding challenge in microbial community ecology. In this work, we compared two microbial co-occurrence networks representing bacterial soil communities from two different sections of a pH, temperature and humidity gradient occurring along a western slope of the Andes in the Atacama Desert. In doing so, a topological graph alignment of co-occurrence networks was used to determine the impact of a shift in environmental variables on OTUs taxonomic composition and their relationships. We observed that a fraction of association patterns identified in the co-occurrence networks are persistent despite large environmental variation. This apparent resilience seems to be due to: (1) a proportion of OTUs that persist across the gradient and maintain similar association patterns within the community and (2) bacterial community ecological rearrangements, where an important fraction of the OTUs come to fill the ecological roles of other OTUs in the other network. Actually, potential functional features suggest a fundamental role of persistent OTUs along the soil gradient involving nitrogen fixation. Our results allow identifying factors that induce changes in microbial assemblage configuration, altering specific bacterial soil functions and interactions within the microbial communities in natural environments.
BackgroundPiscirickettsiosis or Salmonid Rickettsial Septicaemia (SRS) is a bacterial disease that has a major economic impact on the Chilean salmon farming industry. Despite the fact that Piscirickettsia salmonis has been recognized as a major fish pathogen for over 20 years, the molecular strategies underlying the fish response to infection and the bacterial mechanisms of pathogenesis are poorly understood. We analysed and compared the head kidney transcriptional response of Atlantic salmon (Salmo salar) families with different levels of susceptibility to P. salmonis infection in order to reveal mechanisms that might confer infection resistance.ResultsWe ranked forty full-sibling Atlantic salmon families according to accumulated mortality after a challenge with P. salmonis and selected the families with the lowest and highest cumulative mortalities for microarray gene expression analysis. A comparison of the response to P. salmonis infection between low and high susceptibility groups identified biological processes presumably involved in natural resistance to the pathogen. In particular, expression changes of genes linked to cellular iron depletion, as well as low iron content and bacterial load in the head kidney of fish from low susceptibility families, suggest that iron-deprivation is an innate immunity defence mechanism against P. salmonis. To complement these results, we predicted a set of iron acquisition genes from the P. salmonis genome. Identification of putative Fur boxes and expression of the genes under iron-depleted conditions revealed that most of these genes form part of the Fur regulon of P. salmonis.ConclusionsThis study revealed, for the first time, differences in the transcriptional response to P. salmonis infection among Atlantic salmon families with varied levels of susceptibility to the infection. These differences correlated with changes in the abundance of transcripts encoding proteins directly and indirectly involved in the immune response; changes that highlighted the role of nutritional immunity through iron deprivation in host defence mechanisms against P. salmonis. Additionally, we found that P. salmonis has several mechanisms for iron acquisition, suggesting that this bacterium can obtain iron from different sources, including ferric iron through capturing endogenous and exogenous siderophores and ferrous iron. Our results contribute to determining the underlying resistance mechanisms of Atlantic salmon to P. salmonis infection and to identifying future treatment strategies.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1716-9) contains supplementary material, which is available to authorized users.
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