Browsing by Author "Cambiazo, Verónica"

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    Bacterial communities associated to Chilean altiplanic native plants from the Andean grasslands soils
    (2019) Fernandez-Gomez, Beatriz; Maldonado, Jonathan; Mandakovic, Dinka; Gaete, Alexis; Gutiérrez Ilabaca, Rodrigo Antonio; Maass, Alejandro; Cambiazo, Verónica; González, Mauricio
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    Overexpression of amyloid precursor protein increases copper content in HEK293 cells
    (2009) Suazo, Miriam; Hodar, Christián; Morgan, Carlos; Cerpa Nebott, Francisco Waldo; Cambiazo, Verónica; Inestrosa Cantín, Nibaldo; González, Mauricio
    Amyloid precursor protein (APP) is a transmembrane glycoprotein widely expressed in mammalian tissues and plays a central role in Alzheimer’s disease. However, its physiological function remains elusive. Cu2+ binding and reduction activities have been described in the extracellular APP135–156 region, which might be relevant for cellular copper uptake and homeostasis. Here, we assessed Cu2+ reduction and 64Cu uptake in two human HEK293 cell lines overexpressing APP. Our results indicate that Cu2+ reduction increased and cells accumulated larger levels of copper, maintaining cell viability at supra-physiological levels of Cu2+ ions. Moreover, wild-type cells exposed to both Cu2+ ions and APP135–155 synthetic peptides increased copper reduction and uptake. Complementation of function studies in human APP751 transformed Fre1 defective Saccharomyces cerevisiae cells rescued low Cu2+ reductase activity and increased 64Cu uptake. We conclude that Cu2+ reduction activity of APP facilitates copper uptake and may represent an early step in cellular copper homeostasis.
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    Testing the stress gradient hypothesis in soil bacterial communities associated with vegetation belts in the Andean Atacama Desert
    (2023) Mandakovic, Dinka; Aguado-Norese, Constanza; García-Jiménez, Beatriz; Hodar, Christian; Maldonado, Jonathan E.; Gaete, Alexis; Latorre, Mauricio; Wilkinson, Mark D.; Gutiérrez Ilabaca, Rodrigo Antonio; Cavieres, Lohengrin A.; Medina, Joaquín; Cambiazo, Verónica; Gonzalez, Mauricio
    Background Soil microorganisms are in constant interaction with plants, and these interactions shape the composition of soil bacterial communities by modifying their environment. However, little is known about the relationship between microorganisms and native plants present in extreme environments that are not affected by human intervention. Using high-throughput sequencing in combination with random forest and co-occurrence network analyses, we compared soil bacterial communities inhabiting the rhizosphere surrounding soil (RSS) and the corresponding bulk soil (BS) of 21 native plant species organized into three vegetation belts along the altitudinal gradient (2400–4500 m a.s.l.) of the Talabre–Lejía transect (TLT) in the slopes of the Andes in the Atacama Desert. We assessed how each plant community influenced the taxa, potential functions, and ecological interactions of the soil bacterial communities in this extreme natural ecosystem. We tested the ability of the stress gradient hypothesis, which predicts that positive species interactions become increasingly important as stressful conditions increase, to explain the interactions among members of TLT soil microbial communities. Results Our comparison of RSS and BS compartments along the TLT provided evidence of plant-specific microbial community composition in the RSS and showed that bacterial communities modify their ecological interactions, in particular, their positive:negative connection ratios in the presence of plant roots at each vegetation belt. We also identified the taxa driving the transition of the BS to the RSS, which appear to be indicators of key host-microbial relationships in the rhizosphere of plants in response to different abiotic conditions. Finally, the potential functions of the bacterial communities also diverge between the BS and the RSS compartments, particularly in the extreme and harshest belts of the TLT. Conclusions In this study, we identified taxa of bacterial communities that establish species-specific relationships with native plants and showed that over a gradient of changing abiotic conditions, these relationships may also be plant community specific. These findings also reveal that the interactions among members of the soil microbial communities do not support the stress gradient hypothesis. However, through the RSS compartment, each plant community appears to moderate the abiotic stress gradient and increase the efficiency of the soil microbial community, suggesting that positive interactions may be context dependent.