The goal of this study was to investigate how plant selenium (Se) hyperaccumulation may affect ecological interactions and whether associated partners may affect Se hyperaccumulation. The Se ...hyperaccumulator Astragalus bisulcatus was collected in its natural seleniferous habitat, and x-ray fluorescence mapping and x-ray absorption near-edge structure spectroscopy were used to characterize Se distribution and speciation in all organs as well as in encountered microbial symbionts and herbivores. Se was present at high levels (704-4,661 mg kg(-1) dry weight) in all organs, mainly as organic C-Se-C compounds (i.e. Se bonded to two carbon atoms, e.g. methylselenocysteine). In nodule, root, and stem, up to 34% of Se was found as elemental Se, which was potentially due to microbial activity. In addition to a nitrogen-fixing symbiont, the plants harbored an endophytic fungus that produced elemental Se. Furthermore, two Se-resistant herbivorous moths were discovered on A. bisulcatus, one of which was parasitized by a wasp. Adult moths, larvae, and wasps all accumulated predominantly C-Se-C compounds. In conclusion, hyperaccumulators live in association with a variety of Se-resistant ecological partners. Among these partners, microbial endosymbionts may affect Se speciation in hyperaccumulators. Hyperaccumulators have been shown earlier to negatively affect Se-sensitive ecological partners while apparently offering a niche for Se-resistant partners. Through their positive and negative effects on different ecological partners, hyperaccumulators may influence species composition and Se cycling in seleniferous ecosystems.
IS DEEP-SEA MINING WORTH IT? Peacock, Thomas; Alford, Matthew H
Scientific American,
05/2018, Letnik:
318, Številka:
5
Magazine Article
In September 2017 the Japan Oil, Gas and Metals National Corporation conducted one of the first large commercial trials. A prototype excavator gathered tons of zinc and other metals from deposits ...1,600 meters deep near Okinawa, inside Japan's exclusive economic zone (EEZ)-its national waters. Small island nations and regions, such as Tonga and Cook Islands, which have limited resources to build such an industry themselves, are discussing whether to offer mining rights inside their EEZs to outside investors. And the International Seabed Authority (ISA), which regulates commercial activity in international waters, has issued 28 exploration permits to institutions from 20 countries to sample sea- floor minerals.
The synthesis of the fused tetracyclic pyrroloquinolones
9a–
i in four steps is described. The PDE5 inhibitory activities of these compounds, their selectivities against PDE1, PDE2, PDE3, PDE4 and ...PDE6, the preclinical pharmacokinetic assessments and the in vivo efficacy in increasing intracavernosal pressure are presented and discussed.
Synthesis of pyrroloquinolones
9a–
9i and their biological activities towards PDE5 were described.
Alzheimer's disease (AD) is characterized by progressive decline in memory and other cognitive domains, accompanied by early loss of presynaptic terminals, amyloid-bearing neuritic plaques and ...neurofibrillary tangles containing hyperphosphorylated tau. The mechanisms leading to neurodegeneration are not completely understood, however, recent evidence suggests that alterations in p59Fyn kinase, an Src family tyrosine kinase, might contribute to AD pathogenesis. In this context, the main objective of the present study was to investigate the relationship between Fyn protein levels and the neurological and neuropathological alterations in AD. We found, by quantitative immunoblotting, that in AD, Fyn levels were increased in the insoluble fraction and decreased in the soluble fraction. Soluble Fyn levels were directly correlated with the cognitive scores and levels of synaptophysin immunoreactivity, and inversely correlated with neurofibrillary tangle counts in the frontal cortex. Consistent with these findings, the immunocytochemical analysis showed that in AD cases, Fyn levels were decreased in the synapses and increased in the neuronal cell bodies where it was colocalized with neurofibrillary tangles. Taken together, these findings suggest that alterations in Fyn localization might be associated with neurofibrillary pathology and synapse loss in AD.
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