Increase of available soil silicon by Si-rich manure for sustainable rice production

International audienceDepletion of bioavailable silicon, Si, in paddy soils can decrease the yields of rice. A potential solution is to amend soil with Si-rich organic wastes such as manure from animals fed with rice crop residues. Here, we studied Si in soils from 2000 to 2010 field experiments without manure, with 5 and 10 years of manure, in Eastern China. Results showed that available Si in soils increased from 130 to 270 mg kg−1 after 10 years of manure amendment. This finding is explained either by direct input of available Si or by Si produced by mineralization of Si minerals. To conclude, our results show that amending soil with Si-rich manure in the long term is a solution for sustainable rice production

Reduced gliotransmitter release from astrocytes mediates tau-induced synaptic dysfunction in cultured hippocampal neurons

Tau is a microtubule-associated protein exerting several physiological functions in neurons. In Alzheimer\u2019s disease (AD) misfolded tau accumulates intraneuronally and leads to axonal degeneration. However, tau has also been found in the extracellular medium. Recent studies indicated that extracellular tau uploaded from neurons causes synaptic dysfunction and contributes to tau pathology propagation. Here we report novel evidence that extracellular tau oligomers are abundantly and rapidly accumulated in astrocytes where they disrupt intracellular Ca2+ signaling and Ca2+-dependent release of gliotransmitters, especially ATP. Consequently, synaptic vesicle release, the expression of pre- and post-synaptic proteins, and mEPSC frequency and amplitude were reduced in neighboring neurons. Notably, we found that tau uploading from astrocytes required the amyloid precursor protein, APP. Collectively, our findings suggests that astrocytes play a critical role in the synaptotoxic effects of tau via reduced gliotransmitter availability, and that astrocytes are major determinants of tau pathology in AD