Efficient removal of nano- and micro- sized plastics using a starch-based coagulant in conjunction with polysilicic acid.

Microplastic (MP) pollution has increasingly become an enormous global challenge due to the ubiquity and uncertain environmental performance, especially for nano- and micro- sized MPs. In this work, the performance and mechanisms in coagulation of 100 nm-5.0 µm sized polystyrene particles using an etherified starch-based coagulant (St-CTA) assisted by polysilicic acid (PSA) were systematically studied on the basis of the changes in MPs removal rates under various pH levels and in the presence of different coexisting inorganic and organic substances, zeta potentials of supernatants, and floc properties. St-CTA in conjunction with PSA had a high performance in coagulation of nano- and micro- sized MPs from water with a lower optimal dose and larger and compacter flocs. Besides, the MPs removal rate can be improved in acidic and coexisting salt conditions. The efficient performance in removal of MPs by this enhanced coagulation was owing to the synergic effect, that is, the effective aggregation of MPs through the charge neutralization of St-CTA followed by the efficient netting-bridging effect of PSA. The effectiveness of this enhanced coagulation was further confirmed by removal of two other typical nano-sized MPs, such as poly(methyl methacrylate) and poly(vinyl chloride), from different water sources including tap water, river water, and sludge supernatant from a sewage treatment plant. This work provided a novel enhanced coagulation technique that can effectively remove nano- and micro- sized MPs from water.

Acetylation of calmodulin regulates synaptic plasticity and fear learning.

Synaptic plasticity is critical for brain function, including learning and memory. It is regulated by gene transcription and protein synthesis as well as posttranslational modifications at synapses. Although protein acetylation has been shown to be involved in the regulation of synaptic plasticity, this was mainly for histone protein acetylation. To investigate whether acetylation of nonhistone proteins is important for synaptic plasticity, we analyzed mouse brain acetylome and found that calmodulin (CaM), a ubiquitous Ca2+ sensor, was acetylated on three lysine residues, which were conserved across species. NMDA receptor-dependent long-term potentiation (LTP) is considered the most compelling form of synaptic plasticity. During LTP induction, activation of NMDA receptor triggers Ca2+ influx, and the Ca2+ binds with CaM and activates calcium/calmodulin-dependent protein kinase IIα (CaMKIIα), which is essential for LTP induction. By using home-generated and site-specific antibodies against acetylated CaM, we show that CaM acetylation is upregulated by neural activities in an NMDA receptor-dependent manner. Moreover, mutation of acetyllysines in CaM1 proteins disrupts synaptic plasticity and fear learning in a mouse model. We further demonstrate that acetylation of CaM reduces the binding free energy and increases the binding affinity toward CaMKIIα, a protein kinase pivotal to synaptic plasticity and learning. Taken together, our results demonstrate importance of CaM acetylation in regulating synaptic plasticity and learning.