E-Syt1 Regulates Neuronal Activity-Dependent Endoplasmic Reticulum-Plasma Membrane Junctions and Surface Expression of AMPA Receptors.

Endoplasmic reticulum (ER)-plasma membrane (PM) contact sites/junctions play important roles in cell physiology including signal transduction, ion and lipid transfer, and membrane dynamics. However, little is known about the dynamic regulation and functional roles of ER-PM junctions in neurons. Using a split green fluorescent protein-based membrane contact probe, we find that the density of ER-PM contact sites changes dynamically in the dendrites of hippocampal neurons undergoing long-term synaptic potentiation (LTP). We show that the Ca2±-sensing membrane tethering protein Extended Synaptotagmin 1 (E-Syt1) mediates the formation of ER-PM contact sites during LTP. We also show that E-Syt1 is required for neuronal activity-dependent surface expression of the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid-type glutamate receptors. These findings implicate ER-PM junctions in the regulation of neurotransmitter receptor trafficking and synaptic plasticity.

Comprehensive analysis of the lysine acetylome in Aeromonas hydrophila reveals cross-talk between lysine acetylation and succinylation in LuxS.

Lysine acetylation and succinylation are both prevalent protein post-translational modifications (PTMs) in bacteria species, whereas the effect of the cross-talk between both PTMs on bacterial biological function remains largely unknown. Our previously study found lysine succinylated sites on proteins play important role on metabolic pathways in fish pathogenic Aeromonas hydrophila. A total of 3189 lysine-acetylation sites were further identified on 1013 proteins of this pathogen using LC-MS/MS in this study. Functional examination of these PTMs peptides showed associations with basal biological processes, especially metabolic pathways. Additionally, when comparing the obtained lysine acetylome to a previously obtained lysine succinylome, 1198 sites in a total of 547 proteins were found to be in common and associated with various metabolic pathways. As the autoinducer-2 (AI-2) synthase involved in quorum sensing of bacteria, the site-directed mutagenesis of LuxS at the K165 site was performed and revealed that the cross-talk between lysine acetylation and succinylation exerts an inverse influence on bacterial quorum sensing and on LuxS enzymatic activity. In summary, this study provides an in-depth A. hydrophila lysine acetylome profile and for the first time reveals the role of cross-talk between lysine acetylation and succinylation, and its potential impact on bacterial physiological functions.

Controlled synthesis of Au-loaded Fe3O4@C composite microspheres with superior SERS detection and catalytic degradation abilities for organic dyes.

Bifunctional Au-loaded Fe3O4@C composite microspheres were controllably synthesized by coating of Au nanoparticles (NPs) on the surface of the poly(diallyldimethylammonium chloride) (PDDA) functionalized Fe3O4@C microspheres. The amount of Au loading can be effectively tuned by altering the feeding amounts of solution Au NPs or further growth. The obtained Au-loaded Fe3O4@C composite microspheres exhibit both superior surface-enhanced Raman scattering (SERS) sensitivity and catalytic degradation activity for organic dyes. The SERS signal intensity of methylene blue (MB) distinctly enhances with the increase of Au loading, which endows increased Raman 'hot spots' and provides a significant enhancement of the Raman signal through electromagnetic (EM) field enhancements. Furthermore, the catalytic experiments of the Fe3O4@C@Au composite microspheres with the highest Au loading demonstrate that the model organic dye of MB molecules could be degraded within 10 min and the catalytic activity could be recovered without sharp activity loss in six runs, which indicates their superior catalytic degradation activity. The reason could be mainly ascribed to the synergistic effects of small size of Au NPs, the good adsorption behavior of carbon layers and the excellent dispersivity of the composite microspheres induced by the sandwiched carbon layers. The results indicate that the bifunctional Au-loaded Fe3O4@C composite microspheres could be served as promising materials in wastewater treatment.

Influence of floc size and structure on membrane fouling in coagulation-ultrafiltration hybrid process--the role of Al13 species.

Coagulation application prior to ultrafiltration process was carried out to increase humic acid (HA) removal and membrane permeability. The [Al(13)O(4)(OH)(24)(H(2)O)(12)](7+) polycation (Al(13) species) was used in the coagulant process and polyaluminum chloride (PACl) was also used for comparison. Characteristics of aggregates pre-coagulated by Al(13) species and PACl were investigated using a laser diffraction particle sizing device. Additionally, membrane fouling was investigated under different coagulation conditions. The various resistances caused by Al(13) and PACl treatment effluents were determined using the membrane fouling index equation. The results indicated that at dose of 1 and 3mg/L, Al(13) produced larger flocs than PACl; while when dosage further increased, the PACl-HA flocs were much larger. The flocs formed by Al(13) were strong and compact, and those formed by PACl were weak and loosely structured with the exception of the flocs generated at 1mg/L. The investigation of membrane fouling demonstrated that Al(13) contributed to the best effluent permeating at 5mg/L and the corresponding dose for PACl was 7 mg/L. The adsorption resistance of effluent pre-treated by Al(13) accounted for a smaller percentage of the total resistances compared with that by PACl.