Search

Surface-patterned platinum microelectrodes insulated with 300 nm thick fused silica were fabricated using contact photolithography. These electrodes exhibit low noise and were used for monitoring single vesicle exocytosis from chromaffin cells by constant potential amperometry as well as fast-scan cyclic voltammetry. Amperometric spike parameters were consistent with those obtained with conventional carbon fiber electrodes. Catecholamine voltammograms acquired with platinum electrodes exhibited redox peaks with full width at half-maximum of ~45 mV, much sharper than those of carbon fiber electrode recordings. The time course of voltammetrically measured release events was similar for platinum and carbon fiber electrodes. The fused-silica-insulated platinum electrodes could be cleaned and reused repetitively and allowed incorporation of micrometer precision surface-patterned poly-D-lysine. Poly-D-lysine-functionalized devices were applied to stimulate mast cells and record single release events without serotonin preloading. Microfabricated platinum electrodes are thus able to record single exocytotic events with high resolution and should be suitable for highly parallel electrode arrays allowing simultaneous measurements of single events from multiple cells. 10.1021/ac900674g

Synapsin proteins are implicated in synaptic maintenance and in vesicle supply for exocytosis. Synapsin I has been observed to bind and be regulated by calmodulin. It is now shown that a representative of synapsin II binds calmodulin. Calmodulin binding by synapsins is not confined to mammals and it is concluded that calmodulin binding to synapsins could be a general aspect of synaptic function regulation.

The mouse sperm surface galactosyltransferase acts as a receptor for the zona pellucida, acellular coat that surrounds the egg during fertilization. The galactosyltransferase does not help in signal transduction events resulting in acrosomal exocytosis. The mouse zona pelludica consists of ZP1, ZP2 and ZP3 glycoproteins. The ZP3 serves as the adhesion ligand for the sperm that initiates acrosome reaction.