Multiple Site Optical Recording of Transmembrane Voltage (MSORTV) has been used to measure, continuously and simultaneously, the spontaneous electrical activity from all of the neurons in individual ganglia or up to five interconnected ganglia of the submucous plexus of the guinea pig small intestine. These are the first optical recordings of electrical activity with single-cell resolution from a mammalian nervous system. They are used to investigate the effects of acute and chronic application of nicotine on the firing patterns of this neural network containing important cholinergic components. After washout of acutely applied nicotine, the firing rates of selected neurons were dramatically elevated. These results suggest that nAChRs that reversibly desensitize after exposure to nicotine may be responsible for the enhancement of activity that is observed after a brief application of this agonist. In addition, immunostaining with monoclonal antibodies was used to localize alpha3/alpha5, alpha7, and beta2 nAChR subunits, and the results demonstrate the prevalence of alpha3/alpha5. It is this alpha3-containing nAChR subtype that probably accounts for most of the excess activity elicited by nicotine application.
In order to enable the future construction of molecular devices made of functional proteins, we have developed a technique for microimmobilization of proteins into organized patterns on a silicon wafer. A specific binding reaction between streptavidin and biotin forms the basis of our method. Active and inactive biotin regions were created on a silicon wafer using a photolithographic technique. Circuit-type patterns and 0.75/1.5 µm line-and-space patterns of a model fluorescent protein, B-phycoerythrin, were successfully created on a silicon wafer.
We construct a kink solution on a non-BPS D-brane using Berkovits' formulation of superstring field theory in the level truncation scheme. The tension of the kink reproduces 95% of the expected BPS D-brane tension. We also find a lump-like solution which is interpreted as a kink-antikink pair, and investigate some of its properties. These results may be considered as successful tests of Berkovits' superstring field theory combined with the modified level truncation scheme.
A DOPH-Millipore membrane shows electric self-sustained oscillations with periods of a few seconds under salt-concentration gradient, electric current and pressure difference. We have found that the oscillations with periods of a few seconds are induced by the addition of acid without the electric current and the pressure difference.
The electric resistance of phospholipid-mixed DOPH-Millipore membranes changed more rapidly according to the change of salt concentration than a DOPH-Millipore membrane. It was suggested that the phase transition of lipid molecules from multilayer leaflets to micelles or oil droplets occurs more rapidly in these membranes.
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