Single Molecule Observations of DNA Hybridization Kinetics

Abstract

Ca 2þ sparklets are local elevations in intracellular Ca 2þ produced by the opening of a single or a small cluster of sarcolemmal L-type Cav1.2 Ca 2þ channels. At present, however, the spatial organization and mechanisms of modulation of Ca 2þ sparklets in cardiac myocytes is unknown. Here, we tested the hypothesis that Ca 2þ sparklets activity varies within the sarcolemma of neonatal cardiac myocytes and that chemically-induced translocation of PKCa increases the Ca 2þ sparklet activity in these cells. Consistent with this hypothesis we found that application of the PKC activator phorbol 12,13-dibutyrate (PDBu; 500 nM) increased Ca 2þ sparklet activity in neonatal cardiac myocytes. Analysis of the spatial distribution Ca 2þ sparklet activity was not random (i.e. did not have a Poisson distribution). Rather, as in reported in smooth muscle cells, Ca 2þ sparklet activity was higher at specific regions of the cell. Translocation of PKCa to the sarcolemma of neonatal cardiac myocytes resulted in an increase in Ca 2þ sparklet activity in specific regions of the cell. Data will be presented on the relationship between Ca 2þ sparklet activity and Ca 2þ release from the sarcoplasmic reticulum via ryanodine receptors (i.e. Ca 2þ sparks) during excitation-contraction coupling. Our data suggest that Ca 2þ sparklet (i.e. L-type Ca 2þ channels) activity varies within the sarcolemma of neonatal cardiac myocytes and that they are modulated by PKCa, potentially regulating SR Ca 2þ release during EC coupling in heart.

Statistical predictions on the encapsulation of single molecule binding pairs into sized-dispersed nanocontainers

“…2,8,31 However, an important application of single molecule encapsulation is the confinement of two types of molecules that can bind to each other. 2,31,[35][36][37][38] In such a case, the simple calculation above does not account for the effect of the binding constant in bulk solution, which is important to determine the probability that the molecular binding pair will be encapsulated together. There appears to be no statistical treatment of this situation, and no description of the effect that the size distribution of the container may have.…”