Parvovirus capsid disorders cholesterol-rich membranes.

In this study canine parvovirus, CPV, was found to induce disorder in DPPC:cholesterol membranes in acidic conditions. This acidicity-induced fluidizing effect is suggested to originate from the N-terminus of the viral capsid protein VP1. In accordance with the model membrane studies, a fluidizing effect was seen also in the endosomal membranes during CPV infection implying an important functional role of the fluidization in the endocytic entry of the virus.

Properties and roles of BKCa channels in cultured cerebellar granule neuron: Experimental and simulation studies

We studied the properties and roles of large-conductance calcium-sensitive potassium channels (BK"C"a) in cultured rat cerebellar granule neurons. In intact cells these channels had chord conductances of 130-200pS. The conductance, threshold for channel activation and the mean open time and open probability depend on the age of cells. In computer simulations the elimination of BK"C"a channel decreases the maximum and minimum peak values of an action potential, causes reduced hyperpolarization and increases firing frequency. The observed alterations may be linked to the complexity of granule neuron excitability during maturation and provide new insight into modeling the developmental changes…

A model integrating the cerebellar granule neuron excitability and calcium signaling pathways

Abstract The activation of various intracellular biochemical pathways is influenced by the electroresponsiveness of the neuron. There exists a close and constant co-operation between the membrane-bound cellular functions and intracellular signaling. This work aims at integrating the biophysical and biochemical data available for the cultured cerebellar granule neuron. The models of calcium-protein kinase C signaling pathways are combined with the model of the granule neuron excitability. The latter model can be used to provide the realistic stimulus for the signaling pathway models. The integrated model makes it possible to explore the participation of intracellular mechanisms in the neuron…

Simulations of the cultured granule neuron excitability

Abstract We have developed a biophysical model of a cultured rat cerebellar granule neuron and simulated its excitability under different experimental conditions. The basic excitability properties of such a small neuron; the specific action potential waveforms, the overall firing patterns induced by current stimulations, and the linear frequency-current relation, are the main model constraints. Simulations show that for a one-compartmental granule neuron model, the constraints are met using six voltage- and time-dependent ion channel types and calcium dynamics linked to BK Ca ion channel function. This kind of model of a single neuron forms a solid basis for building the increasingly more c…

Quantification of vesicles in differentiating human SH-SY5Y neuroblastoma cells by automated image analysis

A new automated image analysis method for quantification of fluorescent dots is presented. This method facilitates counting the number of fluorescent puncta in specific locations of individual cells and also enables estimation of the number of cells by detecting the labeled nuclei. The method is here used for counting the AM1-43 labeled fluorescent puncta in human SH-SY5Y neuroblastoma cells induced to differentiate with all-trans retinoic acid (RA), and further stimulated with high potassium (K+) containing solution. The automated quantification results correlate well with the results obtained manually through visual inspection. The manual method has the disadvantage of being slow, labor-i…

Endosomal escape of canine parvovirus is assisted by membrane fluidization