Digitized fluorescence microscopes have advantages in studies of biological membrane fusion. Human red blood cell membranes labelled with specific fluorescence probes were fused with MDCK cell membranes by influenza virus hemagglutinin, Single events of fusion were observed by the microscopes and redistribution of fluorescence after fusion was analyzed. Usage of several kinds of fluorescence labels, including a membrane lipid probe, a water-soluble probe, and probes specific for membrane proteins, provided an overall understanding of membrane fusion.
Many types of central nervous system neurons generate action potentials not only at their soma and axons but also at the dendrites. It has been a matter of dispute where in the dendrites do dendritic spikes fire. This question was studied by optically monitoring transient Ca/Na changes from single neurons in brain slice preparations. It has been shown 1) that cerebellar Purkinje neurons fire Ca spikes all over the dendritic field; 2) that cerebellar Purkinje neurons fire Na spikes at the soma and the initial segment; 3) that hippocampal CA1 pyramidal neurons fire Na spikes at proximal 2/3 of the apical dendrites; 4) that hippocampal CA1 pyramidal neurons have voltage-gated Ca channels all over the dendrites; and 5) that most Ca rise at dendrites in cerabellar Pukinje neurons and hippocampal CA1 pyramidal neurons are related to dendritic spikes.
Department of Anatomy and Physiology, University of Dundee Peter J. Stoward Many enzymes diffuse out of sections of unfixed tissue when they are incubated in conventional aqueous media. This invalidates their quantitative assay by microdensitometry. The quantitative effectiveness of three methods for overcoming this problem are reviewed. The methods utilise semipermeable membranes, polyvinyl alcohol-containing media, and agarose gel films. Unfortunately, most applications of these techniques reported to date have given data that do not meet criteria of validity. A new approach based on the gel film technique for the kinetic analysis of a soluble enzyme in situ by computer-assisted image analysis is described in detail.
Room-temperature phosphorescence (RTPP) from two proteins (LADH, E. coli AP) was first detected by Saviotti and Galley in 1974. Kai and Imakubo (1978) found additional proteins; RNase T1, aldolase and trypsin. Nowadays, it is recognized that more proteins exhibit the emission. In this article, characteristics of RTPP and various processes related to the appearance of RTPP are discussed, and its applications to reserch of protein dynamics are described.
A brief account is made for applications of a high-resolution solid-state NMR spectroscopy to reveal the three-dimensional structure of a variety of membrane proteins, proteins of higher molecular weight and their complexes, with emphasis on introduction of new experimental techniques. Some illustrative examples were also demonstrated to this end.
Particular interest of long term potentiation (LTP) is whether LTP is expressed in a pre-or postsynaptic site. The quantal analysis shows that there are three types of LTP, that is, presynaptic type, postsynaptic type, and the type which involves changes in both sites. On the other hand, it has been shown that several different receptors participate in induction of LTP, including voltage dependent Ca++ channel as well as NMDA receptor. These recent studies suggest that there are wide synaptic heterogeneity concerning LTP induction and expression.