Confocal laser scanning microscopy has played an essential role in cell biology and immunology by allowing visualization of specific intracellular signaling molecules. Especially green fluorescent protein (GFP) fusion technology has enabled us to visualize essentially any protein in living cells. Here we describe the recent progress in study of nuclear signaling, degranulation, and the communication to nerve using GFP chimera proteins in mast cells. GFP chimera proteins give us a lot of useful information for studying molecular mechanisms in mast cell activation.
One of the most useful method of understanding physicochemical properties of biopolymers as a thread of life is to pull and stretch them out. In this article, the method of manipulation of biopolymers by an elongational flow field was presented. As an elongational flow field generator, an opposed jets and a four roller mill apparatuses were shown. An ability of the elongational flow field of stretching flexible polymers was demonstrated by showing the elongational behavior of DNA molecules interacting with DNA binding protein HU. Orientation of monodisperse collagen molecules was shown as a model of rigid rod-like polymer orientation in the elongational flow field.
One of the interactions between macromolecules is the attractive force through the excluded volume effect. We studied the attraction between the molecules of muscle protein, actin, from the following two points by using the extended scaled particle theory (XSPT). I) we verified the basic assumption used in the XSPT that topological elements which determine the analytical expression of the excluded volume are almost unchanged through the scaling down of the solute molecule in the thought experiment. Results of the computational geometry method (α-shape method) showed that this assumption is valid even in the case of the actin molecule. II) we calculated the attraction between actin monomer molecules, G-actin. Calculated differences of the values of the attraction potential of two macromolecules between at contact and at one macromolecule apart by the XSPT is almost the same as those by the Asakura-Oosawa theory.
The nucleus in eukaryotic cells is an important organelle to maintain, replicate and express genetic information on DNA. While little is known about the basis underlying the relationship between the structure and function in nuclei, recent studies on molecular kinetics in living cells have shown that most macromolecules, like proteins and RNAs, diffuse freely in the crowded soup, suggesting that the recruitment of transcription/repair factors is stochastic by random collision of diffusible molecules to relatively static chromatin. Nuclear substructures like nuclear 'speckle's are also built as steady-state structures by rapid association and dissociation of their components.