A quarter of century has passed since the fluid mosaic model was proposed by Singer and Nicolson. The model has exerted a strong influence on studies in biological sciences. New techniques introduced into biological research, e.g. X-ray diffraction, spin label, differential scanning calorimetry and freezefractured electron microscopy, have contributed to the model.

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Transmembrane ion channels regulate ion movoment across cellular membranes. Primary structures of many ion channels have been deduced from the gene cloning technique. These ion channels were classified from the similarity of amino acid sequences. In this review, at first, general aspect of these ion channels are summarized. In the second part, gating and ion selective mechanisms of nicotinic acetylcholine receptor channels were discussed.

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Since the first application of X-ray diffraction study for the structure determination of bacterial photosynthetic reaction center, it has turned out that the technique can be utilized for high-resolution structural analysis of various types of membrane protein. Cryo-electron microscopy has also contributed to the structural studies on membrane proteins which rarely assembled into three-dimensional crystal. A number of remarkable findings obtained by these techniques are summarized. Some interesting topics for the future researches are also pointed out, including expected application of another technique such as atomic force microscopy (AFM).

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Recent progresses on membrane protein dynamics and their functions are discussed. Electron transfer interactions have been analyzed by measuring rotational diffusion of cytochrome P450scc and reductases in adrenocortical mitochondria. Intracellular signal transduction in adrenocortical cells has been demonstrated by measuring the hormone-induced calcium oscillations and incorporation of low density lipoprotein using video-enhanced microscopy and laser scanning confocal microscopy. These investigations contributed significantly to the understanding of molecular mechanisms of steroidogenesis in adrenal cortex. Analysis of dynamic topology is also discussed for rat liver type cytochrome P450IA1 genetically expressed in yeast microsomes.

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The video-enhanced contrast DIC microscopy is very useful for observation of dynamic activities of intracellular organelles. Exocytosis of secretory granules, transport and trafficking of vesicles, endocytosis of nerve terminals, phagocytosis and lysosome-phagosome fusion of neutrophils, agonist-induced activation of nuclei, division of mitochondria were observed by this technique. A quantitative aspect and a dynamic rate of each response were described. Some images of nuclei, mitochondria, photoreceptor cells, as well as artificial membranes made of geranylgeraniol phosphates were also illustrated. The resolution achieved in this imaging were superior to most other light microscopies reported to date.

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Using network thermodynamics, I showed the applicability of bond graphs to the power coupling phenomena which include thermal conduction, thermo-osmotic and thermoelectric phenomena.

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Network thermodynamics provides a tool of analysis and synthesis of an open dynamic system. On an open dynamic system, processes of energy and entropy, that is, their transports and their changing rates are considered. The first law of thermodynamics can be expressed by a balance between the energy storage and the net energy transport. The second law of thermodynamics can be expressed by a balance between the entropy storage and sum of the entropy production and the net entropy transport. Both balance relations of energy and entropy can be unified when we define an availability function. Using the availability function and assuming local equilibrium, the thermodynamic basis for network thermodynamics is discussed.

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Cyclodextrin is produced with utilizing reverse osimosis to concentrate reaction mixture and ultra filtration to remove turbid materials. In production of 4^G-β-D-galactosylsucrose (“Nyuka-oligosaccharide”), is indigestive and bifidobacterium growing factor, ultra filtration is also utilized to remove turbid materials.

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