Colonies of bacteria grown on agar plates can display morphological patterns of surprising varieties depending on culture conditions. For instance, B. subtilis shows a dense-branching morphology on a nutrient-poor semi-solid agar medium, while some chemotactic strains of E. coli form a spot pattern on a pseudo-hexagonal lattice. Based on such experimental data, diffusion-reaction models that incorporate cell movements and interactions between bacterial cells and chemical substances have been constructed, and used to explain how the observed patterns are generated.
The energy thresholds of the sensory cell of the cricket wind receptor were determined to be the thermal noise level kBT (4×10-21J at 300K). The determination was based on a laser-Doppler velocimetry of the receptor hair and the Stokes’ theory for viscous force. The mechanoreceptor exhibits fluctuations in spike timing to near-threshold stimuli. Simultaneous double recordings revealed independency of the fluctuations between cells. The cells employ the internal thermal noise as the seed of stochastic sampling. The thermal noise paradoxically enhances the detection of weak signal below the threshold.
We demonstrate that structural data on the protein-DNA complex can be used to predict DNA target sequences for regulatory proteins, and to quantitatively estimate the relationship between the structure and specificity in protein-DNA interactions.
A novel method has been developed in order to determine both structure and dynamics of proteins using a molecular simulation and experimental data. This is based on the concept of the Jumping-Among-Minima model. In this method, inter-substate fluctuations are determined by molecular simulation and inter-substate motions are determined so as to reproduce experimental data. Slow dynamics of proteins and its relation to protein functions are discussed.
We found that a type of bent DNA appears periodically in the genomic DNA of higher eukaryotes and mapped their positions in a total of 93kb regions. Based on the structural characteristics and the relationship to nucleosome phases, this periodic bent DNA appears once in four nucleosomes on average and determines the phases first at these positions and then at the neighboring positions, thereby eventually aligning all nucleosomes on the genomic DNA.
With less than 105 neurones, and subject to powerful genetic techniques, the fruit fly Drosophila melanogaster is a good model system for drawing a circuit diagram or the whole brain. The GAL4 enhancer-trap strains label specific subsets of brain cells according to their gene expression pattern. The FRT-GAL4 system labels neurones according to their cell lineage. The three dimensional fibre structures of the cells labelled with these techniques can be visualised using various reporters such as Tau and GFP A comprehensive catalogue of neurones, and the neural circuits they form, are being compiled by the large-scale screening of the labelled cells.
Historical works addressed to elucidating roles of water on a gating process of voltage-gated ion channels were critically reviewed. My recent works on squid sodium channels showed a unified interpretation about these preceding works, i.e. viscosity or osmolarity models. A water-nonelectrolytes mixture solvent affects a voltage-dependent process accompanying gating currents viscosity-dependently and a final step to open osmolarity-dependently. In the latter step, a transient hydration of around 5 water molecules in the pore was essential.