Research works on the self-organization phenomena in chemical systems are reviewed with particular emphasis on their response to the photo-irradiation, for which most of the works have been performed in the author’s laboratory. In the present review, a brief survey is given for the recent developments of research on the self-organization phenomena observed in dark. Then, the determination of action spectra for the photo-irradiated self-organizing chemical systems is described with a few examples, together with a discussion on the advantages of employing the irradiated light intensity as a control parameter. Experimental results for the chemical systems under the stationary and pulse light irradiation are summarized and discussed for the redox oscillators including the Belousov-Zhabotinsky and the Briggs-Rauscher systems and their variations. Discussions are also given for various types of pH oscillators under photo-irradiation. Finally, experimental observations on chaos and multistability, the most characteristic features in the field of self-organizing chemical systems, are surveyed and discussed. Possibility of the photo-control of chaos and multistability is discussed with examples of the Briggs-Rauscher system and of the pH oscillator system, H2O2-SO32--Fe(CN)64--HCO3-.
(Communicated by Saburo NAGAKURA, M. J. A., Nov. 12, 2003)
We have developed a new sapphire-anvil cell to generate shear stress at high pressures. The new cell is similar to a diamond-anvil cell. Bis(diphenylglyoximato)metal(II), M(dpg)2(M = Ni and Pt) are pressure-sensitive one-dimensional metal complexes. By use of this cell we have observed in situ the shear stress effect on a thin film of M(dpg)2 under the microscope. Furthermore, electronic absorption spectra of both complexes have been simultaneously measured under applied shear deformation and non-hydrostatic conditions. When the pressure is increased, the color of a thin film of Pt(dpg)2 turns from red-brown at ambient pressure to green at 0.4 GPa. One sapphire anvil is rotated by applied force in order to generate the shear stress at 0.4 GPa. The color of the thin film changes remarkably from green to yellow at the outer part on the anvil, but the color at the center is green, insensitive to the shear stress. The region changed by the shear stress can be observed with the naked eye. Absorption spectra of the yellow region at the outer part change markedly; the intensity of the d-p band decreases sharply and this peak abruptly shifts to the near-infrared region. On the other hand, electronic spectra at the center part are insensitive to the shear deformation. The similar shear stress effect on the optical spectrum of Ni(dpg)2 is also observed. We have found that electronic states of M(dpg)2 essentially change by applying shear deformation.
(Contributed by Hiroo INOKUCHI, M. J. A., Nov. 12, 2003)
Feast/famine regulatory proteins (FFRPs) include a diverse family of transcription factors of archaea and eubacteria. The best characterized among FFRPs is E. coli Lrp (the leucine-responsive regulatory protein). A full length FFRP is composed of an N-terminal DNA-binding domain and a C-terminal assembly domain. The C-domain is involved in formation of a dimer, and higher structures (e.g. a disk composed of 4 dimers, a chromatin-like cylinder) are further assembled. A pair of DNA-binding domains in an FFRP dimer bind the DNA site NANBNCNDNETTTNENDNCNBNA, where NA and NA, e.g., are bases complementary to each other, and NE is either A or T. Such 13 bp sequences repeat with insertions of 7-8 or ∼18 basepairs in promoters regulated by FFRPs. Ligands of the size of amino acids (e.g. leucine, asparagine) signal metabolic or environmental changes directly to FFRPs by binding at the interface formed between dimers. This interaction alters the assembly form, and thus the overall DNA-binding specificity. In this way, Lrp regulates a large number of genes differently in E. coli. In Pyrococcus sp. OT3, 14 FFRPs possibly regulate many of the ∼1, 500 genes coded. It is widely believed that the common ancestor of all organisms first differentiated to archaea and eubacteria. Thus, global (i.e. genome wide) regulation by FFRPs can be the prototype of highly differentiated transcription regulatory systems found in organisms nowadays.
(Communicated by Masanori OTSUKA, M. J. A., Nov. 12, 2003)
Spores of bacteria Bacillus subtilis were examined for their potential for storing cloned genes in the dry state at ambient temperature for long years. A model plasmid used in this study is pTE22, which is 8.7 Kb in size and carries test Escherichia coli plasmid pBR322 in a backbone B. subtilis plasmid pHW1. After 14.8 years of storage of spores containing pTE22, plasmids recovered from the germinated spores maintained the antibiotics resistance and intact size of the restriction fragments.
(Communicated by Takashi SUGIMURA, M. J. A., Sept. 12, 2003)