Seibutsu Butsuri
Online ISSN : 1347-4219
Print ISSN : 0582-4052
ISSN-L : 0582-4052
Volume 40, Issue 3
Issue 229
Displaying 1-12 of 12 articles from this issue
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  • Nanako SHIGESADA, Kohkichi KAWASAKI
    2000 Volume 40 Issue 3 Pages 151-155
    Published: 2000
    Released on J-STAGE: April 26, 2001
    JOURNAL FREE ACCESS
    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.
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  • Tateo SHIMOZAWA
    2000 Volume 40 Issue 3 Pages 156-161
    Published: 2000
    Released on J-STAGE: April 26, 2001
    JOURNAL FREE ACCESS
    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.
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