POLYTENE CHROMOSOMES ISOLATED FROM NUCLEI OF TOKUNAGAYUSURIKA AKAMUSHI (DIPTERA, CHIRONOMIDAE): STRUCTURAL TRANSFORMATION CAUSED BY SALT, DETERGENT POLYANIONS AND ENZYMES

Polytene chromosomes of Tokunagayusurika akamushi (Chironomidae) were isolated from nuclei of the salivary glands. The isolated chromosomes retained their normal morphology, revealing bands by phase contrast microscopy.
Extensive structural transformations were observed when the isolated chromosomes were immersed in solutions of high salt concentration, polyanions (dextran sulfate and heparin), the ionic detergent SDS (0.01% or more) or enzymes. The morphological changes could be described in terms of combinations of the following characteristics: (1) reversible or irreversible changes, (2) expansion or no expansion, (3) disappearance of bands, and (4) appearance of new bands. The structural features of the transformed chromosomes are described.     

单分子纳米生物技术

生物分子需要相互协调组成各种分子机器,例如：分子马达、细胞信号处理器、DNA转录机、蛋白质合成器等,来实现他们负责的各种生理功能。一方面,这些分子机器的功能对于环境改变有着很强的适应性,这种适应性对于生物体和生物系统的稳定来说是必须的。另一方面,由于分子机器的大小只有几纳米并且结构具有可变性,它们的运转倾向于受到热扰动的影响具有随机性,此外,分子机器所利用的输入能量的水平与平均热运动能量kBT近似,分子机器可以高效地将热噪声的能量转化利用于行使其功能,对于这些能量的利用效率也很高,这与人造机器运转所需能量远远高于热运动能量相比有着十分显著的差别。因此,分子机器的潜在机理比人造机器复杂了许多。近些年来,随着单分子探测技术和纳米技术在生命科学的各个领域的广泛应用,使得生物分子的动力学性质,以及以往被隐藏在系综平均结果后的单个分子机器运转规律逐渐被揭示。我们研究的目标是希望通过揭示分子机器的独特运转规律进而能够了解、掌握具有适应性的生物系统中包含的工程学原理。本文综述了我们所作的一些关于分子马达、酶促反应、蛋白质动力学和细胞信号转导的单分子探测试验,并且讨论了热涨落（噪声）是怎样在具有独特的运转规律的生物分子机器中起到正效应,进而允许生物系统具有可变性和适应性的。     

The calliphorid larvae parasitic on birds in Japan (Diptera: Calliphoridae)

The immature stages of Protocalliphora maruyamensis Kano et Shinonaga are newly described and the third instar larva of P. azurea (Fallén) is redescribed from specimens collected in Japan. The larval morphology of Protocalliphora is discussed. A key to the third instar larvae of Japanese bird-parasitic blowflies is given.