Ueda T, Kobatake Y
Eur J Cell Biol. 1980 Dec;23(1):37-42.
The plasmodium of Physarum polycephalum exhibits a characteristic protoplasmic shuttle streaming and generates periodical tension. We determined the factors which govern the period of the contraction rhythm by measuring isometric tension of the plasmodial strand and the motive force of the protoplasmic streaming under a variety of conditions by changing the size of plasmodia, chemical composition of environment and surrounding temperatures. The results are: (1) The period of contraction rhythm, tau, increased linearly with the amplitude of oscillating tension, F, and was expressed by the following empirical equation when F was lower than a certain critical value, Fc, i.e., tau = aF+tau O. Above Fc, tau stayed at a constant level of tau S. There, a tau O and tau S are numerical constants which are independent of F. A similar relationship is valid for the amplitude of the motive force of the protoplasmic streaming, delta P. (2) Values of tau O were 1.0 min in air and 1.6 min in an aqueous medium and they were independent of temperature. (3) The Arrhenius plots of the parameter "a" exhibited different straight lines in air and in aqueous medium, from which the values of Q10 were determined to be 4.0 and 10, respectively. (4) Lowering of temperature decreased Fc, and eventually diminished it at Tc (= 15 degrees C). (5) The presence of glucose, CaCl2, MgCl2 and NaCl gave the identical tau-F relationship. Applications od D2O and ethanol slowed down the contraction rhythm, while that of KCl accelerated the rhythm. However, all these chemicals did not affect the tau O value. All results described above indicate that the contraction rhythm in the plasmodium is influenced by three components: a limit cycle which is independent of tension generation, a component which is strongly linked to the amplitude of the tension, F, and the part which is independent of the value of F. External factors appear to influence separately these three components of the contraction rhythm.
多头绒泡菌的原生质团表现出典型的原生质穿梭流动，并产生周期性张力。我们通过在各种条件下改变原生质团的大小、环境的化学成分和周围温度，测量原生质团丝的等长张力和原生质流动的驱动力，确定了控制收缩节律周期的因素。结果如下：（1）收缩节律的周期τ随振荡张力的振幅F线性增加，当F低于某个临界值Fc时，由以下经验方程表示，即τ = aF + τO。高于Fc时，τ保持在τS的恒定水平。其中，a、τO和τS是与F无关的数值常数。原生质流动驱动力的振幅ΔP也有类似关系。（2）τO在空气中的值为1.0分钟，在水介质中为1.6分钟，且与温度无关。（3）参数“a”的阿累尼乌斯图在空气和水介质中呈现不同的直线，由此确定Q10值分别为4.0和10。（4）温度降低会降低Fc，并最终在Tc（= 15℃）时使其消失。（5）葡萄糖、CaCl2、MgCl2和NaCl的存在给出相同的τ - F关系。D2O和乙醇的应用减缓了收缩节律，而KCl的应用加速了节律。然而，所有这些化学物质都不影响τO值。上述所有结果表明，原生质团中的收缩节律受三个成分影响：一个与张力产生无关的极限环，一个与张力振幅F紧密相关的成分，以及一个与F值无关的部分。外部因素似乎分别影响收缩节律的这三个成分。
