Oelze-Karow H, Schopfer P, Mohr H
Proc Natl Acad Sci U S A. 1970 Jan;65(1):51-7. doi: 10.1073/pnas.65.1.51.
Synthesis of the enzyme lipoxygenase in the cotyledons of the mustard seedling (Sinapis alba L.) is controlled by phytochrome (P(fr)) through a threshold mechanism. The repression of enzyme synthesis by P(fr) is a very rapid process after the threshold level is surpassed. Similarly, enzyme synthesis starts instantaneously and with full speed as soon as the P(fr) level decreases below the threshold level. Thus P(fr) rapidly inhibits synthesis of an enzyme and functions through an all-or-none control mechanism of high precision.
芥菜幼苗（白芥）子叶中脂氧合酶的合成受光敏色素（P(fr)）通过阈值机制控制。当超过阈值水平后，P(fr)对酶合成的抑制是一个非常迅速的过程。同样，一旦P(fr)水平降至阈值水平以下，酶合成即刻以全速启动。因此，P(fr)迅速抑制一种酶的合成，并通过一种高精度的全或无控制机制发挥作用。
