Mark K K
J Gen Virol. 1982 Feb;58(Pt 2):457-60. doi: 10.1099/0022-1317-58-2-457.
To measure the length of heating required to convert a lambda lysogen in the immune (im+) phase into the anti-immune (im-) phase, rex gene activity was used as an indicator. It was observed that 5 min heating at 41 degrees C did not shift any lysogenic cells of 594 (lambda N-c1857O-) from the im+ phase into the im- phase, and it took 17 min heating at 41 degrees C followed by long hours of culture at 30 degrees C to shift half of the lysogenic cells into the im- phase. Such a length of heating is too long to be accounted for by blocking of the expression of lambda repressor by cro gene product. The result is more consistent with accumulation of a certain level of cro gene product during heating so that the synthesis of the repressor is blocked even after a return to low temperature.
为了测定将处于免疫（im+）阶段的λ溶原菌转化为抗免疫（im-）阶段所需的加热时长，采用rex基因活性作为指标。观察到在41℃加热5分钟并不会使594（λN-c1857O-）的任何溶原细胞从im+阶段转变为im-阶段，而在41℃加热17分钟，随后在30℃长时间培养，才能使一半的溶原细胞转变为im-阶段。这样的加热时长过长，无法用cro基因产物对λ阻遏物表达的阻断来解释。该结果更符合加热过程中cro基因产物积累到一定水平，以至于即使恢复到低温后阻遏物的合成仍被阻断的情况。
