GOODGAL S H, HERRIOTT R M
J Gen Physiol. 1961 Jul;44(6):1201-27. doi: 10.1085/jgp.44.6.1201.
A procedure has been developed for obtaining Hemophilus influenzae of such competence that 1 to 10 per cent transform to any of several genetic factors by utilizing a period of aerobic growth followed by a non-aerobic period. Differences in levels of competence were not due to differences in genetic background. Competence was due to at least one factor intrinsic to the cell or site on the cell and was not transferable to non-competent cells. Competence was affected by salt concentration, pH, and temperature. Washing competent cells reduces their ability to transform, but not their capacity to bind DNA reversibly. The irreversible step could be restored with little or no accompanying growth. These facts suggest that reversible and irreversible binding represent separate biochemical steps. DNA initiates a reaction in cells leading to a loss of competence. In the absence of DNA the cells remain competent for at least an hour. Competence correlates quantitatively with predictability of multiple transformations. The observed and calculated values of multiple transformations are in closer agreement, the higher the frequency of transformation for single markers. The correction needed to bring the two figures into agreement is a measure of the fraction of non-competent cells.
已开发出一种程序来获取具有感受态的流感嗜血杆菌，通过利用一段需氧生长时期接着一段厌氧时期，这种感受态的流感嗜血杆菌有1%到10%会转化为几种遗传因子中的任何一种。感受态水平的差异并非由于遗传背景的差异。感受态是由于细胞内至少一种内在因子或细胞上的位点引起的，并且不能转移到无感受态的细胞。感受态受盐浓度、pH值和温度的影响。洗涤感受态细胞会降低其转化能力，但不会降低其可逆结合DNA的能力。不可逆步骤几乎可以在没有伴随生长或仅有少量伴随生长的情况下恢复。这些事实表明可逆结合和不可逆结合代表不同的生化步骤。DNA在细胞中引发反应导致感受态丧失。在没有DNA的情况下，细胞至少一小时内仍保持感受态。感受态与多次转化的可预测性在数量上相关。单次标记的转化频率越高，多次转化的观察值和计算值就越接近一致。使这两个数值一致所需的校正量是无感受态细胞比例的一种度量。
