Bard E, Colwill R, L'Anglais R, Kaplan J G
Can J Biochem. 1978 Sep;56(9):900-4. doi: 10.1139/o78-139.
In order for significant DNA synthesis to be observed in the case of human lymphocytes stimulated for 36 h in presence of phytohemagglutinin (PHA), Ca2+ must be present in the medium continuously for at least 20 h; access to Ca2+ for 10-h periods during the first 30 h was not sufficient to permit DNA synthesis to occur. Addition of the chelator EGTA from 0 to 60 h after stimulation caused severe inhibition of incorporation of labelled thymidine when this was measured after 36 to 144 h of culture. Equimolar calcium reversed the inhibition caused by EGTA. Incorporation of labelled uridine and leucine showed a temporal pattern of dependence on the presence of Ca2+ in the medium similar to that of thymidine. Ca2+ appears not to be required in the medium during the last half (i.e., 20-36 h) of the presynthetic G1 phase nor during S phase since removal of Ca2+ from the medium after 20 h did not prevent a subpopulation of lymphocytes from entering S phase 16 h later.
为了在存在植物血凝素（PHA）的情况下观察到人类淋巴细胞在刺激36小时后有显著的DNA合成，培养基中必须持续存在Ca2+至少20小时；在最初30小时内每10小时有Ca2+供应不足以使DNA合成发生。在刺激后0至60小时添加螯合剂乙二醇双四乙酸（EGTA），当在培养36至144小时后测量时，会导致标记胸腺嘧啶核苷掺入的严重抑制。等摩尔的钙可逆转EGTA引起的抑制作用。标记尿苷和亮氨酸的掺入显示出对培养基中Ca2+存在的时间依赖性模式，类似于胸腺嘧啶核苷。在合成前G1期的后半段（即20 - 36小时）以及S期，培养基中似乎不需要Ca2+，因为在20小时后从培养基中去除Ca2+并没有阻止一部分淋巴细胞在16小时后进入S期。
