TIME SEQUENCE OF NUCLEAR PORE FORMATION IN PHYTOHEMAGGLUTININ-STIMULATED LYMPHOCYTES AND IN HELA CELLS DURING THE CELL CYCLE
TIME SEQUENCE OF NUCLEAR PORE FORMATION IN PHYTOHEMAGGLUTININ-STIMULATED LYMPHOCYTES AND IN HELA CELLS DURING THE CELL CYCLE
复制标题
细胞周期期间植物血凝素刺激的淋巴细胞和 HELA 细胞中核孔形成的时间序列
作者：
G. Maul;H. Maul;J. E. Scogna;M. Lieberman;G. Stein;B. Hsu;T. Borun
测定了植物血凝素（phytohemagglutinin， PHA）刺激的人淋巴细胞和HeLa S-3细胞在细胞周期内核孔频率变化的时间序列。核孔/核数由实验测定的核孔/µ2和核表面计算得到。在淋巴细胞系统中，在PHA刺激后的48小时内，孔/核的数量大约增加一倍。孔隙频率的增加是双相的，第一次增加似乎与蛋白质合成速度的增加有关。孔/核的第二次增加似乎与DNA合成的开始有关。在HeLa细胞系统中，我们也可以观察到孔隙形成的双相变化。核孔在有丝分裂后的第一个小时内形成速度最快。孔形成速率的第二次增加与S期前不久核酸性蛋白合成速率的增加在时间上相对应。HeLa细胞的核孔总数从G1期的~ 2000个增加到细胞周期末期的~ 4000个。核体积和核孔数量的增加可能与DNA含量的增加有关。另一个与S期核孔数对应的是同时复制的复制位点的数量。这个数字可能是偶然的，但导致了相当推测的可能性，即核孔可能是DNA起始和/或复制的位置以及核胞质交换的位置。也就是说，核孔复合物可能具有多种功能。
The time sequence of nuclear pore frequency changes was determined for phytohemagglutinin (PHA)-stimulated human lymphocytes and for HeLa S-3 cells during the cell cycle. The number of nuclear pores/nucleus was calculated from the experimentally determined values of nuclear pores/µ2 and the nuclear surface. In the lymphocyte system the number of pores/nucleus approximately doubles during the 48 hr after PHA stimulation. The increase in pore frequency is biphasic and the first increase seems to be related to an increase in the rate of protein synthesis. The second increase in pores/nucleus appears to be correlated with the onset of DNA synthesis. In the HeLa cell system, we could also observe a biphasic change in pore formation. Nuclear pores are formed at the highest rate during the first hour after mitosis. A second increase in the rate of pore formation corresponds in time with an increase in the rate of nuclear acidic protein synthesis shortly before S phase. The total number of nuclear pores in HeLa cells doubles from ∼2000 in G1 to ∼4000 at the end of the cell cycle. The doubling of the nuclear volume and the number of nuclear pores might be correlated to the doubling of DNA content. Another correspondence with the nuclear pore number in S phase is found in the number of simultaneously replicating replication sites. This number may be fortuitous but leads to the rather speculative possibility that the nuclear pore might be the site of initiation and/or replication of DNA as well as the site of nucleocytoplasmic exchange. That is, the nuclear pore complex may have multiple functions.