冠突伪尾柱虫（Pseudourostyla cristata）实验再生研究

冠突伪尾柱虫(Pseudvurostyla cristata) 含约70枚大核。我们用显微手术横切G1期细胞,得前后两块相等断片;分别培养。60小时后,断片再生完成。在再生过程中,随细胞体积增大,大核数目也增加。大核的数目和细胞体积存在着一定的均衡关系。在细胞无性分裂过程中,许多大核改组后,融合成一个融合大核。这个融合大核具两个仔虫的大核数目和DNA量。我们用显微手术得到含融合大核的后断片。在后断片再生后恢复的虫体内,我们发现本应分配到两个仔虫中去的大核数目,被限制在一个虫体的大核数目上。这说明了细胞质可以影响和调节大核的数目。并还证明了这种虫体大核DNA量较正常虫的大核DNA量约多一倍。其中大部分虫体分裂时,大核不经改组就开始融合和分裂;从而使DNA量回复正常。同讨还发现小部分虫体通过排出大核多余核物质方式来调节大核DNA量。这些现象说明了细胞核质之间存在着一种调节相对平衡和相互协调的机制。

EXPERIMENTAL REGENERATION IN PSEUDOUROSTYLA CRISTATA

The process of regeneration in Pseudourostyla cristata containing about 70 macronuclei was studied by means of microsurgery. Cells of Gl period were excised transversally into two halves. After about 60 hours regeneration of both segments was completed. During the process of regeneration, we found that there was a correlation between the macronuclear number of the organism and its body size; the number of macronuclei increased with the increase of the cell size. During asexual division, after DNA synthesis in the macronuclear replication band, all the macronuclei fused into a single macronucleus. The fused macronucleus possessed the macronuclear number and DNA contents of the two daughter cells. At this stage, using microsurgery, the fused micronucleus was pushed to the posterior end of the organism and the posterior fragments containing fused macronucleus were obtained. After the posterior fragments had recovered to their normal Gl period, we found that the number of the macronuclei which ought to be equal to the sum of the macronuclei of the 2 daughter cells, was equal to the those of 1 daughter cell. We postulated thus that the. number, shape and location of macronuclei may be influenced or regulated by the cell cytoplasm. The DNA content of the fragment with fused macronuclei was about twice as much as normal. No replication bands could be observed in most of the cells during their division, i.e. these cells divided without DNA replication, and their DNA content was recovered to the normal level of macronuclear DNA content after their first division. We also observed that the macronuclear DNA content may be adjusted by another way, i.e. by extrusion of excess nuclear material of the macronucleus. these phenomena showed that the mechanism of the relative equilibrium and relative coordination may be present between the nucleus and cytoplasm.