PROGRAMMED NUCLEAR DEATH - APOPTOTIC-LIKE DEGRADATION OF SPECIFIC NUCLEI IN CONJUGATING TETRAHYMENA
PROGRAMMED NUCLEAR DEATH - APOPTOTIC-LIKE DEGRADATION OF SPECIFIC NUCLEI IN CONJUGATING TETRAHYMENA
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DOI：
10.1016/0012-1606(92)90080-z
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发表时间：
1992-12-01
影响因子：
2.7
通讯作者：
ALLIS, CD
中科院分区：
文献类型：
--
作者：
DAVIS, MC;WARD, JG;ALLIS, CD
在纤毛原生动物Tetrahymena的接合过程中，新的大核分化从germinalzyoticmicronuclei，而父母（老）的大核被淘汰在两个阶段，冷凝或pycnosis一致的转录停止，然后再吸收。我们发现，在各种真核生物系统中，固缩伴随着旧的大核DNA降解成染色体大小的片段，这是程序性细胞死亡或凋亡的标志。正如预期的那样，在新的微核和大核中没有发生染色体的形成，证实了在共同的细胞质中不同细胞核的不同发育命运的协调。NULLI 3接合子具有野生型旧大核，但缺少3号染色体，因此在新大核中缺少3号染色体。在NULLI 3接合子中，旧大核固缩和核小体碎裂正常发生，但再吸收步骤失败，并且固缩的旧大核被保留，这表明这两个步骤在遗传上是可分离的，因此是不同的，并暗示新大核中的3号染色体上的基因是再吸收步骤所需的。在野生型和NULLI 3杂交中，在大核发育阶段合成的全细胞多肽的比较揭示了相似的概况。然而，在NULLI 3结合体中未观察到在旧大核消除过程中合成的多肽（表观Mrof 53 kDa）;其在旧大核消除中的作用（如果有的话）尚不清楚。结果表明，旧的大核被选择性地破坏的机制，这是非常相似的细胞凋亡在其他真核生物和合子基因组所需的再吸收步骤。
During conjugation in the ciliated protozoanTetrahymena, new macronuclei differentiate from germinal zygotic micronuclei while parental (old) macronuclei are eliminated in two stages, condensation or pycnosis coincident with cessation of transcription followed by resorption. We show that pycnosis is accompanied by degradation of old macronuclear DNA into oligonucleosome-sized fragments, a hallmark of programmed cell death, or apoptosis, in a variety of eukaryotic systems. As expected, oligonucleosome formation does not occur in the new micro- and macronuclei, confirming the coordination of different developmental fates for different nuclei in a common cytoplasm. NULLI 3 conjugants have wild-type old macronuclei but lack chromosome 3 germinally and hence in the new macronucleus. In NULLI 3 conjugants, old macronuclear pycnosis and oligonucleosome fragmentation occur normally but the resorption step fails, and the pycnotic old macronucleus is retained, demonstrating that the two steps are genetically separable and thus distinct and implying that genes on chromosome 3 in the new macronucleus are required for the resorption step. Comparison of whole cell polypeptides synthesized during stages of macronuclear development in both wild-type and NULLI 3 crosses reveal similar profiles. However, a polypeptide (apparentMrof 53 kDa) synthesized during old macronuclear elimination is not observed in NULLI 3 conjugants; its role, if any, in elimination of the old macronucleus is unknown. The results show that the old macronucleus is selectively destroyed by a mechanism which is remarkably similar to apoptosis in other eukaryotes and that the zygotic genome is required for the resorption step.