EFFECTS OF CA-2+ IONS ON THE FORMATION OF METAPHASE CHROMOSOMES AND SPERM PRONUCLEI IN CELL-FREE PREPARATIONS FROM UNACTIVATED RANA-PIPIENS EGGS
EFFECTS OF CA-2+ IONS ON THE FORMATION OF METAPHASE CHROMOSOMES AND SPERM PRONUCLEI IN CELL-FREE PREPARATIONS FROM UNACTIVATED RANA-PIPIENS EGGS
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DOI：
10.1016/0012-1606(84)90331-2
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发表时间：
1984-01-01
影响因子：
2.7
通讯作者：
MASUI, Y
中科院分区：
文献类型：
--
作者：
LOHKA, MJ;MASUI, Y
细胞核移植到未活化的两栖动物卵后凝聚成中期染色体；那些移植到活化卵子中的细胞会去致密和增大。用库蚊卵制备无细胞细胞质，可诱导脱膜的非洲爪蟾精子发生与完整卵相似的变化。精子染色质在含有3毫米EGTA（乙二醇-二氨基乙醚- n， n -四乙酸酯）的缓冲液中孵育3小时后，诱导形成中期染色体。当染色质在不含EGTA的未激活的卵子制剂和激活的卵子制剂中孵育时，形成去致密间期核。当Ca2+离子加入到由EGTA制成的未激活的卵子制剂中时，该制剂失去了诱导中期染色体形成的能力，并能够使精子染色质去致密化。一旦去致密染色质的能力发展起来，无论是在未激活的还是激活的鸡蛋制剂中，它都不能被EGTA的添加所抑制。激活卵子制剂中精子染色质的去浓缩可以通过添加由EGTA制成的未激活卵子制剂来抑制。在这种情况下，培养的精子染色质被诱导形成中期染色体。当Ca2+离子水平较低时，无细胞制备中未活化的卵细胞浆的染色体凝聚活性可以维持，但当Ca2+离子水平升高时，这种活性丧失并被一种新的去致密染色质活性所取代。由于这种细胞质活动的变化与受精后完整卵子中发生的变化相当，这些结果表明Ca2+离子在改变控制核行为的细胞质活动的激活过程中起着至关重要的作用。
Nuclei transplanted into unactivated amphibian eggs condense into metaphase chromosomes; those transplanted into activated eggs decondense and enlarge. Cell-free cytoplasmic preparations were made from R. pipiens eggs which can induce demembranated Xenopus laevis sperm to undergo changes similar to those seen in intact eggs. Sperm chromatin which is incubated for 3 h in unactivated egg preparations made using a buffer containing 3 mm EGTA [ethyleneglycol-bis-aminoethylether-N,N-tetraacetate] is induced to form metaphase chromosomes. Decondensed interphase nuclei are formed when chromatin is incubated in unactivated egg preparations made without EGTA and in activated egg preparations. When Ca2+ ions are added to unactivated egg preparations made with EGTA, the preparations lose the ability to induce metaphase chromosome formation and become capable of decondensing sperm chromatin. Once the ability to decondense chromatin has developed, either in unactivated or activated egg preparations, it cannot be suppressed by the addition of EGTA. Decondensation of sperm chromatin in activated egg preparations can be suppressed by the addition of unactivated egg preparations made with EGTA. In this case, the incubated sperm chromatin is induced to form metaphase chromosomes. Chromosome condensation activity of unactivated egg cytoplasm can be sustained in cell-free preparations when Ca2+ ion levels are kept low, but when Ca2+ ion levels increase, this activity is lost and replaced by a new activity which can decondense chromatin. Since this change in cytoplasmic activities is comparable to that occurring in the intact egg following fertilization, these results suggest that Ca2+ ions play a crucial role during activation in altering the cytoplasmic activities which control nuclear behavior.