2 STEPS REQUIRED FOR MALE PRONUCLEUS FORMATION IN THE SEA-URCHIN EGG
2 STEPS REQUIRED FOR MALE PRONUCLEUS FORMATION IN THE SEA-URCHIN EGG
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DOI：
10.1006/excr.1993.1066
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发表时间：
1993-03-01
影响因子：
3.7
通讯作者：
POCCIA, DL
中科院分区：
文献类型：
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作者：
COTHREN, CC;POCCIA, DL
我们已经开发了一个系统，海胆精子核显微注射到活卵和卵母细胞，以研究原核发育所需的条件。该系统绕过精子引发的表面事件，导致卵子激活。与正常受精卵或未成熟卵母细胞的雄性核相比，注射的核忠实地反映了卵细胞质促进雄性原核发育的能力。孤核注入受精卵后，与内源雄原核相似，发生膨胀并转化为雄原核。注入未成熟卵母细胞的细胞核仍呈圆锥形，类似于精子核。如果将精子核注入未受精、未激活的卵子，它们会经历不完全的解凝聚，不能形成原核。这种部分去凝聚作用可以用6-二甲基氨基嘌呤（6-DMAP）抑制。如果未受精的卵子首先通过用氨提高内部pH值而不完全激活，则注入的精子核将完成原核发育。增加pH或Ca 2+不会导致未成熟卵母细胞中精子核肿胀或染色质去浓缩。这些实验揭示了原核形成的两个必要条件。第一种情况，导致部分解凝聚，在减数分裂成熟过程中发展，并可被6-DMAP阻断。第二个需要细胞质碱化，但不是受精诱导的内部Ca 2+增加或肌醇三磷酸途径激活。
We have developed a system for microinjection of sea urchin sperm nuclei into live eggs and oocytes in order to study conditions which are required for pronuclear development. The system bypasses sperm-initiated surface events that result in egg activation. By comparison to male nuclei of normally fertilized eggs or immature oocytes, the injected nuclei faithfully reflect the ability of the egg cytoplasm to promote male pronuclear development. Isolated nuclei injected into fertilized eggs swell and transform into male pronuclei like the endogenous male pronuclei. Nuclei injected into immature oocytes remain conical like fertilizing sperm nuclei. If sperm nuclei are injected into unfertilized, unactivated eggs, they undergo incomplete decondensation and fail to form pronuclei. This partial decondensation can be inhibited with 6-dimethylaminopurine (6-DMAP). If unfertilized eggs are first incompletely activated by raising internal pH with ammonia, injected sperm nuclei will complete pronuclear development. Increasing pH or Ca2+does not cause sperm nuclear swelling or chromatin decondensation in immature oocytes. These experiments reveal two conditions necessary for pronuclear formation. The first condition, resulting in partial decondensation, develops during meiotic maturation and can be blocked by 6-DMAP. The second requires cytoplasmic alkalinization, but not the fertilization-induced internal Ca2+increase or inositol triphosphate pathway activation.