Spatiotemporal characteristics and mechanisms of intracellular Ca2+ increases at fertilization in eggs of jellyfish (Phylum Cnidaria, Class Hydrozoa)
Spatiotemporal characteristics and mechanisms of intracellular Ca2+ increases at fertilization in eggs of jellyfish (Phylum Cnidaria, Class Hydrozoa)
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DOI：
10.1016/j.ydbio.2004.11.036
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发表时间：
2005-03-15
影响因子：
2.7
通讯作者：
Itoh, J
中科院分区：
文献类型：
--
作者：
Deguchi, RU;Kondoh, E;Itoh, J
我们已经澄清，为第一次，在受精和Ca 2+动员机制的水螅水母，这属于进化古老的双胚层门，刺胞藻卵细胞内Ca 2+增加的时空模式。在所测试的四种水螅虫中，受精后的初始Ca 2+增加以Ca 2+波的形式从卵的一个锥形区域开始并传播到其对极：Cytaeis uchidae，Cladonema pacificum，Clytia sp.，和绿戈ionema vertens。Ca ~（2+）波的起始位点仅限于动物极，这是已知的水螅虫卵中精卵融合的唯一区域，并且波的传播速度估计为4.2-5.9 μ m/s。在初始Ca ~（2+）波达到一个Ca ~（2+）峰值后，升高的Ca ~（2+）逐渐下降，并在受精后7-10 min恢复到接近静息值。注射肌醇1，4，5-三磷酸（IP 3），一种IP 3受体（IP 3R）的激动剂，在诱导未受精卵的Ca 2+增加方面非常有效;最终细胞内浓度为12-60 nM的IP 3产生了与受精时观察到的完全传播的Ca 2+波。相比之下，较高浓度的环状ADP-核糖（cADPR），兰尼碱受体（RyR）的激动剂，只产生了局部的钙离子增加，不传播的鸡蛋。此外，咖啡因，另一种RyR的刺激剂，完全没有效果。预注射肝素（IP 3R释放Ca ~（2+）的所有抑制剂）严重影响精子诱导的Gonionema卵中Ca ~（2+）升高。这些结果强烈表明，有一个发达的IP 3R-，但不是RyR-介导的Ca 2-释放机制的水螅虫卵，前者系统主要功能在受精。我们目前的数据还表明，空间特征和机制的Ca 2+的增加在水螅虫卵受精类似于那些报道在更高的三胚层动物。(C)2004年爱思唯尔公司All rights reserved.
We have clarified, for the first time, the spatiotemporal patterns of intracellular Ca2+ increases at fertilization and the Ca2+ -mobilizing mechanisms in eggs of hydrozoan jellyfish, which belong to the evolutionarily old diploblastic phylum, Cnidaria. An initial Ca2+ increase just after fertilization took the form of a Ca2+ wave starting from one conical region of the egg and propagating to its antipode in all of four hydrozoan species tested: Cytaeis uchidae, Cladonema pacificum, Clytia sp., and Gonionema vertens. The initiation site of the Ca2+ wave was restricted to the animal pole, which is known to be the only area of sperm-egg fusion in hydrozoan eggs, and the wave propagating velocity was estimated to be 4.2-5.9 mum/s. After a Ca2+ peak had been attained by the initial Ca2+ wave, the elevated Ca2+ gradually declined and returned nearly to the resting value at 7-10 min following fertilization. ln jection of inositol 1,4,5-trisphosphate (IP3), an agonist of IP3 receptors (IP3R), was highly effective in inducing a Ca2+ increase in unfertilized eggs; IP3 at a final intracellular concentration of 12-60 nM produced a fully propagating Ca2+ wave equivalent to that observed at fertilization. In contrast, a higher concentration of cyclic ADP-ribose (cADPR), an agonist of ryanodine receptors (RyR), only generated a localized Ca2+ increase that did not propagate in the egg. In addition, caffeine, another stimulator of RyR, was completely without effect. Sperm-induced Ca2+ increases in Gonionema eggs were severely affected by preinjection of heparin, ail inhibitor of Ca2+ release from IP3R. These results strongly suggest that there is a well-developed IP3R-, but not RyR-rnediated Ca2- release mechanism in hydrozoan eggs and that the former system primarily functions at fertilization. Our present data also demonstrate that the spatial characteristics and mechanisms of Ca2+ increases at fertilization in hydrozoan eggs resemble those reported in higher triploblastic animals. (C) 2004 Elsevier Inc. All rights reserved.