Experimental induction of gonadal maturation and spawning in the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizostomeae)
Experimental induction of gonadal maturation and spawning in the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizostomeae)
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DOI：
10.1007/s00227-007-0722-0
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发表时间：
2007-09-01
期刊：
影响因子：
2.4
通讯作者：
Uye, Shin-ichi
中科院分区：
文献类型：
--
作者：
Ohtsu, Kohzoh;Kawahara, Masato;Uye, Shin-ichi
我们研究了近年来在日本海开花的巨型水母Nemopilema nomurai的性腺成熟，产卵，受精和胚胎发育的过程。健康的水母活跃地在近海游泳，它们的性腺不成熟，但是受损的和漂到岸上的水母的性腺相对成熟。动物保持在一个小网在近岸模仿漂流条件下显示诱导性腺成熟的卵母细胞直径的增加和黑暗中的矩阵。在相同温度下孵育的卵巢中也发生了类似的成熟过程。完全发育的卵母细胞，可能停止在第一次减数分裂的前期重新启动成熟分裂，在曝光后的80-100分钟，大量产卵。卵母细胞首先在生殖窦内释放，然后向外周运输，最后脱落到胃血管腔内。雄鱼性腺的成熟和产卵与雌鱼相似，但雄鱼产卵发生在光照后30 min内，且总是先于雌鱼产卵。因此，推测黎明后动物通过抽水活动从周围海水中进入的精子可能在雌性胃血管腔中进行受精。在日本海，机械损伤可能会促进该物种的受精成功。
We studied the processes of gonadal maturation, spawning, fertilization and embryonic development of the giant jellyfish Nemopilema nomurai, which has been blooming in recent years in the Sea of Japan. Healthy medusae actively swimming offshore had immature gonads, but damaged and ashore-drifted animals had relatively mature gonads. The animals maintained in a small net on the nearshore to mimic the drifted condition showed induced gonadal maturation by the increase in oocyte diameter and darkness in the matrix. A similar maturation process also occurred in isolated pieces of ovary incubated at the same temperature. Fully grown oocytes that probably stopped at the prophase of the first meiosis reinitiated maturation divisions in response to light exposure, and massive spawnings occurred 80-100 min after the exposure. The spawned oocytes were first released within the subgenital sinus, then transported peripherally and finally shed into the gastrovascular cavity. Maturation and spawning in male gonads were similar to those of females except that the male spawning occurred within 30 min after the light exposure and always preceded the female spawning. Hence, it was suggested that fertilization might take place in the female gastrovascular cavity by the sperm that came in from surrounding seawater by animals' pumping activities after dawn. Having mechanical damages might promote fertilization success of this species in the Sea of Japan.