Research progress in scyphozoan polyp strobilation-induced factors and regulation mechanism

Strobilation is a key stage for polyp-to-jellyfish transition. Knowledge about the strobilation-induced factors and the underlying molecular regulation mechanism could help control jellyfish bloom in nature, improve jellyfish artificial breeding, as well as get insight about the ancestral molecular origin of metamorphosis of amphibians, insect and cnidarians. Natural factors, including temperature, illumination, salinity, and symbiotic zooxanthellae, could induce strobilation. The mode of strobilation and how these natural factors irritate strobilation are distinct in different jellyfish species. Chemicals including indole derivates, 9-cis retinoic acid, elemental iodine, hydrogen peroxide, could also induce strobilation in laboratory. Indole derivates are effective inducers to most scyphozoan species. The molecular mechanism of strobilation is unclear. Results from moon jelly reveal that RxR signaling pathway plays an important role during strobilation. A secreted moon jelly-special protein named CL390 may serve as a strobilation-induced hormone precursor. These results imply that morphological differences in medusa production may mask similarities at the cellular level in different jellyfish species. The molecular mechanism of metamorphosis in jellyfish may share some consistency with amphibians and insects.横裂是水螅体世代向水母体世代转变的重要阶段.对水螅体横裂诱发条件及调控分子机制的研究不仅对水母爆发生态学和水母人工繁育具有重要意义,而且对比较研究两栖类、昆虫以及刺胞动物等具有复杂生活史生物的变态分子机制起源也具有很好的理论价值.现有研究表明,诱发水螅体横裂的自然环境因素有温度、光照、盐度和共生虫黄藻等,不同门类水母的横裂方式以及环境诱导因素各不相同.能够诱导水螅体横裂的化学因素有吲哚类化合物、9-顺式维甲酸、碘元素和过氧化氢等,其中吲哚类化合物对绝大多数水母水螅体都有诱导作用.尽管水螅体横裂的分子机制尚未明晰,但对海月水母的研究表明,RxR信号通路以及一种横裂诱导激素前体假定蛋白CL390在水母横裂过程中起着重要的作用,提示水母变态分子机制与两栖类和昆虫在分子水平上存在一定程度的共性.