Brekhman Vera, Malik Assaf, Haas Brian, Sher Noa, Lotan Tamar
Marine Biology Department, The Leon H. Charney School of Marine Sciences, University of Haifa, 31905, Haifa, Israel.
Bioinformatics Service Unit, University of Haifa, 31905, Haifa, Israel.
BMC Genomics. 2015 Feb 14;16(1):74. doi: 10.1186/s12864-015-1320-z.
The moon jellyfish Aurelia aurita is a widespread scyphozoan species that forms large seasonal blooms. Here we provide the first comprehensive view of the entire complex life of the Aurelia Red Sea strain by employing transcriptomic profiling of each stage from planula to mature medusa.
A de novo transcriptome was assembled from Illumina RNA-Seq data generated from six stages throughout the Aurelia life cycle. Transcript expression profiling yielded clusters of annotated transcripts with functions related to each specific life-cycle stage. Free-swimming planulae were found highly enriched for functions related to cilia and microtubules, and the drastic morphogenetic process undergone by the planula while establishing the future body of the polyp may be mediated by specifically expressed Wnt ligands. Specific transcripts related to sensory functions were found in the strobila and the ephyra, whereas extracellular matrix functions were enriched in the medusa due to high expression of transcripts such as collagen, fibrillin and laminin, presumably involved in mesoglea development. The CL390-like gene, suggested to act as a strobilation hormone, was also highly expressed in the advanced strobila of the Red Sea species, and in the medusa stage we identified betaine-homocysteine methyltransferase, an enzyme that may play an important part in maintaining equilibrium of the medusa's bell. Finally, we identified the transcription factors participating in the Aurelia life-cycle and found that 70% of these 487 identified transcription factors were expressed in a developmental-stage-specific manner.
This study provides the first scyphozoan transcriptome covering the entire developmental trajectory of the life cycle of Aurelia. It highlights the importance of numerous stage-specific transcription factors in driving morphological and functional changes throughout this complex metamorphosis, and is expected to be a valuable resource to the community.
海月水母是一种广泛分布的钵水母纲物种，会形成大规模的季节性水华。在此，我们通过对从浮浪幼虫到成熟水母的各个阶段进行转录组分析，首次全面呈现了红海海月水母整个复杂的生命周期。
利用Illumina RNA测序数据，从海月水母生命周期的六个阶段组装出了一个从头转录组。转录本表达谱分析产生了与每个特定生命周期阶段相关功能的注释转录本聚类。发现自由游动的浮浪幼虫高度富集了与纤毛和微管相关的功能，并且浮浪幼虫在构建未来水螅体时所经历的剧烈形态发生过程可能由特异性表达的Wnt配体介导。在螅状体和碟状幼体中发现了与感觉功能相关的特定转录本，而由于胶原蛋白、原纤蛋白和层粘连蛋白等转录本的高表达，细胞外基质功能在水母中富集，这些转录本可能参与了中胶层的发育。被认为作为横裂激素起作用的CL390样基因，在红海物种的晚期螅状体中也高度表达，并且在水母阶段，我们鉴定出了甜菜碱 - 高半胱氨酸甲基转移酶，一种可能在维持水母钟状体平衡中起重要作用的酶。最后，我们鉴定了参与海月水母生命周期的转录因子，发现这487个鉴定出的转录因子中有70%以发育阶段特异性的方式表达。
本研究提供了首个覆盖海月水母生命周期整个发育轨迹的钵水母转录组。它突出了众多阶段特异性转录因子在驱动整个复杂变态过程中的形态和功能变化方面的重要性，有望成为该领域的宝贵资源。
