涡虫(planarian)拥有非常强的再生任何身体缺失部分的能力,因而被人们大量地研究。不过,如今,它们也可能作为研究包括人类在内的脊椎动物眼睛发育和眼睛疾病的模式系统。2012年8月2日,这项关于涡虫眼睛中有活性的基因详细目录的研究发表在《细胞》期刊子刊Cell Reports上。
为了构建在涡虫眼睛中表现出活性加强的基因列表,Peter Reddien实验室的研究生Sylvain Lapan分析了2000多个涡虫眼睛。Lapan和Reddien发现600个有活性的基因,并且更加详细地研究了其中200个基因,而且他们鉴定出的基因当中有几个基因已知在脊椎动物眼睛中发挥着作用,但是没有在果蝇眼睛中发现过。在这些基因当中,有一些基因参与眼睛发育,其他基因与眼睛相关的黄斑变性(macular degeneration)和亚瑟综合症(Usher syndrome)相关联。
他们鉴定出的参与在涡虫眼睛发育的关键性基因之一就是转录因子ovo,它能够在眼睛形成时激活很多其他基因表达。在此之前,科学家们已发现ovo与其他有机体中的神经管和生殖细胞发育相关联,但是未发现与眼睛相关联。ovo在成年涡虫的眼睛再生和眼睛维护中发挥着至关重要的作用,而且在胚胎内眼睛发育中也有活性。事实上,当在实验中ovo被关闭时,头部截断的涡虫不能再生它们的眼睛,而且其他方面正常的成年涡虫的眼睛在几个月之后消失掉。
Lapan说,“类似机制也被用来在涡虫体内平衡、再生和胚胎发育期间制造眼睛。如今,除了果蝇之外的其他脊椎动物中,我们更多地了解关于这些动物体内调节眼睛形成的基因方面的信息。涡虫眼睛与果蝇眼睛非常不同,而且我们已正在观察到研究多种模式物种的益处,比如发现ovo的一种关键性作用。”(生物谷:Bioon.com)
本文编译自Planarians offer a better view of eye development
doi: 10.1016/j.celrep.2012.06.018
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Transcriptome Analysis of the Planarian Eye Identifies ovo as a Specific Regulator of Eye Regeneration
Sylvain W. Lapan, Peter W. Reddien
Among the millions of invertebrate species with visual systems, the genetic basis of eye development and function is well understood only in Drosophila melanogaster. We describe an eye transcriptome for the planarian Schmidtea mediterranea. Planarian photoreceptors expressed orthologs of genes required for phototransduction and microvillus structure in Drosophila and vertebrates, and optic pigment cells expressed solute transporters and melanin synthesis enzymes similar to those active in the vertebrate retinal pigment epithelium. Orthologs of several planarian eye genes, such as bestrophin-1 and Usher syndrome genes, cause eye defects in mammals when perturbed and were not previously described to have roles in invertebrate eyes. Five previously undescribed planarian eye transcription factors were required for normal eye formation during head regeneration. In particular, a conserved, transcription-factor-encoding ovo gene was expressed from the earliest stages of eye regeneration and was required for regeneration of all cell types of the eye.