Molecular analysis of the amphioxus frontal eye unravels the evolutionary origin of the retina and pigment cells of the vertebrate eye.
文昌鱼额眼的分子分析揭示脊椎动物视网膜与色素细胞的演化起源

Authors / 作者: Vopalensky P, Pergner J, Liegertova M, Benito-Gutierrez E, Arendt D, Kozmik Z.
Journal / 期刊: Proceedings of the National Academy of Sciences of the United States of America
Year / 年份: 2012
DOI: 10.1073/pnas.1207580109
Publisher / 出版社: https://www.pnas.org/doi/10.1073/pnas.1207580109
Abstract source / 摘要来源: https://europepmc.org/article/MED/22949670

Author abstract / 作者原文摘要
The origin of vertebrate eyes is still enigmatic. The "frontal eye" of amphioxus, our most primitive chordate relative, has long been recognized as a candidate precursor to the vertebrate eyes. However, the amphioxus frontal eye is composed of simple ciliated cells, unlike vertebrate rods and cones, which display more elaborate, surface-extended cilia. So far, the only evidence that the frontal eye indeed might be sensitive to light has been the presence of a ciliated putative sensory cell in the close vicinity of dark pigment cells. We set out to characterize the cell types of the amphioxus frontal eye molecularly, to test their possible relatedness to the cell types of vertebrate eyes. We show that the cells of the frontal eye specifically coexpress a combination of transcription factors and opsins typical of the vertebrate eye photoreceptors and an inhibitory Gi-type alpha subunit of the G protein, indicating an off-responding phototransductory cascade. Furthermore, the pigmented cells match the retinal pigmented epithelium in melanin content and regulatory signature. Finally, we reveal axonal projections of the frontal eye that resemble the basic photosensory-motor circuit of the vertebrate forebrain. These results support homology of the amphioxus frontal eye and the vertebrate eyes and yield insights into their evolutionary origin.

Summary basis / 解读依据
摘要解读依据已查看的索引作者摘要；如已保存全文，可用于进一步阅读。
Summary based on the inspected indexed author abstract; archived full text, when available, is provided for further reading.

Key findings / 主要发现
文昌鱼额眼细胞表达与脊椎动物视网膜相似的光感受器转录因子、视蛋白和 Gi 型信号组分。相邻色素细胞的黑色素及调控特征与视网膜色素上皮相似，神经投射也呈现基础感光—运动回路的特征。
Amphioxus frontal-eye cells express photoreceptor transcription factors, opsins and a Gi-type signaling component resembling vertebrate retinal cells. Adjacent pigment cells share melanin and regulatory signatures with retinal pigment epithelium, and their neural projections resemble a basic photosensory–motor circuit.

Conclusions / 结论
结果支持文昌鱼额眼细胞与脊椎动物视网膜光感受器及色素细胞同源，为脊索动物祖先视觉系统提供分子证据。
The findings support homology between amphioxus frontal-eye cell types and vertebrate retinal photoreceptors and pigment cells, providing molecular evidence for an ancestral chordate visual system.

Relevance / 关联说明
直接研究清单物种，或研究广义类群中的代表物种。
Direct research on the listed species or a representative of the broadly named group.