Holland Linda Z, Holland Nicholas D
Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States.
Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States.
Curr Top Dev Biol. 2022;147:563-594. doi: 10.1016/bs.ctdb.2021.12.011. Epub 2022 Feb 16.
Amphioxus (cepholochordates) have long been used to infer how the vertebrates evolved from their invertebrate ancestors. However, some of the body part homologies between amphioxus and vertebrates have been controversial. This is not surprising as the amphioxus and vertebrate lineages separated half a billion years ago-plenty of time for independent loss and independent gain of features. The development of new techniques in the late 20th and early 21st centuries including transmission electron microscopy and serial blockface scanning electron microscopy in combination with in situ hybridization and immunocytochemistry to reveal spatio-temporal patterns of gene expression and gene products have greatly strengthened inference of some homologies (like those between regions of the central nervous system), although others (like nephridia) still need further support. These major advances in establishing homologies between amphioxus and vertebrates, together with strong support from comparative genomics, have firmly established amphioxus as a stand-in or model for the ancestral vertebrate.
文昌鱼（头索动物）长期以来一直被用于推断脊椎动物是如何从其无脊椎动物祖先进化而来的。然而，文昌鱼和脊椎动物之间的一些身体部位同源性一直存在争议。这并不奇怪，因为文昌鱼和脊椎动物的谱系在5亿年前就分开了——有足够的时间让特征独立丧失和独立获得。20世纪末和21世纪初新技术的发展，包括透射电子显微镜和连续块面扫描电子显微镜，结合原位杂交和免疫细胞化学来揭示基因表达和基因产物的时空模式，极大地加强了对一些同源性的推断（如中枢神经系统区域之间的同源性），尽管其他一些同源性（如肾管）仍需要进一步的支持。在确立文昌鱼和脊椎动物之间同源性方面的这些重大进展，加上比较基因组学的有力支持，已牢固地确立文昌鱼作为原始脊椎动物的替身或模型。
