School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, UK.
Arthropod Struct Dev. 2010 Nov;39(6):478-90. doi: 10.1016/j.asd.2010.07.005.
The phylogenetic position of onychophorans is still being debated; however, most phylogenies suggest that onychophorans are a sister group to the arthropods. Here we have analysed neurogenesis in the brain of the onychophoran Euperipatoides kanangrensis. We show that the development of the onychophoran brain is considerably different from arthropods. Neural precursors seem to be generated at random positions rather than in distinct spatio-temporal domains as has been shown in insects and chelicerates. The different mode of neural precursor formation is reflected in the homogenous expression of the proneural and neurogenic genes. Furthermore, the morphogenetic events that generate the three-dimensional structure of the onychophoran brain are significantly different from arthropods. Despite the different mode of neural precursor formation in insects and chelicerates (neuroblasts versus neural precursor groups), brain neurogenesis shares more similarities in these arthropods as compared to the onychophoran. Our data show that the developmental processes that generate the brain have considerably diverged in onychophorans and arthropods.
有爪动物的系统发育位置仍存在争议；然而，大多数系统发育树表明有爪动物是节肢动物的姊妹群。在这里，我们分析了有爪动物 Euperipatoides kanangrensis 大脑中的神经发生。我们表明，有爪动物大脑的发育与节肢动物有很大的不同。神经前体细胞似乎是随机产生的，而不是像在昆虫和螯肢动物中那样在特定的时空域产生。神经前体细胞形成的不同模式反映在神经前体细胞和神经发生基因的均匀表达上。此外，生成有爪动物大脑三维结构的形态发生事件与节肢动物有显著差异。尽管昆虫和螯肢动物的神经前体细胞形成模式不同（神经母细胞与神经前体细胞群），但与有爪动物相比，这些节肢动物的脑神经发生具有更多的相似之处。我们的数据表明，生成大脑的发育过程在有爪动物和节肢动物中已经有了很大的分歧。
