Ungerer Petra, Scholtz Gerhard
Institut für Biologie/Vergleichende Zoologie, Humboldt-Universität zu Berlin, Philippstrasse 13, 10115 Berlin, Germany.
Proc Biol Sci. 2008 Feb 22;275(1633):369-76. doi: 10.1098/rspb.2007.1391.
The complex spatio-temporal patterns of development and anatomy of nervous systems play a key role in our understanding of arthropod evolution. However, the degree of resolution of neural processes is not always detailed enough to claim homology between arthropod groups. One example is neural precursors and their progeny in crustaceans and insects. Pioneer neurons of crustaceans and insects show some similarities that indicate homology. In contrast, the differentiation of insect and crustacean neuroblasts (NBs) shows profound differences and their homology is controversial. For Drosophila and grasshoppers, the complete lineage of several NBs up to formation of pioneer neurons is known. Apart from data on median NBs no comparable results exist for Crustacea. Accordingly, it is not clear where the crustacean pioneer neurons come from and whether there are NBs lateral to the midline homologous to those of insects. To fill this gap, individual NBs in the ventral neuroectoderm of the crustacean Orchestia cavimana were labelled in vivo with a fluorescent dye. A partial neuroblast map was established and for the first time lineages from individual NBs to identified pioneer neurons were established in a crustacean. Our data strongly suggest homology of NBs and their lineages, providing further evidence for a close insect-crustacean relationship.
神经系统发育和解剖结构复杂的时空模式在我们对节肢动物进化的理解中起着关键作用。然而，神经过程的解析程度并不总是足够详细，无法确定节肢动物类群之间的同源性。一个例子是甲壳类动物和昆虫中的神经前体及其后代。甲壳类动物和昆虫的先驱神经元显示出一些相似性，表明存在同源性。相比之下，昆虫和甲壳类动物神经母细胞（NBs）的分化显示出深刻的差异，它们的同源性存在争议。对于果蝇和蚱蜢，已知几个神经母细胞直至先驱神经元形成的完整谱系。除了关于中神经母细胞的数据外，甲壳纲动物没有可比的结果。因此，尚不清楚甲壳类动物的先驱神经元来自何处，以及中线外侧是否存在与昆虫同源的神经母细胞。为了填补这一空白，用荧光染料在体内标记了甲壳类动物卡氏跳钩虾腹侧神经外胚层中的单个神经母细胞。建立了部分神经母细胞图谱，并首次在甲壳类动物中建立了从单个神经母细胞到已鉴定的先驱神经元的谱系。我们的数据有力地表明了神经母细胞及其谱系的同源性，为昆虫与甲壳类动物的密切关系提供了进一步的证据。
