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Abstract：
In the early embryonic grasshopper, two pairs of sibling cells near the apex of the antenna pioneer its dorsal and ventral nerve tracts to the brain. En route, the growth cones of these pioneers contact a so-called base pioneer associated with each tract and which acts as a guidepost cell. Both apical and basal pioneers express stereotypic molecular labels allowing them to be uniquely identified. Although their developmental origins are largely understood, the fates of the respective pioneers remain unclear. We therefore employed the established cell death markers acridine orange and TUNEL to determine whether the apical and basal pioneers undergo apoptosis during embryogenesis. Our data reveal that the apical pioneers maintain a consistent molecular profile from their birth up to mid-embryogenesis, at which point the initial antennal nerve tracts to the brain have been established. Shortly after this the apical pioneers undergo apoptosis. Death occurs at a developmental stage similar to that reported elsewhere for pioneers in a leg - an homologous appendage. Base pioneers, by contrast, progressively change their molecular profile and can no longer be unequivocally identified after mid-embryogenesis. At no stage up to then do they exhibit death labels. If they persist, the base pioneers must be assumed to adopt a new role in the developing antennal nervous system.
摘要：
在早期胚胎蝗虫中，触角顶端附近的两对兄弟姐妹细胞将其背侧和腹侧神经束开辟到大脑。在途中，这些先驱者的生长锥接触与每个管道相关的所谓的基地先驱者，并充当路标单元。顶端和基础先驱都表达定型分子标记，从而可以对其进行唯一鉴定。虽然它们的发育起源在很大程度上被理解，各自先驱者的命运仍不清楚。因此，我们使用已建立的细胞死亡标记吖啶橙和TUNEL来确定顶端和基础先驱是否在胚胎发生过程中发生凋亡。我们的数据显示，根尖先驱从他们的出生到胚胎中期都保持着一致的分子谱，此时，已经建立了通往大脑的初始触角神经束。此后不久，根尖先驱者经历了凋亡。死亡发生在类似于其他地方报道的腿部先驱的发育阶段-同源附属物。基地先驱,相比之下,逐渐改变其分子谱，并且在胚胎中期发生后不再明确识别。到那时为止，他们没有表现出死亡标签。如果他们坚持,必须假定基础先驱在发育中的触角神经系统中扮演新角色。
