Ichijo Hiroyuki, Toyama Tomoko
Department of Anatomy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama, 930-0194, Japan,
Anat Sci Int. 2015 Sep;90(4):229-34. doi: 10.1007/s12565-014-0252-z. Epub 2014 Aug 22.
We generated transgenic mice lines with a construct consisting of the zif268/egr1 promoter and the gene for the normal long-life yellow fluorescent protein (Venus) with a membrane localization sequence. One of the lines exhibited topographic labeling in the medial habenular nucleus (MHb) during postnatal development, which confirmed the previous findings that the medial, lateral, and dorsal areas of MHb project to the ventral, dorsal, and lateral parts of the interpeduncular nucleus, respectively. In addition, the membranous localization of the labeling allowed us to observe spacial arrangement of the labeled axons in the fasciculus retroflexus (FR) in the transgenic mice. Here, we report topographic sorting of the MHb axons in the FR. At postnatal day (P) 5 and P10, the labeled axons from the medial MHb were fasciculated and ran through the narrow path in the core of the FR. At P24, the labeled axons from the medial and dorsal MHb were fasciculated and ran through the broad path in the FR core. No labeling occurred in the lateral MHb throughout development; correspondingly, parts of the FR core remained unlabeled. The results indicated that the axons from the medial and dorsal areas of the MHb are grouped together in the FR of this transgenic line and are sorted out from the axons from the lateral MHb.
我们构建了一种转基因小鼠品系，其携带由zif268/egr1启动子和带有膜定位序列的正常长寿命黄色荧光蛋白（金星）基因组成的构建体。其中一个品系在出生后发育过程中在内侧缰核（MHb）表现出拓扑标记，这证实了先前的研究结果，即MHb的内侧、外侧和背侧区域分别投射到脚间核的腹侧、背侧和外侧部分。此外，标记的膜定位使我们能够观察转基因小鼠中标记轴突在缰核束（FR）中的空间排列。在此，我们报告了FR中MHb轴突的拓扑分选情况。在出生后第（P）5天和P10天，来自内侧MHb的标记轴突成束，并穿过FR核心的狭窄路径。在P24时，来自内侧和背侧MHb的标记轴突成束，并穿过FR核心的宽阔路径。在整个发育过程中，外侧MHb均未出现标记；相应地，FR核心的部分区域仍未标记。结果表明，该转基因品系中，来自MHb内侧和背侧区域的轴突在FR中聚集在一起，并与来自外侧MHb的轴突分选开来。
