Expression of the genes Emx1, Tbr1, and Eomes (Tbr2) in the telencephalon of Xenopus laevis confirms the existence of a ventral pallial division in all tetrapods
Expression of the genes Emx1, Tbr1, and Eomes (Tbr2) in the telencephalon of Xenopus laevis confirms the existence of a ventral pallial division in all tetrapods
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DOI：
10.1002/cne.20152
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发表时间：
2004-07-05
影响因子：
2.5
通讯作者：
Medina, L
中科院分区：
文献类型：
--
作者：
Brox, A;Puelles, L;Medina, L
为了研究两栖动物的白质组织以及腹侧白质的确切位置和延伸，我们克隆了一段同源盒形爪蟾Tbr1 （xTbr1）基因片段，并将其与爪蟾胚胎和幼虫发育过程中端脑的xEomes （Tbr2）和xEmx1基因的表达进行了比较。xEmx1在成年蛙中的表达也进行了分析。我们将这些白质标记基因与白质下基因xDistal-less-4 （xDll4）的表达模式进行了比较。我们的研究结果表明，在胚胎和幼体发育过程中，非洲爪蟾的整个苍白膜都表达T-box基因xTbr1和xEomes（在增殖细胞和/或套膜中），这些基因的表达与苍白膜下xDll4的表达在地形上是互补的。除了在白质中大量表达外，xTbr1和xEomes还在少数分散的白质下细胞中表达，这可能代表了白质起源的移民细胞，因为这些基因在白质下增殖细胞中没有发现。另一方面，在发育过程中，xEmx1在大部分白质（增殖细胞和有丝分裂后细胞）中表达，除了白质-白质下边界附近的区域，在那里仅在一些套细胞中观察到xEmx1。这一苍白区缺乏xEmx1和苍白质下基因xDll4的表达，但表达苍白质标记基因xTbr1和xEomes，似乎代表了两栖动物的腹侧苍白质，与其他脊椎动物相似（Puelles et al. [2000] J. Comp. Neurol. 424:409-438）。在成年蛙中，腹侧侧皮层似乎包括外侧杏仁核的吻侧部分以及内侧杏仁核的大部分（如Marin et al. [1998] J. Comp. Neurol. 392:285-312）。相反，之前被称为外侧杏仁核的尾侧部分显示出强烈的xEmx1表达，可能是外侧苍白的衍生物。讨论了这些两栖动物杏仁核可能的同源性。最后，xTbr1、xEomes和xEmx1的表达在早期发育阶段的嗅球二尖瓣细胞层中被观察到，进一步支持该结构是一个pallial衍生物。(C) 2004 Wiley-Liss, Inc。
To investigate the pallial organization and the exact location and extension of the ventral pallium in amphibians, we cloned a fragment of the homeobox Xenopus Tbr1 (xTbr1) gene and analyzed its expression compared with that of the genes xEomes (Tbr2) and xEmx1 in the telencephalon of the frog Xenopus laevis during embryonic and larval development. The expression of xEmx1 was also analyzed in the adult frog. We compared the expression patterns of these pallial marker genes with that of the subpallial gene xDistal-less-4 (xDll4). Our results indicate that the whole pallium of Xenopus expresses the T-box genes xTbr1 and xEomes (in proliferating cells and/or mantle) during embryonic and larval development, and the expression of these genes is topographically complementary to that of xDll4 in the subpallium. In addition to their massive expression in the pallium, both xTbr1 and xEomes are expressed in a few dispersed cells in the subpallium, which may represent immigrant cells of pallial origin, because these genes are not found in the subpallial proliferating cells. On the other hand, during development xEmx1 is expressed in a large part of the pallium (proliferating and postmitotic cells) except for an area adjacent to the pallio-subpallial boundary, where xEmx1 is observed only in some mantle cells. This pallial area poor in xEmx1 expression and poor in expression of the subpallial gene xDll4, but expressing the pallial marker genes xTbr1 and xEomes, appears to represent the amphibian ventral pallium, comparable to that described in other vertebrates (Puelles et al. [2000] J. Comp. Neurol. 424:409-438). In the adult frog, the ventral pallium appears to include the rostral part of the lateral amygdalar nucleus as well as a large part of the medial amygdalar nucleus (as defined by Marin et al. [1998] J. Comp. Neurol. 392:285-312). In contrast, the caudal part of the previously termed lateral amygdalar nucleus shows strong xEmx1 expression and may be a lateral pallial derivative. The possible homology of these amphibian amygdalar nuclei is discussed. Finally, expression of xTbr1, xEomes, and xEmx1 is observed in the mitral cell layer of the olfactory bulb from early developmental stages, further supporting that this structure is a pallial derivative. (C) 2004 Wiley-Liss, Inc.