Pitx homeobox genes in Ciona and amphioxus show left-right asymmetry is a conserved chordate character and define the ascidian adenohypophysis
Pitx homeobox genes in Ciona and amphioxus show left-right asymmetry is a conserved chordate character and define the ascidian adenohypophysis
复制标题
DOI：
10.1046/j.1525-142x.2002.02021.x
复制
发表时间：
2002-09-01
影响因子：
2.9
通讯作者：
Shimeld, SM
中科院分区：
文献类型：
--
作者：
Boorman, CJ;Shimeld, SM
所有的脊椎动物在其内部器官的组织中都具有方向不对称性。在有颌脊椎动物中，不对称性的发育是由一个保守的分子途径控制的，其中包括Pitx2，它由胚胎左侧的侧板中胚层细胞表达。Pitx 2是Pitx同源框基因家族的成员，其表达也标志着口膜外胚层和腺垂体。在这里，我们报告的Pitx基因的特征Branchiostoma floridae（文昌鱼）和玻璃海鞘（urochordate），代表两个基础脊索动物谱系和脊椎动物的更深的外类群。B的表达。floridae Pitx与B报道的相似。belcheri，一种不同的文昌鱼。玻璃海鞘的直系同源物在胚胎原始咽和成人神经复合体的表达，使我们提出玻璃海鞘原始咽和纤毛漏斗是同源的腺垂体基板和腺垂体，分别。此外，在这两个物种中，我们确定不对称的左侧表达Pitx基因在胚胎发育过程中。这表明，不对称的Pitx基因表达，并推断方向不对称，生活脊索动物的辐射之前，应被视为脊索动物的字符。
All vertebrates have directional asymmetries in the organization of their internal organs. In jawed vertebrates, development of asymmetry is controlled by a conserved molecular pathway that includes Pitx2 , which is expressed by lateral plate mesoderm cells on the left side of the embryo. Pitx2 is a member of the Pitx homeobox gene family, the expression of which also marks stomodeal ectoderm and the adenohypophysis. Here we report the characterization of Pitx genes from Branchiostoma floridae (an amphioxus) and Ciona intestinalis (a urochordate), representatives of two basal chordate lineages and successively deeper outgroups to the vertebrates. Expression of B. floridae Pitx is similar to that reported from B. belcheri , a different amphioxus species. Expression of the Ciona Pitx ortholog in the embryonic primordial pharynx and adult neural complex leads us to propose the Ciona primordial pharynx and ciliated funnel are homologous to the adenohypophyseal placode and adenohypophysis, respectively. Additionally, in both species we identify asymmetrical left-sided expression of Pitx genes during embryonic development. This shows that asymmetrical Pitx gene expression, and by inference directional asymmetry, evolved before the radiation of living chordates and should be considered a chordate character.