Brachyury (T) expression in embryos of a Larvacean Urochordate, Oikopleura dioica, and the ancestral role of T
Brachyury (T) expression in embryos of a Larvacean Urochordate, Oikopleura dioica, and the ancestral role of T
复制标题
DOI：
10.1006/dbio.2000.9647
复制
发表时间：
2000-04-15
影响因子：
2.7
通讯作者：
Postlethwait, J
中科院分区：
文献类型：
--
作者：
Bassham, S;Postlethwait, J
Brachyury或T基因是所有三个脊索亚门动物脊索发育所需的，并且可能在脊索谱系的最后共同祖先中也具有这种作用。在两个脊索动物亚门（脊椎动物和头索动物）中，T也在退化的内胚层和中胚层细胞的原肠胚形成期间表达，并且至少在脊椎动物中，该表达结构域是正常发育所必需的。在基本分歧的脊索动物亚门尾索动物，动物纲Ascidiacea不采用T在原肠胚形成期间在内胚层或非轴向中胚层细胞，它已被建议，nonnotochordal作用的T收购后，头索动物脊椎动物谱系分裂尾索动物。为了验证这一假设，我们克隆T从Oikopleura dioica，一个成员的urochordate类Aphellularia（或幼虫），其中分歧的亚门。在发展中的Oikopleura胚胎的表达模式的调查显示，在推定的脊索前体细胞，脊索，并在部分发展中的肠道和细胞的内胚层链的早期表达。我们的结论是，祖先的作用T可能包括在发展中的肠道表达，并成为必要的脊索动物的建设脊索。(C)北京大学出版社.
The Brachyury, or T, gene is required for notochord development in animals occupying all three chordate subphyla and probably also had this role in the last common ancestor of the chordate lineages. In two chordate subphyla (vertebrates and cephalochordates), T is also expressed during gastrulation in involuting endodermal and mesodermal cells, and in vertebrates at least, this expression domain is required for proper development. In the basally diverging chordate subphylum Urochordata, animals in the class Ascidiacea do not employ T during gastrulation in endodermal or nonaxial mesodermal cells, and it has been suggested that nonnotochordal roles for T were acquired in the cephalochordate-vertebrate lineage after it split with Urochordata. To test this hypothesis, we cloned T from Oikopleura dioica, a member of the urochordate class Appendicularia (or Larvacea), which diverged basally in the subphylum. Investigation of the expression pattern in developing Oikopleura embryos showed early expression in presumptive notochord precursor cells, in the notochord, and in parts of the developing gut and cells of the endodermal strand. We conclude that the ancestral role of T likely included expression in the developing gut and became necessary in chordates for construction of the notochord. (C) 2000 Academic Press.