Morokuma Junji, Ueno Motoko, Kawanishi Hiroshi, Saiga Hidetoshi, Nishida Hiroki
Department of Biological Sciences, Tokyo Institute of Technology, Nagatsuta, Yokohama 226-8501, Japan.
Dev Genes Evol. 2002 Oct;212(9):439-46. doi: 10.1007/s00427-002-0242-3. Epub 2002 Sep 4.
The nodal-related genes are well known for their fundamental roles during vertebrate development, including mesoderm induction, neural induction, and left-right axis formation, as several nodal-related genes show left-sided expression in mesodermal lineages. We have isolated the first non-vertebrate nodal-related gene, HrNodal, from the ascidian Halocynthia roretzi. During the late cleavage and gastrula stages, HrNodal is transiently and bilaterally expressed in several different cell lineages. Expression at the tailbud stage is observed asymmetrically in the left side, but unexpectedly only in the epidermis of the embryo. We also demonstrate the relationship of HrNodal with HrPitx, a Halocynthia homologue of the Pitx2 gene. HrNodal overexpression results in the disturbance of left-sided HrPitx expression. Our results demonstrate that left-right specification during ascidian embryogenesis involves the HrNodal gene, and that the left-sidedness of the expression is evolutionarily conserved throughout the chordate clade.
结节相关基因因其在脊椎动物发育过程中的重要作用而闻名，这些作用包括中胚层诱导、神经诱导和左右轴形成，因为一些结节相关基因在中胚层谱系中呈左侧表达。我们从海鞘罗式海鞘中分离出了首个非脊椎动物结节相关基因HrNodal。在晚期卵裂和原肠胚阶段，HrNodal在几个不同的细胞谱系中短暂且双侧表达。在尾芽阶段，在左侧观察到不对称表达，但出乎意料的是仅在胚胎的表皮中表达。我们还证明了HrNodal与HrPitx（Pitx2基因的海鞘同源物）之间的关系。HrNodal的过表达导致左侧HrPitx表达紊乱。我们的结果表明，海鞘胚胎发生过程中的左右不对称决定涉及HrNodal基因，并且表达的左侧性在整个脊索动物类群中在进化上是保守的。
