Hotta Kohji, Yamada Shigehiro, Ueno Naoto, Satoh Nori, Takahashi Hiroki
Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan.
Dev Growth Differ. 2007 Jun;49(5):373-82. doi: 10.1111/j.1440-169X.2007.00935.x.
Formation of the chordate body is accomplished by a complex set of morphogenetic movements including convergent extension of notochord cells. In the ascidian Ciona intestinalis, Brachyury plays a key role in the formation of the notochord, and more than 30 Bra-downstream notochord genes have been identified. In the present study, we examined the effects of functional suppression of nine Bra-downstream notochord genes, which include Ci-PTP, Ci-ACL, Ci-prickle, Ci-netrin, Ci-trop, Ci-Noto3, Ci-ASAK, Ci-ERM and Ci-pellino. When the function of the first two genes (Ci-PTP and Ci-ACL) was suppressed with specific morpholinos, the notochord cells failed to converge, while functional suppression of Ci-prickle resulted in a failure of intercalation, and therefore the cells in these three types of embryo remained in the mid-dorsal region of the embryo. Functional suppression of the next four genes (Ci-netrin, Ci-trop, Ci-Noto3 and Ci-ASAK) resulted in the partial defect of intercalation, and the notochord did not consist of a single row. In addition, when the function of the last two genes (Ci-ERM and Ci-pellino) was suppressed, notochord cells failed to elongate in the embryo, even though convergence/extension took place normally. These results indicate that many Bra-downstream notochord genes are involved in convergence/extension of the embryo.
脊索动物身体的形成是通过一系列复杂的形态发生运动完成的，包括脊索细胞的汇聚延伸。在海鞘Ciona intestinalis中，Brachyury在脊索的形成中起关键作用，并且已经鉴定出30多个Brachyury下游的脊索基因。在本研究中，我们检测了9个Brachyury下游脊索基因功能抑制的影响，这些基因包括Ci-PTP、Ci-ACL、Ci-prickle、Ci-netrin、Ci-trop、Ci-Noto3、Ci-ASAK、Ci-ERM和Ci-pellino。当用特异性吗啉代寡核苷酸抑制前两个基因（Ci-PTP和Ci-ACL）的功能时，脊索细胞无法汇聚，而Ci-prickle功能抑制导致插入失败，因此这三种类型胚胎中的细胞停留在胚胎的中背部区域。接下来四个基因（Ci-netrin、Ci-trop、Ci-Noto3和Ci-ASAK）的功能抑制导致插入部分缺陷，脊索不是由单列组成。此外，当抑制最后两个基因（Ci-ERM和Ci-pellino）的功能时，尽管汇聚/延伸正常发生，但胚胎中的脊索细胞未能伸长。这些结果表明，许多Brachyury下游的脊索基因参与胚胎的汇聚/延伸。
