The homeobox transcription factor Caudal has conserved roles in all Bilateria in defining the posterior pole and in controlling posterior elongation. These roles are seemingly similar and are difficult to disentangle. We have carried out a detailed analysis of the expression, function and interactions of the caudal ortholog of the milkweed bug, Oncopeltus fasciatus, a hemimetabolous insect with a conservative early development process, in order to understand its different functions throughout development. In Oncopeltus, caudal is not maternally deposited, but has a sequence of roles in the posterior of the embryos throughout early development. It defines and maintains a posterior-anterior gradient in the blastoderm and modulates the activity of segmentation genes in simultaneous segmentation during the blastoderm stage. It later defines the invagination site and the posterior segment addition zone (SAZ) in the germband. It maintains the posterior SAZ cells in an undifferentiated proliferative state, while promoting dynamic expression of segmentation genes in the anterior SAZ. We show that rather than being a simple posterior determinant, Caudal is involved in several distinct regulatory networks, each with a distinct developmental role.

同源盒转录因子Caudal在所有Bilateria中在定义后极和控制后延伸方面均具有保守作用。这些角色看似相似，很难分开。我们已经对乳草臭虫尾鳍直系同源基因Oncopeltus fasciatus的表达，功能和相互作用进行了详细分析，以了解其早期发育过程是保守的半代谢昆虫，以了解其在整个发育过程中的不同功能。在Oncopeltus，尾它不是母体沉积的，但在整个早期发育过程中在胚胎的后部具有一系列作用。它定义并维持胚盘中的前后梯度，并在胚盘阶段的同时分割中调节分割基因的活性。后来，它定义了种带中的内陷部位和后段附加区（SAZ）。它使后SAZ细胞保持未分化的增殖状态，同时促进前SAZ中分割基因的动态表达。我们表明，Caudal不是简单的后继决定因素，它参与了几个不同的监管网络，每个网络都具有不同的发展作用。