Javois L C, Bode P M, Bode H R
Department of Biology, Catholic University of America, Washington, D.C. 20064.
Dev Biol. 1988 Oct;129(2):390-9. doi: 10.1016/0012-1606(88)90386-7.
The body column of hydra is polarized such that a new head will regenerate from the apical end when both extremities are removed. This is due to a graded property of the tissue termed the head activation gradient. The aim of the experiments presented here was to determine what events connect a two-dimensional segment of the activation gradient in an isolated piece of tissue with the formation of a head structure at a particular location. To this end, tissue pieces with three different shapes were excised and analyzed during and after regeneration. The most apical tissue of each piece was labeled with the DNA-intercalating dye, DAPI, and the area where developmental changes were occurring was monitored using the monoclonal antibody CP8 (Javois et al., 1986). First, it was shown that polarity of regeneration was maintained regardless of the fraction of body length included in the excised pieces. Second, while head structures usually formed from the original apical tissue, they could be located anywhere in the regenerate. This was an effect of the healing process which shaped the apical edge differently in different pieces. Third, early CP8 binding occurred in similarly shaped areas suggesting that patterning events were initiated in a contiguous manner wherever apical tissue was located. And finally, not all of the CP8-marked tissue successfully formed structures. Apparently some regions were favored to continue the patterning process, and these in turn extinguished the process in neighboring regions.
水螅的体柱是极化的，以至于当两端都被切除时，新的头部会从顶端再生。这是由于一种被称为头部激活梯度的组织分级特性。本文所呈现实验的目的是确定在一块分离的组织中，激活梯度的二维片段与特定位置头部结构形成之间有哪些事件相联系。为此，切除了三种不同形状的组织块，并在再生过程中和再生后进行分析。每块组织最顶端的组织用DNA嵌入染料DAPI标记，并用单克隆抗体CP8监测发生发育变化的区域（Javois等人，1986年）。首先，结果表明，无论切除组织块中包含的体长比例如何，再生的极性都得以维持。其次，虽然头部结构通常由原来的顶端组织形成，但它们可以位于再生体的任何位置。这是愈合过程的一种效应，在不同的组织块中，顶端边缘的形状有所不同。第三，早期CP8结合发生在形状相似的区域，这表明无论顶端组织位于何处，模式形成事件都是以连续的方式启动的。最后，并非所有CP8标记的组织都成功形成结构。显然，一些区域更有利于继续模式形成过程，而这些区域反过来又会终止相邻区域的这一过程。
