A MODEL FOR PATTERN-FORMATION OF HYPOSTOME, TENTACLES, AND FOOT IN HYDRA - HOW TO FORM STRUCTURES CLOSE TO EACH OTHER, HOW TO FORM THEM AT A DISTANCE
A MODEL FOR PATTERN-FORMATION OF HYPOSTOME, TENTACLES, AND FOOT IN HYDRA - HOW TO FORM STRUCTURES CLOSE TO EACH OTHER, HOW TO FORM THEM AT A DISTANCE
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DOI：
10.1006/dbio.1993.1138
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发表时间：
1993-06-01
影响因子：
2.7
通讯作者：
MEINHARDT, H
中科院分区：
文献类型：
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作者：
MEINHARDT, H
提出了水螅头、触须和足的形成模型。该模型表明，系统，建议的位置信息计划可以实现一组分层耦合的模式形成系统：一个结构产生的先决条件，第二个结构，但不包括该结构本地。通过这种方式，实施了结构的良好调节的邻域。根据该模型，头部，肌腱和足部的形成是在单独的激活剂-抑制剂系统的控制下。这些系统通过源密度耦合。头部激活器增加源密度，并且激活优先发生在最高源密度的区域中。脚部激活具有相反的行为。它出现在最低的源密度，并进一步降低有效源密度。因此，头和脚的激活优先出现在场的相对位置。触手激活发生在没有被初级头部激活占据的最高源密度的区域。触手的激活需要一定的源密度阈值水平。正如计算机模拟所示，该模型解释了许多迄今无法解释的观察结果，例如在再生过程中，组织获得了触手样的特性，直到新形成的下口将触手转移到下口区域。由于头和脚之间没有直接的抑制，在实验情况下，这两个结构可以看起来彼此靠近。用甘油二酯处理的戏剧性效果，例如在形成额外的下口之前形成新的触角，在简单的假设下，该试剂增加了源密度，变得可以理解。萌芽被认为是第二个头部激活剂最大值的触发。由于头部抑制器，出芽只能发生在距头部的最小距离之外，并且发生在距脚部的最小距离之外，因为那里的源密度太低。该模型占的周期性间隔的次生结构周围的初级组织区域，如发现在安排的叶和花的元素在植物周围的初级分生组织。讨论了秀丽隐杆线虫外阴发育和昆虫分割的相似之处。
A model for head, tentacle, and foot formation in Hydra is proposed. The model shows that systems which suggest a positional information scheme may be realized by a set of hierarchically coupled pattern forming systems: a structure generates the precondition for a second structure but excludes this structure locally. In this way, a well-regulated neighborhood of structures is enforced. According to the model, head, tentacle, and foot formation are under the control of separate activator-inhibitor systems. These systems are coupled via the source density. The head activator increases the source density and the activation takes place preferentially in regions of highest source density. The foot activation has the opposite behavior. It appears at the lowest source density and lowers the effective source density further. Therefore, head and foot activation appear preferentially at opposite positions of the field. Tentacle activation occurs in the region of highest source density that is not occupied by a primary head activation. Tentacle activation requires a certain threshold level of the source density. As shown by computer simulations, the model accounts for many so far unexplained observations, such as during regeneration the tissue obtains tentacle-like properties until the newly formed hypostome displaces the tentacles into a subhypostomal region. Since no direct inhibition between head and foot is involved, both structures can appear close to each other in experimental situations. The dramatic effects of treatment with diacylglycerol, such as the formation of new tentacles preceding the formation of additional hypostomes, become understandable under the simple assumption that the agent increases the source density. Budding is regarded as a trigger of a second head activator maximum. Budding can occur only beyond a minimum distance from the head due to the head inhibitor and beyond a minimum distance from the foot since the source density would be too low there. The model accounts for the periodic spacing of secondary structures around a primary organizing region such as that found in the arrangement of leaves and flower elements in plants around the primary meristem. Similarities to the vulva development ofCaenorhabditis elegansand to the segmentation of insects are discussed.