Fachbereich Physik, Universität Konstanz, Universitätstrasse 10, Fach 688, 78457 Konstanz, Germany.
Mech Dev. 2009 Dec;126(11-12):942-9. doi: 10.1016/j.mod.2009.09.002. Epub 2009 Sep 11.
Morphogenesis, the process by which all complex biological structures are formed, is driven by an intricate interplay between genes, growth, as well as intra- and intercellular forces. While the expression of different genes changes the mechanical properties and shapes of cells, growth exerts forces in response to which tissues, organs and more complex structures are shaped. This is exemplified by a number of recent findings for instance in meristem formation in Arabidopsis and tracheal tube formation in Drosophila. However, growth not only generates forces, mechanical forces can also have an effect on growth rates, as is seen in mammalian tissues or bone growth. In fact, mechanical forces can influence the expression levels of patterning genes, allowing control of morphogenesis via mechanical feedback. In order to study the connections between mechanical stress, growth control and morphogenesis, information about the distribution of stress in a tissue is invaluable. Here, we applied stress-birefringence to the wing imaginal disc of Drosophila melanogaster, a commonly used model system for organ growth and patterning, in order to assess the stress distribution present in this tissue. For this purpose, stress-related differences in retardance are measured using a custom-built optical set-up. Applying this method, we found that the stresses are inhomogeneously distributed in the wing disc, with maximum compression in the centre of the wing pouch. This compression increases with wing disc size, showing that mechanical forces vary with the age of the tissue. These results are discussed in light of recent models proposing mechanical regulation of wing disc growth.
形态发生是指所有复杂生物结构形成的过程，它是由基因、生长以及细胞内和细胞间力之间复杂的相互作用所驱动的。虽然不同基因的表达会改变细胞的力学性质和形状，但生长会产生响应这些力的力，从而塑造组织、器官和更复杂的结构。最近在拟南芥分生组织形成和果蝇气管管形成等方面的一些发现就是这方面的例证。然而，生长不仅会产生力，机械力也会对生长速度产生影响，这在哺乳动物组织或骨生长中可以看到。事实上，机械力可以影响模式基因的表达水平，从而通过机械反馈来控制形态发生。为了研究机械应力、生长控制和形态发生之间的联系，了解组织内的应力分布信息是非常宝贵的。在这里，我们应用双折射法研究了黑腹果蝇的翅 imaginal 盘，这是一个常用于器官生长和模式形成的模型系统，以评估该组织中存在的应力分布。为此，我们使用定制的光学装置测量了与应力相关的延迟差异。通过应用这种方法，我们发现应力在翅盘内不均匀分布，在翅囊的中心有最大的压缩。这种压缩随着翅盘的大小而增加，表明机械力随组织的年龄而变化。这些结果与最近提出的机械调节翅盘生长的模型进行了讨论。
