Reaction-diffusion microtubule concentration patterns occur during biological morphogenesis

Reaction-diffusion processes can lead to a macroscopic concentration patter n from an initially homogeneous solution, and thus provide a physical-chemi cal mechanism for biological pattern formation and morphogenesis. The centr al prediction of reaction-diffusion theory is that the patterns contain per iodic concentration variations in some of the reactives. Microtubules assem bled in vitro spontaneously self-organise and form stationary striped macro scopic structures. In agreement with reaction-diffusion theory. Here we sho w, in agreement with reaction-diffusion theory, that these preparations con tain substantial microtubule concentration variations. Similar striped micr otubule patterns arise during Drosophila embryogenesis. A characteristic of these patterns is their dependence on sample dimensions. In Drosophila egg s shortened by ligation, we found that thr microtubule pattern varied with egg fragment length in the same way as the in vitro microtubule pattern var ied with sample length, and as expected from theory. This is evidence that reaction-diffusion structures occur during Drosophila morphogenesis. (C) 19 99 Elsevier Science B.V. All rights reserved.