被称为“成形素”的某些分子的浓度梯度已知在胚胎形成过程中控制组织发育。这种梯度怎样形成是一个人们很不了解的问题,Yu等人对此进行了研究。他们采用一种用于在活体中对分子进行成像的先进的高精密度技术(荧光校正光谱)发现,活斑马鱼胚胎中的扩散性FGF8“成形素”梯度由一个简单的源-汇机制形成。(生物谷Bioon.com)
生物谷推荐原始出处:
Nature 461, 533-536 (24 September 2009) | doi:10.1038/nature08391
Fgf8 morphogen gradient forms by a source-sink mechanism with freely diffusing molecules
Shuizi Rachel Yu1,3,4, Markus Burkhardt2,3,4, Matthias Nowak1,3, Jonas Ries2,3, Zdenk Petráek2,3, Steffen Scholpp1,5, Petra Schwille2,3 & Michael Brand1,3
1 Developmental Genetics, Biotechnology Center, TUD,
2 Biophysics, Biotechnology Center, TUD, and,
3 Center for Regenerative Therapies, TUD, Tatzberg 47-49, 01307 Dresden, Germany
4 These authors contributed equally to this work.
5 Present address: Institute of Toxicology and Genetics, Forschungszentrum Karlsruhe, D-76021 Karlsruhe, Germany.
Correspondence to: Petra Schwille2,3Michael Brand1,3 Correspondence and requests for materials should be addressed to P.S. or M.Br.
It is widely accepted that tissue differentiation and morphogenesis in multicellular organisms are regulated by tightly controlled concentration gradients of morphogens1, 2. How exactly these gradients are formed, however, remains unclear3, 4, 5, 6, 7, 8, 9, 10, 11, 12. Here we show that Fgf8 morphogen gradients in living zebrafish embryos are established and maintained by two essential factors: fast, free diffusion of single molecules away from the source through extracellular space, and a sink function of the receiving cells, regulated by receptor-mediated endocytosis. Evidence is provided by directly examining single molecules of Fgf8 in living tissue by fluorescence correlation spectroscopy, quantifying their local mobility and concentration with high precision. By changing the degree of uptake of Fgf8 into its target cells, we are able to alter the shape of the Fgf8 gradient. Our results demonstrate that a freely diffusing morphogen can set up concentration gradients in a complex multicellular tissue by a simple source-sink mechanism.