https://phys.org/news/2018-10-importance-growth-factor-diffusion-sensory.html

A research team comprising Prof Holger KNAUT and Prof Eli ROTHENBERG from New York University, Prof Martin MEIER-SCHELLERSHEIM from National Institutes of Health and Prof Thorsten WOHLAND from the Departments of Biological Sciences and Chemistry, NUS have discovered that Anosmin1 regulates and enhances the FGF10 signalling mechanism during sensory organ formation in zebrafish models by facilitating its diffusion within developing tissues. From their findings, a potential hypothesis is that mutations in the Anos1 gene can cause a reduction in the signalling range of FGF10. This in turn leads to abnormal development causing Kallmann syndrome.

The team used fluorescence correlation spectroscopy (FCS), an analytical technique to measure the diffusion and interactions of fluorescence-tagged molecules in zebrafish embryos. FCS is able to quantify the diffusion coefficient of molecules by monitoring the fluctuations in fluorescence emitted by the molecules. Their FCS studies on the FGF10 molecules showed the presence of two different types of FGF10. One of them diffuses slowly while the other diffuses at a much faster rate. The slow-diffusing type is bound to the extracellular matrix (ECM) while the fast-diffusing type diffuses freely in the zebrafish embryo. Using a related technique, fluorescence cross-correlation spectroscopy (FCCS), the team showed that Anosmin1 diffused together with FGF10. This suggests that Anosmin1 liberates FGF10 from the ECM, thus increasing the number of freely diffusing FGF10. Through this mechanism, Anosmin1 increases the diffusivity and the signalling range of FGF10 for normal development of sensory organs in zebrafish.