Tissue Clearing Reagents (Plant)

The reasons why biological tissues are opaque are due to the heterogeneity of the refractive index in vivo and the pigments contained in them that absorb light. In particular, the cell wall and cytoplasm of plant cells have different refractive indices, and thus illuminated light is refracted every time it passes through a cell. In addition, plants contain a large amount of chlorophyll, a pigment that absorbs light. To make plants transparent, it is necessary to make the refractive index of the whole plant uniform and to remove light-absorbing pigments (chlorophyll, etc.).

Warner and colleagues tried to make plants transparent using the Scale method, a tissue clearing method for animals, and reported that 1-3 weeks were required to make them transparent¹⁾. This was because chlorophyll, which is abundant in plants, could not be removed and inhibited the clearing. Therefore, effective removal of chlorophyll was necessary to make plants transparent more rapidly.

ClearSee™, developed by Dr. Daisuke Kurihara and colleagues at Nagoya University Graduate School, is a plant-clearing reagent that can effectively remove chlorophyll while maintaining the fluorescence of fluorescent proteins²⁾. ClearSee™ achieves the conservation of fluorescence of fluorescent proteins and the rapid removal of chlorophyll by screening compounds based on the composition of reagents used in the Scale method and using sodium deoxycholate as a surfactant.