Micromanipulation of chloroplasts using optical tweezers

This paper describes experiments using optical tweezers to probe chloroplas t arrangement, shape and consistency in cells of living leaf tissue and in suspension. Dual optical tweezers provided two-point contact on a single ch loroplast or two-point contact on two adhered chloroplasts for manipulation in suspension. Alternatively, a microstirrer consisting of a birefringent particle trapped in an elliptically polarized laser trap was used to induce motion and tumbling of a selected chloroplast suspended in a solution. We demonstrate that displacement of chloroplasts inside the cell is extremely difficult. presumably due to chloroplast adhesion to the cytoskeleton and c onnections between organelles. The study also confirms that the chloroplasts are very thin and extremely c up-shaped with a concave inner surface and a convex outer surface.