Fluorescent Detection of Fluid Phase Endocytosis Allows for In Vivo Estimation of Endocytic Vesicle Sizes in Plant Cells with Sub-Diffraction Accuracy

Using the bright, photostable, charged and hydrophilic fluorescent dye Alexa 488 hydrazide to label the fluid phase around intact guard cells, we show that these cells incorporate the fluid phase during constitutive endocytosis against the high turgor. Mobile, cortical and diffraction-limited signals were not observed if a concentration