Fig. 2. Sequential fluorescence images of an Ax2 cell with an extending protrusion induced by quinine. Cells had been stained with RH-795 10 minutes before quinine application. Time=0, 3.1, 6.2, 9.2, 15.4, 21.5, 27.7, 40.0 and 52.3 seconds from left to right. The estimated area of the apical membrane region with the fluorescence intensity higher than that of the original cell membrane was almost constant throughout the period of elongation. For this calculation, it was assumed that the protrusion is in the shape of a hemisphere attached to a cylinder and that the sections are on the horizontal median plane of the protrusion. In the presence of quinine, the difference in the fluorescence intensity between the contractile vacuole membrane and plasma membrane was usually not as large as without quinine, partly because the contractile vacuole membrane is integrated in the plasma membrane upon its expulsion, as shown here and Fig. 6C. Bar, 10 µm. Movies of this and other sequential images are available at http://www.biologists.com/JCS/movies/jcs1984.html).
