Fig. 7. Vacuolar H⁺-ATPase specific activity levels in different yolk granule (YG) fractions during days 0 and 3 of development. LYGs and SYGs were submitted to membrane fraction separation and assayed for H⁺-ATPase activity. (A) Vacuolar H⁺-ATPase activity levels during days 0 and 3 of embryogenesis. White bars represent day 0 activities and gray bars represent day 3 activities. Values are means ± s.e.m. of 3 different experiments. To investigate the location of the H⁺-ATPase, YGs were incubated with AO in the presence of ATP during day 0 (B,C) and day 3 (D,E) of embryogenesis. Arrows indicate acidic SYGs and arrowheads indicate acidic LYGs. (B,D) DIC images; (C,E) corresponding fluorescence images. Scale bars, 25 µm.