Acidic vesicles and the uptake of amines by sea urchin eggs

The radioactive amine [14C]methylamine is accumulated to a great extent by eggs, with kinetics that are dependent upon temperature (Q10 = 5) and sensitive to metabolic inhibitors. Efflux of [14C]methylamine from eggs (preloaded with tracer concentrations) is increased immediately after fertilization or NH4Cl activation. Fluorescent amines (9-aminoacridine (9AA) and acridine orange (AO)) are concentrated in small intracellular compartments, presumably vesicles. The possible role of these vesicles in the accumulation of amines by sea urchin eggs and the activation of the metabolism that ensues is discussed.