CHARGE DEPENDENT DISTRIBUTION OF ENDOGENOUS PROTEINS WITHIN VITELLOGENIC OVARIAN FOLLICLES OF ACTIAS-LUNA

In vitellogenic ovarian follicles of Actis luna, internal Ca2+ activit y currents create an electrical gradient which influences the distribu tion of charged macromolecules between nurse cells and oocyte, We show that, between oocyte and nurse cells, there is an ionic gradient of 1 -12 mV with the nurse cells being more electronegative than the oocyte by an average 3.5+/-0.2 mV(s.e.)(p<0.001). As previously reported for another saturniid, Hyalophora cecropia, the transbridge ionic gradien t of luna: (1) is focused across the intercellular bridges, (2) is abo lished by 200 mu M vanadate and (3) includes a [Ca2+](i) gradient. End ogenous soluble proteins collected from control and from vanadate trea ted populations of nurse cells and oocytes were separated by two-dimen sional (2-D) gel electrophoresis and visualized with sliver stain, Den sitometric analysis showed that 14 out of the 19 acidic proteins and s ix of the eight basic proteins studied, changed their oocyte-to-nurse cell distribution in consort with change in the transbridge ionic grad ient, This suggests that a transbridge ionic gradient may be, at least within the saturniidae, a method for maintaining different molecular concentrations in nurse cells compared to oocytes. (C) 1997 Elsevier S cience Ltd.