Mercuric chloride acting through Mg stimulates protein synthesis in Xenopus oocytes

In Xenopus laevis oocytes, addition of HgCl2 (Hg) to the medium rapidly stimulated incorporation of [35S]methionine (MET) into protein, increasing incorporation up to five-fold over control values. The action of inorganic mercury persisted after removal of Hg. Microinjection of HgCl2 into oocytes maintained in buffer also increased MET incorporation. However, no such stimulation was found when Hg was microinjected into oocytes maintained under oil, suggesting that Hg action was dependent on a cell-medium interaction. Removing medium Mg2+ decreased insulin- and Hg-stimulated methionine incorporation. Increasing medium Mg2+ from 1 mM to 10 mM increased Hg-stimulated methionine incorporation twofold. Hypotonic swelling of oocytes stimulated hexose transport but inhibited protein synthesis. Together these data indicate that inorganic mercury activates translation in the oocyte through an Mg-dependent mechanism, possibly increased Mg2+ influx.