CELL DIVISION INHIBITION OF ARBACIA AND CHAETOPTERUS EGGS AND ITS REVERSAL BY KREBS CYCLE INTERMEDIATES AND CERTAIN PHOSPHATE COMPOUNDS ,

Abstract

Division of Arbacia eggs was inhibited by low oxygen tension, cyanide, azide, dinitrophenol (DNP) and malonate. Various high and low energy phosphate compounds, and succinate and fumarate were added to the inhibited eggs. The results were extended to malonate-inhibited Chaetopterus eggs and the effects of succinate and fumarate were noted. 1. Addition of 10^-5 to 10^-4 M ATP completely reversed Arbacia egg division inhibition produced by cyanide and low oxygen tension. ATP incompletely reversed inhibitions caused by DNP and malonate. The maximum division stimulations were: with low oxygen tension and cyanide, division was increased from 50 per cent to 100 per cent of the control value; with 1.6 x 10^-5 M DNP, division was increased from 23 to 51 per cent; with 7.5 x 10^-2 M malonate, division was increased from 44 per cent to 71 per cent. With Chaetopterus eggs, the maximum stimulation obtained in the presence of 0.1 M malonate was from 28 per cent to 58 per cent of the control value. 2. Adenylic acid, hydrolyzed ATP, inorganic phosphate, and the ∼ P compounds, inorganic triphosphate and pyrophosphate, did not stimulate division of Arbacia eggs when inhibited by any of the above agents. 3. Division of Arbacia and Chaetopterus eggs was completely inhibited by 10^-1 to 10^-2 M malonate. The malonate effect was completely reversed, in both egg types, by the addition of 5.7 x 10^-2 M succinate or fumarate. 4. Azide inhibition was not relieved by added ATP or any of the other phosphorylated compounds tested. 5. These results suggest, in Arbacia and Chaetopterus eggs, that division is intimately related to a functioning Krebs cycle, the function of which cannot be completely accounted for on the basis of ∼ P production.