THE EFFECTS OF SULFANILAMIDE AND AZIDE ON OXYGEN CONSUMPTION AND CELL DIVISION IN THE EGG OF THE SEA URCHIN, ARBACIA PUNCTULATA

¹ Marine Biological Laboratory, Woods Hole, Mass.

1. Sulfanilamide depresses the rate of cell division in the fertilized egg of the sea urchin, Arbacia punctulata, and simultaneously the rate of oxygen consumption is lowered. Complete suppression of division by this agent is associated with a 45% inhibition of oxygen consumption. Sulfanilamide does not inhibit oxygen consumption in the unfertilized egg.

2. Azide does not inhibit respiration in the unfertilized cells although it depresses both oxygen consumption and cell division in the fertilized egg. The maximum effect of azide in the latter case results in a lowering of the rate of oxygen consumption to approximately 50% of the normal value, and it is necessary to produce this maximum effect in order to stop cell division (data of Krahl et al).

3. When added to a preparation already maximally inhibited with azide, sulfanilamide cannot produce additional inhibition. Urethane, on the contrary, does depress further the respiration maximally inhibited by azide.

4. The effect of urethane on respiration in the presence of the maximum azide effect can be described by an expression of the mass law. The value of a in this equation is similar to that for the urethane inhibition of the respiration of the unfertilized egg, and to that deduced for the effect of urethane on the basal system of the fertilized egg.

5. These observations all suggest the conclusion that cell division depends upon the normal function of a discrete chain of respiratory reactions, the "activity" system. This system is normally responsible for approximately 50% of the total oxygen consumption of the fertilized egg but it is inactive in the resting cell. Inhibition of cell division by sulfanilamide as well as by narcotics and azide, accompanies inhibition of the activity system. It is undoubtedly the latter inhibition which brings about the depression of the rate of cell divison. The significance of these findings with relation to the effects of the sulfonamides in bacteria is discussed.