1. The C14O2 production by Arbacia eggs and embryos from glucose-1-C14, glucose-2-C14, and glucose-6-C14 has been measured without and with dinitrocresol in the incubation medium. In the absence of the dinitrocresol, the C14O2 production from glucose-1-C14 is more rapid than from glucose-2-C14 and much more rapid than from glucose-6-C14; this, together with previous findings, indicates that glucose is utilized in Arbacia eggs predominantly via the TPN shunt rather than via the aldolase step of the glycolytic pathway. In the presence of the dinitrocresol, C14O2 from glucose-6-C14 approaches that from glucose-1-C14, indicating that, in the presence of this reagent, glucose utilization is diverted from the shunt to the glycolytic pathway.
2. Incorporation of C14 from glucose labelled in the 1-, 2-, or 6- positions into other metabolic products of the eggs and embryos is also inhibited by dinitrocresol, particularly incorporation into the acid-insoluble fraction containing nucleoproteins.