Relationship Between the Activity of the Succinoxidase System and the Rate of Oxygen Consumption During the Embryonic Development of the Mealworm, Tenebrio Molitor Linnaeus

Abstract

For many years cytochrome oxidase has been considered a rate-limiting enzyme involved in oxygen consumption. This relationship was postulated by Wolsky (1938) to explain the U-shaped changes in oxygen consumption which occur during the pupal stage of Drosophila melanogaster. It has received support from the work of Boell (1945) for the embryonic development of the salamander, Amblystoma punctalum. He found a straight line relationship between the activity of cytochrome oxidase and the rate of oxygen consumption and observed that approximately 97 per cent of the respiration was abolished by treatment with cyanide. Sacktor (1951) observed that during the pupal stage of the house fly, Musca domestic.a, both the activity of cytochrome oxidase and the rate of oxygen consumption follow the characteristic U-shaped curve. A similar relationship was shown to exist in the pupa of the Japanese beetle, Popilliajaponica, by Ludwig (1953). However, Wolsky (1941) suggested that the U-shaped respiratory curve in Drosophila pupae may be connected with variations in the activities of the dehydrogenase systems. Agrell (1949) found that in the bow fly, Calliphora erythrocephala, malic, citric, and glutamic dehydrogenases all follow a U-shaped activity curve. Sacktor (1951) found that, in the pupa of the house fly, other factors in addition to the cytochrome system may contribute to the total respiration. A part of the pupal respiration is cyanide-insensitive, and there is in addition to cytochrome oxidase, another cyanide-sensitive system, probably involving tyrosinase.The metabolism of the insect egg may be complicated by the presence of a diapause or resting stage. Bodine (1934) showed that the respiration of the pre-and postdiapause egg of the grasshopper, Melanoplus differentialis, is markedly inhibited by cyanide, whereas that of the diapause egg is cyanideinsensitive. Hence, respiration of the diapanse egg is believed to be mediated by some mechanism other than the cytochrome system, while a portion of the *