The Genetic Control of Growth Metabolism

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Abstract
The respiration of the wing and leg discs of wild type, miniature wing, and vestigial wing Drosophila was measured with the Cartesian diver ultramicrorespirometer. Their weights were measured by the quartz fiber balance of Lowry. At each of several stages studied, before, at, and after pupation, the Q o2 of wild type wing discs and the leg discs of all stocks used varied only slightly from 20 mm3 O2/hr./mg. tissue. The Q o2 of miniature wing discs was 18 mm3 O2/hr./mg./tissue and of vestigial wing discs 9 mm3 O2/hr./mg. The wts. of vestigial, miniature and normal wing discs are the same at corresponding developmental stages in the larvae and 1- or 2-hr. pupae, although the adult wings are of different sizes. Both the wts. of the wing discs and the rate of O2 consumption per disc increase sharply just before pupation. The mutant genes, vestigial and miniature, produce their effects by altering the rate of some chemical reaction in the wing disc which is reflected by a lowered rate of O2 consumption. It is interesting to note that the metabolism of the leg and probably of other discs is not changed although the cells contain the mutant genes. These genes, therefore, produce their physiological as well as their morphological effects only in certain cells of the body, presumably by the interaction of the gene or gene products with specific components of the cytoplasm of those cells.