Intermediary Metabolism in Aseptically Reared Blowfly Larvæ, calliphora erythrocephala (MEIG.) II. Biosynthesis of Fatty Acids and Amino Acids

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Abstract
1) The biosynthesis of fatty acids and amino acids in aseptically reared (axenic) larvae of the bluebottle Calliphora erylhrocephala has been studied with the aid of acetate-1-14C. 2) The results of these experiments showed that in this insect saturated and unsaturated fatty acids are not interconvertible by hydrogenation and dehydrogenation and that their biosynthesis takes place by two separate pathways. 3) Degradation studies showed that the saturated fatty acids as well as the unsaturated fatty acids have been synthesized by β-condensation from two different sources of 2-carbon units. 4) Among the isolated amino acids heavy incorporation of 14C was found in glutamic acid, aspartic acid, and alanine, whereas lesser quantities of isotope were incorporated into serine, glycine and proline. No significant amounts of isotope were measured in: phenylalanine, tyrosine, isoleucine, leucine, valine, histidine, arginine and lysine. 5) The isotope distribution in the isolated glutamic acid, aspartic acid and alanine shows that the biosynthesis of these amino acids takes place in the same manner as in mammals. However, the presence of isotope in carbon-2 of glutamic acid is an indication that also other pathways have been used in the formation of this amino acid. 6) Tyrosine is synthesized intermediarily from phenylalanine. 7) Biosynthesis of proline takes place from glutamic acid, probably in a similar manner as found in higher animals. 8) Serine and glycine are closely linked together in the intermediary metabolism of the larvae.