Qualitative and quantitative changes observed in the free α-amino nitrogen fraction of Tenebrio molitor pupal tissues during metamorphosis

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Abstract
The total free alpha-amino nitrogen content of T. molitor pupal tissues was measured during metamorphosis. For a considerable period (5 days), the level of alpha-amino nitrogen was approximately constant. A decrease in the free amino acid titer observed at the beginning of metamorphosis is associated with high deaminase activity, and the increase which was seen at about the time of ecdysis is probably a result of the absorption of pupal cuticle protein. Semi-quantitative examination of the free amino acids by means of two-dimensional chromatography generally reflected the changes in total free alpha-amino nitrogen. The rate of deamination measured by the rate of accumulation of the ultimate nitrogenous end-product uric acid in the pupal tissues was noticed to be greatest at the very beginning of the metamorphosis, constant during the middle and elevated towards the end of pupal life. There was no evidence for the accumulation of citrate in Tenebrio pupal tissues being directly related to sunchronous accumulation of free amino acids. The ratio RNA:DNA decreased after the beginning of the pupal period and increased towards its end. The maxima were thought to correspond with intensive protein synthetic activity during the formation of adult tissues and when the adult cuticle protein was being synthesized.