Amino Acids and Related Compounds in the Haemolymph of Oryctes Nasicornis and Melolontha Vulgaris

Abstract

Summary. The haemolymph of the larvae of the beetle Melolontha vulgaris was found to contain between 280 and 450 mg% nonprotein amino nitrogen; in haemolymph from the related Oryctes nasicornis between 219 and 316 mg% was found. This amino nitrogen originates from three main sources, namely a) real amino acids, b) low peptides (di‐ and tripeptides) and c) amides (glutamine and asparagine). In Melolontha blood the presence of the following substances was established: lysine, arginine, histidine, tyrosin, leucine, valine, tryptophane and the amides asparagine (in some eases) and glutamine; the presence of hydroxyproline in an appreciable amount was indicated. Moreover a small amount of peptides and some dicarbonic amino acid or acids was present. In Oryctes blood hydroxyproline was identified; this substance and the basic amino acids play the most important part among the real amino acids. Low peptides are present in considerable amounts. Glutamine seems always to be present, whereas asparagine has not been met with. The non‐protein amino‐nitrogen in the content of the midgut of Melolontha has been examined. It was found that the concentration of all amino acids analyzed for was much lower in the gut than in the haemolymph. The variations in the amino‐N concentration of the haemolymph is briefly discussed.