Free Amino Acids in the Eggs and Hemolymph of the Grasshopper Melanoplus sanguinipes (Orthoptera: Acrididae). 1. Identification and Quantitative Changes Throughout Development1

Abstract

This study involved identification by paper chromatographic techniques and quantization of the free amino acids in the blood of the migratory grasshopper, Melanoplus sanguinipes (F.). Differences between sexes, stage of development, and effects of adult aging were considered. The egg yolk of this species of grasshopper contained 26 amino acids. Of interest was the appearance of several amino acids at different periods during embryonic development. Among others, citrulline and ± and ³ aminobutyric acids were found in postdiapause but not in diapause eggs, and methionine was found in diapause but not in postdiapause eggs. Alpha-aminobutyric acid appeared during the middle of postdiapause development and then was absent until the 2nd nymphal stage. Twenty-six amino acids were identified in the blood of nymphal M. sanguinipes . Tryptophan was observed until the 2nd nymphal stage, after which it was not: observed in any subsequent stage of development. Aspartic acid had a similar pattern except that it was in the 4th, perhaps the 5th, nymphal stage and was not found again except in old grasshoppers. Of particular interest was the high concentration of numerous amino acids in the 3rd nymphal instar. Asparagine, proline, alanine, glycine, glutamine and valine, especially, showed increases at this stage. Most amino acids showed a high concentration during the 3rd nymphal stage. Arginine and glutamic acid showed a high concentration at the 2nd nymphal stage. Twenty-six amino acids also were identified in the blood of adult grasshoppers. However, they are not the same 26 amino acids found in the egg yolk or in nymphal grasshoppers. Taurine was found only in adult grasshoppers, and tryptophan was observed only in the egg yolk. There were sex-related qualitative and quantitative differences in the amino acid patterns. These included the presence of methionine sulfone almost exclusively in females, the more frequent occurrence of ³ aminobutyric acid in females, and the alpha isomer in males. Additionally, there was an apparent correlation between the occurrence of methionine sulfone and sulfoxide and egg formulation and/or gonad maturation. A total of ten ninhydrin-positive compounds were not identified.