Amino Acid Absorption in the Locust (Schistocerca Gregaria Forsk.)

Abstract

1. Chromatographic analysis of the haemolymph revealed the presence of ten amino acids of which glycine and serine occurred in the relatively high concentrations of 33.2 and 34.6 mM./l. respectively. These two amino acids, together with glutamine (10.9 mM./l), were selected for the study of absorption from the gutlumen. 2. An experimental solution containing ¹⁴C-labelled glycine and serine was injected into the gut lumen and the subsequent changes in concentration and radioactivity of the gut fluid were followed. 3. The uptake of ¹⁴C-labelled glycine and serine was shown to occur rapidly in the mid-gut region and especially from the lumen of the caeca. 4. The concentrations of glycine and serine, and also of glutamine, in the caecal fluid were found to increase significantly above their concentrations in the haemolymph, an effect which was paralleled by a relatively rapid decrease in fluid volume. During this time rapid exchange of ¹⁴C-labelled glycine and serine between the haemolymph and the gut lumen was demonstrated. 5. On the basis of these observations it was concluded that the net absorption of these substances depended, in part at least, upon the diffusion gradient created by the relatively rapid movement of water into the haemolymph.