Amino acid absorption by the gut of the black bass, Huro salmoides

The active transport of glycine, L-alanine, L-lysine, L-methionine, and L-proline were shown to occur in the gut of the black bass, Huro salmoides, using the tissue incubation technique of Agar (1954 and 1956). In defining active transport the following criteria were met: (1) the test amino acids were transported against their concentration gradients; (2) the transport mechanism proved to be dependent upon both metabolic energy and temperature; (3) the transport mechanism showed a molecular specificity because only the L-stereoisomer of alanine was transported against its concentration gradient; (4) chromatographic analysis Indicated that the transported amino acids were structurally unchanged; and (5) saturation of the carrier mechanism was approached. Certain generalizations can be made in comparing the carnivorous freshwater teleost (e.g., bass) and the omnivorous freshwater teleost (e.g., catfish) because there seems to be a difference in the ability of the gut of these two teleosts to absorb amino acids. The gut of the omnivorous teleost seems to have a greater ability to transport amino acids at lower concentrations. There also appears to be a regional difference in the amino acid absorption ability of the guts of the two types of fish. The maximum rate of absorption of amino acids occurred in medial region of the carnivorous bass, while the anterior intestine was reported to be the optimal region of absorption in the omnivorous freshwater teleost.