ENVIRONMENTAL CONTROL OF AMYLASE PHENOTYPE IN AMPHIPODS OF THE GENUS GAMMARUS

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Abstract
The amylases of 3 spp. of Gammarus amphipods, G. palustris, G. mucronatus and G. lawrencianus, were studied using polyacrylamide gel electrophoresis. In all 3 spp. there are 2 principal zones of activity (Amy-1 and Amy-2), but occasional individuals exhibit a 3rd band (Amy-X). Amy-X variants are more common in the deeper water species and in collections made during late winter or early spring than in the shallower water species or in summer collections. Experimental work shows that Amy-X can be induced by a diet rich in amylose or glycogen, but not by amylopectin or other foods and by reducing the temperature at which they are maintained. The relative expressions of Amy-X and Amy-1 vary seasonally. This variation probably is an adaptive response to seasonal variation in diet, or conditions for the hydrolysis of substrate.