The control of saccharide synthesis during development of myxamoebae of Dictyostelium discoideum containing differing amounts of glycogen

摘要

1. Myxamoebae initially containing 5.59mg of glycogen/10⁸ cells accumulate approx. 25% more cell-wall polysaccharide, 100% more mucopolysaccharide, 200% more glucose and 300% more trehalose during their development than do myxamoebae initially containing less than 0.3mg of glycogen/10⁸ cells. 2. These observations restrict the number of possible control mechanisms operating to regulate carbohydrate metabolism during development. 3. Cells accumulating a large amount of trehalose (approx. 400μg/10⁸ cells) have the same amount and pattern of changes in specific activity of trehalase and trehalose 6-phosphate synthase as do cells accumulating a smaller amount of trehalose (approx. 100μg/10⁸ cells). 4. These two populations of cells do, however, differ markedly in the amount of UDP-glucose and glucose 6-phosphate that they contain. 5. It is concluded that this change in the intracellular pools of the metabolic precursors of trehalose accounts for the increased amount of trehalose synthesized by cells derived from myxamoebae containing an increased glycogen content.