ENVIRONMENTAL INFLUENCE ON TREHALOGENESIS IN AMEBAS OF THE CELLULAR SLIME-MOLDS

Vegetative trehalase from Dictyostelium discoideum was purified to nea r homogeneity in a two-step procedure involving in situ enzymatic dete ction after SDS-PAGE and electroelution. The purified enzyme was used to quantify the levels of trehalose in a variety of dormant structures and in stressed amoebae of the cellular slime molds. It was found tha t the trehalose levels of vegetative amoebae of D. discoideum and Poly sphondylium pallidum increased to levels, comparable to those seen dur ing multicellular development, during heat shock (30 C) or cold shock (4 C) and decreased during recovery (23 C) from thermal stress. This a ccumulation of trehalose during thermal stress was not dependent on pr otein synthesis. Exposure to heavy metals, but not to agents that incr eased the osmotic potential of the surrounding medium, similarly affec ted trehalose levers in amoebae of D. discoideum. The activity and dis tribution of key enzymes involved in trehalose metabolism, trehalose-6 -phosphate synthetase and trehalase, remained unchanged during thermal stress. The data support the view that trehalose plays a protective r ole in cells exposed to heat shock and other adverse conditions, in ad dition to being a storage form of energy and carbon during development .