Inhibitory effect of 2-deoxyglucose on cell wall α-1,3-glucan synthesis and cleistothecium development in Aspergillus nidulans

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2-Deoxy- d-glucose (2-DG) (0.1% w/v) added at inoculation time to cultures of Aspergillus prevents α-1,3-glucan, α-1,3-glucanase, and cleistothecium formation. 2-DG given after α-1,3-glucan synthesis, inhibits α-1,3-glucanase and glucan breakdown partially, and cleistothecium formation completely, perhaps because 2-DG, a toxic analog, is the only sugar available to the organism. When 2-DG is provided after about half the α-1,3-glucan is already made, about half the amount of α-1,3-glucanase is synthesized. Cleistothecia do develop, probably because at the time of addition of 2-DG glucose is still available in the medium. Experiments designed to test whether 2-DG acts primarily on α-1,3-glucan, α-1,3-glucanase, or both show that extra glucose appears mainly in an alkali-insoluble fraction and only little is synthesized into α-1,3-glucan. This is the reverse of what happens in the absence of 2-DG. These results indicate that both α-1,3-glucan and α-1,3-glucanase are indispensable for fructification in Aspergillus. Moreover, 2-DG primarily influences the synthesis of α-1,3-glucan, and the inhibition of α-1,3-glucanase is either a secondary effect or a consequence of disturbing the cell's metabolism.