Oxine, Ferric Oxine and Copper Oxine as Inhibitors of Growth and Differentiation of Allomyces macrogynus

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Abstract
Oxine is an inhibitor of growth and differentiation in A. macrogynus. Growth was inhibited by as little as 4.mu.g/ml and the 1st effect was inhibition of nucleic acid synthesis, followed by inhibition of protein synthesis. Consistent inhibition by oxine of the development of zoosporangia in starving plants required a concentration of 60.mu.g/ml. The degradation of RNA, which always occurs in starving plants, continued in the presence of oxine, showing that this is an independent phenomenon. When glucose was available, oxine increased the synthesis of trehalose without a comparable effect on glycogen synthesis. Cycloheximide increased trehalose synthesis to an even greater extent. The inhibition of glucose metabolism by oxine was concentration- and time-dependent. Oxine inhibition was reversible on transfer to nutrient solutions. Iron oxine and copper oxine bind rapidly to the fungal walls. Evidently, the site of binding is wall galactopeptide and cell transport systems are disorganized. In the presence of glucose, plants recovered from inhibition by ferric oxine without transfer. Results conflict with a theory that oxine inhibits transcription by chelating Mg and Mn.