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Proceedings of the Indiana Academy of Science






Previous work suggested a role of reactive oxygen species (ROS) metabolism on branch density, the statistical distribution of physical distances between branch points along a growing hypha in Neurospora. Here we report the results of experiments designed to ask more generally about the relationship between ROS and branch density by examining the branching effects of selected ROS metabolism gene knockout mutants as well as the impact on branching of exogenously added antioxidants. In all ROS metabolism mutants tested, growth was shown to branch less densely (hypobranching) when grown at lower temperatures, a shift not observed in the wild-type. Interestingly, this holds true for knockouts of genes expected to reduce ROS as well as those expected to produce them. In addition, in tests on wild type Neurospora, added ascorbic acid produced unusual branching patterns. Hypha exposed to exogenous antioxidants display dose dependent hypobranching with hypha becoming more hypobranched as doses increase. At higher doses, however, the branch distribution becomes bimodal with one maximum continuing to shift toward hypobranching and the second maximum representing a spike of very closely spaced branch points.