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Publisher Summary This chapter presents the nuclear and cytoplasmic control of morphology in Neurosporacrassa. The mechanism of control of the abn phenotype is closely related to the cytochrome pattern, which, in turn, is probably related to the overall metabolic pattern and to cell wall synthesis. There is no evidence of qualitative changes in cytochromes. As in yeast extra nuclear petites, the Neurosporaab n cytochrome pattern would seem to be under mitochondrial regulatory control. Whether this is via mitochondrial DNA controlling expression and repression of nuclear genes for cytochrome synthesis, controlling mitochondrial membranes, thereby affecting the uptake of cytochromes, or controlling mitochondrial structural proteins, thereby affecting the maintenance of the respiratory enzymes, cannot be decided. However, extra nuclear control of mitochondrial properties, probably through its DNA, is responsible for such cytoplasmic Neurospora mutants as poky, mi, and abnormal, and further definition and resolution of the control mechanisms involved will be both exciting and rewarding. |
