The Relation of Thiamin to the Production of Perithecia by Ceratostomella Fimbriata

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Abstract
SUMMARY The isolate of C. fimbriata used throughout these experiments was found to be completely deficient for thiamin and to show no deficiency for biotin, pyridoxine or inositol. By keeping the amount of nutrients constant and high, and by reducing the amount of thiamin added to the medium, the formation of perithecia was inhibited. The dry weight of mycelium produced in liquid media with varying thiamin content is compared with the diameter growth on the same media solidified with purified agar. The effects of these media upon the formation of perithecia are also given. Thiamin-starved mycelium formed perithecia when and only when transferred to distilled water (or distilled water and agar) plus thiamin. Distilled water without thiamin was without effect. Evidence is presented which leads to the conclusion that sexual reproduction occurs only when the ratio of thiamin to the amount of nutrients in the medium is relatively high.