Thiazole Effect on Phycomyces

The Lens Effect and Phototropism of Phycomyces

Normally, the dioptrics in air of the cylindrical sporangiophore of Phycomyces blakesleeanus confer on the distal side a focusing advantage of about 30 per cent for unilateral stimuli of parallel light. This advantage can be nullified or reversed to produce negative curvatures by means of diverging light stimuli. A thin cylindrical glass lens was positioned 0.15 mm from the light-adapted growin...

Effect of glucose on isocitrate lyase in Phycomyces blakesleeanus.

Repression of the synthesis of isocitrate lyase by glucose and/or induction of the synthesis of isocitrate lyase by acetate in Phycomyces blakesleeanus were demonstrated. Both glycerol and ethanol failed to induce isocitrate lyase activity. Furthermore, glucose appeared to cause an in vivo catabolite inactivation of the derepressed enzyme. Isocitrate lyase was inactivated both reversibly and ir...

Effect of glycine on thiazole biosynthesis in Escherichia coli.

Glycine was found to replace thiamine thiazole for the growth of the thiazoleless mutant of Escherichia coli; it also stimulated the production of thiamine thiazole by washed cell suspensions of the mutant.

On "reversal" of Phototropism in Phycomyces

Alleged reversal of the phototropism of the sporangiophores of Phycomyces by high intensities of light does not occur if infra-red radiation is properly excluded. Phototropic "indifference" alone occurs at high intensities due to equal photic action on both sides of the sporangiophore. If heat radiation is not screened out, a gradual, negative thermotropic bending takes place.

Studies in carotenogenesis. 12. The effect of temperature and thiamine concentration on carotenogenesis by Phycomyces blakesleeanus.