Figure 9.—

Biosynthesis of carotenoids in N. crassa wild-type and mutant mycelia. (A) Light-dependent accumulation of carotenoids in mycelia of CHZ10 and hygromycin-resistant strains. Total carotenoids were extracted from mycelia that had been exposed to white light (10 W/m² blue light) for 1 day (24 hr) or kept in the dark. Values obtained with wild type and a carotenoid overproducing strain (vivid) are included for comparison. The plot shows the average and standard error of the mean, for carotenoid accumulation in two or three independent experiments. (B) Photoactivation of the albino genes al-1, al-2, and al-3 in CHZ10, and hygromycin-resistant strains. Quantitative PCR experiments were performed to measure the relative accumulation of mRNA in mycelia exposed to white light (10 W/m² blue light) for 30 min or five hours, or kept in the dark (D). The plots show the average and standard error of the mean of the relative mRNA accumulation in two independent experiments. The results from each PCR for each albino gene were normalized to the corresponding PCR for tub-2 to correct for sampling errors. Then, the results were normalized to those obtained with CHZ10 after exposure to 30 min of light.