Fig. 4.

CrCHLH1 is deficient in hmox1 and gun4 mutants. (A) Comparative growth of 4A+, hmox1, gun4, cDNA complemented line ho1C2 and genomic DNA complemented lines gun4::GUN4-STII #1∼3 in the dark or under constant white fluorescent light. STII, twin-strep-tag. (B) Immunoblot analyses of representative tetrapyrrole biosynthetic enzymes using corresponding monospecific antibodies. C. reinhardtii cells grown in TAP medium under moderate light (∼30 μmol photons m⁻² s⁻¹) were diluted to a density around ∼1 × 10⁶ cells/mL. Half of the cell cultures were acclimated to darkness for 24 h (dark 24 h), whereas the other half were grown in the dark for 12 h and then exposed to light (∼30 μmol photons m⁻² s⁻¹) for another 12 h (dark 12 h + light 12 h). Similar amount of protein (∼30 μg) was loaded for each sample. A dilution series (25% and 50%) of the 4A+ WT strain is included for both growth conditions. CB, Coomassie blue staining. Lanes with significant reduction in CrCHLH1 or CrGluTR proteins are indicated with red boxes and asterisks, respectively. (C) Rescue of CHLH1 polypeptide accumulation by BV feeding. Exponential-phase cell cultures grown in darkness were supplemented with or without 20 μM BV.