Figure 3

Relative transcription levels of four astaxanthin synthesis-related genes in MK19, CS19, and CSR19 as a function of time. Each strain was flask-cultured for 5 days. β-actin was used as an internal reference gene for normalization. Expression of crtE in MK19 at 48 h was defined as 1, and expression levels of other genes were measured relative to this value. Differences of gene expression between CS19 and CSR19 were analyzed by t test, and significant differences are indicated by **(p < 0.01) or *(0.01 < p < 0.05). The crtS expression was much higher in CSR19 and CS19 than in MK19. Values shown are means of three individual cultures. Error bars SD from three independent biological replicate experiments.