Fig. 6

Impact of upstream enhancing UAS1B elements (U4) and the TEF intron (INT) on the expression strength of the PUFA cluster genes pfa1, pfa2, pfa3, and ppt during glycerol-based docosahexaenoic acid (DHA) production in Y. lipolytica. The data comprise the average (A) and the time-resolved gene expression (B) in the strains TEF Af4 (left bars) and U4 TEF Af4 (right bars). For the latter, the time-resolved expression was measured during the exponential phase (ca. 15 h), the early production phase (stationary 1, ca. 38 h), and the late production phase (stationary 2, ca. 135 h). The same data are shown for the strains TEF Af4 (left bars) and TEF INT Af4 (right bars) (C, D). The gene expression level was measured using q-RT‒PCR. Statistical significance was assessed by Student’s t test (* p = 0.05 and ** p = 0.01). n = 3