Unchanged RC enzyme activity and mitochondrial respiration capacity in dldh–/– zebrafish larvae. (A) Measurement of the DLD (E3) activity in dldh–/– zebrafish showed significantly decreased activity as compared with WT; n = 3; ***P < 0.001 by Student’s t test. (B) Enzyme activities of complex I (CI), CII, and CIV and citrate synthase (CS); n = 3. Data are shown as mean ± SD. No significant differences between 7 dpf dldh/ larvae and WT by Student’s t test. (C) Oxygen flux measurements obtained by high-resolution polarography with an Oxygraph-2k (Oroboros) on 5 dpf zebrafish homogenate. Basal respiration is the measurement before addition of substrates. OXPHOSCI is the capacity of CI taken after the addition of glutamate. OXPHOSCI+CII is the capacity of both CI+CII taken after the addition of succinate. LEAKCI+CII is the nonphosphorylating electron transfer across the mitochondrial inner membrane. ETSCII is in the presence of succinate and rotenone. TMPD-Az is the ascorbate driven complex IV activity. A typical time course and experimental details are presented in Supplemental Figure 3C. None of the differences reached statistical significance by Welch’s t test. Data are shown as mean ± SD (n = 3).
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