Relation between pmp22 transcription levels and peripheral NCV, and swimming ability in medaka fish. (A) The transgene, FLAG tagged ol_pmp22, expression in 8dpf fish. RT-PCR was performed with primers to FLAG and the SV40 polyadenylation site. M: 100 bp marker, w: wild type, g: GFP fish, p: pmp22 fish. (B) Relative transcription levels of ol_pmp22 in 8 dpf wild type, GFP fish and pmp22 fish. Beta-actin transcripts were used for an internal control. Relative transcription levels were quantified by defining the wild type average as 1.0 (0.656 to 1.522). Relative quantification of the GFP fish and pmp22 fish was 1.123 (0.898 to 1.405) and 2.056 (1.781 to 2.372), respectively. The minimum and maximum were estimated according to the manufacturer's instructions. Ct: threshold cycle. (**P < 0.05) (C) Population spikes stimulated by 100 μA with or without 1 μM TTX. The large spike is an artifact observed at around 5 seconds (black arrow). The spikes appearing at 6 to 7 seconds, action potential (black arrowhead), were not observed with TTX. (D, F, E) Population spikes of the wild type, D, GFP fish, E, and the pmp22 fish, F. Samples were stimulated with 60 μA. Spikes recorded at two adjacent channels (300 μm distance) were merged. The vertical dashed lines are drawn on each peak time. (G) Peripheral NCV was measured by dividing the distance between two channels by the time lag of the peaks. The peripheral NCV values of wild type, GFP fish and pmp22 fish were 9.566 ± 1.542 m/s, 9.700 ± 1.457 m/s and 1.924 ± 0.738 m/s, respectively (n = 5, **P < 0.05). (H) Flow distance of each line in running water (0.25 m/s). Positions from the start point was recorded every 0.5 seconds (n = 3, *P < 0.1).