Characterization of eaat2b mutant zebrafish. The mutation causes a deletion that results in a premature stop codon, leading to a predicted truncated EAAT2b protein (A,B). Retinal histological sections from adult wild-type (C), adult eaat2b^−/− (D), 5 dpf wild-type (E) and 5 dpf eaat2b^−/− (F) zebrafish show no apparent morphological abnormalities in either larval or adult eyes. Immunofluorescence staining for EAAT2b (green) and Bodipy (magenta) is shown in adult wild-type (G) and eaat2b^−/− (H) retinas. GCL, ganglion cell layer; INL, inner nuclear layer; IPL, inner plexiform layer; OPL, outer plexiform layer; PhR, photoreceptors; TM, transmembrane domain.

eaat2b mutant zebrafish larvae exhibit reduced ERG b-wave amplitude and impaired response kinetics. Representative ERG responses of WT controls (A) and eaat2b mutants (B) at different flash intensities. (C) Quantification of the b-wave amplitude across five different light intensities. eaat2b^−/− larvae (in red) show a significant reduction in ERG b-wave amplitudes compared to WT controls (in black). Statistical significance: p = 0.0142 at log 0, p = 0.0013 at log −1, p < 0.0001 at log −2, p = 0.0005 at log −3 and p = 0.0771 at log −4. In addition, the time to peak was quantified (D). Statistical significance of time to peak: p = 0.6161 at log −4, p = 0.0074 at log −3, p < 0.0001 at log −2, p < 0.0001 at log −1 and p < 0.0001 at log 0. Statistical analysis was performed using t-tests and nonparametric tests in GraphPad Prism, v. 8. Data are presented as mean ± s.e.m. Significance levels are indicated as follows: *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.

Temporal resolution of flicker ERG responses is reduced in eaat2b mutant fish. (A) Representative flicker ERG responses to a 5 Hz stimulus in WT controls (black) and eaat2b^−/− larvae (red). Corresponding FFT power plots for WT (A′) and eaat2b^−/− (A″) were generated in MATLAB from the traces shown in (A). (B) Representative flicker ERG responses to an 8 Hz stimulus in WT controls (black) and eaat2b^−/− larvae (red). Corresponding FFT power plots for WT (B′) and eaat2b^−/− (B″) were generated from the traces shown in (B). (C) Normalized power of flicker ERG responses at specified frequencies in WT controls and eaat2b^−/− larvae. Power values were normalized to the 50 Hz line-noise peak. Statistical significance: p = 0.0039 at 5 Hz, p = 0.0007 at 8 Hz, p = 0.0031 at 10 Hz, p = 0.0133 at 15 Hz. Statistical analysis was performed using t-tests and nonparametric tests in GraphPad Prism, v. 8. Data are presented as mean ± s.e.m. Significance levels are indicated as follows: *p < 0.05; **p < 0.01; ***p < 0.001.