The photic reflex seizures of gabrg2−/−fish are transient during the early larval stage. (A) Quantification of the maximum acceleration upon light stimulus of gabrg2−/− and gabrg2+/+ siblings at different ages (from 3 to 11 dpf). A significant difference is observed at 3, 4, 5 and 6 dpf only. (****P<0.0001, ***P<0.001, unpaired t-test.) (B) Representative swimming tracks (15 s following photic stimulus) of gabrg2+/+ versus gabrg2−/− larvae at different ages, showing that the stereotypical whirlpool behavior is not observable from 8 dpf. Of note is that the phenotype is the strongest and the most penetrant at 5 dpf. (C) RT-PCR for gabra1 and gabrg2 transcripts over wild-type zebrafish development. The polr2d gene is used as a house-keeping gene. (D) Whole-mount in situ hybridization on whole-mount embryos using an anti-sense probe against gabra1 or gabrg2 transcripts. Both genes are strongly expressed in the brain and their expression is largely overlapping. (A sense probe is shown as a negative control.)
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