Colonization of the zebrafish GI tract with A. veronii:dTomato is sufficient to block behavioral hyperactivity at 10 dpf. Axenic embryos were colonized with A. veronii:dTomato at 1 dpf and imaged at 2–6 dpf or subjected to locomotor testing at 10 dpf. Axenic embryos were also colonized with V. cholerae:GFP at 1 dpf and tested for locomotor activity at 10 dpf. (A) Experimental design. (B) Representative images of axenic embryos conventionalized on day 1 with A. veronii (AX + A. veronii) at 2–6 dpf. At 10 dpf, distance moved in axenic larvae colonized on day 1 with (C,D) A. veronii or (E,F) V. cholerae (AX + V. cholerae) for each 2 min period or mean distance during the 10 min dark period are shown. Black and white bars represent dark and light periods, respectively. N = 19–36 larvae per group. Different letters indicate significance (p < 0.05). Error represents SEM.

Conventionally colonized (CC) zebrafish embryos were colonized with A. veronii:dTomato or V. cholerae:GFP at 1 dpf and imaged or subjected to locomotor testing at 10 dpf. Distance moved (A) each 2 min period or (B) mean distance during the 10 min dark period are shown. Black and white bars represent dark and light periods, respectively. N=32 larvae per group. Different letters indicate significance (p<0.05). (C) Representative images of CC:A. veronii or CC:V. cholerae larvae at 10 dpf showing that labeled microbes enter the intestinal tract in conventionally colonized larvae.

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