Fig. 2

otpa mutant reveals a new cluster of hypothalamic OXT neurons.

(A–F) In situ hybridization of oxt mRNA in 5 day-old wild type (otpa^+/+) and otpa^−/− mutant on the background of a transgenic OXT reporter Tg(oxt:egfp) followed by confocal imaging (dorsal view, anterior to the top). otpa^+/+;Tg(oxt:egfp) fish do not express detectable levels of oxt mRNA (A), but express EGFP in the posterior tuberculum (PT; B). otpa^−/−; Tg(oxt:egfp) mutants express oxt mRNA (D) in oxt:egfp-positive cells of the PT (E). PT OXT neurons are indicated by arrowheads. Scale bar, 20 µm. (G–I) A representative image (single confocal plane) of a transgenic [otpa^+/+;Tg(oxt:egfp)] larvae, which was subjected to fluorescent in situ hybridization (FISH) with a single-molecule oxt mRNA probe (Stellaris) showing co-localization (arrowhead) of oxt in EGFP-labelled PT cells. NPO, neurosecretory preoptic area. Scale bar, 20 µm.