Morpholino-mediated knockdown of FIT2 in zebrafish. (A) FIT2 morphants showed decreased staining for Oil red O in liver (outlined by dashed line in wild type) and intestine (outlined by solid line in wild type), compared with control fish (no morpholino control, WT; and nonspecific control morpholino, contmorph). Swim bladders of zebrafish stain with Oil red O (indicated by arrow). FIT2 morphants did not exhibit defects in feeding as judged by ingestion of nonabsorbable fluorescent microbeads. A WT control fed a high-fat diet without microbeads is shown (no beads) to demonstrate that fluorescence is because of ingested microbeads, not autofluorescence of fish. These images are representative of n = 400 fish, three independent experiments. (Scale bar: 0.4 mm.) (B) Quantification of Oil red O staining by spectrophotometric analysis in WT, contmorph, FIT2morph1, and FIT2morph2 fish (n = 20 fish per group, averaged over four independent experiments). *, WT versus morphants (P < 0.001) and shown as mean ± SD.