Fig. 3

Suppression of the ER Ca²⁺ pump affects left–right laterality in the brain and gut. (A) Side view of pitx2 expression at the 22–25 somite stage (20 hpf). pitx2 is expressed in ventral and dorsal regions of the diencephalon. (B) Rostral view of a control embryo, treated with DMSO from 4 to 6 hpf, showing left-sided pitx2a expression in the dorsal diencephalon. (C and D) Embryos treated with 0.5 μM thapsigargin from 4 to 6 hpf frequently display right-sided (C) or bilateral (D) pitx2a expression in the dorsal diencephalon. The arrowheads point to pitx2a expression in the dorsal diencephalon. (E) Overlay of bright field image (grey-scale) and immunolabeling of neural patterns (green) in a DMSO-treated control embryo at 4 days post fertilization. (F) The prominent habenular nucleus was located on the left side in all DMSO-treated controls (n = 15). (G) Inhibition of the ER Ca²⁺ pump during gastrulation induces a left–right reversal of the prominent habenular nucleus in 39% of the embryos (n = 49). Neural patterns were labeled with an acetylated tubulin antibody and were imaged by confocal microscopy. (H) DMSO-treated control embryo at 3 dpf with a left-sided gut. (I) Thapsigargin treatment induces a reversal of gut laterality in 41% of the embryos (n = 41). The gut is stained in vivo by methylene blue in the culture medium. L, left habenular nucleus; R, right habenular nucleus. Panels B–D and E–G are oriented with embryo’s left on the left side of the image. Scale bar = 50 μm.