Fig. 4

Cell-autonomous requirement for Hdac1 in hepatocyte differentiation. Ventral views of wild type (A) and hdac1 mutant (B) organ-forming region at 48 hpf using the Tg(gutGFP)^s854 line. (C, D) Morphological analysis of cell transplantation experiments; wild type cells (red) transplanted into hdac1 mutants expressing the Tg(gutGFP)^s854 transgene. (C) Wild type cells contributing to the mesoderm fail to rescue liver morphology in hdac1 mutants. (D) Wild type cells contributing to the endoderm of hdac1 mutants rescue liver morphology. (E–P) Cell transplantation experiments were analysed by fluorescent in situ hybridisation in conjunction with immunostaining in transverse sections at liver level, using the Tg(gutGFP)^s854 line (blue) to highlight the endoderm, cp (red) to assess hepatocyte differentiation, and transplanted wild type cells labelled with fluorescein (green). (E, H, K, N) Wild type embryos express cp in the liver at 48 hpf. Wild type cells contributing to the hepatic endoderm of hdac1 mutants express cp (arrowhead, F, I, L, G, J, M), however wild type cells contributing to the adjacent digestive tract fail to express cp (F, G). To validate that transplanted host cells injected with cas mRNA contribute to the endoderm, Tg(gutGFP)^s854 embryos were used as donors in a subset of transplants (E, N, G, P); due to the mild mosaicism of the Tg(gutGFP)^s854 expression, we observe in a subset of transplanted cells very low GFP expression. Asterisks indicate liver, white dashed lines outline the digestive tract.