Figure 1
Nrl Is Conserved and Required for Rod Specification in Larval Zebrafish
(A) Nrl is the master regulator of photoreceptor specification in mice, being both necessary and sufficient for rod photoreceptor development from progenitor cells. Elegantly simple models can account for cell fate specification and generating the full complement of photoreceptor types in mice (and all mammals studied) using only two factors, NRL and THRB (thyroid hormone receptor β), to generate rods, red cones, and blue cones expressing RH1, LWS, and SWS opsins, respectively. However, most vertebrates possess additional cone subtypes.
(B) Zebrafish Nrl protein is recognizably similar to mammalian homologs. An
(C and D) CRISPR-engineered null Nrl mutants lack rods in larval zebrafish, matching the phenotype of adult
(E and F) Retina of
(G) Nrl protein is not detectable in
(H) Assessment of
(I) Quantification of photoreceptor types in