Figure 3

The Cone Cell Lineage Does Not Appreciably Contribute to Rod Production in Zebrafish but Inducing Ectopic Nrl Shows It has This Capacity

(A) Adult zebrafish retina grows from proliferating cells in the ciliary marginal zone (CMZ), generating all cell types including regularly spaced UV cones.

(B) Following ectopic expression of Nrl in differentiating UV cones, adult retina is mostly devoid of UV cones, except sparse newly born UV-opsin-positive cells near the CMZ. (A) and (B) are anti-UV opsin immunohistochemistry (magenta) with nuclear counterstain.

(C) The adult zebrafish cone cell lineage gives rise to all cone cell types, and few other cell types are appreciably generated from that lineage, as detected by Cre-lox lineage tracing via a cone-transducin-α (gnat2) Cre driver line. No history of gnat2 expression (yellow) is detectable in rod cells (4C12+), despite the lineage trace reporter being abundant in all other photoreceptors (cones). (C’) and (C″) are alternate views of dashed box outlined in (C). See also associated Figure S4.

(D) The fate of UV-opsin-positive cells that are absent from mature retina in (B) includes their transmutation into rods. Note a subset of rod cells (arrows, identified as 4C12+ and with nuclei in the basal-most layer of the ONL) shows a history of gnat2 expression (yellow), indicating they were generated from the cone lineage.