FIGURE SUMMARY
Title

Concerted action of two dlx paralogs in sensory placode formation

Authors
Solomon, K.S. and Fritz, A.
Source
Full text @ Development

dlx3 and dlx7 are co-expressed by the same otic and olfactory cells. (A,B) Whole-mount RNA in situ hybridization with probes for (A) dlx3 and (B) dlx7 at 18 somites. Lateral views, anterior towards the left. (C,D) Flat-mount double in situ hybridization showing (C) olfactory and (D) otic expression of dlx3 and dlx7 at 18 somites. dlx3 expression is shown in red in both panels with dlx7 expression shown in purple. Anterior is towards the top. ot, otic vesicle; olf, olfactory placode; va, visceral arches. Scale bars: in A, 100 µm for A,B; in C, 25 µm for C,D.

EXPRESSION / LABELING:
Genes:
Fish:
Anatomical Terms:
Stage: 14-19 somites

Loss of dlx3 and dlx7 function leads to a reduction in otic vesicle size. Lateral views, anterior towards the left, of otic vesicles in (A-E) 24 hour and (F-J) 27 hour embryos. (A,F) Wild-type, (B) dlx7 MO, (C,G) dlx3 MO, (D,I) dlx3+7 MO, (E) b380 mutant, (H) dlx3 MO + dlx3 RNA and (J) dlx3+7 MO + dlx7 RNA embryos. otl, otolith. Scale bars: in A, 25 µm for A-G; in F, 75 µm for F-J.

Expression of otic and olfactory differentiation markers is reduced by loss of dlx3 and dlx7 function. (A,G,M) Wild-type, (B,H,N) control MO, (C,I,O) dlx7 MO, (D,J,P) dlx3 MO, (E,K,Q) dlx3+7 MO and (F,L,R) b380 mutant embryos. (A-L) Expression of eya1 at 18 somites in (A-F) whole-mount and (G-L) flat-mount embryos. (M-R) Flat-mount in situ hybridization with anxV at 24 hours. (A-F) Lateral views, anterior towards the left. (G-R) Dorsal view, anterior towards the top of the panels. ot, otic vesicle; olf, olfactory placode; ap, anterior pituitary. Scale bars: in A, 100 µm in A-F; in G, 25 µm in G-L; in M, 25 µm in M-R.

dlx3 and dlx7 affect otic placode formation before the onset of pax2.1 otic expression but after that of pax8. Wholemount RNA in situ hybridization at 3 somites with (A,F) wild-type, (B,G) dlx7 MO, (C,H) dlx3 MO, (D,I) dlx3+7 MO and (E,J) b380 mutant embryos. (A-E) pax8 is expressed in the presumptive otic primordia (ot) and the pronephros (pn) at this stage. Expression of this gene is unaffected by a loss of dlx3 or dlx7 function. (F-J) pax2.1 is expressed in the presumptive otic primordia (ot), pronephros (pn), midbrainhindbrain boundary (mhb) and optic stalk (not shown) at this stage. Expression is reduced specifically in the otic primordia of (H) dlx3 MOinjected embryos, and is undetectable in (I) embryos injected with dlx3+7 MO and in (J) b380 mutants. All panels show dorsal views with anterior towards the left. Scale bar: 100 µm.

Cross- and autoregulatory mechanisms monitor expression levels of dlx3 and dlx7. Whole-mount in situ hybridization with (A,E,I,M) wild-type, (B,F,J,N) dlx7 MO, (C,G,K,O) dlx3 MO and (D,H,L,P) dlx3+7 MO embryos. (A-D) dlx3 and (E-F) dlx7 expression at 6 somites, dorsal views, anterior towards the left. (I-P) dlx3 expression at 21 somites. (I-L) Lateral views with anterior towards the left, (M-P) dorsoanterior views with anterior towards the top. ot, otic region; olf, olfactory region; va, visceral arches. Scale bar: 100 µm.

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Acknowledgments
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