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Fig. 1
Centra-associated subsets of otherwise uniformly distributed chordoblasts express cyp26b1 in an RA-dependent manner. (A-N) Lateral views of notochords at the level of centra 3-5 in control (A,D, n=67; G,J, n=72; M,N, n=10), RA-treated (B,E, n=84/84; H,K, n=53/53) or DEAB-treated (C,F, n=77/77; I,L, n=32/32) larvae bearing the indicated YFP- or GFP-encoding transgenes. Anterior is to the left; calcified extracellular matrix is labeled by Alizarin Red. (A-C,G-I,M) Projections of confocal stacks with merged green, magenta and transmitted light channels. (D-F,J-L,N) Corresponding single green channel projections. Insets (A,G) show single confocal planes, revealing that YFP- and GFP-positive cells are located on the inner surface of the mineralized notochord sheath. (O-R) Fluorescence in situ hybridization of cyp26b1 transcripts on transverse (O-Q; level of chordacentra) and sagittal (R) sections through the notochord, co-labeled by immunofluorescence against Laminin (yellow) and Tg(R2-col2a1a:EGFP)-encoded EGFP (green). Arrowheads highlight notochord basement membrane, arrows cyp26b1-positive cells outside the notochord, possibly representing somite-derived scleroblasts generating the outer autocentra (Bensimon-Brito et al., 2012). Scale bars: 50 µm (A-N); 20 µm (O-R). AR, Alizarin Red; nc, notochord; WT, DMSO/ethanol-treated wild-type control.