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. 2024 Mar 13;22(3):e3002555. doi: 10.1371/journal.pbio.3002555

Fig 2. Novel genetic markers label distinct cell types of the papillae.

Fig 2

(A) GFP reporter plasmid (green) constructed using the cis-regulatory sequences from the KH.L96.43 gene labels basal cells in between and surrounding the protruding papillae labeled by Foxg reporter plasmid (pink). (B) TGFB>GFP reporter (green) labels PNs, the axons of which make contacts with BTN axons labeled by a BTN-specific Islet reporter (pink), at 23.5 h hpf, approximately corresponding to Hotta stage 30. (C) A KH.C4.78 reporter (C4.78>GFP) also labels PNs, which are also labeled by Foxg>H2B::mCherry (mCh) reporter (pink nuclei). (D) Lack of overlap between expression of C4.78>GFP (green) and a papilla-specific Islet reporter plasmid (pink nuclei) showing that PNs do not arise from Islet+ cells. (E, F) Co-electroporation of C11.360>GFP (green) with H2B::mCherry reporter plasmids (pink nuclei) indicates these cells come from Foxg-expressing cells that also express Islet. (G) C11.360>mCherry reporter (pink) labels centrally located ICs adjacent to ACCs labeled by CryBG>LacZ reporter (green). (H, I) L141.36>GFP reporter (green) labels OCs that arise from Foxg+ cells (pink nuclei) but do not express Islet (pink nuclei). (J) ICs and OCs are distinct cells as there is no overlap between C11.360 (green) and L141.36 (pink) reporter plasmid expression. (K) Ciona intestinalis (Type B) larva ICs labeled with a reporter plasmid made from the corresponding cis-regulatory sequence of the C. intestinalis Chr11.1038 gene, orthologous to C. robusta KH.C11.360. (L) C. intestinalis larva OCs labeled by a Chr7.130 reporter, corresponding to the C. robusta ortholog KH.L141.36. (M) Summary of the main marker genes and corresponding reporter plasmids used in this study to label different subsets of papilla progenitors and their derivative cell types. All GFP and mCherry reporters fused to the Unc-76 tag, unless specified (see Methods and supplement for details). Weaker Foxg -2863/-3 promoter used in panel A, all other Foxg reporters used the improved Foxg -2863/+54 sequence instead. All Islet reporters shown correspond to the Islet intron 1 + bpFOG>H2B::mCherry plasmid. White channel shows either DAPI (nuclei) and/or larva outline in brightfield, depending on the panel. All C. robusta raised at 20 °C to 18 hpf (roughly st. 28) except: panel B (23.5 hpf, ~st. 30); panels C–F (17 hpf, ~st. 27); panels H–J (20 hpf, ~st. 29). C. intestinalis raised at 18 °C to 20–22 hpf (Hotta stage 28). ACC, axial columnar cell; BTN, bipolar tail neuron; hpf, hours post-fertilization; IC, inner collocyte; OC, outer collocyte; PN, papilla neuron.