tbx16-dependent paraxial mesoderm formation is essential for proximodistal nephron patterning. Whole-mount in situ hybridization analysis for nephron segment markers (purple) and mhc (red) at the 28 somite stage in wild-type embryos and tbx16 morpholino (MO) -injected embryos. Embryos are shown in lateral views with anterior to the left. Black brackets and arrows indicate expression domains, and numbers correspond to somite position. A: tbx16 knockdown in wild-types was associated with formation of reduced podocyte numbers, shown by reduced wt1b expression, and shorter proximal segments, shown by smaller nbc1, slc10a1a, and trpm7 gene expression domains; conversely, distal segments were expanded, shown by longer clck, slc12a1, and slc12a3 expression domains. The DL (gata3-expressing segment) was unaffected. B: tbx16 morpholino injected animals have a reduced rostral domain (hnf4a), and shifts in the central (irx3b), and caudal (mecom) domains at 28 somites that are consistent with shorter proximal and expanded distal segments. C,D: tbx16 morpholino injected animals have dramatically reduced expression of aldh1a2 at 28 somites (C) and 5 somites (D).
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