Figure 3

The expression domains of slc genes identify three distinct segments in the proximal tubule. Stage 35/36 Xenopus embryos were stained for marker gene expression by whole-mount in situ hybridization. For each distinct class of expression pattern obtained, lateral views of embryos stained for two representative slc genes are shown accompanied by enlargements of the pronephric region. A color-coded scheme of the nephron depicts the deduced segmental expression domains. (a) Examples of slc genes expressed in all segments of the proximal tubule. (b-d) Examples of slc genes with expression confined to proximal tubule (PT)1 (panel b), PT2 (panel c), or PT3 (panel d) alone. Arrowheads are shown to highlight specific proximal tubule segments stained. (e,f) Examples of slc genes with expression either in PT1 and PT2 (panel e) or in PT2 and PT3 (panel f). In panel e, arrowheads and arrows highlight the PT1 and PT2 segments, respectively. In panel f, arrowheads and arrows highlight the PT2 and PT3 segments, respectively. The localization of the slc7a13 expression domains has previously been reported [22]. They are shown here for comparative purposes.