Figure 3. Extensive structural and functional homology between planarian protonephridia and vertebrate nephrons.
(A) Tables summarize expression domains of selected slc genes in planarian protonephridia and rodent metanephros. Cartoons showing segmental organization of planarian protonephridia and rodent metanephros are on the left. Gray color in the tables indicates expression domain of slc in planarian protonephridia and rodent metanephros. Planarian slc sequence nomenclature (e.g., slc1a-3) doesn't reflect direct orthology to the mammalian counterparts. Abbreviations for segments of protonephridia are as follows: PT1, PT2, and PT3, segments of the proximal tubule (PT); DT1 and DT2, segments of the DT; CD, the collecting duct. Abbreviations for segments of the metanephros are as follows: S1, S2, and S3, segments of the PT; DTL, descending thin limb; ATL, ascending thin limb; TAL, thick ascending limb; DCT, distal convoluted tubules; CNT, connecting tubule; CD, collecting duct. (B) Fluorescent overlay of reabsorbed dextran with PT marker (AcTub). (C) pHi reporter assay using SNARF-5F-AM in Control(RNAi) and slc4a-6(RNAi).