Fig. 1

etv5a transcripts show early expression in the renal progenitor field where the MCC domain later emerges. (A) Schematic of the fully segmented zebrafish pronephros at 24 hpf, shown in both a lateral and dorsal view. Enlargement depicts the somite map of transporter cell segments and the MCC domain. (B) WISH at the 15 ss reveals that the etv5a (purple) expression domain correlates to the rostral and central regions of the renal progenitor field, demarcated by the marker slc4a4a (purple). slc12a3 (purple) denotes the caudal region, and somites are stained by smyhc1 in red. Black brackets highlight etv5a, slc4a4a, and slc12a3 expression domains in the pronephros. (C) The expression domain of etv5a is restricted in the proximal tubule during nephrogenesis, where the MCC domain, marked by odf3b (purple), expands. Insets show magnified view of etv5a and odf3b domains in the pronephros, denoted by the black bars. At the 28 ss, the etv5a domain is largely restricted to the PST (black bar), with weak expression in neighboring pronephros segments (black dots). The expression domain of odf3b at the 28 ss stage spans a caudal portion of the PCT (black dots), the PST (black bar), and the DE segment (black dots). (D) Schematic of etv5a cDNA depicting the two functional domains, acidic (light green) and ETS (dark gray), of the Etv5a protein. Abbreviations: P (podocyte), N (neck), PCT (proximal convoluted tubule), PST (proximal straight tubule), DE (distal early), CS (corpuscle of Stannius), DL (distal late), PD (pronephric duct), C (cloaca), ss (somite stage), etv5a (ets variant 5a), slc4a4a (solute carrier family 4 (sodium bicarbonate cotransporter), member 4a), slc12a3 (solute carrier family 12 (sodium/chloride transporter), member 3), smyhc1 (slow myosin heavy chain 1), odf3b (outer dense fiber of sperm tails 3b), TAD (transactivation domain).