Figure 3.
(A) Conversion of T4 to T3 in tadpole limb buds but not tail tissue. Stage-54 tadpoles were reared in methimazole with or without iopanoic acid for 24 h and then incubated with [125I]T4 for 24 h followed by nonradioactive medium for another 24 h. Limbs and tails were extracted in methanol for radioactive TH, and the concentrated extracts were chromatographed. A lane contains extract from four hind limbs or one tail. Hind limb (lane 1), tail (lane 2), and hind limb with iopanoic acid (lane 3). (B) Stage-59 tadpoles were incubated in either iopanoic acid (IOP) or methimazole (MET) for 1 day and then were incubated for a day in 0.5 μCi/ml radioactive NaI. TH was extracted from whole tadpoles and separated by TLC. Duplicate samples were chromatographed, and each lane represents about one-third of a tadpole. CON, control.