Abstract
Tail tips of Xenopus laevis tadpoles were cultured in vitro and treated with triiodothyronine (T3) to induce tail regression. Poly (A)-containing RNA [poly (A)-RNA] was isolated from regressing tail tips and characterized. The properties of poly (A)-RNA synthesis did not change throughout tail regression. The newly synthesized poly (A)-RNA was accumulated linearly for at least 24 h of labeling time, while the proportion of poly (A)-RNA to total labeled RNA remained approximately 3%. The major part of poly(A)-RNA labeled for 24 h showed a heterogeneous size distribution ranging from 0.5×106 to 3.0×106 daltons, with a broad peak around 2.0×106 daltons, and the poly (A) segment consisted of 100-150 nucleotides of 3.3-5.0×104 daltons. The results are discussed in relation to previous findings on RNA and protein synthesis in regressing tails.
