Adult haemoglobin in developmentally retarded tadpoles of Xenopus laevis

Tadpoles of Xenopus laevis reared in water containing 0-01% propylthiouracil continue to grow but fail to develop or metamorphose. The haemoglobin of such tadpoles has been extracted in buffer, converted to a cyanmet form, and run on polyacrylamide gels. The developmentally retarded tadpoles are found to possess adult-type haemoglobin rather than the tadpole type which normally characterizes their developmental stage.