The haemoglobins of healthy and anaemic Xenopus laevis.

The haemoglobins of Xenopus laevis have been studied by carboxymethyl-cellulose column chromatography and by polyacrylamide gel disk electrophoresis. In Xenopus tadpoles, 2 haemoglobins are found (Xenopus-HbFx and Xenopus-HbF^). Both haemoglobins persist throughout tadpole life: Xenopus-HbF\ is the main tadpole haemoglobin; Xenopus-HbFt is present in rather smaller amounts. The proportion of Xenopus-HbF\ to Xenopus-HbF3 increases as the tadpoles age. Almost all the tadpole haemoglobin disappears soon after metamorphosis, although traces persist throughout adult life. Two adult haemoglobins occur in Xenopus: they first appear during the later tadpole stages. Xenopus-HbAx comprises the majority of the adult haemoglobin. Between one-twentieth and one-tenth of the adult haemoglobin consists of XenopusHbAt, which is not a polymer of Xenopus-HbA1. Immunoglobulins respectively specific to pooled Xenopus-HbF^ and Xenopus-HbFt, and to pooled Xenopus-HbA1 and Xenopus-HbA2 were raised. Samples of these antibodies were conjugated with fluorescein isothiocyanate. Adult Xenopus were made anaemic by bleeding or by injection of phenylhydrazine. Fourteen days after the induction of anaemia it was found, using both chromatographic and electrophoretic techniques, that most anaemic toads had started to resynthesize Xenopus-HbF^ In some animals up to 11 % of the haemoglobin present was found to be Xenopus-HbF1; and precipitin lines were obtained when the pooled haemoglobins from these animals were tested with a specific anti-_Xeno/WM-HbF immunoglobulin. During recovery from anaemia greatly enhanced amounts of Xenopus-HbA^ (up to 58 % of the total haemoglobin) were present in the blood. The amounts of tadpole haemoglobins present in such recovering toads were not noticeably greater than in healthy animals. Between 42 and 120 days after the induction of anaemia the haemoglobin profile of the toads regained normality.