Dorn A R, Broyles R H
Proc Natl Acad Sci U S A. 1982 Sep;79(18):5592-6. doi: 10.1073/pnas.79.18.5592.
Anurans (frogs and toads) switch from tadpole to adult hemoglobin synthesis during metamorphosis. A number of workers have attempted to determine whether tadpole and adult Hb types are expressed in the same or different erythroid cells during the switch. If the different Hb types are found in different cells during the transition, the switch in globin gene expression occurs at an early stage of cellular differentiation. Previous studies, in which immunocytochemical techniques were used to approach this question, are in conflict in regard to the metamorphic Hb switch of the North American bullfrog Rana catesbeiana. We have purified newly differentiating erythroid cells from the blood of metamorphosing tadpoles by using Percoll gradients. These new cells have an immature morphology, are very active in the synthesis of adult Hb, and contain no detectable tadpole Hb. The tadpole cells have no detectable adult Hb, are synthetically inactive, increase in density during the switch, and are then cleared from the circulation. Thus, only adult Hb expression is detected in newly differentiating erythroid cells during metamorphosis.
无尾目动物（青蛙和蟾蜍）在变态过程中从蝌蚪血红蛋白合成转变为成体血红蛋白合成。许多研究人员试图确定在转变过程中蝌蚪型和成体型血红蛋白是否在相同或不同的红细胞中表达。如果在转变过程中不同的血红蛋白类型存在于不同的细胞中，那么珠蛋白基因表达的转变发生在细胞分化的早期阶段。此前使用免疫细胞化学技术来探讨这个问题的研究，在北美牛蛙牛蛙的变态血红蛋白转换方面存在冲突。我们通过使用Percoll梯度从变态期蝌蚪的血液中纯化出新分化的红细胞。这些新细胞具有未成熟的形态，在成体血红蛋白的合成中非常活跃，并且不含有可检测到的蝌蚪血红蛋白。蝌蚪细胞中没有可检测到的成体血红蛋白，合成不活跃，在转换过程中密度增加，然后从循环中清除。因此，在变态过程中，仅在新分化的红细胞中检测到成体血红蛋白的表达。
