Hematopoietic tissue environment and molecular interactions in erythropoiesis

非洲爪蟾（Xenopus laevis）的促红细胞生成素（EPO）及其受体（EPO）的哺乳动物同源物在成体肝脏中表达。非洲爪蟾EPO与哺乳动物EPO蛋白的同源性仅为38%。通过首次在两栖动物中建立集落测定，我们不仅能够证明肝脏中存在能够形成红系集落的红系祖细胞，而且还能够证明爪蟾EPO的特异性功能和贫血血清中EPO的存在。在低温性贫血的条件下，新的红细胞保留在肝脏中。这是首次在生理动物模型中描述研究两栖动物造血组织中红系祖细胞的直接证据。

In African clawed frog, Xenopus laevis, mammalian homologues of erythropoietin (EPO) and its receptor (EPO) express in the adult liver. Xenopus EPO had only 38% identity with mammalian EPO protein. By establishing a colony assay for the first time in amphibian, we were able not only to demonstrate the presence of erythroid progenitors in the liver capable of forming erythroid colonies but also the specific function of Xenopus EPO and the presence of EPO in anemic serum. Under conditions of hypothermic anemia, new erythrocytes were retained in the liver. This is the first study to describe the direct evidences in a physiological animal model to investigate the erythroid progenitor in amphibian hematopoietic tissues.