Until recently, different families of urodele amphibians were thought to express distinct subsets of immunoglobulin (Ig) isotypes. In this study, we explored cDNAs encoding Ig heavy-chains (H-chains) in three species of urodele amphibians. We found that Cynops pyrrhogaster, Pleurodeles waltl, and Ambystoma mexicanum each carry genes encoding four Ig H-chain isotypes, including IgM, IgY, IgD, and IgX, similar to those found in anuran amphibians. We also found that urodele IgDs have a long constant region similar to those found in anuran, reptiles, and bony fishes. We also found several putative IgD splice variants. Our findings indicated that P. waltl IgP is not a novel isotype but an IgD splice variant. Altogether, our findings indicate that IgD splice variants may be universally expressed among amphibian species.

直到最近，人们认为不同的 urodele 两栖动物家族表达不同的免疫球蛋白 (Ig) 同种型子集。在这项研究中，我们探索了三种 urodele 两栖动物中编码 Ig 重链（H 链）的 cDNA。我们发现Cynops pyrrhogaster、Pleurodeles waltl和Ambystoma mexicanum各自携带编码四种 Ig H 链同种型的基因，包括 IgM、IgY、IgD 和 IgX，类似于在无尾两栖动物中发现的基因。我们还发现 urodele IgDs 有一个长的恒定区，类似于在无尾类、爬行动物和硬骨鱼中发现的那些。我们还发现了几个推定的 IgD 剪接变体。我们的研究结果表明，P. waltlIgP 不是一种新的同种型，而是一种 IgD 剪接变体。总之，我们的研究结果表明 IgD 剪接变体可能在两栖动物物种中普遍表达。