Du Pasquier L, Hsu E
Eur J Immunol. 1983 Jul;13(7):585-90. doi: 10.1002/eji.1830130714.
The expression of species-specific surface IgM was studied in various Xenopus species hybrids. Whether the hybrids are diploid or polyploid, a lymphocyte does not produce all of the immunoglobulins (Ig) encloded by the Ig genes present in its genome. This suggests that the selection pressure to make a lymphocyte synthesize only one antibody is high and that allelic exclusion already existed in the ancestors of amphibians which appeared 300 million years ago. The apparent lack of cells producing multiple Ig in polyploid hybrids having more than one pair of functional Ig genes suggests that if a stochastic model for allelic exclusion is correct, the frequency of multiple successful rearrangements has to be very low, resulting in a huge waste of lymphocyte precursors. Given the particularity of frog development it is argued that this is not likely to be the case.
在各种非洲爪蟾物种杂交体中研究了物种特异性表面免疫球蛋白M（IgM）的表达。无论杂交体是二倍体还是多倍体，淋巴细胞都不会产生其基因组中存在的免疫球蛋白（Ig）基因所编码的所有免疫球蛋白。这表明促使淋巴细胞仅合成一种抗体的选择压力很大，并且等位基因排斥在3亿年前出现的两栖动物祖先中就已经存在。在具有不止一对功能性Ig基因的多倍体杂交体中明显缺乏产生多种Ig的细胞，这表明如果等位基因排斥的随机模型是正确的，那么多次成功重排的频率必定非常低，从而导致淋巴细胞前体的大量浪费。鉴于青蛙发育的特殊性，有人认为情况不太可能如此。
