Lucero J E, Rosenberg G H, Miller R D
Department of Biology, University of New Mexico, Albuquerque 87131, USA.
J Immunol. 1998 Dec 15;161(12):6724-32.
The Ig lambda chains in the South American opossum, Monodelphis domestica, were analyzed at the expressed cDNA and genomic organization level, the first described for a nonplacental mammal. The V lambda segment repertoire in the opossum was found to be comprised of at least three diverse V lambda families. Each of these families appears to be related to distinct V lambda families present in placental mammals, suggesting the divergence of these genes before the separation of metatherians and eutherians more than 100 million years ago. Based on framework and constant region sequences from full-length cDNAs and intron sequences from genomic clones, it appears that there are multiple functional J lambda-C lambda pairs in the opossum locus. The opossum J lambda-C lambda sequences are phylogenetically clustered, suggesting that these gene duplications are more recent and species specific. Sequence analysis of a large set of functional, expressed V lambda-J lambda recombinations is consistent with an unbiased, highly diverse lambda light chain repertoire in the adult opossum. Overall, the complexity of the Ig lambda locus appears to be greater than that found in the Ig heavy chain locus in the opossum, and light chains are therefore likely to contribute significantly to Ig diversity in this species.
对南美负鼠（Monodelphis domestica）的Ig λ链在表达的cDNA和基因组组织水平上进行了分析，这是首次对非胎盘哺乳动物进行此类描述。发现负鼠的Vλ区段库至少由三个不同的Vλ家族组成。这些家族中的每一个似乎都与胎盘哺乳动物中存在的不同Vλ家族相关，这表明这些基因在1亿多年前有袋类动物和真兽类动物分离之前就已经发生了分化。根据全长cDNA的框架和恒定区序列以及基因组克隆的内含子序列，负鼠基因座中似乎存在多个功能性Jλ-Cλ对。负鼠的Jλ-Cλ序列在系统发育上聚类，表明这些基因重复是最近发生的且具有物种特异性。对大量功能性、表达的Vλ-Jλ重组体的序列分析与成年负鼠中无偏向性、高度多样化的λ轻链库一致。总体而言，Ig λ基因座的复杂性似乎大于负鼠Ig重链基因座的复杂性，因此轻链可能对该物种的Ig多样性有显著贡献。
