Edholm Eva-Stina, Wilson Melanie, Sahoo Manoranjan, Miller Norman W, Pilström Lars, Wermenstam Niklas E, Bengtén Eva
Department of Microbiology, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA.
Immunogenetics. 2009 May;61(5):353-70. doi: 10.1007/s00251-009-0365-z. Epub 2009 Mar 31.
Immunoglobulin light (IGL) chain genes encoding sigma and lambda from channel catfish, Ictalurus punctatus, and lambda from Atlantic cod, Gadus morhua, were identified by mining of expressed sequence tag databases, 5'-RACE and RT-PCR protocols. cDNAs for each of these IGL chains encode typical variable (V), joining (J), and constant (C) regions and Southern blot analyses and genomic sequencing show that genes encoding these isotypes, like other teleost IGL genes, are found in a cluster organization of one or two V gene segments, followed by single J and C gene segments, all in the same transcriptional orientation. However, unlike the teleost kappa genes, genes encoding catfish sigma and lambda are few in number and the two isotypes are each encoded by only two clusters. Similarly, Atlantic cod lambda genes are predicted to be encoded by two or three clusters. As expected, sequence and phylogenetic analyses comparisons demonstrate that catfish Vsigma and Csigma genes are most similar to Vsigma and Csigma genes of other ectothermic vertebrates. Although catfish and Atlantic cod Vlambda genes cluster with other vertebrate Vlambda genes, their Clambda sequences cluster in a distinct group separate from other vertebrate IGL C sequences. However, support for classifying these sequences as lambda, is their V and J recombination signal sequence (RSS) organization. The catfish and Atlantic cod genes have typical lambda-like RSS with the Vlambda RSS consisting of heptamer-23 bp spacer-nonamer and the Jlambda RSS consisting of heptamer-12 bp spacer-nonamer. This is the first report demonstrating the presence of Iglambda in teleosts.
通过挖掘表达序列标签数据库、5'-RACE和RT-PCR方法，鉴定了斑点叉尾鮰（Ictalurus punctatus）编码西格玛（sigma）和兰姆达（lambda）的免疫球蛋白轻链（IGL）基因以及大西洋鳕鱼（Gadus morhua）编码兰姆达的基因。这些IGL链各自的cDNA编码典型的可变区（V）、连接区（J）和恒定区（C），Southern印迹分析和基因组测序表明，编码这些同种型的基因，与其他硬骨鱼IGL基因一样，以一个或两个V基因片段的簇状组织形式存在，随后是单个J和C基因片段，所有片段都处于相同的转录方向。然而，与硬骨鱼kappa基因不同的是，编码鲶鱼西格玛和兰姆达的基因数量很少，这两种同种型各自仅由两个簇编码。同样，预计大西洋鳕鱼兰姆达基因由两个或三个簇编码。正如预期的那样，序列和系统发育分析比较表明，鲶鱼Vsigma和Csigma基因与其他变温脊椎动物的Vsigma和Csigma基因最为相似。尽管鲶鱼和大西洋鳕鱼Vlambda基因与其他脊椎动物Vlambda基因聚类，但它们的Clambda序列聚在一个与其他脊椎动物IGL C序列不同的独特组中。然而，将这些序列归类为兰姆达的依据是它们的V和J重组信号序列（RSS）组织。鲶鱼和大西洋鳕鱼基因具有典型的类似兰姆达的RSS，Vlambda RSS由七聚体-23 bp间隔区-九聚体组成，Jlambda RSS由七聚体-12 bp间隔区-九聚体组成。这是首次报道在硬骨鱼中存在Iglambda。
