Identification of Igσ and Igλ in channel catfish, Ictalurus punctatus, and Igλ in Atlantic cod, Gadus morhua
Identification of Igσ and Igλ in channel catfish, Ictalurus punctatus, and Igλ in Atlantic cod, Gadus morhua
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DOI：
10.1007/s00251-009-0365-z
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发表时间：
2009-05-01
期刊：
影响因子：
3.2
通讯作者：
Bengten, Eva
中科院分区：
文献类型：
--
作者：
Edholm, Eva-Stina;Wilson, Melanie;Bengten, Eva
通过挖掘表达序列标签数据库、5‘-RACE和RT-PCR方法，鉴定了斑点叉尾鱼和大西洋鳕鱼的免疫球蛋白轻链基因igma和lambda。每条IGL链的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，与其他硬骨鱼IGL基因一样，编码这些异型的基因存在于一个或两个V基因片段的簇状组织中，紧随其后的是单个J和C基因片段，均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sigma和lambda的基因数量很少，而且这两种同功型都只由两个簇编码。同样，大西洋鳕鱼的lambda基因预计由两到三个簇编码。正如预期的那样，序列分析和系统发育分析比较表明，叉尾鱼的V sigma和C sigma基因与其他温带脊椎动物的V sigma和C sigma基因最相似。虽然鲶鱼和大西洋鳕鱼V lambda基因与其他脊椎动物V lambda基因聚在一起，但它们的C lambda序列与其他脊椎动物的IGL C序列分开聚在一个不同的组中。然而，支持将这些序列归类为lambda的是它们的V和J重组信号序列(RSS)组织。鳕鱼和大西洋鳕鱼都有典型的类lambda RSS，其中V lambda RSS由七聚体-23bp间隔物-九聚体组成，J lambda RSS由七聚体-12bp间隔物-九聚体组成。这是第一个证明硬骨鱼中存在Ig lambda的报告。
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 V sigma and C sigma genes are most similar to V sigma and C sigma genes of other ectothermic vertebrates. Although catfish and Atlantic cod V lambda genes cluster with other vertebrate V lambda genes, their C lambda 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 V lambda RSS consisting of heptamer-23 bp spacer-nonamer and the J lambda RSS consisting of heptamer-12 bp spacer-nonamer. This is the first report demonstrating the presence of Ig lambda in teleosts.