Godwin U B, Flores M, Quiniou S, Wilson M R, Miller N W, Clem L W, McConnell T J
N108 Howell Science Complex, Department of Biology, East Carolina University, Greenville, NC 27858-4353, USA.
Dev Comp Immunol. 2000 Sep-Oct;24(6-7):609-22. doi: 10.1016/s0145-305x(00)00005-7.
In order to characterize the Major histocompatibility complex (MHC) class II A genes of the channel catfish (Ictalurus punctatus) a cDNA library was screened and PCR was performed. Four different full-length cDNA sequences for MHC class II A genes were obtained from a clonal B cell line derived from an outbred fish. Two different genomic sequences and corresponding cDNAs were obtained from a presumably homozygous gynogenetic catfish. The A genes have five exons and four phase one introns. The first exon encodes the 5' untranslated region (UTR) and leader peptide; the second and third exons encode the alpha1 and alpha2 domains, respectively. The connecting peptide, transmembrane and cytoplasmic domains, as well as part of the 3' UTR, are encoded by the fourth exon and the rest of the 3' UTR is encoded by the fifth exon. Southern blot analyses using an exon three probe revealed two to four hybridizing fragments with considerable restriction fragment length polymorphisms evident among randomly selected outbred channel catfish. These findings are consistent with the presence of at least two functional polymorphic MHC class II A gene loci. An unusual aspect of the channel catfish MHC class II alpha chain is its lack of N-linked glycosylation sites.
为了鉴定斑点叉尾鮰（Ictalurus punctatus）的主要组织相容性复合体（MHC）II类A基因，构建了cDNA文库并进行了PCR。从一条远交系鱼的克隆B细胞系中获得了4种不同的MHC II类A基因全长cDNA序列。从一条推测为纯合雌核发育的斑点叉尾鮰中获得了2种不同的基因组序列及相应的cDNA。这些A基因有5个外显子和4个1相内含子。第一个外显子编码5'非翻译区（UTR）和前导肽；第二个和第三个外显子分别编码α1和α2结构域。连接肽、跨膜和胞质结构域以及部分3'UTR由第四个外显子编码，其余的3'UTR由第五个外显子编码。使用外显子3探针进行的Southern印迹分析显示有2至4个杂交片段，在随机选择的远交斑点叉尾鮰中存在明显的限制性片段长度多态性。这些结果与至少两个功能性多态MHC II类A基因座的存在一致。斑点叉尾鮰MHC II类α链的一个不同寻常之处在于其缺乏N-连接糖基化位点。
