RABBIT ALLOTYPES--STRUCTURE, ORGANIZATION AND REGULATED EXPRESSION OF IG GENES

我们用分子生物学技术研究了兔免疫系统的基因， 生物学和免疫学。 艾丽西亚兔的免疫系统发生了突变 影响重链表达的球蛋白重链基因座 编码α 2同种异型的可变区基因（VH）。 早些时候，我们发现了一个 含有3' VH基因的区段的相对小的缺失， 重要的调节功能，失去这些功能会导致ALI 表型 VH基因座的3'端可能在以下方面起关键作用： 兔中VH基因表达的调控，因为这种调控中的VH基因 该地区是优先VDJ重排的目标。 替代 基因转换等机制可能有助于多样化 抗体库中的一部分。我们用PCR技术 扩增突变Alicia和正常a2兔的表达VH基因， 为了确定VHa基因编码序列， 对于α 2分子以及编码α-分子的VHa-基因， 在突变的艾丽西亚兔中表达升高。 我们发现 第一功能性VH基因（VH 4a 2）或VH 4a 2样基因的产物 在2到8周龄的突变体艾丽西亚中表达， a-阴性基因的VHx和VHy型也升高， VHx和VHy的相对比例随年龄的增长而下降，尤其是VHx; 与此同时，VH 4a 2或VH 4a 2-like的相对表达水平也与VH 4a 2的相对表达水平相关。 基因增加。 序列的出现类似于 突变体中缺失的VH 1a 2基因可能是由于基因转换所致 改变了重排的VH 4a 2的序列; 上游VH 1a 2样基因也可能在发育后期出现。 我们使用 逆转录和PCR扩增以分离完整的编码 兔RAG-2基因。 从胸腺mRNA中克隆了两个cDNA克隆， 测序并与K博士的基因组DNA克隆序列进行比较 鲁 采用RT-PCR方法观察了兔RAG-2基因的遗传多态性， 测序和Southern分析。 胸腺mRNA的北方分析 结果表明，兔RAG-2转录物的大小几乎是 同源小鼠转录物。 Southern分析使用来自5'端的探针， RAG-2编码区表明兔有几个外显子 对mRNA序列有贡献。 RAG-1的兔mRNA为 RAG-1编码区的一个片段， 序列也已经通过类似的PCR技术克隆，并且序列 与基因组RAG-1相比。

We study genes of the rabbit immune system by techniques of molecular biology and immunology. Alicia rabbits have a mutation in the immuno- globulin heavy chain locus that affects the expression of heavy chain variable region genes (VH) encoding the a2 allotype. Earlier, we found a relatively small deletion of a segment containing 3' VH genes with important regulatory functions, the loss of which leads to the ali phenotype. The 3' end of the VH locus probably plays a key role in regulation of VH gene expression in rabbits because VH gene(s) in this region are the targets of preferential VDJ rearrangements. Alternative mechanisms such as gene conversion may contribute to the diversification of the antibody repertoire in this species. We used the PCR technique to amplify the expressed VH genes of mutant Alicia and normal a2 rabbits of different ages, in order to determine the sequences of VHa genes coding for a2 molecules as well as VHa- genes coding for the a- molecules whose expression is elevated in mutant Alicia rabbit. We found that the products of the first functional VH gene (VH4a2) or VH4a2-like gene(s) were expressed in two to eight-week-old mutant Alicia; expression of both the VHx and VHy types of a-negative genes was also elevated but the relative proportions of VHx and VHy, especially VHx, decreased with age; meanwhile, the relative levels of expression of the VH4a2 or VH4a2-like gene(s) increased. The appearance of sequences resembling that of the VH1a2 gene which is deleted in the mutants may be due to gene conversions that altered the sequence of the rearranged VH4a2; rearrangement of upstream VH1a2-like genes may also occur later in development. We used reverse transcription and PCR amplification to isolate the complete coding region of the rabbit RAG-2 gene. Two cDNA clones from thymic mRNA were sequenced and compared to the sequence of a genomic DNA clone from Dr. K Roux. Genetic polymorphism of the rabbit RAG-2 gene was observed by sequencing and Southern anal-yses. Northern analysis of thymic mRNA showed that the rabbit RAG-2 transcript was almost twice the size of the homologous mouse transcript. Southern analyses using a probe from 5' of the RAG-2 coding region indicate that the rabbit has several exons contributing to the mRNA sequence. The rabbit mRNA for RAG-1 is of comparable size to those of mouse and man. A fragment of RAG-1 coding sequence has also been cloned by similar PCR techniques and the sequence compared with genomic RAG-1.