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Abstract：
The leukocyte receptor complex (LRC) in humans encodes many receptors with immunoglobulin-like (Ig-like) extracellular domains, including the killer Ig-like receptors (KIRs) expressed on natural killer (NK) cells among others, the leukocyte Ig-like receptors (LILRs) expressed on myeloid and B cells, and an Fc receptor (FcR), all of which have important roles in the immune response. These highly-related genes encode activating receptors with positively-charged residues in the transmembrane region, inhibitory receptors with immuno-tyrosine based motifs (ITIMs) in the cytoplasmic tail, and bi-functional receptors with both. The related chicken Ig-like receptors (ChIRs) are almost all found together on a microchromosome, with over 100 activating (A), inhibitory (B), and bi-functional (AB) genes, bearing either one or two extracellular Ig-like domains, interspersed over 500-1,000 kB in the genome of an individual chicken. Sequencing studies have suggested rapid divergence and little overlap between ChIR haplotypes, so we wished to begin to understand their genetics. We chose to use a hybridization technique, reference strand-mediated conformational analysis (RSCA), to examine the ChIR-AB1 family, with a moderate number of genes dispersed across the microchromosome. Using fluorescently-labeled references (FLR), we found that RSCA and sequencing of ChIR-AB1 extracellular exon gave two groups of peaks with mobility correlated with sequence relationship to the FLR. We used this system to examine widely-used and well-characterized experimental chicken lines, finding only one or a few simple ChIR haplotypes for each line, with similar numbers of peaks overall. We found much more complicated patterns from a broiler line from a commercial breeder and a flock of red junglefowl, but trios of parents and offspring from another commercial chicken line show that the complicated patterns are due to heterozygosity, indicating a relatively stable number of peaks within haplotypes of these birds. Some ChIR-AB1 peaks were found in all individuals from the commercial lines, and some of these were shared with red junglefowl and the experimental lines derived originally from egg-laying chickens. Overall, this analysis suggests that there are some simple features underlying the apparent complexity of the ChIR locus.
摘要：
人类的白细胞受体复合物（LRC）编码许多具有免疫球蛋白样（Ig样）胞外域的受体，包括在自然杀伤（NK）细胞上表达的杀手Ig样受体（KIR），在骨髓和B细胞上表达的白细胞Ig样受体（LILRs），和Fc受体（FcR），所有这些在免疫反应中都有重要作用。这些高度相关的基因编码激活受体，在跨膜区带有带正电荷的残基，在胞质尾部具有基于免疫酪氨酸的基序（ITIM）的抑制性受体，和双功能受体。相关的鸡Ig样受体（ChIR）几乎都在微染色体上发现，超过100个激活（A），抑制性（B），和双功能（AB）基因，带有一个或两个细胞外Ig样结构域，散布在单个鸡的基因组中超过500-1,000kB。测序研究表明，ChIR单倍型之间存在快速分歧和少量重叠，所以我们希望开始了解他们的基因。我们选择使用杂交技术，参考链介导的构象分析（RSCA），为了检查ChIR-AB1家族，有中等数量的基因分散在微染色体上。使用荧光标记的参考（FLR），我们发现RSCA和ChIR-AB1细胞外外显子测序给出了两组峰，其迁移率与FLR的序列关系相关。我们使用这个系统来检查广泛使用和特征明确的实验鸡系，每个品系只能找到一个或几个简单的ChIR单倍型，具有相似数量的峰值。我们从商业饲养员的肉鸡生产线和一群红色丛林猫头鹰中发现了更复杂的图案，但是来自另一个商业鸡系的父母和后代的三重奏表明，复杂的模式是由于杂合性，表明这些鸟类的单倍型中的峰数量相对稳定。在来自商业生产线的所有个体中发现了一些ChIR-AB1峰，其中一些是与红色丛林猫头鹰和最初来自产蛋鸡的实验系共享的。总的来说,这项分析表明，ChIR基因座的明显复杂性背后有一些简单的特征。
