Guiliano D B, Hall N, Jones S J M, Clark L N, Corton C H, Barrell B G, Blaxter M L
Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh EH9 3JT, UK.
Genome Biol. 2002 Sep 26;3(10):RESEARCH0057. doi: 10.1186/gb-2002-3-10-research0057.
Comparisons between the genomes of the closely related nematodes Caenorhabditis elegans and Caenorhabditis briggsae reveal high rates of rearrangement, with a bias towards within-chromosome events. To assess whether this pattern is true of nematodes in general, we have used genome sequence to compare two nematode species that last shared a common ancestor approximately 300 million years ago: the model C. elegans and the filarial parasite Brugia malayi.
An 83 kb region flanking the gene for Bm-mif-1 (macrophage migration inhibitory factor, a B. malayi homolog of a human cytokine) was sequenced. When compared to the complete genome of C. elegans, evidence for conservation of long-range synteny and microsynteny was found. Potential C. elegans orthologs for II of the 12 protein-coding genes predicted in the B. malayi sequence were identified. Ten of these orthologs were located on chromosome I, with eight clustered in a 2.3 Mb region. While several, relatively local, intrachromosomal rearrangements have occurred, the order, composition, and configuration of two gene clusters, each containing three genes, was conserved. Comparison of B. malayi BAC-end genome survey sequence to C. elegans also revealed a bias towards intrachromosome rearrangements.
We suggest that intrachromosomal rearrangement is a major force driving chromosomal organization in nematodes, but is constrained by the interdigitation of functional elements of neighboring genes.
对亲缘关系密切的线虫秀丽隐杆线虫和briggsae线虫的基因组进行比较，发现重排率很高，且偏向于染色体内事件。为了评估这种模式是否普遍适用于线虫，我们利用基因组序列比较了两个大约在3亿年前拥有共同祖先的线虫物种：模式生物秀丽隐杆线虫和丝虫寄生虫马来布鲁线虫。
对Bm-mif-1（巨噬细胞迁移抑制因子，一种人类细胞因子的马来布鲁线虫同源物）基因侧翼的一个83 kb区域进行了测序。与秀丽隐杆线虫的完整基因组相比，发现了长程同线性和微同线性保守的证据。在马来布鲁线虫序列中预测的12个蛋白质编码基因中的2个，确定了其潜在的秀丽隐杆线虫直系同源物。其中10个直系同源物位于染色体I上，8个聚集在一个2.3 Mb的区域内。虽然发生了一些相对局部的染色体内重排，但两个各包含三个基因的基因簇的顺序、组成和结构是保守的。将马来布鲁线虫BAC末端基因组调查序列与秀丽隐杆线虫进行比较，也发现了偏向于染色体内重排的情况。
我们认为染色体内重排是推动线虫染色体组织形成的主要力量，但受到相邻基因功能元件相互交错的限制。
