Data from: A FISH-based chromosome map for the European corn borer yields insights into ancient chromosomal fusions in the silkworm

A significant feature of the genomes of Lepidoptera, butterflies and moths, is the high conservation of chromosome organization. Recent remarkable progress in genome sequencing of Lepidoptera has revealed that syntenic gene order is extensively conserved across phylogenetically distant species. The ancestral karyotype of Lepidoptera is thought to be n = 31; however, that of the most well studied moth, Bombyx mori, is n = 28, and diverse studies suggest that three chromosomal fusion events occurred in this lineage. To identify the boundaries between predicted ancient fusions involving B. mori chromosomes 11, 23 and 24, we constructed FISH-based chromosome maps of the European corn borer, Ostrinia nubilalis (n = 31). We first determined 511 Mb genomic sequence of the Asian corn borer, Ostrinia furnacalis, a congener of O. nubilalis, and isolated BAC and fosmid clones that were expected to localize in candidate regions for the boundaries using these sequences. Combined with FISH and genetic analysis, we narrowed down the candidate regions to 40 kb-1.5 Mb, in strong agreement with a previous estimate based on the genome of a butterfly, Melitaea cinxia. The significant difference in the lengths of the candidate regions where no functional genes were observed may reflect the evolutionary time after fusion events.鳞翅目（Lepidoptera，包括蝶类与蛾类）的基因组具有一项显著特征，即染色体组织的高度保守性。近年来，鳞翅目基因组测序领域取得了突破性进展，研究表明系统发育关系较远的物种间，共线性基因的排布顺序具有广泛的保守性。学界普遍推测鳞翅目的祖先核型染色体基数为n=31；但研究最为深入的蛾类物种家蚕（Bombyx mori）的核型染色体基数为n=28，多项研究显示该演化支曾发生过三次染色体融合事件。为明确家蚕11号、23号与24号染色体所涉及的预测远古融合事件的边界，我们以染色体基数为n=31的欧洲玉米螟（Ostrinia nubilalis）为实验材料，构建了基于荧光原位杂交（Fluorescence In Situ Hybridization，FISH）的染色体物理图谱。我们首先完成了同属物种亚洲玉米螟（Ostrinia furnacalis）的511 Mb基因组测序，并依托该基因组序列，分离得到预期定位于融合边界候选区域的细菌人工染色体（Bacterial Artificial Chromosome，BAC）克隆与黏粒（fosmid）克隆。结合荧光原位杂交实验与遗传分析，我们将候选区域的范围缩小至40 kb至1.5 Mb区间，该结果与此前基于蝶类网蛱蝶（Melitaea cinxia）基因组所得到的估算结果高度一致。未检测到功能基因的候选区域长度存在显著差异，这一现象或可反映各染色体融合事件发生后的进化时长差异。