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Studies of the ascidian genome system as a model of chordates and its evolution

作为脊索动物模型的海鞘基因组系统及其进化研究

基本信息

批准号：
12202001
负责人：
SATOH Noriyuki
金额：
$ 165.12万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2004
项目状态：
已结题

项目摘要

Ascidians, or sea squirts, are sessile marine invertebrate chordates. Although the adults are simple filter feeders, the fertilized eggs develop quickly into so-called tadpole larvae. The larva is composed of only〜2600 cells, which constitute a small number of organs including epidermis, central nervous system (CNS), endoderm and mesenchyme in the trunk, and notochord and muscle in the tail, representing the most simplified chordate body plan. We have decoded the draft genome of Cion intestinalis, and its〜120 Mbp euchromatic genome contains〜16,000 protein-coding genes. Among these is a fundamental set of conserved chordate genes encoding transcriptional factors and cell signaling molecules. Comparison of the Ciona genome with those of invertebrates and vertebrates suggests genetic changes which might have been associated with the evolution of chordates and vertebrates. In addition, we mapped by FISH methodology the genome information onto the 14 pairs of chromosomes of this anima. A thorough examination of Ciona gene expression (the transcriptome) is ongoing, including large scale EST analyses (〜700,000 ESTs), cDNA sequencing, in situ hybridization, and microarray analyses. Transgenic DNAs can be introduced into developing embryos using simple electroporation methods. Together with computational searching of conserved sequences between C. intestinalis and C. savignyi, this method permits rapid identification of cis-regulatory motifs governing the spatio-temporal expression of developmental genes. Together with recent advances in the methodology used to investigate gene regulation and function, these research circumstances make ascidians an appealingly simple experimental system for investigating the molecular mechanisms that underlie chordate development.

海鞘，或海鞘，是固着的海洋无脊椎动物脊索动物。尽管成虫是简单的滤食性动物，但受精卵很快就会发育成所谓的蝌蚪幼虫。幼虫仅由约2600个细胞组成，这些细胞构成了少数器官，包括躯干中的表皮、中枢神经系统（CNS）、内胚层和间充质，以及尾部的脊索和肌肉，代表了最简化的脊索动物身体平面。我们已经解码了Cion的基因组草图，其约120 Mbp的常染色质基因组包含约16，000个蛋白质编码基因。在这些基因中，有一组基本的保守脊索动物基因编码转录因子和细胞信号分子。玻璃海鞘基因组与无脊椎动物和脊椎动物的基因组比较表明，可能与脊索动物和脊椎动物的进化有关的遗传变化。此外，我们还利用FISH技术将基因组信息定位到了该动物的14对染色体上。目前正在对玻璃海鞘基因表达（转录组）进行全面检查，包括大规模EST分析（约70万个EST）、cDNA测序、原位杂交和微阵列分析。可以使用简单的电穿孔方法将转基因DNA引入发育中的胚胎中。并结合C.和C. Savignyi，该方法允许快速鉴定控制发育基因时空表达的顺式调节基序。再加上最近在研究基因调控和功能的方法上取得的进展，这些研究环境使海鞘成为研究脊索动物发育的分子机制的一个非常简单的实验系统。