| 研究実績の概要 |
Planarian is a non-parasitic Platyhelminthes (flatworm) that is famous for its regeneration ability and for having acquired a very early functional brain structure during evolution. Dugesia japonica is a typical planarian species widely spread in the Far East. Cellular and molecular experimental methods have been extensively developed to identify the functions of thousands of genes in this species, which have made this planarian a good experimental model. However, no genome information is available for this animal, and few gene regulatory mechanisms have been identified thus far. To obtain the overall genetic information of this species and to study its gene regulatory mechanisms, we firstly extracted genomic DNA from a laboratory-bred asexual clonal strain, and sequenced 476 Gb of data by second-generation sequencing. The Kmer frequency distribution graph and fosmid sequences analysis indicated a complicated genome that would be difficult to assemble by using pair-end sequencing data. Therefore, we used a new assembly strategy and successfully improved the de novo genome assembly. As a result, a 1.56 Gb genome sequence (including 213,090 scaffolds and N50 length 23,204bp) was achieved. To search for possible gene regulatory mechanisms, we further analyzed the conserved non-coding elements (CNEs) between two planarian genuses, and performed transgenic experiments that proved that a CNE in the Djndk gene is a regulatory element. Thus, this draft genome and CNE analysis based on it will have many long-term benefits for planarian research in the future.
|
