Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan.
Frontier Research Base for Global Young Researchers, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan.
PLoS One. 2018 Nov 14;13(11):e0205609. doi: 10.1371/journal.pone.0205609. eCollection 2018.
The crustacean Daphnia magna is an important model in multi-disciplinary scientific fields such as genetics, evolutionary developmental biology, toxicology, and ecology. Recently, the draft genome sequence and transcriptome data became publicly available for this species. Genetic transformation has also been achieved via the introduction of plasmid DNA into the genome. The identification of a screenable marker gene and generation of mutant strains are essential to further advance D. magna functional genomics. Because crustaceans are closely related to insects, we hypothesized that, similar to Drosophila genetic studies, eye color-related genes can function as marker genes in Daphnia. We searched orthologs of Drosophila eye pigment transporters White, Scarlet, and Brown in the genome of D. magna. Amino acid sequence alignment and phylogenetic analysis suggested that D. magna has six white and one scarlet orthologs, but lacks the brown ortholog. Due to the multiplicity of white orthologs, we analyzed the function of the scarlet ortholog, DapmaSt, using RNA interference. DapmaSt RNAi embryos showed disappearance of black pigments both in the compound eye and in the ocellus, suggesting that DapmaSt is necessary for black pigmentation in Daphnia eyes. To disrupt DapmaSt using the Crispr/Cas9 system, we co-injected DapmaSt-targeting gRNAs with Cas9 mRNAs into eggs and established white-eyed DapmaSt mutant lines that lack eye pigments throughout their lifespan. Our results suggest that DapmaSt can be used as a transformation marker in D. magna and the DapmaSt mutants would be an important resource for genetic transformation of this species in the future.
大型溞(Daphnia magna)是遗传学、进化发育生物学、毒理学和生态学等多学科科学领域的重要模式生物。最近,该物种的基因组草图序列和转录组数据已经公开。通过将质粒 DNA 引入基因组,也实现了遗传转化。筛选标记基因的鉴定和突变株的产生对于进一步推进大型溞功能基因组学至关重要。由于甲壳类动物与昆虫密切相关,我们假设,类似于果蝇的遗传研究,与眼睛颜色相关的基因可以在大型溞中作为标记基因。我们在大型溞的基因组中搜索了果蝇眼色素转运蛋白 White、Scarlet 和 Brown 的同源物。氨基酸序列比对和系统发育分析表明,大型溞有六个 White 同源物和一个 Scarlet 同源物,但缺乏 Brown 同源物。由于 White 同源物的多样性,我们使用 RNA 干扰分析了 Scarlet 同源物 DapmaSt 的功能。DapmaSt RNAi 胚胎在复眼和小眼都显示出黑色色素的消失,表明 DapmaSt 对于大型溞眼睛中的黑色色素形成是必需的。为了使用 Crispr/Cas9 系统破坏 DapmaSt,我们将靶向 DapmaSt 的 gRNAs 与 Cas9 mRNA 共注射到卵子中,并建立了终生缺乏眼色素的白眼 DapmaSt 突变系。我们的结果表明,DapmaSt 可以作为大型溞转化标记,并且 DapmaSt 突变体将是该物种未来遗传转化的重要资源。