Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan.
Advanced Science Course, Department of Integrated Science and Technology, National Institute of Technology, Tsuyama College, 624-1 Numa, Tsuyama, Okayama 708-8509, Japan.
Sci Rep. 2017 Mar 24;7:45175. doi: 10.1038/srep45175.
Many metazoans start germ cell development during embryogenesis, while some metazoans possessing pluripotent stem cells undergo postembryonic germ cell development. The latter reproduce asexually but develop germ cells from pluripotent stem cells or dormant primordial germ cells when they reproduce sexually. Sexual induction of the planarian Dugesia ryukyuensis is an important model for postembryonic germ cell development. In this experimental system, hermaphroditic reproductive organs are differentiated in presumptive gonadal regions by the administration of a crude extract from sexual planarians to asexual ones. However, the substances involved in the first event during postembryonic germ cell development, i.e., ovarian development, remain unknown. Here, we aimed to identify a bioactive compound associated with postembryonic ovarian development. Bioassay-guided fractionation identified ʟ-tryptophan (Trp) on the basis of electrospray ionization-mass spectrometry, circular dichroism, and nuclear magnetic resonance spectroscopy. Originally masked by a large amount of ʟ-Trp, ᴅ-Trp was detected by reverse-phase high-performance liquid chromatography. The ovary-inducing activity of ᴅ-Trp was 500 times more potent than that of ʟ-Trp. This is the first report describing a role for an intrinsic ᴅ-amino acid in postembryonic germ cell development. Our findings provide a novel insight into the mechanisms of germ cell development regulated by low-molecular weight bioactive compounds.
许多后生动物在胚胎发生期间开始生殖细胞发育，而一些具有多能干细胞的后生动物则经历胚胎后生殖细胞发育。后者通过无性繁殖繁殖，但在有性繁殖时从多能干细胞或休眠原始生殖细胞中发育生殖细胞。扁形动物门 Dugesiryukyuensis 的性诱导是胚胎后生殖细胞发育的重要模型。在这个实验系统中，通过将来自有性扁形动物的粗提取物施用于无性扁形动物，将假定的生殖腺区域中的两性生殖器官分化。然而，在胚胎后生殖细胞发育的第一个事件（即卵巢发育）中涉及的物质仍然未知。在这里，我们旨在鉴定与胚胎后卵巢发育相关的生物活性化合物。基于电喷雾电离质谱、圆二色性和核磁共振波谱的生物测定指导的分馏确定了 ʟ-色氨酸（Trp）。最初被大量 ʟ-Trp 掩盖，ᴅ-Trp 通过反相高效液相色谱法检测到。ᴅ-Trp 的卵巢诱导活性比 ʟ-Trp 强 500 倍。这是第一个描述内在 ʟ-氨基酸在胚胎后生殖细胞发育中的作用的报告。我们的研究结果为受低分子量生物活性化合物调节的生殖细胞发育机制提供了新的见解。
