Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, 201306, China.
National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, 201306, China.
Dev Genes Evol. 2021 Mar;231(1-2):11-19. doi: 10.1007/s00427-020-00671-8. Epub 2020 Nov 26.
Germ cell-specific genes play an important role in establishing the reproductive system in sexual organisms and have been used as valuable markers for studying gametogenesis and sex differentiation. Previously, we isolated a vasa transcript as a germ cell marker to trace the origin and migration of germ cells in the oriental river prawn Macrobrachium nipponense. Here, we identified a new germ cell-specific marker MnTdrd RNA and assessed its temporal and spatial expression during oogenesis and embryogenesis. MnTdrd transcripts were expressed in high abundance in unfertilized eggs and embryos at cleavage stage and then dropped significantly during late embryogenesis, suggesting that MnTdrd mRNA is maternally inherited. In situ hybridization of ovarian tissue showed that MnTdrd mRNA was initially present in the cytoplasm of previtellogenic oocyte and localized to the perinuclear region as the accumulation of yolk in vitellogenic oocyte. Whole-mount in situ hybridization of embryos showed that MnTdrd-positive signals were only localized in one blastomere until 16-cell stage. In the blastula, there were approximately 16 MnTdrd-positive blastomeres. During embryonized-zoea stage, the MnTdrd-positive cells aggregated as a cluster and migrated to the genital rudiment which would develop into primordial germ cells (PGCs). The localized expression pattern of MnTdrd transcripts resembled that of the previously identified germ cell marker vasa, supporting the preformation mode of germ cell specification. Therefore, we concluded that MnTdrd, together with vasa, is a component of the germ plasm and might have critical roles in germ cell formation and differentiation in the prawn. Thus, MnTdrd can be used as a novel germ cell marker to trace the origin and migration of germ cells.
生殖细胞特异性基因在有性生物生殖系统的建立中起着重要作用，并且已被用作研究配子发生和性别分化的有价值的标记。以前，我们分离了一个 vasa 转录物作为生殖细胞标记，以追踪东方沼虾 Macrobrachium nipponense 中生殖细胞的起源和迁移。在这里，我们鉴定了一个新的生殖细胞特异性标记 MnTdrd RNA，并评估了其在卵发生和胚胎发生过程中的时空表达。MnTdrd 转录物在未受精卵和卵裂期胚胎中大量表达，然后在晚期胚胎发生过程中显著下降，表明 MnTdrd mRNA 是母源性遗传的。卵巢组织的原位杂交显示，MnTdrd mRNA 最初存在于卵母细胞的细胞质中，并随着卵母细胞中卵黄的积累而定位于核周区。胚胎的整体原位杂交显示，直到 16 细胞期，MnTdrd 阳性信号仅局限于一个分裂球中。在囊胚期，大约有 16 个 MnTdrd 阳性分裂球。在胚胎变形期，MnTdrd 阳性细胞聚集为一团并迁移到生殖原基，生殖原基将发育成原始生殖细胞（PGCs）。MnTdrd 转录物的局部表达模式与先前鉴定的生殖细胞标记 vasa 相似，支持生殖细胞特化的预定模式。因此，我们得出结论，MnTdrd 与 vasa 一起是生殖质的组成部分，可能在虾的生殖细胞形成和分化中发挥关键作用。因此，MnTdrd 可以用作追踪生殖细胞起源和迁移的新的生殖细胞标记。
