Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, UK.
Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling, UK.
Gene. 2019 Mar 10;688:62-70. doi: 10.1016/j.gene.2018.11.078. Epub 2018 Nov 30.
Primordial germ cells (PGCs) are specified by maternally provided determinants in fish. PGCs migrate then into prospective gonadal sites during early development and give rise to germ cell lineage. PGC disrupted animals do not sexually mature which has a range of commercial as well as environmental benefits. To find potential target genes for sterilisation of Nile tilapia, relative mRNA abundance patterns and tissue distribution of four nanos, two piwil, dnd1, vasa and three pum genes were investigated during ontogenic development from unfertilised eggs to newly hatched larvae and in adult tissues, respectively. The ontogenic pattern of RNA abundance revealed that all the investigated gene transcripts are maternally deposited to varying degrees, except for nanos2 which is not expressed in eggs. The ontogenic patterns of relative RNA abundance could be grouped into three categories. The first one, including nanos3, piwil1, piwil2, dnd1 and vasa, showed abundant transcript levels during early developmental stages which are then degraded during the period of maternal to zygotic transition between blastula and gastrula stages with a reduction in expression of four to five orders of magnitude by hatching stage. Another, including pum2 and pum3, showed similar patterns to the first group, but the transcript levels are reduced by only two orders of magnitude. The third group, including nanos1a, nanos1b and pum1, was characterised by a zygotic increase. nanos2 had no detectable transcripts until hatching stage. The tissue screening of nanos1a, nanos1b, pum1, pum2 and pum3 showed that they are expressed in various tissues, implying their potential pleiotropic effects in these tissues apart from gonads. In contrast, nanos3, piwil1, piwil2, dnd1 and vasa appeared to be exclusively expressed in gonads (both ovary and testis), and nanos2 showed testis-specific expression. Based on these results nanos3, piwil1, piwil2, dnd1 and vasa were prioritised among the 11 selected genes as potential target genes for sterilisation in Nile tilapia as they have no significant zygotic expression during embryogenesis, they are expressed exclusively in gonads and maternally deposited. These features suggest a potential role of these genes in the specification and maintenance of PGCs during the ontogenic development of Nile tilapia.
原始生殖细胞 (PGCs) 是由鱼类母体提供的决定因素指定的。PGCs 然后在早期发育过程中迁移到预期的性腺部位，并产生生殖细胞谱系。PGC 被破坏的动物不会性成熟，这在商业和环境方面都有一系列好处。为了找到尼罗罗非鱼绝育的潜在靶基因，分别在从受精卵到刚孵化的幼虫和成年组织的个体发育过程中，研究了四个 nanos、两个 piwil、dnd1、vasa 和三个 pum 基因的相对 mRNA 丰度模式和组织分布。RNA 丰度的个体发生模式表明，除了在卵中不表达的 nanos2 外，所有研究的基因转录本都以不同程度母体沉积。相对 RNA 丰度的个体发生模式可分为三类。第一类，包括 nanos3、piwil1、piwil2、dnd1 和 vasa，在早期发育阶段表现出丰富的转录水平，然后在原肠胚和囊胚阶段之间从母体到合子的过渡期间降解，到孵化阶段表达减少四到五个数量级。另一个，包括 pum2 和 pum3，与第一组表现出相似的模式，但转录水平仅减少两个数量级。第三组，包括 nanos1a、nano1b 和 pum1，以合子增加为特征。nano2 在孵化阶段之前没有检测到转录本。nano1a、nano1b、pum1、pum2 和 pum3 的组织筛选表明它们在各种组织中表达，这表明它们除了性腺之外，在这些组织中可能具有多效性效应。相比之下，nano3、piwil1、piwil2、dnd1 和 vasa 似乎仅在性腺（卵巢和睾丸）中表达，而 nano2 表现出睾丸特异性表达。基于这些结果，在 11 个选定基因中，nano3、piwil1、piwil2、dnd1 和 vasa 被优先作为尼罗罗非鱼绝育的潜在靶基因，因为它们在胚胎发生过程中没有明显的合子表达，它们仅在性腺中表达并母体沉积。这些特征表明这些基因在尼罗罗非鱼个体发育过程中 PGCs 的指定和维持中可能发挥作用。
