State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiangan District, Xiamen, Fujian, 361102, China; School of Life Sciences, Xinjiang Normal University, Saybagh District, Urumqi, Xinjiang, 830054, China.
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiangan District, Xiamen, Fujian, 361102, China.
Gene Expr Patterns. 2020 Dec;38:119152. doi: 10.1016/j.gep.2020.119152. Epub 2020 Oct 25.
Cephalochordate amphioxus contain two Brachyury genes (AmphiBra1 and AmphiBra2). Using probes from the highly conserved coding regions, a summation of their expression profiles in amphioxus embryos have been investigated by several previous studies. However, their respective expression patterns have not been determined up to date. We here address this issue using both qRT-PCR and in situ hybridization methods (with probes from the divergent untranslated regions). qRT-PCR detected a very low maternal expression for AmphiBra2, but not for AmphiBra1. Zygotic expression of both genes are activated around early gastrula stage and change in a similar pattern at subsequent stages. However, compared to AmphiBra1, the expression level of AmphiBra2 is much higher in all examined stages of embryos; in some extreme cases an over fifty-times difference is observed. In situ hybridization and embryonic sections reveal that while AmphiBra2 is highly expressed in the blastopore, the tail bud and the notochord, AmphiBra1 is weakly transcribed only in the notochord. Our results show that the two Brachyury genes, resulted from a lineage-specific duplication in amphioxus, have evolved different embryonic expression profiles.
文昌鱼含有两个 Brachyury 基因（AmphiBra1 和 AmphiBra2）。利用高度保守的编码区探针，以前的几项研究调查了它们在文昌鱼胚胎中的表达谱总和。然而，它们各自的表达模式至今尚未确定。我们在这里使用 qRT-PCR 和原位杂交方法（来自不同的非翻译区探针）来解决这个问题。qRT-PCR 检测到 AmphiBra2 的母源表达非常低，但 AmphiBra1 没有。这两个基因的合子表达在早期原肠胚期左右被激活，并在随后的阶段以相似的模式发生变化。然而，与 AmphiBra1 相比，AmphiBra2 的表达水平在胚胎所有检查阶段都要高得多；在某些极端情况下，观察到五十多倍的差异。原位杂交和胚胎切片显示，虽然 AmphiBra2 在原肠胚孔、尾芽和脊索中高度表达，但 AmphiBra1 仅在脊索中弱转录。我们的结果表明，这两个 Brachyury 基因是文昌鱼谱系特异性复制的结果，它们已经进化出不同的胚胎表达模式。
