Division of Genetics and Physiology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
Division of Genetics and Physiology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
Gene. 2014 May 10;541(1):60-6. doi: 10.1016/j.gene.2014.03.007. Epub 2014 Mar 7.
Oxygen availability has been a major force in shaping the physiological evolution of animals. Under reduced oxygen availability (hypoxia) major changes in gene expression are mediated by hypoxia-inducible factors (HIF alphas). Tetrapods have three hif alpha genes, whereas zebrafish (Danio rerio) and other cyprinids have six due to a teleost lineage-specific genome duplication. We studied the transcriptional divergence of the six teleost-specific hif alphas by inspecting the tissue-specific transcription patterns in adult zebrafish and by monitoring the early developmental transcription of normoxia- and hypoxia-grown zebrafish embryos. Overall we observed the highest hif alpha mRNA levels in tissues that are important for hypoxic survival, including the brain, gill and heart. Of the paralogs that have not previously received attention (hif alpha-1A, hif alpha-2B and hif alpha-3B) especially the hif alpha-2B transcription levels suggest functional relevance. The hif alpha-1A/B paralogs that have considerable coding sequence divergence displayed more overall transcriptional divergence than the hif alpha-2A/B paralog pair. The hif alpha-2A/B paralogs that are similarly conserved in coding sequence had a divergent transcription pattern during early development. When zebrafish grown in modest hypoxia were compared to normoxia grown fish, only hif alpha-3A transcription was significantly altered. These results suggest that, in zebrafish, the evolutionary retention of each hif alpha paralog pair has involved unique patterns of coding sequence divergence, adult tissue-specific transcriptional divergence or developmental transcriptional divergence.
氧气供应是塑造动物生理进化的主要力量。在缺氧（低氧）的情况下，主要的基因表达变化是由缺氧诱导因子（HIFα）介导的。四足动物有三个 hifα基因，而斑马鱼（Danio rerio）和其他鲤科鱼类由于硬骨鱼谱系特异性基因组复制有六个 hifα基因。我们通过检查成年斑马鱼的组织特异性转录模式，并监测正常氧和低氧生长的斑马鱼胚胎的早期发育转录，研究了这六个硬骨鱼特异性 hifα的转录分化。总的来说，我们观察到在对低氧生存很重要的组织中 hifα mRNA 水平最高，包括大脑、鳃和心脏。在以前没有受到关注的同源基因中（hifα-1A、hifα-2B 和 hifα-3B），特别是 hifα-2B 的转录水平表明其具有功能相关性。具有相当大编码序列差异的 hifα-1A/B 同源基因显示出比 hifα-2A/B 同源基因对更多的总体转录分化。在编码序列上相似保守的 hifα-2A/B 同源基因在早期发育过程中具有不同的转录模式。当将在适度低氧中生长的斑马鱼与在正常氧中生长的鱼进行比较时，只有 hifα-3A 的转录明显改变。这些结果表明，在斑马鱼中，每个 hifα 同源基因对的进化保留都涉及独特的编码序列分化、成年组织特异性转录分化或发育转录分化模式。
