Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway.
School of Biological and Chemical Sciences, Queen Mary University of London, London, UK.
Nat Ecol Evol. 2021 Feb;5(2):231-242. doi: 10.1038/s41559-020-01327-6. Epub 2020 Nov 16.
The causes and consequences of genome reduction in animals are unclear because our understanding of this process mostly relies on lineages with often exceptionally high rates of evolution. Here, we decode the compact 73.8-megabase genome of Dimorphilus gyrociliatus, a meiobenthic segmented worm. The D. gyrociliatus genome retains traits classically associated with larger and slower-evolving genomes, such as an ordered, intact Hox cluster, a generally conserved developmental toolkit and traces of ancestral bilaterian linkage. Unlike some other animals with small genomes, the analysis of the D. gyrociliatus epigenome revealed canonical features of genome regulation, excluding the presence of operons and trans-splicing. Instead, the gene-dense D. gyrociliatus genome presents a divergent Myc pathway, a key physiological regulator of growth, proliferation and genome stability in animals. Altogether, our results uncover a conservative route to genome compaction in annelids, reminiscent of that observed in the vertebrate Takifugu rubripes.
动物基因组缩减的原因和后果尚不清楚，因为我们对这一过程的理解主要依赖于进化速度通常异常高的谱系。在这里，我们对小型底栖环节蠕虫双毛环虫(Dimorphilus gyrociliatus)的紧凑 7380 万碱基基因组进行了解码。D. gyrociliatus 基因组保留了与较大和进化较慢的基因组相关的典型特征，例如有序、完整的 Hox 簇、通常保守的发育工具包和祖先后口动物的连锁痕迹。与其他一些基因组较小的动物不同，对 D. gyrociliatus 表观基因组的分析揭示了经典的基因组调控特征，排除了操纵子和反式剪接的存在。相反，基因密集的 D. gyrociliatus 基因组呈现出一种不同的 Myc 途径，这是动物生长、增殖和基因组稳定性的关键生理调节剂。总的来说，我们的研究结果揭示了环节动物基因组紧凑化的保守途径，这让人联想到脊椎动物红鳍东方鲀(Takifugu rubripes)中观察到的途径。
