Tianjin Key Laboratory of Conservation and Utilization of Animal Diversity, Tianjin Normal University, Tianjin, China.
Tianjin Key Laboratory of Animal and Plant Resistance, Tianjin Normal University, Tianjin, China.
Mol Ecol Resour. 2021 Aug;21(6):1996-2012. doi: 10.1111/1755-0998.13377. Epub 2021 Mar 30.
Chironomidae species are universally used for studying the impact of pollutants in aquatic systems. The nonbiting midge Propsilocerus akamusi is often found in urban streams and is suitable for use as a toxicological bioindicator. However, few studies have previously examined metal stress in this species. We sequenced the genome of this urban midge to address this question. Here, we present the first chromosome-level genome of P. akamusi, obtained from Illumina short-read and PacBio long-read sequences with Hi-C technology. The size of the very small assembled genome was 85.83 Mb with a contig N50 of 6.2 Mb and a scaffold N50 of 26.1 Mb. This assembly revealed significant expansion of haemoglobin (Hb) genes, some of which formed large tandem repeats. Transcriptomic studies for copper tolerance identified four genes in the tandem array that were highly expressed, all of which presented intron loss. This characteristic might highlight the potential role of Hb genes in copper tolerance. Additionally, detoxification genes, chemosensory genes and heat shock protein genes of this midge were identified, some of which are associated with metal stress. The high-quality assembled genome of P. akamusi and the transcriptomic analyses provide new insight into the molecular mechanisms of heavy metal stress. Our comparison of the P. akamusi genome with other dipteran genomes provides valuable resources for understanding the evolutionary history, genetics, and ecology of this species as well as those of other midges.
摇蚊科的物种被普遍用于研究污染物对水生系统的影响。不取食的蠓类 Propsilocerus akamusi 通常在城市溪流中发现，适合用作毒理学生物标志物。然而，以前很少有研究检查过这种物种的金属胁迫。我们对这种城市蠓进行了基因组测序，以解决这个问题。在这里，我们展示了 P.akamusi 的第一个染色体水平的基因组，它是通过 Illumina 短读和 PacBio 长读序列与 Hi-C 技术获得的。组装的非常小的基因组大小为 85.83 Mb，其 contig N50 为 6.2 Mb，scaffold N50 为 26.1 Mb。该组装揭示了血红蛋白 (Hb) 基因的显著扩张，其中一些形成了大串联重复。铜耐受性的转录组研究鉴定了串联阵列中的四个高度表达的基因，它们都缺失了内含子。这个特征可能突出了 Hb 基因在铜耐受性中的潜在作用。此外，这种蠓的解毒基因、化学感觉基因和热休克蛋白基因被鉴定出来，其中一些与金属胁迫有关。高质量组装的 P.akamusi 基因组和转录组分析为重金属胁迫的分子机制提供了新的见解。我们将 P.akamusi 基因组与其他双翅目基因组进行比较，为了解该物种以及其他蠓类的进化历史、遗传学和生态学提供了有价值的资源。
