Precision Medicine Center, Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450000, China.
Department of Biology, Evolutionary Ecology Laboratories, and Monte L. Bean Museum, Brigham Young University, Provo, UT, USA.
G3 (Bethesda). 2021 Jan 18;11(1). doi: 10.1093/g3journal/jkaa045.
Plectus murrayi is one of the most common and locally abundant invertebrates of continental Antarctic ecosystems. Because it is readily cultured on artificial medium in the laboratory and highly tolerant to an extremely harsh environment, P. murrayi is emerging as a model organism for understanding the evolutionary origin and maintenance of adaptive responses to multiple environmental stressors, including freezing and desiccation. The de novo assembled genome of P. murrayi contains 225.741 million base pairs and a total of 14,689 predicted genes. Compared to Caenorhabditis elegans, the architectural components of P. murrayi are characterized by a lower number of protein-coding genes, fewer transposable elements, but more exons, than closely related taxa from less harsh environments. We compared the transcriptomes of lab-reared P. murrayi with wild-caught P. murrayi and found genes involved in growth and cellular processing were up-regulated in lab-cultured P. murrayi, while a few genes associated with cellular metabolism and freeze tolerance were expressed at relatively lower levels. Preliminary comparative genomic and transcriptomic analyses suggest that the observed constraints on P. murrayi genome architecture and functional gene expression, including genome decay and intron retention, may be an adaptive response to persisting in a biotically simplified, yet consistently physically harsh environment.
褶胸麦杆虫是南极大陆生态系统中最常见和最丰富的无脊椎动物之一。由于它在实验室中很容易在人工培养基上培养，并且对极其恶劣的环境具有高度耐受性，褶胸麦杆虫正在成为理解对多种环境胁迫（包括冷冻和干燥）的适应性反应的进化起源和维持的模式生物。褶胸麦杆虫的从头组装基因组包含 2.25741 亿个碱基对和总共 14689 个预测基因。与秀丽隐杆线虫相比，褶胸麦杆虫的结构成分的特点是编码基因数量较少，转座元件较少，但与来自较不恶劣环境的密切相关的分类群相比，外显子更多。我们比较了实验室培养的褶胸麦杆虫和野生褶胸麦杆虫的转录组，发现与细胞代谢和抗冻性相关的几个基因在实验室培养的褶胸麦杆虫中表达水平相对较低，而与生长和细胞处理相关的基因则上调。初步的比较基因组学和转录组学分析表明，观察到的褶胸麦杆虫基因组结构和功能基因表达的限制，包括基因组退化和内含子保留，可能是对持续存在于生物简化但物理环境恶劣的环境的适应性反应。
