Institut de Biologie de l'Ecole Normale Supérieure, CNRS, Inserm, Paris, France.
EMBO Rep. 2023 Dec 6;24(12):e58116. doi: 10.15252/embr.202358116. Epub 2023 Nov 20.
The animal germline lineage needs to be maintained along generations. However, some Caenorhabditis elegans wild isolates display a mortal germline phenotype, leading to sterility after several generations at 25°C. Using a genome-wide association approach, we detect a significant peak on chromosome III around 5 Mb, confirmed by introgressions. Thus, a seemingly deleterious genotype is maintained at intermediate frequency in the species. Environmental rescue is a likely explanation, and indeed associated bacteria and microsporidia suppress the phenotype of wild isolates as well as mutants in small RNA inheritance (nrde-2) and histone modifications (set-2). Escherichia coli strains of the K-12 lineage suppress the phenotype compared to B strains. By shifting a wild strain from E. coli K-12 to E. coli B, we find that memory of the suppressing condition is maintained over several generations. Thus, the mortal germline phenotype of wild C. elegans is in part revealed by laboratory conditions and may represent variation in epigenetic inheritance and environmental interactions. This study also points to the importance of non-genetic memory in the face of environmental variation.
动物生殖系谱系需要沿着世代维持。然而，一些秀丽隐杆线虫野生分离株表现出致命的生殖系表型，在 25°C 下经过几代后导致不育。使用全基因组关联方法，我们在染色体 III 上大约 5Mb 处检测到一个显著的峰，通过导入得到证实。因此，一种看似有害的基因型在物种中以中等频率维持。环境拯救是一个可能的解释，事实上，相关细菌和微孢子虫抑制了野生分离株的表型，以及小 RNA 遗传（nrde-2）和组蛋白修饰（set-2）突变体的表型。与 B 株相比，K-12 谱系的大肠杆菌菌株抑制了表型。通过将野生菌株从大肠杆菌 K-12 转移到大肠杆菌 B，我们发现抑制条件的记忆在几代中得以维持。因此，野生秀丽隐杆线虫致命的生殖系表型部分是由实验室条件揭示的，可能代表了表观遗传遗传和环境相互作用的变异。这项研究还指出了在面对环境变化时非遗传记忆的重要性。
