Table of values used in Fig 5B.

Some epigenetic information can be transmitted between generations without changes in the underlying DNA sequence. Changes in epigenetic regulators, termed epimutations, can occur spontaneously and be propagated in populations in a manner reminiscent of DNA mutations. Small RNA-based epimutations occur in C. elegans and persist for around 3–5 generations on average. Here, we explored whether chromatin states also undergo spontaneous change and whether this could be a potential alternative mechanism for transgenerational inheritance of gene expression changes. We compared the chromatin and gene expression profiles at matched time points from three independent lineages of C. elegans propagated at minimal population size. Spontaneous changes in chromatin occurred in around 1% of regulatory regions each generation. Some were heritable epimutations and were significantly enriched for heritable changes in expression of nearby protein-coding genes. Most chromatin-based epimutations were short-lived but a subset had longer duration. Genes subject to long-lived epimutations were enriched for multiple components of xenobiotic response pathways. This points to a possible role for epimutations in adaptation to environmental stressors.

部分表观遗传信息（epigenetic information）可在代际间传递，且不伴随基础DNA序列的改变。表观遗传调控因子的改变被称为表观突变（epimutations），其可自发产生，并以类似DNA突变的方式在种群中传播。基于小RNA的表观突变可在秀丽隐杆线虫（C. elegans）中发生，平均可维持约3至5代。本研究旨在探究染色质状态是否也会发生自发改变，以及这是否可能是基因表达变化跨代遗传的潜在替代机制。我们对以最小种群规模传代培养的3个独立秀丽隐杆线虫谱系的对应时间点的染色质与基因表达谱进行了比较分析。每一代中，约1%的调控区域会发生染色质自发改变。其中部分属于可遗传表观突变，且显著富集于邻近蛋白编码基因表达发生可遗传改变的区域。大多数基于染色质的表观突变存续时间较短，但有一部分存续周期更长。携带长时程表观突变的基因显著富集于异生物质响应通路的多种组分。这表明表观突变可能在生物体适应环境胁迫过程中发挥作用。