Table of values used in Table 2.

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（epigenetic）信息可在代际间传递，且无需改变底层DNA序列。表观调控因子的改变被称为表观突变（epimutations），这类改变可自发产生，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，平均存续约3至5代。本研究旨在探究染色质状态（chromatin states）是否同样会发生自发改变，以及这是否可能是基因表达改变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三株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对分析。每一代中，约有1%的调控区域会出现染色质自发改变。其中部分属于可遗传的表观突变，且显著富集于邻近蛋白质编码基因的可遗传表达变化区域。多数基于染色质的表观突变存续时间较短，但有一部分可维持更长时长。受长时程表观突变影响的基因，显著富集于异生物质应答通路（xenobiotic response pathways）的多种组分。上述结果提示，表观突变可能在生物体适应环境胁迫的过程中发挥潜在作用。