BisPCRSeq analysis of ribosomal DNA in mouse sperm exposed to protein restriction during different critical time windows

Background: Environmental influences fluctuate throughout the life course of an organism. It is therefore important to understand how the timing of exposure impacts the molecular response. Here we examine the responses of two key molecular markers of dietary stress – variant-specific methylation at ribosomal DNA (rDNA) and small RNA distribution including tRNA fragments – in a mouse model of protein restriction (PR) with exposures pre- and/or post-weaning. Results: We first confirm that pre-weaning PR exposure modulates the methylation state of rDNA in a genotype-dependent manner whereas post-weaning PR exposure has no such effect. Conversely, post-weaning PR induces a shift in small RNA distribution, but there is no effect in the pre-weaning PR model. Intriguingly, mice exposed to PR throughout their lives show neither of these two dietary stress markers, similar to controls. Overall design: sperm DNA from four different diet groups (CTCT, CTPR, PRCT and PRPR) with all males from each litter being represented背景：生物体整个生命进程中，环境影响始终处于动态波动状态。因此，探明暴露时机如何影响分子应答至关重要。本研究以蛋白质限制（protein restriction, PR）小鼠模型为研究对象，探究断奶前和/或断奶后暴露时，两类饮食应激相关关键分子标志物的应答情况——核糖体DNA（ribosomal DNA, rDNA）的变异特异性甲基化，以及包含tRNA片段（transfer RNA fragments）在内的小RNA分布特征。结果：本研究首先证实，断奶前蛋白质限制暴露会以基因型依赖的方式调控核糖体DNA的甲基化状态，而断奶后蛋白质限制暴露无此类调控效应。与之相反，断奶后蛋白质限制会诱导小RNA分布发生偏移，但在断奶前蛋白质限制模型中未观察到该影响。值得注意的是，终身暴露于蛋白质限制的小鼠未出现上述两种饮食应激标志物，与对照组小鼠表现一致。总体设计：采集四个不同饮食组（CTCT、CTPR、PRCT及PRPR）的精子DNA，每窝的所有雄性个体均被纳入样本覆盖范围。