Biological processes depend on the differential expression of genes over time, but methods to make physical recordings of these processes are limited. Here we report a molecular system for making time-ordered recordings of transcriptional events into living genomes. We do this via engineered RNA barcodes, based on prokaryotic retrons1, which are reverse-transcribed into DNA and integrated into the genome using the CRISPR-Cas system2. The unidirectional integration of barcodes by CRISPR integrases enables reconstruction of transcriptional event timing based on a physical record via simple, logical rules rather than relying on pre-trained classifiers or post-hoc inferential methods. For disambiguation in the field, we will refer to this system as a Retro-Cascorder.

中文翻译：

---

通过CRISPR添加retron条形码记录DNA中的基因表达顺序

生物过程依赖于基因随时间的差异表达，但对这些过程进行物理记录的方法是有限的。在这里，我们报告了一种分子系统，用于将转录事件按时间顺序记录到活的基因组中。我们通过基于原核生物逆转录酶的工程化 RNA 条形码来做到这一点，这些 RNA 条形码被逆转录成 DNA 并使用 CRISPR-Cas 系统整合到基因组中。CRISPR 整合酶对条形码的单向整合能够通过简单的逻辑规则基于物理记录重建转录事件时间，而不是依赖于预先训练的分类器或事后推理方法。为了消除该领域的歧义，我们将此系统称为 Retro-Cascorder。