Biochemical analysis of Polycomb protein-chromatin dynamics in vivo

我们身体中的几乎每个细胞都包含我们完整的遗传蓝图（DNA），但每个细胞只使用蓝图的一小部分来指导其功能。例如，免疫细胞专门对抗感染，脑细胞专门处理信息。在发育过程中，细胞接受关于使用蓝图的哪一部分（哪些基因）的指令。他们组织他们的遗传物质，以便将使用的部分很容易获得，而不需要的部分则被藏起来。因此，不同的细胞具有以不同方式组织的相同基因组。这种基因组组织是由与DNA相关的蛋白质进行的。这些蛋白质和DNA一起形成了一种称为染色质的结构。每次细胞分裂时，它都会复制染色质的组织，以便两个新细胞使用基因组的相同部分。这是“细胞记忆”的一部分，或者说细胞如何记住它们的身份和历史，包括环境的影响。

Nearly every cell in our bodies contains our full genetic blueprint (DNA), but each cell uses only a small part of the blueprint to direct its function. For example, immune cells are specialized to fight infection and brain cells to process information. During development, cells receive instructions about which part of the blueprint (which genes) to use. They organize their genetic material so that parts that will be used are easy to access, while parts that aren’t needed are stashed away. Thus different cells have the same genome organized in different ways. This genome organization is carried out by proteins that associate with DNA. Together, these proteins and the DNA form a structure called chromatin. Each time a cell divides, it duplicates the organization of chromatin so that the same parts of the genome are used by the two new cells. This is part of “cellular memory”, or how cells remember their identities and their histories, including effects of the environment.