{
  "id": 7840029,
  "title": "DNA replication is dispensable for developmental progression, but required for heterochromatin organization at mouse zygotic genome activation",
  "url": "https://urgent.news/2026/09/16/dna-replication-is-dispensable-for-developmental-progression-but",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-16T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.14.751383v1?rss=1"
  },
  "original_language": "en",
  "account": "Mammalian early development undergoes a limited number of cleavage divisions, accompanied by significant transcriptional and epigenetic changes that determine the initial cell decisions, culminating in blastocyst formation. While prior studies indicated that development can advance without standard cell division, the role of DNA replication in this process has remained uncertain. Specifically, it is unclear whether DNA replication is necessary solely for proliferation or also for creating cellular conditions that govern expression during distinct developmental stages. This study elucidates that mouse preimplantation development can advance without DNA replication, yet it is crucial for preserving proper heterochromatin organization at the 2-cell stage, which marks zygotic genome activation. Using aphidicolin to inhibit DNA replication, the researchers observed that while cleavage divisions were halted, zygotic genome activation, embryonic morphogenesis, activation of lineage determination factors, and the setup of stage-specific transcriptional programs were not affected. However, replication interruption uniquely impacted the expression of developmental genes located in late-replicating, Polycomb-enriched chromatin regions, and decreased overall levels of H3K27me3 and H3K9me3. These discoveries imply that developmental timing in the early embryo is largely separate from DNA replication and cell-cycle progression. Instead, DNA replication plays a role in ensuring transcriptional accuracy by establishing or maintaining repressive chromatin states during the extensive genome remodeling that occurs alongside zygotic genome activation.",
  "summary": "Early mammalian development progresses through a small number of cleavage divisions with extensive transcriptional and epigenetic reprogramming that result in the very first lineage decisions, leading to blastocyst formation. Although classical embryological studies suggested that developmental progression can occur independently of normal cell division, the extent to which DNA replication…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}