The establishment of cell identity during embryonic development involves the activation of specific gene expression programmes and is underpinned by epigenetic factors including DNA methylation and histone post-translational modifications. G-quadruplexes are four-stranded DNA secondary structures (G4s) that have been implicated in transcriptional regulation and cancer. Here, we show that G4s are key genomic structural features linked to cellular differentiation. We find that G4s are highly abundant in human embryonic stem cells and are lost during lineage specification. G4s are prevalent in enhancers and promoters. G4s that are found in common between embryonic and downstream lineages are tightly linked to transcriptional stabilisation of genes involved in essential cellular functions as well as transitions in the histone post-translational modification landscape. Furthermore, the application of small molecules that stabilise G4s causes a delay in stem cell differentiation, keeping cells in a more pluripotent-like state. Collectively, our data highlight G4s as important epigenetic features that are coupled to stem cell pluripotency and differentiation.

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This paper presents the family language policies of four Estonian-non-Estonian bilingual, transnational families, with focus paid to the language management efforts of the fathers and the challenges they faced, including child agency and imbalances of power. The findings indicate that minority-language fathers also engage in 'language work' (Okita 2002), and demonstrated that the fathers' language management efforts were constrained and determined by factors such as the level of competence the men's spouse has in his L1, child agency, and access to a same languageculture community as a supportive resource.