It remains poorly understood about the regulation of gene and transposon transcription during human early embryogenesis. Here, we report that broad H3K27ac domains are genome-widely distributed in human 2-cell and 4-cell embryos and transit into typical peaks in the 8-cell embryos. The broad H3K27ac domains in early embryos before zygotic genome activation (ZGA) are also observed in mouse. It suggests that broad H3K27ac domains play conserved functions before ZGA in mammals. Intriguingly, a large portion of broad H3K27ac domains overlap with broad H3K4me3 domains. Further investigation reveals that histone deacetylases are required for the removal or transition of broad H3K27ac domains and ZGA. After ZGA, the number of typical H3K27ac peaks is dynamic, which is associated with the stage-specific gene expression. Furthermore, P300 is important for the establishment of H3K27ac peaks and the expression of associated genes in early embryos after ZGA. Our data also indicate that H3K27ac marks active transposons in early embryos. Interestingly, H3K27ac and H3K18ac signals rather than H3K9ac signals are enriched at ERVK elements in mouse embryos after ZGA. It suggests that different types of histone acetylations exert distinct roles in the activation of transposons. In summary, H3K27ac modification undergoes extensive reprogramming during early embryo development in mammals, which is associated with the expression of genes and transposons.
This study examines the impact of credit rating downgrade risk on acquisition decisions. I find that firms at risk of a rating downgrade conduct fewer acquisitions. This result is robust to different measures of downgrade risk, instrumental variable analyses and matched sample tests.
The correlation between downgrade risk and acquisitionpropensity is likely driven by the concern that risks associated with acquisitions lead to downgrades as evidenced by the more cautious approach of acquirers facing downgrade risk. These firms take more time to complete deals, hire more and higher-quality financial advisors, issue less debt to finance merger consideration, adopt target termination fee clauses and select targets with lower information asymmetry and higher ratings. This more cautious approach is associated with better long-term post-merger performance and reduced future-downgrade risk. Subgroup analyses reveal credit rating downgrade risk is negatively associated with acquisition decisions and positively associated with performance for investment-grade firms, especially BBB-firms, which are on the brink of being downgraded to non-investment grade. Such associations are not significant for non-investment-grade firms. Overall, the results suggest that firms at risk of a rating downgrade conduct acquisitions more cautiously, leading to fewer but more value-creating deals.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.