N6-methyladenosine (m6A) has been demonstrated to regulate RNA metabolism and various biological processes, including gametogenesis and embryogenesis. However, the landscape and function of m6A at single cell resolution have not been extensively studied in mammalian oocytes or during pre-implantation. In this study, we developed a single-cell m6A sequencing (scm6A-seq) method to simultaneously profile the m6A methylome and transcriptome in single oocytes/blastomeres of cleavage-stage embryos. We found that m6A deficiency leads to aberrant RNA clearance and consequent low quality of Mettl3Gdf9 conditional knockout (cKO) oocytes. We further revealed that m6A regulates the translation and stability of modified RNAs in metaphase II (MII) oocytes and during oocyte-to-embryo transition, respectively. Moreover, we observed m6A-dependent asymmetries in the epi-transcriptome between the blastomeres of two-cell embryo. scm6A-seq thus allows in-depth investigation into m6A characteristics and functions, and the findings provide invaluable single-cell resolution resources for delineating the underlying mechanism for gametogenesis and early embryonic development.

PurposeChoroidal neovascularization (CNV) is the defining feature of neovascular age-related macular degeneration (nAMD). Gut microbiota might be deeply involved in the pathogenesis of nAMD. This study aimed to reveal the roles of the gut microbiome and fecal metabolome in a mouse model of laser-induced CNV.MethodsThe feces of C57BL/6J mice with or without laser-induced CNV were collected. Multi-omics analyses, including 16S rRNA gene sequencing and untargeted metabolomics, were conducted to analyze the changes in the gut microbial composition and the fecal metabolomic profiles in CNV mice.ResultsThe gut microbiota was significantly altered in CNV mice. The abundance of Candidatus_Saccharimonas was significantly upregulated in the feces of CNV mice, while 16 genera, including Prevotellaceae_NK3B31_group, Candidatus_Soleaferrea, and Truepera, were significantly more abundant in the controls than in the CNV group. Fecal metabolomics identified 73 altered metabolites (including 52 strongly significantly altered metabolites) in CNV mice compared to control mice. Correlation analysis indicated significant correlations between the altered fecal metabolites and gut microbiota genera, such as Lachnospiraceae_UCG-001 and Candidatus_Saccharimonas. Moreover, KEGG analysis revealed six pathways associated with these altered metabolites, such as the ABC transporter, primary bile acid biosynthesis and steroid hormone biosynthesis pathways.ConclusionThe study identified an altered fecal microbiome and metabolome in a CNV mouse model. The altered microbes, metabolites and the involved pathways might be associated with the pathogenesis of nAMD.