Fig. 1: Maternal mRNAs are methylated to an unprecedented extent in both vertebrate and invertebrate species by NSUN2 and NSUN6.
a Phylogenic tree (left) and sampled developmental stages of the species in this study (right). The mammals separated from frogs, zebrafish, and D. mel about 352, 435, and 797 mya, respectively34. The divergence between humans and mice is estimated to be 90 mya and the divergence of the two frog species is estimated to be 57 mya34. Stages in which mRNAs were largely transcribed from the maternal genome are underlined. For humans and mice: GV germinal vesicle, MII Metaphase II, TE trophectoderm, hESC human embryonic stem cell, 1-cell 1-cell embryo. For zebrafish: hpf, hours post-fertilization. For D. mel: em embryo, L larva, hr hour. Zebrafish embryo images were adapted from Webb et al., 2006;63 adult zebrafish images were adapted from Kimmel et al.,1995;64 fly ovary image was adapted from AVILéS et al., 2018;65 other fly sample images were adapted from Wolpert et al., 201566. b The number and methylation level of m5C sites, the percentage of transcribed genes with m5C sites, and the density of m5C sites in the samples we profiled. The density was defined as the number of m5C sites per thousand Cs that are covered by at least 20 reads. The mouse muscle sample that has the highest m5C level in adult tissues29 was selected to represent the zygotic mRNA m5C pattern. AdM, adult male; H1, hESC H1 line. Boxplots: 25th to 75th percentiles (boxes), medians (horizonal lines), and 1.5 times of the interquartile range (whiskers). The number of data points are provided in Source Data. Numbers of biological replicates are provided in Supplementary Fig. 1. c Genic locations of maternal m5C sites in each species. The number of m5C sites and the percentages of Type I and Type II sites are indicated. d The distribution of maternal m5C sites along the transcripts in different species. In this analysis, each m5C site was binned and the m5C density of each bin was calculated (Methods). Bin numbers were based on average lengths among transcripts in different species. Bin numbers (5'UTR:CDS:3'UTR): humans, 10:50:40; mice, 10:60:50; X. tropicalis, 10:60:40; X. laevis, 10:60:30; zebrafish, 10:80:30; D. mel, 10:60:20. Source data are provided as a Source Data file.
