Gene Expression Dynamics in Preimplantation Embryos

During preimplantation development, a fertilised oocyte undergoes a tightly orchestrated series of molecular events that establish the foundations of embryonic growth. Initially dependent on maternally deposited RNAs and proteins, the embryo executes the maternal-to-zygotic transition, in which programmed clearance of maternal transcripts coincides with activation of the embryonic genome. Waves of embryonic genome activation vary among mammals, typically at defined cleavage stages, and are accompanied by extensive epigenetic reprogramming of DNA methylation and histone modifications to establish totipotency. Single-cell RNA sequencing has revealed unexpected heterogeneity among blastomeres, uncovering asynchronous gene expression patterns and early biases in lineage potential prior to visible differentiation. Sequential engagement of transcription factors, RNA-binding proteins and chromatin remodellers orchestrates stage-specific gene networks essential for successful implantation, informs assisted reproduction strategies and underpins investigations into early developmental disorders.

Research from Nature Portfolio

Single-cell transcriptomic analysis of porcine IVF and parthenogenetic embryos has mapped minor genome activation at the one-cell stage and major activation at the four-cell stage, alongside progressive clearance of maternal transcripts. Abundant early zygotic transcripts include regulators of cell cycle, DNA methylation and chromatin remodelling, underpinning embryo viability.

High-resolution sequencing of bovine blastomeres at the eight- to 16-cell transition has revealed cell-to-cell transcriptional heterogeneity during major genome activation. Discrete clusters of cells within individual embryos indicate asynchronous developmental trajectories and suggest early diversification before morphological differentiation.

Gene Expression Dynamics in Preimplantation Embryos publication trend

The graph below shows the total number of articles in gene expression dynamics in preimplantation embryos across all publications each year (not limited to Nature Index journals).

Technical terms

Embryonic genome activation (EGA): The initiation of transcription from the zygotic genome, marking the shift from maternal to embryonic control of development.

Maternal-to-zygotic transition (MZT): The developmental period during which maternal RNAs and proteins are degraded and replaced by transcripts derived from the embryonic genome.

Single-cell RNA sequencing (scRNA-seq): A high-throughput method for profiling the transcriptome of individual cells to reveal cellular heterogeneity and developmental dynamics.

Blastomere: A cell formed by the division of the fertilised egg during the early cleavage stages of the embryo.

Epigenetic reprogramming: Global resetting of DNA methylation and histone modification marks following fertilisation to establish totipotency.

References

1. A program of successive gene expression in mouse one-cell embryos. Cell Reports (2023).
2. Whole-genome transcriptome and DNA methylation dynamics of pre-implantation embryos reveal progression of embryonic genome activation in buffaloes. Journal of Animal Science and Biotechnology (2023).
3. Longitudinal profiling of human androgenotes through single-cell analysis unveils paternal gene expression dynamics in early embryo development. Human Reproduction (2024).
4. Single cell RNA-seq reveals genes vital to in vitro fertilized embryos and parthenotes in pigs. Scientific Reports (2021).
5. Single-cell RNA sequencing reveals developmental heterogeneity of blastomeres during major genome activation in bovine embryos. Scientific Reports (2018).