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Updated: Jun 22, 2026
Detection of DNA Double-Stranded Breaks in Mouse Oocytes
Published on: June 23, 2023
Expression profiling of DNA repair genes in human oocytes and blastocysts using microarrays
Souraya Jaroudi1, Georgia Kakourou, Suzanne Cawood
1UCL Centre for PGD, Institute for Women's Health, University College London, 86-96 Chenies Mews, London WC1E 6HX, UK.
Background:
The early preimplantation embryo relies on mRNA and protein from the oocyte to detect DNA damage and activate DNA repair, cell cycle arrest or apoptosis. Expression of some repair genes has been detected in mammalian oocytes and embryos; however, little is known about DNA repair gene expression in human blastocysts. In this study, DNA repair gene expression was investigated in human oocytes and blastocysts to identify the pathways involved at these stages and detect potential differences in repair mechanisms pre- and post-embryonic genome activation.
Methods:
Triplicate sets of pooled metaphase II oocytes or blastocysts were processed for analysis using the Human Genome Survey Microarrays V2.0 (Applied Biosystems).
Results:
Of 154 DNA repair genes investigated, 109 were detected in blastocysts and 107 in oocytes. Among differentially expressed DNA repair genes, 40/55 (73%) had lower expression levels in blastocysts compared with oocytes (P < 0.05, fold change >3).
Conclusion:
Despite experimental limitations due to culture or freezing and thawing of samples, large numbers of repair genes were detected indicating that all DNA repair pathways are potentially functional in human oocytes and blastocysts. The higher mRNA level for most repair genes in oocytes compared with blastocysts ensures sufficient availability of template until embryonic genome activation.
Insights
Human oocytes and blastocysts possess functional DNA repair genes. Most DNA repair gene expression is higher in oocytes than in blastocysts, ensuring sufficient repair capacity until embryonic genome activation.
Area of Science:
- Reproductive Biology
- Molecular Biology
- Genetics
Background:
- Early human embryos depend on oocyte-derived molecules for DNA damage response.
- DNA repair gene expression in human blastocysts remains largely uncharacterized.
- Understanding these mechanisms is crucial for early development and genome activation.
Purpose of the Study:
- Investigate DNA repair gene expression in human oocytes and blastocysts.
- Identify DNA repair pathways active at these developmental stages.
- Compare gene expression pre- and post-embryonic genome activation.
Main Methods:
- Utilized Human Genome Survey Microarrays V2.0 for gene expression analysis.
- Analyzed pooled samples of metaphase II oocytes and blastocysts.
- Examined expression of 154 DNA repair genes.
Main Results:
- Detected 109 DNA repair genes in blastocysts and 107 in oocytes.
- Found 73% of differentially expressed genes showed lower expression in blastocysts compared to oocytes.
- Observed significant differences (P < 0.05, fold change >3) in gene expression levels.
Conclusions:
- All major DNA repair pathways are likely functional in human oocytes and blastocysts.
- Higher mRNA levels of repair genes in oocytes support pre-embryonic genome activation needs.
- Findings highlight the maternal contribution to DNA repair until embryonic self-sufficiency.
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