Epigenetic Changes in Equine Embryos after Short-Term Storage at Different Temperatures.
Authors: Gastal Gustavo D A, Scarlet Dragos, Melchert Maria, Ertl Reinhard, Aurich Christine
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Temperature Effects on Equine Embryo Storage Fresh equine embryos destined for transfer must often be stored during transport, yet the optimal conditions for maintaining developmental competence remain unclear. Researchers compared day-seven embryos stored for 24 hours at either 5°C or 20°C against fresh controls, measuring morphological changes, gene expression profiles (including those governing growth, pregnancy recognition, and cell death), and DNA methylation patterns across multiple genes. Embryos stored at 5°C enlarged whilst those at 20°C shrank; despite these physical differences, both storage temperatures triggered significant alterations in gene expression—with genes like POU5F1, SOX2, NANOG and DNMT1 being either upregulated or downregulated compared to fresh controls (p < 0.05)—and reduced DNA methylation in critical genes including ESR1 and NANOG in the warmer-stored embryos. Whilst 20°C storage showed marginally more favourable methylation patterns than 5°C storage, the findings indicate that short-term storage at either temperature modifies the epigenetic landscape in ways that could compromise post-transfer development and viability. These results highlight the need for practitioners to minimise storage duration wherever possible and suggest that current commercial holding media may require refinement to better preserve embryonic developmental potential during transport.
Read the full abstract on PubMed
Practical Takeaways
- •Storage temperature during embryo transport (5°C vs 20°C) affects embryo size and gene expression, with 20°C showing some beneficial effects on methylation patterns but both temperatures causing molecular changes that may impact pregnancy establishment
- •These findings suggest that embryo transport conditions require optimization to minimize epigenetic changes that could reduce pregnancy success rates in equine embryo transfer programs
- •Practitioners performing embryo transfer should be aware that storage duration and temperature are not neutral procedures and may influence the developmental competence of transferred embryos
Key Findings
- •Embryos stored at 5°C were significantly larger while those stored at 20°C were smaller after 24 hours of storage
- •Both storage temperatures altered mRNA expression of genes related to growth, development, pregnancy recognition, methylation and apoptosis compared to fresh controls
- •Gene-specific DNA methylation in CpG islands of ESR1, NANOG and DNMT1 was significantly lower in 20°C stored embryos compared to day-8 controls
- •Short-term storage at either temperature modified gene expression and methylation status that may compromise embryo viability and post-transfer development