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Table 2 Impact of oocyte vitrification on DNA methylation and histone modifications in animals

From: What impact does oocyte vitrification have on epigenetics and gene expression?

References

Animal model

Materials

Number of oocytes

Number of embryos

Technology of assessment

Studied sequences

Conclusions

Chen et al. [112]

Bovine

Fresh MII, vitrified MII or embryos (D2-D8) from fresh or vitrified MII after IVM

10–15 oocytes or embryos per group

 

Immunofluorescence

5mC, H3K9ac, H3K9me3

Decrease in the global DNA methylation and H3K9me3 levels and increase in H3K9ac for vitrified MII oocytes. No difference observed specifically in the ICM. Decrease in the level of DNA methylation and H3K9ac in trophectoderm after oocyte vitrification.

Cheng et al. [113]

Murine

Blastocysts (D4) from fresh or vitrified MII

 

30–45 blastocysts per condition

Bisulfite treatment + sequencing

H19, Peg3, Snrpn

No significant differences in oocytes. Decrease in DNA methylation levels for H19, Peg3, and Snrpn in blastocysts after oocyte vitrification.

Zhao et al. [114]

Murine

Fresh MII, vitrified MII

100 oocytes per group

 

Bisulfite treatment + sequencing

Dnmt1o, Hat1, promoteur de Hdac1

No significant differences.

Hu et al. [115]

Bovine

Fresh MII after IVM, vitrified MII after IVM

150 oocytes per group

 

Immunofluorescence

Global analysis

Decrease in methylation levels after oocytes slow freezing or after use of DMSO.

Increase in methylation levels after using PROH.

Spinaci et al. [116]

Porcine

Fresh MII after IVM, vitrified MII after IVM

H4K5ac 282 fresh oocytes, 192 vitrified oocytes; H3K9me 98 fresh oocytes, 121 vitrified oocytes

 

Immunofluorescence

H3K9 methylation and H4K5 acetylation

Increase in H4ac level and significant modifications of H3K9me2 levels (decrease or increase) after oocyte vitrification.

Milroy et al. [117]

Murine

Fresh MII, fresh MII after IVM, MII after IVM from vitrified GV

200 oocytes per group

 

Bisulfite treatment + sequencing

Pluripotency promotors Oct4, Nanog, Foxd3, Sox2

Increase in the methylation levels of Oct4 (25%) and Sox2 (4.5%) promoters after vitrification of in vitro matured oocytes compared to in vivo matured and fresh MII.

Yan et al. [118]

Murine

Fresh MII, vitrified MII

66 fresh, 70 vitrified

 

Immunofluorescence

H3K9me, H4K5ac

Increase in the H3K9me and H4K5ac levels after oocyte vitrification.

Suo et al. [119]

Murine

Fresh MII, vitrified MII

At least 78 oocytes per group

 

Immunofluorescence

H4K12ac

Increase in the H4K12ac levels after oocyte vitrification.

Zygotes from vitrified MII have disturbed levels before and after appearance of pronuclei.

  1. D day of embryo culture, GV oocyte at germinal vesicle stage, ICM inner cell mass, IVM in vitro maturation, 5mC 5-methylCytosine, MII oocyte at metaphase II stage