The effects of vitrification on gene expression in mature mouse oocytes by nested quantitative PCR

Abstract

Purpose: this study was conducted on the effects of vitrification cryotop method on gene expression of mature oocytes in Mus musculus.

Methods: transcript analyses of three mouse genes, namely Mater, Hook1 and Sod1, were performed upon non-vitrified and vitrified oocytes with different concentrations of dimethyl sulfoxide (DMSO) and ethylene glycol (EG),15%: 7.5% DMSO + 7.5% EG, and 30%: 15% DMSO + 15% EG, using cryotop following normalization of transcripts with Hprt1 by nested quantitative PCR.

Results: vitrification caused down-regulation of Mater and Hook1 and up-regulation of Sod1 when lower concentrations of cryoprotectants were used as opposed to the control group. The relative expression of Sod1 in vit(2) (30% v/v) was significantly higher than vit(1) (15% v/v)(.) Quantitative transcript analysis of Mater and Hook1 for the vit(2) condition failed to produce any data. Survival rates were the same for both vitrification treatments and significantly lower than control group.

Conclusions: although vit(1) treatment had lower survival rate compared to control group, it demonstrated better stability comparing to vit(2) based on the transcript analysis.

Fig. 1

Mean inverse Ct values of Hprt1 as the relevant abundance of transcript in three groups, Ct = threshold cycle, vit₁ = vitrification with 7.5% DMSO and 7.5% EG, vit₂ = vitrification with 15% DMSO and 15% EG

Fig. 2

Mean inverse Ct values of Mater, Sod1 and Hook1 as the relevant abundance of transcripts in three groups, Ct = threshold cycle, cont = control group (non-vitrified), vit₁ = vitrification with 7.5% DMSO and 7.5% EG, vit₂ = vitrification with 15% DMSO and 15% EG. No detections were observed for Mater and Hook1 with vit₂ treatment. Characters over the bars indicate the significant difference between inverse Ct value means. Bars with the same character are indicative of having no significant difference (P<0.05)