Effect of the acrosome reaction on the efficiency of sperm-mediated DNA transfer

Sperm-mediated gene transfer (SMGT) is based on the ability of spermatozoa to bind exogenous DNA and transfer it into oocytes by fertilization. However, SMGT is still undergoing optimization to improve its efficiency to produce transgenic animals. The acrosome reaction is necessary for spermatozoa to carry the exogenous DNA into oocytes. In this study, the effect of the acrosome reaction on the efficiency of spermatozoa carrying exogenous DNA was evaluated. The results showed that the efficiency of the acrosome reaction was significantly higher (p<0.05) after incubation with 50 mu mol/L progesterone compared to incubation without progesterone. It was significantly higher (p<0.05) in the 20, 40, and 60 min of progesterone treatment groups than in the 0 min treatment group. The spermatozoa were further incubated with cyanine dye Cy5 labeled DNA (Cy5-DNA) for 30 min at 37 degrees C, and positive fluorescence signals were detected after the acrosome reaction was induced by progesterone at concentrations of 0 and 50 mu mol/L for 40 min. The percentage of positive Cy5-DNA signals in spermatozoa was 96.61 +/- 2.06% and 97.51 +/- 2.03% following exposure to 0 and 50 mu mol/L progesterone, respectively. The percentage of partial spermatozoa heads observed following combination with Cy5-DNA was 39.73 +/- 3.03% and 56.88 +/- 3.12% following exposure to 0 and 50 mu mol/L progesterone, respectively. The ratio of positively stained spermatozoa combined with exogenous DNA showed no reduction after the acrosome reaction. These results suggest that the acrosome reaction might not be the key factor affecting the efficiency of SMGT.