Effect of calcium on porcine ICSI embryos expressing EGFP is related to activation of ooplasmic DNase I

Abstract

Several reliable methods to produce transgenic animals use the male genome. After penetration into oocytes, sperm DNA undergoes dramatic conformational changes that might represent an opportunity for exogenous DNA to integrate into the zygote genome. A nuclease, DNase I, with Ca 2+ /Mg 2+ dependent activity and Zn 2+ inhibition, is one of the enzymes responsible for sperm DNA remodeling. To date, the effect of different calcium concentrations in manipulation media on porcine intracytoplasmic sperm injection has not been fully investigated. The present study was conducted to examine the effect of calcium in the surrounding media, and we found that the number of embryos expressing green fluorescent protein (EGFP) was increased in media containing Ca 2+ . However, the number did not change over Ca 2+ concentrations from 2 to 8 mmol$L -1 (P > 0.05). Moreover, free Ca 2+ concentrations in the media were found to affect the efficiency which is porcine intracytoplasmic sperm injection (ICSI) embryos expressing EGFP protein, which was related to the activation of ooplasmic DNase I. These findings reveal a mechanism and pathway involving EGFP expression in ICSI embryos.