Sperm mRNA found in eggs

A team of researchers has observed sperm mRNA in newly fertilized eggs, according to a paper published in the May 13 Nature, in a finding that provides alternative explanations for mammalian parthenogenesis, cloning, and male infertility, the team writes. The results would also have immediate applications for treating infertile couples and for providing a screen for toxicological effects in spermatogenesis, said coauthor Steven Krawetz.

Krawetz's team identified six transcripts present in sperm, but not in unfertilized eggs, and followed the delivery of two of them—clusterin and protamine-2—into eggs using real-time reverse transcriptase polymerase chain reaction.

“It's really the first demonstration that human sperm contain a population of RNAs,” said Krawetz, a professor in the Department of Obstetrics and Gynecology at Wayne State University. “Specifically, we show messenger RNAs, and those are delivered to the oocyte upon fertilization.”

The mRNA must exist before the single fertilized zygote has divided into four ...