Whether aiding in early growth and development, ensuring a healthy nervous system or guarding the body from illness, zinc plays an important role in the human body.
Husband-and-wife team, Thomas O’Halloran 
and Teresa Woodruff, plus other researchers at Northwestern University, evaluated the role that zinc plays in healthy fertilization. The study revealed how mouse eggs gather and release billions of zinc atoms at once in events called zinc sparks. These fluxes in zinc concentration are essential in regulating the biochemical processes that facilitate the egg-to-embryo transition.
The scientists developed a series of techniques to determine the amount and location of zinc atoms during an egg cell’s maturation and fertilization as well as in the following two hours. Special imaging methods allowed the researchers to also visualize the movement of zinc sparks in three dimensions.
Using a fluorescent sensor for live-cell zinc tracking, the scientists located approximately 8,000 zinc-rich packages just below the egg’s surface. They found that an egg, at the time of fertilization, releases thousands of these packages, each containing about 1 million zinc atoms, in four to five surges.
The scientists are the first to capture images of this process and to locate the origin of the sparks. The amount of zinc released by an egg might be a marker for identifying healthy eggs, which could lead to improvements in in vitro fertilization methods.
This work was funded in part by NIH under grants R01GM038784, P01HD021921 and P50HD076188.