Viable sperm sent on a postcard

New Scientist opens a new, fertile field of biological research with the discovery at Japan’s University of Yamanashi that it’s possible to freeze-dry viable sperm and stick it on paper to mail it to remote labs, rather than messing around with fragile vials of frozen samples:

“Until now, sending mouse sperm to other researchers has required a freezing environment such as liquid nitrogen or a freezer,” says [team leader Daiyu] Ito. “Not only is the constant supply of liquid nitrogen and electricity needed for transportation expensive to maintain, but if there is a road disruption or power outage due to an earthquake, all the sperm will melt and become unavailable.”

The researchers thought that an alternative might be to freeze-dry sperm onto a surface and send it through the standard mail. After testing several materials, including filter paper and vinyl sheets, the team discovered that weighing paper – a form of paper used to hold samples being weighed in scientific analyses – was the best option. Mouse sperm could be freeze-dried onto the paper and still remain viable when it was retrieved later. Thousands of mouse sperm samples could be stored this way in a single book, which the researchers have called a “sperm book”.

To put the method to the test, the researchers freeze-dried mouse sperm to a sheet of weighing paper, before sandwiching the paper between plastic sheets for easier handling and sending it through the Japanese postal service, either in an envelope or attached to a postcard.

You can read more of Ito’s research (and his concerns over possible illegal DNA smuggling) here, in iScience.