Dairy Cattle Reproduction Council, June 28, 2012 - Research from the University of Missouri has found how to identify faulty sperm and remove them from the artificial insemination equation. The research was published in the October 2011 issue of the journal Theriogenology.

There are many types of hidden sperm defects that are not obvious and cannot be identified by conventional analysis, says Peter Sutovsky, University of Missouri reproductive scientist. "We look at biomarkers to improve our ability to correctly evaluate semen and to give us an idea about fertility of a bull that is used in an artificial insemination program."

One of those flags is ubiquitin, a protein found in most tissues. One function of ubiquitin is to tag other proteins that are defective or no longer needed. Scientists have dubbed ubiquitin the "kiss of death" because proteins tagged with it are dismantled and recycled.

In faulty sperm, ubiquitin migrates to the surface of the cell. Using nanotechnology, researchers coat small metal particles with an antibody that lets the nanoparticles bind to ubiquitin on the defective sperm, then uses a strong magnet to literally pull down those cells. "When we pull down bad sperm in a test tube, we can skim off the good sperm cells," Sutovsky explains. "That means that we can use fewer cells per dose if we isolate only the good ones."