14 DAY TRIAL // After exploring the synapses and the electrical currents involved in the cerebral processes, researchers have turned their attention to the electrical currents present in other activities in the organisms.
Researchers at Children's Hospital Boston and the Howard Hughes Medical Institute have, for the first time, captured the electrical activity of a single sperm cell and achieved the first measurement of the currents that flow across the sperm's outer membrane.
The ability to measure sperm currents has also enabled the researchers to pin down the role of a protein called CatSper that is vital for male fertility.
CatSper, discovered in 2001 in the Children's Hospital Boston lab of David Clapham, MD, PhD, is found only in the Tails of mature sperm. Mice that lacked CatSper were completely infertile: their sperm were poor swimmers and couldn't penetrate the protective barriers around the egg. But no one was sure what role CatSper played or how it worked.
Experiments carried out by Yuriy Kirichok and Betsy Navarro have showed that is a key channel by which calcium ions enter the sperm's tail. The calcium influx, measurable as an electrical current, "hyperactivates" the tail's motor proteins, giving the sperm the burst of swimming power needed to reach the egg. The current was detectable in sperm from normal mice, but not in sperm from mice that lacked CatSper.
This discovery gives researchers hope that they will be able to obtain a male contraceptive that blocks the CatSper protein. Hydra Biosciences, a biotech company, is working on such a project, but it faces difficulties because of the inability to block only CatSper and not other calcium channels.