In a study that could shed new light on some of the causes of male infertility, researchers at the Howard Hughes Medical Institute have uncovered new information about the mechanisms underlying sperm motility, or movement ability.1
The scientists described a key component discovered in their study that sperm use to abruptly convert their tail motion from a steady swimming movement to a whip-cracking snap that thrusts them into an egg during the fertilization process, known as hyperactivation.
Additionally, they reported on a special technique they used to peer into the electrical currents inside the sperm cell that could help uncover information about its mysterious inner workings.
It’s long been known by scientists that the alkaline environment of the female reproductive tract triggers sperm’s whip-like motion, said David Clapham, MD, PhD, the study’s lead investigator. In earlier studies, Clapham and his colleagues showed that a protein found only in the sperm tail was required for male fertility. This earlier study in conjunction with researchers at the University of Washington and the University of Texas Southwestern also found that this special protein was necessary for hyperactivation to occur, as well.
Finally Clearing a Hurdle
In these earlier experiments, research scientists attempted to use a technique to peer into the electrical activity of a sperm. They attempted to do this by peering into pores in the sperm’s membrane called ion channels. But the sperm’s constant movement and other difficulties made attempts to view its electrical activity useless.
However, one of Clapham’s colleagues perfected the technique, which was finally used in this study to view sperm’s electrical activity successfully. “It’s like opening a chamber in an ancient pyramid because no one had ever seen inside sperm cells to measure all the currents that control their activity,” he explained. “We are already measuring many of these [electrical] currents and beginning to answer questions about what they are and what they do.”
Sperm Mechanics to be Explored
Clapham and his fellow investigators are planning future research to further understand sperm’s electrical activity and determine how calcium, which enters sperm soon after they are ejaculated into the female reproductive tract, controls hyperactivation. Such studies will involve exploration of the sperm’s mechanism from head to tail, as well as processes ranging from tail movement to those involved in the sperm’s delivery of its genetic material into the egg.
Clapham stressed that these future studies could provide further insight into male infertility. Some unknown abnormalities in the protein found in the sperm’s tail could be one cause of male infertility, he speculated.
“We know that defects in [the protein] block fertilization in mice,” Clapham stated.
1. Kirichok Y, Navarro B, Clapham DE. Whole-cell patch-clamp measurements of spermatozoa reveal an alkaline-activated Ca2+ channel. Nature 2006 Feb 9;439(7077):737-40.
John Martin is a long-time health journalist and an editor for CuraScript. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.