Researchers unraveling the mystery of how sperm cells navigate

November 15, 2018, University of Tokyo
This figure depicts how researchers believe sperm cells navigate thanks to PMCA (plasma membrane Ca2 ATPase) and SAAF (sperm activating and attracting factor). Credit: Manabu Yoshida, Misaki Marine Biological Station, The University of Tokyo

Researchers have found that a protein in the cell membranes of sperm plays a key role in how they find their way to eggs. The PMCA protein may also help explain how egg cells only interact with sperm from the same species. PMCA may even be a target of drug discovery.

Sperm are excellent navigators. If they weren't we wouldn't even be here. Professor Manabu Yoshida from the Misaki Marine Biological Station at the University of Tokyo and colleagues investigate why behave the way they do.

Sperm cells, bacteria and other microscopic organisms use varying concentrations of chemicals in their environment—concentration gradients—to approach or avoid something in a process called chemotaxis. Egg release an attractant chemical, which lures the sperm. The researchers studied this action in Ascidia—sea squirts, brainless tubular creatures, which are only mobile as larvae.

"We identified that a calcium transport protein—plasma membrane Ca2+ ATPase (PMCA) - has a key role in sperm chemotaxis," says Yoshida. "PMCA is abundant in the tails or flagella membranes of the ascidian sperm. It binds to the species-specific attractant and alters how the flagella waves, thus directing movement of the ."

The team used a range of techniques to measure the effect they observed. These included a highly selective form of chromatography (separation of mixed compounds by diffusion in a fluid) called affinity column chromatography to isolate the attractant released by the egg; laser-based mass spectrometry, which uses lasers to identify what chemicals are in a sample; a quartz crystal microbalance, a sensitive microscopic weighing scale, to measure samples and how they change; and a high-speed camera to view sperm behavior in slow motion.

"With these methods we also found PMCA is responsible for regulating cellular calcium, whereas it was previously believed PMCA had no role in this," continues Yoshida. "Now we know PMCA plays an important part in cellular function. It makes it a promising target for drug research."

Explore further: Scientists find elusive molecule that helps sperm find egg

More information: Kaoru Yoshida et al. Ca2+ efflux via plasma membrane Ca2+-ATPase mediates chemotaxis in ascidian sperm, Scientific Reports (2018). DOI: 10.1038/s41598-018-35013-2

Related Stories

Scientists find elusive molecule that helps sperm find egg

August 3, 2018

Scientists affiliated with the Marine Biological Laboratory (MBL) have identified a key molecule driving chemoattraction between sperm and egg cells in marine invertebrates. The study was recently published in Nature Communications.

Protein in zebrafish found to keep out sperm of other fish

September 7, 2018

A small team of researchers with the Vienna Biocenter has discovered that a protein that exists on the exterior of zebrafish eggs acts as a sentry—allowing only sperm from zebrafish to enter. In their paper published in ...

Sperm can count

March 7, 2012

The speed at which the calcium concentration in the cell changes controls the swimming behavior of sperm. They can calculate the calcium dynamics and react accordingly.

Researchers describe how sperm can lose their way

February 24, 2017

Sperm tails are actually complex propellant and navigational devices that help push them through fluids and navigate around complex terrain of the female oviduct. Now researchers at Yale and Harvard Universities have identified ...

Key protein in sperm tail assembly identified

May 11, 2018

A study published in the Journal of Cell Biology focuses on the development of the sperm tail, the structure that enables sperm cells to swim and is therefore critical for male fertility.

Recommended for you

To repair DNA damage, plants need good contractors

December 13, 2018

When a building is damaged, a general contractor often oversees various subcontractors—framers, electricians, plumbers and drywall hangers—to ensure repairs are done in the correct order and on time.

Plants' defense against insects is a bouquet

December 13, 2018

Michigan State University scholar Andrea Glassmire and her colleagues have revealed how the mixture of chemical weapons deployed by plants keeps marauding insects off base better than a one-note defense. This insight goes ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.