StemCell Therapy

It takes just one sperm to fertilize a womans egg and for each sperm that reaches the egg, there are millions that dont. You probably knew that already, but heres the thing: not all sperm cells are equal. Some have mutations in their DNA sequence that allow them to swim straighter, rather than in circles, and faster on average than their competition. Whats more, sperm cells can even employ gruesome tactics, such as poisoning their neighbors in order to enhance their odds of fertilizing the egg.

The difference between a loser and a winner sperm cell could be down to a protein: RAC1. In a new study, researchers at the Max Planck Institute for Molecular Genetics (MPIMG) in Germany studied mouse sperm cells under the microscope, finding that this protein is responsible for guiding the sperm in the right direction by chemically signaling from the outside and activating other proteins.

The RAC1 protein plays a critical role in controlling the motility of sperm, in particular the average path velocity and linearity. This protein is produced in sperm that carry a particular DNA sequence known as the t-haplotype.

The researchers in Germany knew from previous research that it is thanks to this genetic sequence that some sperm swim in a straighter path and at a faster velocity than sperm lacking the t-haplotype. However, they were shocked to learn that t-haplotype sperm can also poison their competition by injecting them with certain genes that inhibit movement.

Sperm with the t-haplotype manage to disable sperm without it, study co-author Bernhard Herrmann, director at the MPIMG, said in a statement. The trick is that the thaplotype poisons all sperm, but at the same time produces an antidote, which acts only in t-sperm [those with the t-haplotype] and protects them.

In other words, it literally is a race for life (or death) for the millions of sperm cells on a quest to fertilize egg cells and luck seems to play a minor role.

Imagine a marathon, in which all participants get poisoned drinking water, but some runners also take an antidote, said Herrmann, who is also the director of the Institute of Medical Genetics at Charit Universittsmedizin Berlin. Thats the same hospital where Kremlin critic and Russian opposition leader Alexei Navalny was treated after being poisoned, allegedly by the Russian government.

According to experiments, the vast majority of sperm cells that made little progress on their paths were genetically normal, whereas those that moved in a straight and optimal path mostly had the t-haplotype genetic factor. Poisoned cells literally swam in circles until they died. Meanwhile, t-haplotype sperm that had the antidote that inhibited the effects of the poison charge straight ahead.

Our data highlight the fact that sperm cells are ruthless competitors, says Herrmann.Genetic differences can give individual sperm an advantage in the race for life, thus promoting the transmission of particular gene variants to the next generation, says the scientist.

The findings were reported in the journal PLOS Genetics.

See more here:
Some sperm cells swim faster and even poison their competition to climb to the top - ZME Science

This entry was posted on February 14, 2021 at 6:58 pm and is filed under Molecular Genetics. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. |