A team of scientists from Instituto Max Planck discovered that there are some mammalian spermatozoa capable of disabling others from reaching and fertilizing the ovum. Specifically, this phenomenon was observed in mice and is due to a genetic factor, haplotipo t.
This factor, the authors describe in a Press release, gives a success rate of up to 99% to sperm that contain it. This is possible because the t haplotype would allow them to advance faster than their competitors who do not have it. In addition, it serves as a ‘guide’ to reach the egg.
“Sperm with the t haplotype are able to disable sperm without it,” describes Bernhard Herrmann, director of the Institute and author of the study.
“EThe trick is that the t-haplotype ‘poisons’ all sperm, but at the same time produces an antidote, which acts only on sperm and protects them. Imagine a marathon, in which all the participants are poisoned by drinking water, but some runners also take an antidote ”, he explains.
Herrmann and his colleagues identified that the t haplotype contains certain genetic variants that distort the regulatory signals of sperm. In mice carrying the haplotipo t, these distortion variants are distributed during the initial phase of sperm development. Some thus gain the advantage of administering a “poison” that disturbs the progressive movement of their competitors.
Meanwhile, the “antidote” kicks in after the set of chromosomes is divided evenly between sperm during maturation. Each sperm now contains only half of the chromosomes. Half of the sperm with the t-haplotype produce an additional factor that reverses the negative effect of the distorting factors. And this protective factor is not distributed, but is retained in the sperm t.
The researchers also found that RAC1 molecule, known for its participation in the direction of some cells such as white blood cells, have a greater activity in the expected that contains the haploid t. The authors observed that this molecule helps sperm by giving them the ability to “sniff” their way to the egg.
“Sperm are ruthless competitors (…) Genetic differences can give individual sperm an advantage in the race for life, thereby promoting the transmission of particular genetic variants to the next generation,” Herrmann concludes.
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