What is the oldest known gene.

Human sperm gene is 600 million years old

A gene controls sperm production not only in humans, but also across all lines of the animal kingdom. A study that has now been published in “PloS Genetics” reveals that the “Boule” gene has survived unchanged for almost 600 million years of evolution. This makes it the oldest known gender-specific gene in humans.

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In many sexually reproducing animal species, sperm play a crucial role. Ultimately, they are the main actors in the fertilization of egg cells and thus in the recombination of parental genes. So far, however, it was unclear whether sperm cells developed independently of one another once or several times. Researchers are primarily looking for an answer to this question in the genes that control sperm production. One of these genes, called "Boule," was discovered in 2001 by Eugene Xu, Assistant Professor at the Feinberg School of Medicine at Northwestern University. When he and his colleagues deactivated this gene in male mice, the animals appeared healthy and fit at first glance, but could not produce any sperm.

Same gene in all animal groups

Based on this find, Xu and his colleagues have now made another groundbreaking discovery. As part of their research, they also scanned the genome of other animal species for this gene - across all evolutionary lines of the animal kingdom, from invertebrate sea worms to insects, fish, mammals and humans. And amazingly, all of them had the boule gene in unchanged form. And in all of them, its only function was sperm production.

Unchanged despite selection pressure

"This is really surprising because sperm production is severely affected by natural selection," explains Xu. “There is a particular pressure to become 'super males' in order to increase reproductive success.” But the boule gene appears to have escaped this pressure that normally affects all aspects of mating. “This is a gender-specific element that has not changed across species. It has to be so important that it can't change. "

Origin almost 600 million years ago

To find out how far back the boule gene goes back in evolution, Xu also examined the genetic make-up of one of the most primitive organisms living today, the sea anemone. Fossils of the cnidarians, their superordinate group, are already known from 540 million years ago. And indeed: the boule gene was also found in the anemone. It was therefore clear to the researcher that sperm production in the entire animal kingdom had to be based on a common prototype - and that this came about very early on.

“The results show that we share a fundamental element across all evolutionary lines, regardless of how complex we are,” explains Xu. “This is the first clear evidence that our ability to produce sperm is very old. It probably originated at the very beginning of the animal evolution 600 million years ago. ”This would make Boule the oldest gender-specific human gene known to date.

Applications in prevention and pest control

But the discovery also has very practical significance beyond basic research, for example in reproductive medicine. On the one hand, it provides new insights into possible causes of male infertility, on the other hand, it also offers possible points of attack for a “pill” for men. "A sperm-specific gene is an ideal target for a contraceptive agent used in men," says Xu.

Boule could also inhibit the reproduction of males of pathogens and pests and thus make an important contribution to combating malaria mosquitoes or parasites, for example. “We now know that we have a strong candidate to control their reproduction. That could give the development of new pesticides or agents against infectious parasites and disease carriers a completely new direction in the future. "

(Northwestern University, 07/19/2010 - NPO)

July 19, 2010