Israeli scientists Have Created the Ability to Control Gender in Embryos
COULD NEW ISRAELI RESEARCH ALLOW HUMANS TO CHOOSE THEIR
CHILDREN'S SEX?
“We proved the concept in mouse models, but the concept
could also be demonstrated in cattle, swine, goats, chickens and other
animals," the lead researcher said.
BY MAAYAN JAFFE-HOFFMAN JULY 1, 2019 18:47
Israeli scientists have demonstrated the ability for
mammals to mate and produce only female babies. A similar system based on
identical principles could produce only males.
The research for the study was led by Prof. Udi Qimron,
Dr. Ido Yosef and Dr. Motti Gerlic and conducted by Dr. Liat Edry-Botzer, Rea
Globus, Inbar Shlomovitz and Prof. Ariel Munitz, all of the Department of
Clinical Microbiology and Immunology at Tel Aviv University’s Sackler School of
Medicine. The research was published in EMBO Reports.
“We proved the concept in mouse models, but the concept
could also be demonstrated in cattle, swine, goats, chickens and other
animals,” Qimron said. He noted that humans are likewise mammals and the
concept could ultimately be applied to human children “if a mad ruler decides
he wants to engineer the people to have only male or female offspring – we have
provided the proof of concept.”
Last year, in what became a ground-breaking and
controversial medical first, a scientist in China claimed to have created the
world’s first genetically edited babies. The researcher, He Jiankui of Southern
University of Science and Technology in Shenzhen, said he altered embryos for
seven couples during fertility treatments, with one pregnancy resulting so far.
He said his goal was not to cure or prevent an inherited disease, but to try to
bestow a trait that few people naturally have: an ability to resist possible
future infection with HIV.
This kind of gene editing is banned in most countries.
But the researchers at TAU worked differently and,
according to Qimron, have a different agenda. The researchers crossed two types
of genetically engineered mice. The maternal mouse encoded a Cas9 protein, a
CRISPR-protein that is inactive unless guided by special “guide-RNAs.” The
paternal mouse encoded these guide-RNAs on the Y-sex chromosome, a sex
chromosome present only in males. After fertilization, the guide-RNAs from the
paternal sperm and the Cas9 protein from the maternal egg were combined in the
male mouse embryos, but not in the female embryos (because the females lack the
Y chromosome). The combination of guide-RNAs with Cas9 results in a complex
that eliminates the male embryos.
“We showed that Cas9 was specifically activated only in
male embryos,” said Qimron. “Our results pave the way for a genetic system that
allows biased sex production. When two transgenic types of mice encoding Cas9
or Y-chromosome-encoded guide-RNAs are crossed, lethality of males occurs
because Cas9 is guided from the Y chromosome to target essential genes. This
does not happen in females because the Y chromosome is not transferred to them.
This cross thus halts embryonic development of males without affecting the
development of females.”
The idea for the research came after one of Qimron’s
research fellows, Yosef, saw an advertisement stating that billions of chickens
were killed annually by chicken egg farmers who had no use for so many male
chicks.
“He said, ‘There must be a way to overcome this,’” Qimron
recalled. “It is so cruel and unfair and we thought there must be a scientific
solution.”
The team started with mice, but Qimron said he believes
the same system could transfer to other animals and species of animals,
including cattle.
This could save the lives of thousands of cows who are
killed each year on dairy or meat farms.
The number of male calves being killed straight after
birth is high on dairy farms because it is cheaper to kill them than to rear
them, for example. And on beef farms, the opposite is true, where female cows
are killed in favor of hefty male cattle.
The researchers based the system on one that already
exists for certain plants, insects, crustaceans and fish that possess the
uncanny ability to change the sex of their offspring before they are born.
Mammals, however, have never before demonstrated this genetic skill, until now.
“We approached this problem in an innovative way, using
genetic engineering,” Qimron said. “We believe that the producers of cattle,
swine and chicken may benefit greatly from the technology.”
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