With a switch of a letter in DNA ‘dark matter,’ Israeli scientists change sex of mouse

[IwantToRetire]

Bar-Ilan University researchers use CRISPR tool to alter Enh13 switch controlling Sox9 gene, causing XX mice to develop as males; study may help explain other genetic mutations ...

Gonen laid the groundwork of her research by saying that when people talk about sex, “many people have the tendency to confuse biological sex with gender and with sexual orientation, but those are actually three different pillars or layers.”

Sex determination is a process that is “fully biological,” and it “all happens during embryonic development, giving rise to males or females.”

"We understand much of it, but not all of it,” she said.

The next issue is gender, she said, which may have a biological trait, “but we don’t have really good tools to study that with mice.”

“No mouse will come and tell me, ‘Look, I’m a female, but I feel like I’m a male,'” she said. “Those are things that are really hard to study, but we know they are there.”

She said that one in 100 children and adults around the world, including Israel, will feel like they don’t match their biological sex.

Finally, the last pillar is sexual orientation.

“Most males are attracted to females and females are attracted to males, but you can have females attracted to females and males attracted to males. We know that this also exists in the animal kingdom, but it’s harder to study. Mice won’t say who they’re very attracted to.”

Full article https://www.timesofisrael.com/with-a-switch-of-a-letter-in-dna-dark-matter-israeli-scientists-change-sex-of-mouse/

And for those who can understand the language, this is the paper the artaicle is based on

A single-nucleotide enhancer mutation overrides chromosomal sex to drive XX male development
https://www.nature.com/articles/s41467-026-71328-9

Do you mean sex characteristics?

And why does it only apply to changing it to male?

This is a great summary.

For those asking why they did this and what the possible applications are - this isn’t applied research like development of a treatment for a disease. As @Geneticsbunny and others have said, the aim is to get more of an understanding of how sex differentiation works. Making mice with engineered DSDs is simply a research tool to learn more about the genetics behind the developmental pathways.

I'm unclear reading the Times of Israel article in what context she made those remarks. Was she asked by journalists specifically about gender and did she have to say something without getting the TRA's heckles up? Or did she volunteer these? This is a very good piece of work, I'd be annoyed if all a journalist would ask me about it was centered around fecking gender.
Directed mutagenesis has been used for decades to study biological processes, it's bread and butter stuff for biochemists, it's great to see that non-coding DNA is getting the attention it deserves.

Arent sexual characteristics and sex characteristics the same thing at a biological level?

It would need a different gene or set of genes switching off to change an xy mouse to develop female sex characteristics. E.g. the sry gene.

As others have said they have basically created a new DSD.

May I ask a question? @Geneticsbunny when testing things on mice, do they usually test on male mice to avoid the hormone changes around female cycles? I’m talking about general scientific research. I never thought to ask when I worked in a university.

Depends what they are looking at and whether sex would influence the results. Experiments should always take into account the sex of the mice being used though so either stick to all males or all females, unless of course the experiment is looking at differences between the two.

Ahh ok. That does make more logical sense. Either way this is above my pay grade so thank you for being the one who understands this stuff for us all! 😂

Thanks for the opportunity to nerd out in public. I think the fact that a single cell can grow and divide and change into all the complicated organs inside the body is totally amazing.

Oh dear, I am sure you are right. This just shows I dont know enough about this area of work.

I was applying what I assume in day to day language. ie your sex is one thing, who you are attracted to is sexual.

But then no sure anyone has every done or recognised the sexual activities of dna (though who knows what does on in "dark matter"?!) so will probably not post another question, but am still interested in reading about this.

Because it is probably in its own right something that could be of use, but the article inserting all that nonsense about mice questioning their sexuality has just cause an irrrelevant detour.

But (just a joke) I can imagine if this had been British research and reported in the UK. No doubt they would head the article something like "Brit breakthrough leads to baby bonus" as I imagine the sub editor would no more understand it than I do!