Reproductive scientists create mice from 2 fathers

I will test it out!! i may be a guy but i wanna be a mother so bad.

 

Anyone else floored by the irony that this is coming out of Texas? Also, how long until anti-stem cell research groups tack on that it'll allow gays to have kids to their rhetoric?

On a more serious note, I've been smiling for about an hour since I first read this.

 

It's not really that far-fetched.

Males (no matter what species) have an X and a Y chromosone. Females have an X and X (one is deactivated.) So, through artificial methods you can take the X of one and the X of another (for both males and females) from two same-sex parents and create a fertile embryo. You can do the same to create male children to.

 

Me. That was my exact first though.

 

Except for not. This isn't what everyone is thinking happened.
1. Take cells from mouse fetus that randomly lost the Y chromosome after treatment. The percent of cells that underwent this process was about 1%.
2. Inject the XO cells into a female donated blastocyst.
3. Transplate the XO/XX chimera blastocysts into mothers and they give birth.
4. Breed those female chimera mice with the XO to male mice.
5. Therefore the offspring here will have one contribution from the original father (X or O) and one from the new father (X or Y).

I don't exactly see how this is revolutionary. A child can be produced this way already. Let's say you are male. You inherited the Y chromosome from your father. You then reproduce with a female and your child is XY chromosomally. Your female partner may have passed on the X chromosome she received from her father, essentially meaning the child has chromosomes from two men! Right? Wrong. Clearly the article is stretching the truth of the paper to make it seem more interesting than it actually is.

And if you look at the procedure, this wouldn't be exactly functional in humans even if you eliminated the XO/XX chimera stage by doing it in a petri dish.

 

Having read over what I wrote before posting, I realized that it become very confusing. So I'll be using the following notations to make sure it's clear.

Male parent 1: M1
Male parent 2: M2
Blastocyst Female: F
Blastocyst's fertilization Male: FM
Surrogate Mother of Blastocyst: S
Chimera: C
A/B denotes DNA contribution from A and B

From my understanding of what a chimera is, the female chimera mice are mice with two sets of DNA. One is a set of the F and FM, and the other is the near clone DNA of M1 as the XO cells implanted into the blastocyst were stem cells cultivated from M1 that only had the Y chromosome missing. What I understood from the article (and the one on msnbc not linked here) is that C then mated M2. Those children then would either be M2/(F/FM) children via original blastocyst DNA set or M2/M1 children via XO DNA set. The M2/(F/FM) ones thus not having any genetic derivation from M1 while the M2/M1 children not having any genetic derivation from F or FM.

Perhaps my understanding of it is wrong. I've yet to actually read the published paper and get more than a summary mass market digest of it. But if my understanding is right, then the XO derived children are in fact genetically parented from two male mice. One chromosome in each pair would be from either M1 or M2 and no other mouse.

While yes, your example of the passed down X chromosomes is correct, it isn't the same as what is occurring in the XO derived children. In your example, only the X chromosome is being considered and there are plenty of other chromosome pairs that are not necessarily from the 2nd male. Hence why it would not be considered a child of two male parents. But in the XO derived children, there's an entire half set of DNA from the M1 parent. Your example isn't analogous because it isn't the female's parent's DNA being passed on, it's the cloned chimera DNA being split and used thus making M1 the actual parent genetically.

I think perhaps there is a misconception of what the female chimera is. It's a mouse with two sets of DNA. The first set is the original DNA of the blastocyst which is DNA from F and FM and is analogous to the female in your example. While in the blastocyst stage of embryonic development, cells containing the XO DNA from M1 are introduced. This DNA doesn't replace any of the DNA or cells in the original blastocyst. The continue together developing into a complete mouse. This mouse has some cells with F/FM DNA and some with XO DNA. In the reproductive organs, the eggs that are generated can be created from cells with either F/FM DNA or XO DNA. The ones from F/FM DNA will wind up yielding children with M2 that are genetic children of M2 and C and grandchildren of F and FM. The ones from XO will be genetic children of M2 and M1. This is because the blastocyst's DNA never mixes or combines with the introduced XO DNA. So when an egg is formed from a cell containing XO DNA, half of M1's chromosomes are split into the egg. If the egg contained the X copy of that pair then it's genetically as if M1 created an egg cell to be fertilized. If it doesn't then the resultant impregnated cell would also be of XO type but half the DNA would be from M1 and the other half from M2 still unlike the originally introduced XO type DNA added to the blastocyst which was essentially cloned DNA of M1.

As far as the applicability to humans by removing the chimera stage, I believe that is in line of when they talk about creating egg and sperm from a single male or female contributor, thus bypassing the need to create a chimera and piggyback on its reproductive system to split the cultivated XO DNA. Instead we do the split ourselves. Injecting that split into a donor egg cell or perhaps they mean creating the egg cell along the same lines as the iPS cell culture (as so far as by some sort of manipulation and not to imply the two procedures would be at all related or alike) and then impregnating it with sperm from a secondary male contributor. In which case it would work for humans (in basic theory, I make no claim to informed theory or actuality). Most likely they would be talking about generating the egg since a donor egg will still introduce the donor female's DNA through the mitochondrial DNA.

As I stated at the start, I haven't read the actual scientific article the group published and fully accept I could be mistaken in my understanding of these topics. This is simply how I understood the process described in the linked article and the one msnbc had.

 

Eh. Fair enough. I actually knew I was disregarding pretty much all the chromosomes except for the X/Y set in my brief and admittedly incorrect analysis. Colour me jaded about the excitement bubbling up over a scientific discovery that is really not that impressive.

So yes, I do have a handle on how basic genetics works and what a chimera is. I just... Got annoyed and snapped at the paper? Maybe it is because I firmly disagree with the idea that it is inherently better to have children that share your partner's and your genetic code. I'm tired of surrogates and artificial insemination. I see that they are beneficial for those who want them, but I look at those people as... selfish.

But you are right in that they only have the genetic code of the two males. And I apologize for sounding like an arrogant, ignorant twerp. I should know better than that, what with actually having studied these things before.

 

I don't know how this will work with humans. I don't know anything about mice but humans at least do something called 'imprinting'. That is, certain genes are methylated (turned on/off) and other epigenetic things when sperm and eggs are made. The male imprints the genes in a different way than the female so that each parent passes on a set of chromosomes with different genes "turned off". When this system goes wrong (ie. the child ends up with a chromosome pair where they both have either the female or the male imprint), you are left with children who are stillborn or deformed.

I don't think it's homophobic to say that it is better that children come from a male and female.