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A Mouse With Two Mothers
jabberjaw writes "Both the BBC and Nature are reporting that scientists at Tokyo University of Agriculture have used two sets of chromosomes belonging to a female mouse to create what are essentially fatherless mice. The process by which this was accomplished (parthenogenesis) does not naturally occur in mammals. The mouse used lacked a gene known as H19 which in turn activated the Igf2 which allowed this process to occur."
So does this mean we men have no use anymore?
Parthenogenesis (straight from the Wikipedia Link): Parthenogenesis (Greek , "virgin", + , "birth") means the growth and development of an embryo or seed without fertilization by a male. In other words, an embryo/seed develops without receiving a second set of chromosomes from a 'father'. It doesn't matter if that second set came from a female or a male. When NPR covered this story, one of the scientists interviewed actually SAID this was different from parthenogensis, which had been demonstrated previously in many species.
The Y chromosome is a mutation of the X chromosome and contains much less information
True but misleading.
Yes, the Y chromosomes contains less genetic data but it's information not found in the X chromosome. So because data is repeated, two X chromosomes contain less information than an X and a Y.
Yes, it's likely that the Y chromosome is a mutation of an X chromosome, but it differentiated so long ago that 95% of the Y chromosome is male specific.
BTW: I'm not suggesting that this is a deliberate attempt to mislead.
The Y chromosome is a mutation of the X chromosome and contains much less information.
but you forget that males have both X and Y chromosomes. so, while 2 females (only X's) can only create female offspring, males can create both male (XY), female (XX).
Indeed, if this rare occurrance could happen perchance...I didnt think that this was really possible at all but having shown that it is...
You probably didn't read the article, but hopefully I can explain why this isn't possible by chance in humans.
First, they were only able to do this using a mutant immature mouse egg cell. Two genes had to be mutated in order to stop it from imprinting an egg transcriptome (basically, what genes are on). This also would seem to prevent, at least for the forseeable future, doing this in humans. It's hard to mutagenize humans, while it might be possible to turn off the gene using something like siRNA who knows if we could get human egg cells in that premature of a form
The second, and much larger, problem is that they took genetic material from a second egg and injected it into the first. This is not going to happen naturally. Sperm has a special cellular mechanism that allows it to fuse with an egg. Eggs do not contain these cellular components and therefore would have a hard time (read: impossible) doing this in vivo.
Basically, the process of parthenogenesis does not happen in mammals in vivo. Can we set up an artificial system to do it with humans, yes probably we can eventually. However setting up an in vitro situation has no implications for in vivo possibilities.
I'd like to clarify this a bit. Many plants DO/CAN reproduce "sexually" without crossing with another individual, wheat is an example. They actually self-pollenate (self-mate), a fine distinction from parthenocarpy, which is fruit/seed production without any pollenation (fertilization). While the progreny of a selfed plant essentially have the sample genes, crossing-over and other genetic events usually result in the chromosomes not being identical.
I AM a scientist, and I read the research paper in Nature rather than the popular-press rehashings of the article. Of the 371 embryos that were transferred to recipients there were 8 born live and 2 who survived the perinatal period. That should stop the handwaving about the likelihood of producing humans infants using ths approach on the grounds of cost alone.
An extensive amount of genetic engineering was done in order to produce parthenotes that were capable of surviving past 10d of gestation, which is when naturally-occuring parthenotes usually die. One of the two survivors was raised by a foster mother to adulthood and has herself produced a litter of apparently normal pups. The other survivor was sacrificed for gene expression profile studies.
Some whack job might indeed try this on humans, but it is unlikely. It is easy to obtain enough mice recipients for 371 embryos. It will be significantly more challenging to do that for humans. We also do not know what regulatory differences there may be between mice and humans that would prevent the reported protocol from producing viable embryos in vitro.
Yes, but you'd then need a female to donate eggs, remove the host egg's chromosomes and inject in the two fathers' DNA.
Sounds rather more risky, with more trauma being done to the egg, and the failure rate would be higher due to the possibility of Y-Y pairings which would be unviable.
Michel
Fedora Project Contribut
The gene is called SRY.
And idea that SRY is the only functional/useful gene on the Y chromosome was debunked years ago. Dozens of genes have since been found on the Y chromosome.
First, the alternate mother was a mutant. As they started to mention, she had a gene knocked out - a gene that supresses the expresion of about 1000 other genes.
Second, an X from a female will not align with an X from another female (because of the above, and other reasons). What they effectively did was make a female mouse that could make X chromosomes that behaved in the same way that X chromosomes from a male behave.
To have this occur in humans, they'd have to figure out how to create a mutant human female that produced X chromosomes that behaved like the X chromosomes a male produces. They'd then have to take said X chromosomes out of her eggs, and match them with her partner's eggs, just like in this experiment. As such, this has absolutely no implications for lesbians, unless one just happens to be such a mutant already somehow (they aren't).
The research has little impact on allowing lesbians to reproduce. The process for doing that to two women, when neither is a mutant, is a wholy seperate process. In vitro fertilization is about as related to the eventual female reproduction potential as this experiement is (and this experiment is only that related simply because it *involves* IVF). This has no new implications for that eventuality.