Reproductive researchers have created male and female mice, from parents that were both genetically male.
Considering all the controversy surrounding NASA's press release about arsenic-based lifeforms with different DNA structure, and because of my slowly approaching genetics exam, I thought I would write about an equally interesting genetic development that seems to have skipped the attention of the science tabloids.
I'm referring to a recent paper published by The Society for the Study of Reproduction by Jian Min Deng and his research team. They investigated a technique using induced pluripotent stem cells (iPSes) extracted from mice to create viable male and female children using two fathers!
Traditionally, males are genetically XY and females are XX, this refers to the two sets of chromosomes that contain similar copies of DNA, and are required to produce a fully functioning individual. What was found in the study was that genetic XY male stem cells carried a mutation in a specific gene (H19) that caused the cell to lose one X chromosome and become an XO. The more interesting part was that these cells would develop into female oocytes: eggs!
Mice with the XO sex chromosomes were found to be fully functioning females!
The rate of mutation in H19 was found to be quite low, less than 1%, but further studies showed that deletion of another gene region (Dlk1 - Dio3) greatly increased the chances of producing an XO mutant.
The researchers also showed that the entire process can be induced using somatic stem cells (iPSes) to produce eggs or sperm. In-vitro fertilization could then be used to generate fully normal offspring, which was shown in the mice.
Fully formed normal male and female mice were essentially produced from a combination of XY sperm with XO eggs, which themselves derived from sex-reversed XY males.
There are some barriers to surmount when using this technique however, seeing as how XO genotypes in humans are not fully functioning females but individuals suffering from Turner's Syndrome, a condition that causes cognitive defects and a slew of other health problems. However, further research could lead to a better understanding, or even a potential cure, for diseases like Turner's syndrome or various other genetic diseases.
These developmental methods can also be used to give same sex couples a child that is genetically theirs, or in the distant future even give individuals the ability to self-replicate (try to wrap your head around that concept for a second). The limits are endless to what could be developed, or what it could mean for society's oldest past-times *nudge nudge wink wink*. One thing is certain, it challenges the very notion of what male and female truly are, perhaps they're nothing but social constructs? Hopefully we'll find out soon enough thanks to studies like this.
The paper is free to read here.
Deng MJ, Satoh K, Chang H, et al. (2010). Generation of Viable Male and Female Mice from Two Fathers. Biol of Reprod; 83(6): In press.