Sep 09, 2012
Yesterday afternoon I posted an article about synthetic nucleic acids and processing of arbitrary information from the field of synthetic biology. To recap briefly, by adding synthetic components to bioengineered bacteria researchers have been able to represent and manipulate information with XNA, a variant of DNA which involves synthetic compounds in addition to the four naturally found in DNA. One of the commenters on that post is working somewhere in that field and mentioned a few of the things that can be done with those custom-designed nucleic acids. This reminded me of another article I've had in my to-write queue...
Scientists working in the field of bioengineering at Harvard Medical School recently announced that they have successfully cultured what they refer to as cyborg tissue in the lab. They started by taking a scaffolding of collagen, the protein which forms the superstructure of most of the organs of complex life on this planet and weaving into and through it a meshwork of wires comperable in size to the integrated circuitry of your computer (between 45 and 22 billionths of a meter). These nanoscale wires connected an unknown (but probably very high) number of transistors. Rat cells (specifically, cardiac cells, neurons, blood vessels, and muscle tissue) were added to the nanoelectric scaffolding and encouraged to grow in vitro. To no one's surprise, the cells grew and connected to one another to form tissue of the sort you'd expect (neural networks, self-regulating cardiac cells, muscle tissue, and rat blood vessels), but to everyone's surprise the scientists were able to read and interpret data from the nanoscale sensor network the cells grew around. Let me put it another way: They were pulling realtime diagnostic information from cell cultures. Due to the fact that many biological processes are chemoelectrical in nature (cases in point, the functioning of the heart, nervous system, and musculature all involve measurable electrical activity) this only makes sense. For an encore, they repeated the experiment with human cells, and grew an instrumented section of human blood vessel.
Now, given that a lot of complex biology involves a significant of chemoelectrical activity, and reading that activity is fairly easy and understood, the next logical step involves directly interacting with and influencing that electrical activity. We've been doing this for years; pacemakers are common, cochlear implants are no longer really considered experimental (and are even iProduct compatible!), and deep brain stimulation is used to help treat disorders like Parkinson's Disease and severe clinical depression. We've come a long, long way from Luigi Galvani's experiments with wet cell batteries and dead frogs. So, the next step would have to involve installing programmable computers to write to (not read from) living systems. I don't know how advanced this particular topic is but the creation of a general purpose nanoscale CPU small enough to fit inside a living thing would make an ideal computer to manipulate some life processes through a nanoelectric scaffolding. The key would be getting the scaffolding into the lifeform; these experiments involve growing tissue in a lab environment and not inside of a living thing, and it's not an easy task to precisely get anything the size of a cell (or smaller) into a living thing just where you want it, how you want it without mangling or killing the creature. And now for a post I've been sitting on because I wanted to see what shook loose after the juice was turned on.
A couple of months back the Institute for Reproductive Medicine and Science of Saint Barnabas in New Jersey quietly announced that in the year 2001 thirty healthy, happy human babies who had been genetically modified were born in the United States. Of the thirty babies two were genetically tested and found to carry DNA from no less than three human parents. The children were conceived for women who were having difficulty bearig children due to mitochondrial disorders. The process involved removing the mitochondria from healthy human ova using microsurgical techniques and transplanting them into the patients' ova prior to being fertilized in vitro (reference 'cytoplasmic transfer', original paper linked from this article, I can post a copy of the whitepaper if anyone wants it). The fertilized ova were implanted into the patients' uterii, tick tick tick... babies.
Now, let me point out the really interesting bit: They were conceived in 2001. Here the reports start to get sketchy, some of the articles say that the children were brought to term shortly after conception and other say that they were born recently and are now around 18 months of age. This research took place over a decade ago, so this isn't even in sight of the bleeding edge, it's old news and practically irrelevant insofar as the culture of the Internet is concerned. Mitochondria are inherited from the mother along with half of one's DNA (the other half coming from the father), so it is factually (but not functionally) correct to say that these children have three genetic parents, and any children that they may bear or sire farther down the line may also have those third party genetics.
But let's hit the brakes here: This does not mean that the fertility clinic was splicing and dicing the genomes of these children, not as we think of it (not after our perceptions of the world have been shaped by decades of science fiction). Mitochondrial DNA, as the name suggests is DNA residing within mitochondria and not the cell nucleus, and is not the DNA that encodes your hair color, eye color, general skin tone, general growth potential, or the other traits that you see when you look in the mirror every morning. Mitochondria produce most of the chemical energy that your body runs on, but their DNA doesn't code for any traits. It isn't as if these children have the eye color of the third parent or a predilection toward being artistically inclined when the other two parents aren't. It certainly is not as if the genomes of these children were modified with specific traits in mind. In fact, there is evidence to suggest that some of the children are developmentally impacted and are showing signs of genetic disorders (hence, the DNA workup). So this process does not appear to be as effective as we might wish it had been. The genetic abnormalities might not be mitochondrially linked, either - it's entirely possible that the genomes of one or both of the parents who are responsible for the nuclear DNA are implicated.
That's not to say that having a genetic lineage consisting of more than two parents is impossible. Medical science has documented multiple cases of human genetic chimaerism over the years. The most interesting case in recent memory is that of Lydia Fairchild, a woman who found herself in a unique legal conundrum because it was discovered that two of her children weren't hers, genetically speaking. Phenotypically speaking, Lydia Fairchild does not look appreciably different from any other human on this planet, showing not even anything like heterochromia. Long story short, the court agreed to the genetic testing of Fairchild's extended family as well as biopsies from multiple locations on her body (several of them from internal organs) and discovered that Lydia Fairchild is a human tetragametic chimaera (yes, the link is to Wikipedia; I didn't feel like retyping all of the links in that article's References section, which I recommend you peruse first). Even the birth of her third child, witnessed by legal observers, was found to not be geneticaly related to her. In other words, her body has and expresses DNA of two distinct people. Geneticists hypothesize that the extremely rare phenomenon known as vanishing twin syndrome (or fetal reabsorbtion syndrome) may have been involved.