Earlier this week, I had a conversation with John Chase’s Science 9 class in Edmonton, Canada. We recorded the whole thing via google hangouts (the video is posted below), but we ran out of time and there were a lot of questions that the students had that I didn’t get to, so I thought I’d write them out.
From Abrar: “Is there a difference between genetic modifications in humans and animals? What are possible improved characteristics if a human were to be genetically modified.”
Humans ARE animals, so in principal, the process and the techniques are the same. The major difference at this point is a matter of ethics. We can do experiments on non-human embryos for instance. Genetically engineering a single cell that will give rise to a whole organism is much easier, since that cell will replicate all of the DNA-level changes that are made. Once a person is grown, trying to change the genes in all of that person’s cells is much more difficult.
But genetic engineering of people is already happening. Using engineered viruses, we can presently insert new genes into people. This approach carries a number of risks, so this form of engineering is only being done in order to treat diseases that are already life-threatening, but as we get better at understanding and mitigating the risks, this technique will be used for much more.
Probably within the next 10-20 years, we’ll have the technology to customize our offspring (if you’ve never seen the movie Gattaca, you really should – it’s over 15 years old now, but holds up incredibly well). Whether or not we decide to allow that as a society is a different question.
From Vincent: Is it possible to change multiple genes or cells to make humans supernatural and make them “Super Humans”? At the same time will we be able to use this for “Super soldiers”?
Not yet, but in principal – yes. Sort of. It really depends on what you mean. We’ve been selectively breeding plants and animals for desired traits for a long time, and these traits have genetic components. When we learn more about what genes influence certain traits, we could in principal engineer the genes of people to make them more able to build muscle, or have higher oxygen content in their blood so they get tired less quickly. If we started before birth, we could engineer people to grow taller etc.
But it’s important to remember that we can’t genetically engineer people to have traits that don’t presently exist. For instance, there’s no gene or set of genes that would enable people to breath fire, or have skin that contains kevlar to resist bullets.
Also, processes that require organized tissue growth are much much much more difficult to understand and control. Let’s say for instance you wanted to create the X-man character Archangel, who has wings sprouting from his back. Birds have wings, so in principal, there are genes that control their development that you could potentially engineer into people. However, there are probably hundreds of genes that control that development, all of which have to act together in incredibly coordinated ways. We don’t currently understand exactly a bird’s genes direct the development of the wing, let alone how to get human cells to follow the same developmental pattern. Even if we could figure that bit out, would a human with wings be aerodynamic enough to fly? Would we have to engineer all the bones in the body to be filled with air sacs like bird wings (that would be much harder to do unless it was started from birth)?
I believe that a lot of things will one day be possible with bioengineering. I think we’ll one day be able to grow seeds from buildings and manufacturing will be more like farming. But all of this is a loooooong way off.
From Chikku: We learned that you can genetically engineer organisms and take the more desirable variations from different organisms. What happens at the DNA level for this to happen, like how does the organism change?
The answer to this question could take up several blog posts, depending on the level of detail desired, but the overall answer is that DNA code is inserted into the genome of the recipient. Usually the way that this is done is by using viruses (or in plants, bacteria) that have evolved to insert their own genes into their hosts. We can take advantage of this naturally occurring genetic modification done by pathogens to insert DNA that we care about.
The key is that the desired trait has to be coded for by a gene in the first place. Once the gene is in, the protein coded for by the gene can be expressed, and that protein will perform its function in the cell. For instance in plants, one genetic modification is for the plant to produce a protein toxin that was originally discovered in the bacterium Bacillus thuringiensis. The toxin is deadly to certain insects, so once the plant makes it, they gain the trait of being resistant to those insects. Other genes might code for proteins that increase growth rate of a particular part of the plant, or allow the plant cells to use water more efficiently.
However, as I mentioned above, some traits are incredibly complex, requiring many genes and complex regulatory pathways, and others are determined or at least shaped by the environment.
From Fawaz: “When you clone an organism, is there any chance of variation to occur, or will their genome be exactly identical to their ‘twin?’”
Twins are a good way to think about it. There is a chance of variation, but their genome will be identical. If you know any identical twins, you know that they can have very different personalities, and even look a bit different (parents of identical twins can usually tell them apart), even though their genomes are identical. Some of this variation is due to effects of the environment on development, some of it is due to random chance (unlike a computer program, a lot of what goes into the development of a biological system is governed by chance).
There’s also a lot of complexity due to something called “epigenetics,” which is too complicated to talk about in such a limited space, but you can read more about that here. Also, as I mentioned during class, the receptors of your adaptive immune system are generated randomly, so twins (and clones) will end up with variation in their responses to infections.
Also from Fawaz: I learned that stem cells occur in the bone marrow, where blood cells are created through the process of hematopoiesis, adipose tissue (lipid cells), blood via pheresis, and the umbilical cord post-birth. I also learned that autologous stem cell harvesting is least likely to be rejected by the immune system. Are there any other ways of obtaining stem cells? Artificial? Has there been a case of immune rejection of autologous stem cells? Is stem cell harvesting harmful to donors? Can stem cells be preserved or do they lose their “effect” over time?
All tissues are regenerated by stem cells, but what biologists mean when we say stem cells is somewhat different than the popular understanding of stem cells. Some stem cells (like embryonic stem cells) can give rise to every type of cell found in the body. Some, like the hematoapoietic stem cells you mentioned can only give rise to a limited population of cells (in the case of bone-marrow stem cells, red and white blood cells).
Some stem cells can be harvested from adults – you can donate bone-marrow for instance. This process can be a bit unpleasant – they used to drill into your hip bone and insert a long needle – now you can be given drugs that cause you to make excess bone-marrow stem cells that leak out into your blood (so they can draw blood and harvest them), but those drugs can make you feel quite ill. There isn’t really any long-term damage from these processes though.
The most desirable stem cells are those that can produce any type of tissue (these are called “pluripotent”), but as of now, those can only be harvested from embryos – once you’re an adult, you don’t have any that we’re aware of. There are people working on making these artificially from non-stem cells by activating a set of genes that reverts a cell into a pluripotent state, which has the added advantage that these stem cells would share your genome. As far as I’m aware, it shouldn’t be possible to reject an autologous transplant, since the genetic information would be identical.
I think I answered the other questions in the video, but if there are any others (or if you have new questions based on what I wrote here), please don’t hesitate to ask in the comments.