I’d like to start by saying that I have no intentions of getting political here, but there are times when politics and science intersect. And every once in a while, one of them will hit close to home. And this is one of those times. Lucy K. and I had already been planning to write an entry about model organisms at some point, when the following video clip surfaced online, sparking some anger from the scientific community.
Now, I don’t know about the reference to Paris, France, but I can tell you for sure that fruit fly research is a whole lot more important than Sarah Palin seems to realize. Why? Because fruit fly research isn’t about fruit flies. It’s about human disease and development. And though a lot of scientists understand why, it’s important that the public understands too, so that misconceptions like this don’t get propagated.
So want to know more about how scientists can use insignificant seeming organisms like fruit flies to study important questions about neuroscience, disease, genetics and more?
Why can’t scientists just study disease an development in humans?
Sometimes they can. For example, they do observatory studies. For example, they can sequence the DNA of people who are affected by a disease and try to figure out if a mutation in a gene is causing it. But another important part of science is the ability to change things and see what happens. You might imagine that if scientists find a mutation in a gene that they think may be causing a disease, they would want to mutate that gene in a normal individual and see if it causes the disease. You could also see how this could cause a minor ethical problem when it comes to humans.
That’s where model organisms come in. Because we share many genes and biological processes with smaller organisms, we can use those organisms INSTEAD of humans to study all sorts of things, ranging from how our cells divide to how our brains develop and how some diseases are caused.
What kinds of organisms are we talking about here?
Well, as you already know now, fruit flies are one such example. There are some larger organisms, such as chicks and mice, and less commonly, monkeys, but there are many other smaller organisms also, such as microscopic worms called nematodes and even yeast – yes, the kind that you use to bake your bread!
So really, how can baker’s yeast be used to study human disease and health?
Let’s take a step back for a minute and think about what an organism is. Every organism is made up of cells, which contain genetic material called DNA. This DNA encodes genes, which control how the cell is run. Often, a mutation in one of these genes can lead to a disease. This mutation can be inherited from a parent, or it can be created when a mistake is made during cell division. The key to understanding many diseases is to discover what the mutated gene is supposed to be doing, and thus how the mutated version leads to the disease.
So how can these organisms help us study disease? Operating on the premise that evolution took place over billions of years (and let me be honest here, if you don’t believe in evolution, this blog is probably not the place for you), humans are related to all of these species. This means that many human genes are also found in these species. On a basic level, all cells need to do the same things, regardless of what species they are a part of: divide, react to stressful conditions and maintain their own integrity. So studying how these genes work in a simpler organism can go a long way in understanding what they are doing in humans.
Why use things like fruit flies and yeast instead of mice and monkeys?
In some cases, simpler is better! One benefit to these organisms is that they grow really fast, so you can get a lot more experiments done in a shorter time. Another important benefit is that it is fairly easy to manipulate their genes (especially yeast), so that experiments that would take months or years to do in mice could be done in two weeks. On the other hand, depending on what you’re studying, there are some drawbacks.
Well you can’t use yeast to study brain development and disease, for example. Yeast don’t have brains, and therefore don’t have most of the genes that are important for brain development and maintenance in people. Yeast, however, are a great system for studying other things, like how cell division takes place. Why is this important? Because when human cells lose control of their cell divisions it causes cancer! So for studying cancer at a really basic level, yeast is a great system!
On the other hand, other model organisms like worms, flies and mice DO have brains and also have many of the same genes as humans, which means that they can be a great system to study brain disease.
So let’s get down to it. Why is fruit fly research important?
Flies have been used to study everything from development to neuroscience to the way that genes are expressed. One example? Fruit fly researchers discovered a protein called neurexin that was required for proper connections in the brain. As it turns out, humans also have genes encoding the neurexin protein, and mutations in these genes may be a risk factor for autism. It is difficult to study in humans and mice for a number of reasons, but flies provide a simple and opportune system to learn more about what neurexin is doing in the brain and how it might be linked to autism.
This example brings me to an important point: every model organism has its advantages and disadvantages and is useful for different types of research. Over the next weeks and months, we’ll look to tell you a little bit about each of these organisms, what they’re used for and why the people who work with them love them so much – which could possibly explain why we get so defensive of them when we feel they’re being maligned.