I did my first flagella stretching experiments today, so I thought I would commemorate it by finishing up the series of posts about my research. In this installment, I will discuss some possible applications of the research I am doing.
In the previous installment, we saw how flagella like to pack next to one another. They will either pack with constant spacing between each other, but a limited bundle size, or they will pack with a varying amount of space between adjacent flagella but with an unlimited bundle size. It is this second kind of packing we will be interested in for this post. We will be considering large arrays of flagella that are densely packed in with each other.
So, try to picture this: there are thousands and thousands of curly flagella bundled together. If we are able to put some kind of molecule in between the flagella that would bind to them, we could link them together. It would essentially be like a chain-link fence. There would be flagella acting as stiff rods and there would be small molecules that would just link two flagella together at a certain spot. With enough of these links, the solution of these packed flagella would become a gel as each flagella is stuck in place from all of these cross links. That is why this process is called crosslinking.
Once we have crosslinked a large sample into a gel, we now have something big enough we can hold in our hands, a material that is macroscopic rather than microscopic. This means we can do different kind of tests on it. The most interesting thing about this gel, however, is what happens if we pull on it. In part 4 of this series we discussed what happens if we pull on a single flagella; it changes shape. A curly flagella will become straight or less curly and want to stay that way. That means that if we were to pull on this gel, we would be making the flagella inside the gel want to straighten out. However, because of the crosslinks and their close packing with one another, they will resist straightening out.
If we were able to pull enough to make one of the flagella switch to a straight state, then it would suddenly be not tightly packed with its neighbors and its crosslinks would no longer be aligned with its neighbors. This means that it will pull on its neighbors, trying to straighten them out as well. What this could lead to is a sudden straightening of all of the original straight flagella’s neighbors. Those would then cause their neighbors to straighten out and so forth until all of the flagella were straight in the gel. The interesting part of this comes from the fact that a straight flagella is longer from end to end than a curly flagella. That means that the gel made up of straight flagella would be bigger than the one made up of curly flagella.
That is a very weird property. Imagine you had a brick of something. Then, pulling on either end of that something, you stretch it out and let it go. Rather than returning to its original shape, it snaps into a new longer brick. There are very few materials that would be capable of something like that. And that is why making a new material that exhibits these properties would be interesting.
There are other applications of the research I am doing, but it is way too early to tell if any of them will happen or if even this will happen. Also, I am learning this stuff as I go. As of right now, we do not have a way to crosslink the flagella. We have some ideas, but nothing working yet and it will be a while until we get to that point. But rest assured, for science will continue to march on!