The Essence of Shape

As kids we all learn that various cell types have different shapes and sizes. But how many times have you actually thought a little bit more about it. I think the very first time I thought of this aspect was when we were explained in undergrad what happens in sickle cell anaemia – red blood cells are crescent shaped rather than disc like and hence deliver lower oxygen levels to tissues. And after that it was only during my senior year and now in grad school that I am beginning to grasp the complexity involved in this concept called shape and how vital it is.

Cell division is a fundamental process in which cell shape plays a huge role – imagine how complex a task it actually is for the cell to calculate the location of its central plane (if the division is symmetric of course) and be able to divide into two. I got a chance to read this interesting paper published in Cell this February that came out of the Chang lab at Columbia University. They put sea urchin eggs in microfabricated chambers of different shapes with volume of each being the same as that of the egg. In ways I don’t completely understand the egg now takes up this shape of the chamber – rectangle, ellipse and triangle. They then saw the plane of division in each of these cases and observed the positioning of the nucleus which ultimately is the deciding factor for how a cell divides. They show by experiments and by a very elegant mathematical model that the microtubules ‘sense’ this cell geometry and orient the nucleus along the axis of cell division accordingly by exerting forces on it.

If that didn’t make any sense at all, how about this – a protein X in some organism Y localizes to only to membranes that are convex; all it needs is this geometric cue rather than some cell specific cues. Yes, this was shown to be the case for a spore forming protein in bacteria by Richard Losick’s group at Harvard, published in Science sometime back. They purified the protein and when incubated with different kinds of vesicles in vitro, the protein localized to the smallest vesicle, which is the most convex one.

That’s cool stuff out there.

Getting through the first hitch

I’m just finishing up my 2^nd rotation and would begin the 3^rd very soon. Following that, I’d have to decide a lab and then at some point decide what my thesis would be on – my research for the next few years of my life.

In contrast to the European system, I think for most students (definitely for someone like me as I was not sure what exactly I wanted to work on) rotation is a very good way to decide what kind of work you like and also if you fit in a particular lab, so on and so forth. Halfway through this rotation, I think I have an idea of what I want to study and also beginning to get a hang of what kind of lab culture do I fit into.

Once you figure out these things and join a lab, the next big thing would be picking up a problem to work on. Though I haven’t been there yet, it is a good thing to know where the field you’re interested in is right now and what are the questions you can ask and also answer them. This reminded me of an article I read a year back that Uri Alon wrote – How to choose a good problem. For all those considering research and just about to begin to narrow down what you really like, this is a great resource. Ultimately, you do want to do what you truly enjoy but this gives an insight into things that you’re probably not thinking of right now. To give you a flavour look at this picture he draws. I think it is a really well thought out one and only a person with a lot of insight and who’s been there, done that can come up with something like this.