My Day Job

Our paper was accepted to PRL!

The journal decided it was novel enough to write a summary of it.

A website wrote a story about it.

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2 kinds of mole rats, 2 different cancer-fighting techniques

Did you know there are two (at least) kinds of mole rats? I didn’t until recently. Here they are:
Blind mole rat
Naked mole rat

Beautiful creatures, aren’t they?

Well, they’re fascinating anyway. Naked mole rats have been shown to be cancer-resistant. Their cells are programmed to cease division when they sense they are getting too crowded. So any cancerous cells that develop will eventually crowd themselves out of dividing any further, “contact inhibition,” as the shop talk goes. Basically, the cancer cells keep quiet about their identity, and do no harm.

Recently, in a paper by a team at the University of Rochester, blind mole rats are shown to also have cancer-fighting properties. However, it seems their potential cancer cells take a different tack. When they sense they have divided more than a normal amount of times, they kill themselves with their form of a cyanide capsule: a protein, IFN-beta. Rather than risk wreaking havoc on their sister cells, they take themselves out of the picture.

It’s exciting to think that perhaps these discoveries will help us unleash  hidden knowledge our own cells have. Or to simply help develop a novel drug.

Of course, it’s absurd to think the cells have “free will” as I have analogized. Nonetheless, I couldn’t help thinking about Battlestar Galactica when thinking about cells discovering they were something else. By the way, if you haven’t seen it, don’t wait around, just do it.

Protein Folding

I’m currently in the process of going through a monstrous stack of periodicals I’ve accumulated, including the magazine Physics Today, which comes with my APS membership.

This article by Ashley Smart is simply a research summary on experiments on proteins.

But Smart evoked a lot of thoughts about proteins. We need them to be folded correctly to work, but how are they folded? How is this the minimum energy state.

Smart’s description of various denatured (unfolded) proteins reminded me a lot of the language used in the glass/jamming community. A fried egg consists of proteins denatured by heat. A similar transition happens for
“glassy” systems: raise the temperature and the material will flow.

Mechanical stress can cause also cause the protein in egg white to denature, resulting in a foamy, stiff, meringue. In jammed systems, like mayonnaise, mechanical stress (i.e. using a butter knife) causes the material to unjam (i.e. deform and spread on the sandwich).

The third variable discussed in the jamming community is volume fraction, which I won’t delve into here. The third variable for the egg example is acidity, mixing egg whites with lime juice will also cause the proteins to denature. Completely different, can’t win ’em all.

What also drew me into this simple piece was the description of the experiments. (Smart does a commendable job of trying to explain the math in words.) There are two processes that contribute to the overall signal the researchers measure, only one of which relates to protein folding. But if you change the temperature, each process responds on a vastly different timescale.Taking measurements at the right frequency and using a trick of derivatives, they can isolate the process of interest. An experiment like this would be a great lab in a biophysics class.

Naked Mole Rats FTW

I have seriously been told I resemble a naked mole rat when I’m roused from sweet, sweet slumber. My eyes refuse to open, and I burrow under the sheets. I’m pretty pale and mostly hairless, too.

While I hope I don’t resemble a naked mole rat in all ways (a bit on the uncomely side) I think there’s reason to hope my cells act like their’s.

Naked mole rats never get cancer.

It appears they don’t get cancer because their cells experience “contact inhibition.”

Humans get cancer quite a bit, and the odds increase as we age. The chances of a cell switching to cancerous increase, simply because we’ve given them more chances to do so. Lab mice get cancer about 70% of the time, if allowed to live for several years.

Human and mouse cells experience this contact inhibition phenomenon as well. Cells divide and fill up the space they’re in. Once they touch, they generally slow down their division; there are enough cells.

Cancer cells don’t have this contact inhibition, and grow wildly, unchecked.

Naked mole rat cells, when studied in the lab, exhibit a super kind of contact inhibition – cell division completely stops when cells touch.

In the future, perhaps we can identify what causes this, and turn on a switch in our own bodies if we suspect we have cancer.