Lobsters: The Immortal Crustacean

Ok don’t start panicking, it’s not like that lobster you gulfed down last night is slowly nipping its way out.

 

The immortal crustacean - Don't worry, he's never going to come nipping out of your belly after a lobster dinner. Image credit: U.S. National Oceanic and Atmospheric Administration (Wikimedia Commons)

You see they aren’t exactly “immortal” per se, they can still die, they just don’t exactly age like you and I. We grow up and reach our prime, then it all starts going downhill (my back is already trying to tell me I'm old). Lobsters reach their prime, and then grow to a bigger, better (and more fertile) prime.

I’m guessing you all want to know their secret by now, right? It’s all thanks to a nifty little enzyme known as telomerase. But before I talk about that, I might just start by taking a step back and telling you about these little things called telomeres (the smart ones among you may have noticed a similarity with the names. Don’t worry I’ll get to that).

‘Alright we’ll bite. What’s a telomere?’

Well I’m glad you asked my dear Watson. Telomeres are these funny little bits of DNA on the ends of chromosomes that just repeat the same code again and again. For example, humans just have TTAGGG repeated about 2,500 times.

Human chromosomes with telomeres labelled red. Image credit: Reinhard Stindl (Wikimedia Commons)

‘What do they actually do?’ 

Nothing! That’s the beauty of it, they do absolutely nothing… Well except for hang onto the ends doing nothing.

‘Well that was pointless.’

Not quite. Doing nothing is exactly what makes them so crucial. Your cells can divide as often as once every 24 hours. Now, since they don’t want to split the chromosomes between them, they replicate the whole set so that they can each have one complete set. This involves a complex mechanism of enzymes, cofactors and all that nitty gritty stuff.

Don’t worry I won’t go into replication now but if you’re interested you can find out more here. So far so good (well not really, the process gets riddled with errors, but your body has a way to fix this…most of the time that is). 

But there’s a little problem at the end of this. Not all of it got copied.

Now here’s where it gets complicated

Strap yourselves in and prep an extra tab to quickly whip up a Wikipedia page for explaining the worst parts (don’t worry, if I do my job right you won't have to).

Your chromosomes are made of DNA, but before you can replicate this DNA your enzymes need something similar to grab on to. This is where RNA comes in, it’s essentially DNA but with a few differences we can use to start the process.

The differences between RNA and DNA. Image credit: Sponk (Wikimedia Commons)

Once all the replication is finished that RNA is still clinging to the end. Unfortunately, it doesn’t quite fit in with the others, so it's kicked out (DNA is a bit of a bully like that). This means that every time your chromosomes are replicated a little bit is lost off the ends. Now this could be a problem because we need our DNA to tell the cell what to do. What’s our solution?

‘I know! I know!’

Quiet now Watson this is my blog post. The answer’s quite simple, chuck a bunch of unimportant telomere on the ends and voila it no longer matters that it drops off. 

That is, until we run out of this life-saving telomere. Which is one of the reasons we grow old. After decades of replication we can't rely on our trusty telomeres anymore. When the telomeres are too short the cell is told to stop dividing before we lose anything important (which could lead to disastrous results).

Now I did say I’d tell you what telomerase does. Elementary my dear Watson, telomerase just puts the telomeres back in when they start to disappear. There you have it, the lobster’s anti-aging cream, a funny little enzyme which grows back chromosome ends before anything important in the middle is lost.

'What about us?'

Before you start looking to buy telomerase injections, I’d like to say why you don’t have it naturally (except in your gonads). Telomerase in humans aids cancer growth. Then again losing genes also causes cancer. We kind of sit on a razors edge with telomeres. But that’s where research could get interesting. With more research we could create an effective weapon against cancer and a way to lengthen human lifespans.

You might be wondering now why lobsters don't have that same problem. Do crustaceans not get cancer? Is it only humans who are afflicted by this life-threatening peril?

Well no... any animal can get cancer, it's caused by mutations in our genes causing our own cells to go rogue and turn against us. Lobsters can get cancer too, it's just incredibly rare. See, Decapods (the order lobsters belong too) are resistant to cancer.

Scientists still aren't 100% sure on why that is but it's thought to be due to how they effectively break down carcinogens (cancer-causing agents) and differences in their immune system which make their immune cells extra-specialised cancer fighters (imagine them as like the black ops of cancer fighting, whilst our immune cells are more like a small mob with pitchforks and torches).

Cancer cells. Image credit: Dr. Cecil Fox (Wikimedia Commons)

For more information I’d highly recommend the Nobel prize website. They do lovely summaries perfectly suited for everyone, ranging from experts in the field to people who have never held a micropipette (they even have an illustrated version for when reading seems like too much work).

For even more on telomeres click here, or to learn more about some other animals that have unique ways to combat cancer click here or here.

Okay I will admit I may have gone a bit link happy with this post, but seriously, try some of them out (highly recommend the Nobel prize website). If you've gotten completely and utterly Sci-Tracked from doing any ACTUAL work you might as well go deeper down the rabbit hole and learn something pretty cool. Also one more link (you should totally click it).