Note (12/2015): Hi there! I'm taking some time off here to focus on other projects for a bit. As of October 2016, those other projects include a science book series for kids titled Things That Make You Go Yuck! -- available at Barnes and Noble, Amazon and (hopefully) a bookstore near you!

Co-author Jenn Dlugos and I are also doing some extremely ridiculous things over at Drinkstorm Studios, including our award-winning webseries, Magicland.

There are also a full 100 posts right here in the archives, and feel free to drop me a line at with comments, suggestions or wacky cold fusion ideas. Cheers!

· Categories: Biology, Genetics
What I’ve Learned:

Junk DNA: there's a whole lotta junk in ALL of our trunks.
“Junk DNA: there’s a whole lotta junk in ALL of our trunks.”

Comparing yourself with other people is tricky. George Carlin famously pointed out that “their stuff is shit, but your shit is stuff“. Which is great, if you’re comparing music collections or wardrobes or childrens’ refrigerator art.

But there’s another thing we have in common with other people: our DNA. And when it comes to genetic material, it turns out everybody’s is mostly junk. Yes, even yours. And George Carlin’s.

(Well, at this point, certainly George Carlin’s. Unless you count half of Kelly Carlin. Which you probably should.)

But don’t feel too bad about your junky genome. “You are what you eat,” as the saying goes — so if you’ve ever shoveled down a McRib or a whole bag of powdered mini donuts down your gullet, then you knew some “junk” was probably in there, somewhere.

The question is… how much? No one is entirely sure.

Regrettable food choices aside, the degree of “junkitude” in a species’ DNA was first measured in a very simple way. Somewhere within that DNA are a number of genes — regions that are transcribed into RNA messages, and then translated into proteins, which perform most every function in living cells.

Different species have different sized genomes, and varying numbers of genes. Back in the ’60s or so, scientists took a hard line concerning “junk DNA”: if it can produce a protein, it’s useful. If not? Junk.

That leaves many species with an awful lot of so-called junk DNA — and it makes humans look like downright hoarders. Using this definition, roughly 98% of our DNA is pointless garbage. Expired Fruitopia coupons. Porky’s Revenge Betamax tapes. Last year’s newspapers. Or really, any newspapers.

But a funny thing happened on the way to our deoxyribonucleic intervention. As scientists dug deeper into how our genomes work, they discovered something interesting. Our non-protein-coding DNA may be “junk” — but that junk DNA… is not.

Not junk, that is. At least, some of it isn’t. Because while genes — actual, protein-producing sequences — only make up about 2% of our DNA, other regions are pretty important, too. Like telomeres, for instance — little fiddly bits of DNA that “cap” chromosomes to protect the squishy ends. Or for that matter, centromeres — repetitive sequences where two halves of each chromosome are held together, and which are critical during cell division.

But it’s not just structural elements hiding in the junk DNA. There’s other stuff in that shit, too. Thousands of regulatory sites, for instance. All those protein-encoding genes are great — but on their own, they’re kind of dumb. If you don’t want intestine genes turned on in your brain, or adrenaline released along with melatonin — and seriously, you do not — then something has to regulate how and when and where and why each gene gets expressed.

That “something” is a bunch of proteins, mostly — but they do their jobs by sitting down on stretches of non-coding DNA to direct traffic. Take away those “junk” DNA regions, and your gene expression suddenly goes all higgledy-piggledy. Congratulations, spring cleaner. You’re a sewer mutant now.

There are other important things happening in our “junk” DNA, but we’re still discovering what all of them are. Maybe 10% of our DNA is actually useful. Or 8.2%, according to one study. Maybe as much as 50%. But probably not more than that; nearly half our DNA is thought to come from transposable elements and integrated viruses, which are generally not so useful.

So Carlin wasn’t wrong, but he didn’t have the whole story. True, our shit is stuff, and their stuff is shit. But underneath, we’re all 50 to 98% junk. Sorta makes you want to mutter the seven words you can never say on television, dunnit?

Image sources: Biotechnology and Society (junk DNA), Amazing Spaces (Carlin, finding a place for his stuff), YouTube (powdered donut face), Daily Beast (sewer muties, wavin’)

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· Categories: Biology
What I’ve Learned:

Laser capture microdissection: the best use of lasers this side of the Death Star.
“Laser capture microdissection: the best use of lasers this side of the Death Star.”

The problem with biology is, it’s messy.

You can open up some animal or person — well, not you, necessarily, but a surgeon or researcher with explicit permission, which is kind of important — and pluck out something you’re interested in. A tumor that needs diagnosis, say. Or a part of the brain not behaving itself. Maybe a gall bladder, because it’s infected or malignant or the doctor has a really weird Pandora bracelet thing going on.

It’s all well and good to decide what you want to carve out. But that’s where biology goes and gets messy.

Take the tumor example. Tumors don’t ordinarily grow in nice neat little balls inside the body, just waiting to be sliced away and stored in formaldehyde or used in a macabre match of bocce. Instead, they ooze between other tissues. They spread tendrils through organs and hop from one body part to another, like some kind of inner-space kudzu. To cut out the tumor, you’ve got to cut other stuff, too. And it’s not always clear which bits are which until the globs of flesh are sliced thin, slapped on microscope slides and diagnosed by a pathologist.

Even normal tissues have the same problem. Say you’re a brain researcher, because you’re a smart cookie and a Futurama fan and you don’t want to rely on Philip J. Fry to save the universe some day. That’s kind of a weird path to a career choice, but hey, it’s your life. Who am I to judge?

Anyway, you might want to study neurons pulled from the brains of lab mice or rats. But in that same brain sample are cells of other types. Glial cells. Skull cells, if you’re a little careless with the scalpel. Liver cells, if you’re a lot careless. The point is, to identify the neurons — and just the neurons — you’ll probably have to slice the tissue up, make some slides and find them under the microscope.

The question is: then what?

For decades, scientists could go through the procedures above and figure out that this sample over here was thirty percent pure for the cells they wanted, and that sample over there was ninety percent pure. But if they wanted to study those cells — pull out DNA or RNA or proteins and see what made them tick — they had no way to get rid of the contaminating schmutz scattered around them.

That’s where laser capture microdissection, or LCM, comes in. It sounds like something Darth Vader might do to torture information out of a Wookie, but it’s not. It’s actually more of a way to get rid of blemishes and impurities in a biological sample. Like an Oil of Olay for microscope slides.

So how many scientists does it take to perform a laser capture microdissection? Three, in principle. First, some smart brave person hooks an ultraviolet or infrared laser to the controls of a microscope, so moving the field of view back and forth will burn a line through the sample. Then a very patient careful person stares into the microscope for an hour or two, twisting the controls like an ungodly-expensive Etch-A-Sketch, tracing around the parts of the sample they want to carve out.

Finally, some brilliant crazy person figures out how to get that laser-jigsawed piece off the slide to do more science. Current methods include melting wax and sticking it to the piece (fairly awesome) to using gravity to shake the piece away (more awesome) to something called a laser pressure catapult (ridiculously awesome). This last procedure involves shooting an unfocused laser at the sample, literally punching the cutout into the air with photon force. Which, again: Wookie torture. But no. Science.

So that’s laser capture microdissection. You get just the bits you want, and none of the bits you don’t. And then you can look at just the cells you like, without anything else getting in the way. It’s as easy as Photoshopping George Costanza out of a vacation pic.

Just don’t try it on a Wookie. That would not end well.

Image sources: University of Gothenburg (laser capture microdissection), (Fry and the brains), Hurtin Bombs (angry Chewy, vengeful Chewy, purr purr purr), Woosk (Costanza photobomb)

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