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 secondhandscience@gmail.com with comments, suggestions or wacky cold fusion ideas. Cheers!

Quiescence


· Categories: Biology
What I’ve Learned:

Quiescence: how much less growth could there be? None. None less growth.
Quiescence: how much less growth could there be? None. None less growth.

Isaac Newton said a body at rest tends to stay at rest. That’s the First Law of Motion.

My mother said a body at rest had better tend to get his lazy teenage ass off the couch and mow the lawn before his father gets home, if he knows what’s good for him. I’m not sure that’s a “law” of anything, but it always got me moving. Eventually.

Inside your body are trillions of cells, and right now many of those are also at rest, in a state known as quiescence. What they tend to do next depends on what sort of cells they are, and how they got into that state to begin with.

Like teenagers, most cells go through phases. But instead of “goth skateboarder” or “sparkly vampire”, your cells go through phases of the cell cycle. The cell cycle is a set of steps cells go through to divide, because reproducing requires very careful planning.

If a cell went through the division process without a roadmap, anything could happen. It could split before it’s ready, and produce deflated Whoopie cushion cells that aren’t helping anyone. It could get its DNA scrambled, and serve it to the daughter cells, family-style. Or it could divide into fourteen cells at once, none quite the way they should be. Like Duggars. It’s terrifying. Thank goodness for the cell cycle.

But a cell’s life isn’t all spent thinking about reproducing. This isn’t college. Sometimes, cells need to exit the rat race of dividing over and over, and rest in quiescence. Take heart muscle cells, for instance. Once your heart has grown to full size during development, you don’t want it getting any larger.

(I know people like to think they have a “big heart”. But if it were big enough to squish your lungs between your ribs, you might reconsider that goal.)

To keep your heart from growing three sizes each day, the mature muscle cells are pulled out of the cell cycle right after a division, in a phase called G1. The “G” stands for “growth”, which is what cells typically do after dividing, but quiescence is a resting state, sometimes called phase G0. Because there’s no growth. Or dividing. Or anything else. The cells just sit there, doing their thing. Pumping blood, keeping you alive and leaving all the worrying about reproducing to you. If you’re into that kind of thing.

This also happens with neurons and other cells that stop growing after development; they enter quiescence, and basically never come out. But other cells can slip into the G0 phase from G1, for just a little post-division breather. Think of it as microscopic maternity leave.

Except that once cells divide, there’s no “parent” cell left. So really, it’s the children who were just produced that get a rest. Lazy kids. That grass is never getting mowed.

These “paused” cells — and in theory, any cells — can be pulled out of quiescence under the right set of circumstances. That could be a growth factor released in the body, or some other growth-goosing signal. Or maybe there are little mothers running through our bloodstreams, telling cells to get busy and do their chores.

The textbooks are silent on that last one. But sometimes, it’s the only thing that works. You do not want to be in the quiescence phase when your father gets home.

Actual Science:
Boundless – The cell cycle and the G0 phase
BioMed Central – Proliferation/quiescence: the controversial “aller-retour”
Stanford Medicine – On alert: study identifies cell-cycle phase that primes stem cells for action
Jackson Laboratory – Forcing quiescent leukemia cells to proliferate holds promise for acute myeloid leukemia (AML) chemotherapies
Medscape – Diabetes drug appears to eliminate residual CML

Image sources: University of Texas (cell cycle circle), Unilad (lazy, lazy teen), Mom This Mom That (Grinchy heart growth), Life as a Divorced Dad (quiescent kid, uncut grass)

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Telomeres


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

Telomeres in a nutshell: the short of it is bad, and the long of it isn't great, either.
“Telomeres in a nutshell: the short of it is bad, and the long of it isn’t great, either.”

Many things tend to get shorter as we age. Patience. Hairstyles. Time between bathroom breaks.

But something else shortens when we get older, and it’s more important than all the others. Except maybe the haircuts. Nobody likes a geriatric hippie.

This “something else” is a telomere, and it’s a squiggly bit of genetic material stuck on the end of each of our chromosomes, for protection. Sort of like those fiddly plastic things on the ends of shoelaces that stop them from fraying.

(Those are called “aglets”, by the way. That’s not science. I just thought you’d want to know.)

Telomeres play a similar role in our cells — and the cells of most everything else that isn’t a bacterium. When we’re young, the telomeres on the ends of our chromosomes are long. Each time our cells divide, the telomeres get a little shorter, until they’re very small or gone completely. Cells in that state typically don’t divide any more; they’re content to put on a shawl, find a nice rocking chair and wait for the end.

It’s like the aglets on your shoelaces got shorter every time you wore your sneakers, until they finally disintegrated, the laces unraveled and your shoes fell off. Only instead of going barefoot, your hair and skin and brain cells don’t grow back any longer. Which is somewhat more inconvenient, even if you’ve already moved to that shorter hairstyle.

The other more-than-somewhat inconvenient thing about telomere-less chromosomes is that they can lead to cancer. Without those protective bits at the end, genetic material can get chewed away, which is bad. Or chromosomes can link together and loop around, which is also bad. As in, cancer bad. Much worse than frayed shoelaces.

So longer telomeres are better, right? weeeeeell — it depends. In general, yes. Antioxidants in foods like blueberries and kidney beans and artichoke hearts help to lengthen telomeres, and that’s good.

How you get your chromosomes to eat right, I don’t know. Mine are always binging on chips and deoxyribonucleic Oreos.

The thing is, our cells also make an enzyme — called telomerase — that naturally rebuilds telomeres in certain situations. Production of this enzyme is tightly regulated; it’s not normally produced very often or in large quantities. It’s like liquid gold. Or a really good gin and tonic.

In the lab, though, scientists have shown that extending telomeres can reduce signs of aging in mice and worms. Which is great for cowards and lawyers, I suppose — but someday, it could even be applied to humans. That would be sweet.

But there’s a catch. Most of our cells don’t grow constantly. Outside of skin and hair and the insides of our intestines, many cells really shouldn’t be dividing very often. You don’t want lungs the size of life rafts, or a gall bladder you could play volleyball with. Not unless you’re opening a really weird sporting goods store.

So in those cells, if telomerase was always around, the telomeres would keep getting longer. And that might signal the cells that they should divide and divide, out of control. And what are cells dividing willy-nilly, out of control? That’s right: cancer.

So telomeres are tricky. They’re like the Price Is Right showcase game of life: you want as much as you can get, without going over. Because if you do, the consolation prize might be something way worse than Rice-A-Roni.

Actual Science:
University of Utah – Are telomeres the key to aging and cancer?
Nature / Scitable – Telomeres of human chromosomes
Scientific American blog – Aging: too much telomerase can be as bad as too little
NPR – Healthful living may lengthen telomeres and lifespans
The Scientist – Telomeres show signs of early life stress

Image Sources: The Tao of Dana (chromosome telomeres), Heavy (old hippies), Creative Homeschool (aglets), LEXpert (The Price Is Cancer)

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