Category Archives: Biology

Downtown Raleigh’s NRC

In my readings as of late I’ve seen “NRC” more times than I can count. Each time I see the acronym I struggle to remember what each letter stands for. “N” is for nature. No, wait, it’s for nuclear. Or was it national?

Well, lo and behold, the “N” represents all three of those words, and, you guessed it, I am writing another three-part blog to illustrate each NRC.

Let’s start with the NRC popping up in my local news reading. I’m following the construction of the new Nature Research Center in downtown Raleigh. This NRC extends the North Carolina Museum of Natural Sciences into a two-building, one-globe science haven!

The new Nature Research Center in downtown Raleigh.

Raleigh’s NRC will host interactive research labs, a 24/7 science news stream, and a glass walkway leading to a plethora of research laboratories filled with scientists and graduate students from several of North Carolina’s universities.

The eye-catching centerpiece of the NRC is a gigantic globe. Called the Daily Planet, the science globe will feature enough high definition multimedia to make your technology geek friends jealous.

Within this three-story sphere of science, breaking science news stories will be continually broadcast. Dare I ask: How many segments on your evening news programs focus on science? I’m going to bet my first-born that the answer is an outrageously disgraceful NONE.

Inside the multimedia globe, a Science Immersion Theater offers a 360-degree view of the planet. The National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) will supply images of our planet from space. You, citizen scientist, can inspect NASA and NOAA images to find the devastating effects that population growth and climate change have had on our planet.

This next feature cracks me up. It’s called Meet the Scientist. Have you ever met a scientist? Well, I AM one, and I can tell you that we are not the super duper communicators that you may think we are.

So in this exhibit, scientists will work in their usual lab setting, save one exception: the laboratory walls are glass. Not tapered glass, nor fluted glass, but rather thin, see-through glass. NRC visitors will hang out in the lounge areas surrounding the glass labs, gaping at scientists as they work.

Here you see the concept...

I fully support this idea, and I’m all for science immersion, but my multi-part hypothesis for this experiment is as follows:

    (1) The visitors will peer curiously into the labs.
    (2) The visitors will bang on the glass, just like we all do at the zoo, even though we are not supposed to.
    (3) The scientists will, one day at a time, tape their experimental protocols and photos of their families onto the glass walls, thus protecting themselves from the outside world.
    (4) The visitors, via advanced yoga poses, will find ways to peer into the labs despite the wall coverings.
    (5) The scientists will increase their wall postings until 100 % coverage has been achieved.

Two complementary exhibits at the NRC are Investigate Labs and Citizen Science Center. In both settings, visitors can conduct research experiments. With Investigate Lab, the experiments are designed to be hypothesis-driven, short-term, hands-on kinds of analyses. An example might be to extract DNA from fruit. Oh yes, fruit has DNA.

At the Citizen Science Center, museum visitors participate in long-term research projects, collecting and analyzing data that they’ve gathered from nature. An example here would be tracking butterfly migration or observing tree defoliation. Research projects of this magnitude are much more successful when everyone in the community contributes data.

And, of course, there will be an aquarium. People love aquariums.

Mark your calendars, citizen scientists: the NRC is destined for a Spring 2012 opening!

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Botox is my frenemy

Pufferfish, scorpions and black mamba snakes, oh my! These cuddly critters all make toxins affecting the cell membranes of nerve cells. If you haven’t read my last two posts, “Don’t eat pufferfish” and “Your potassium channel,” now would be the time. I’m experimenting here with a three-part series and this post is the last of the three.

Toxins affecting nerve cells, like those produced by pufferfish, scorpions and snakes, are called neurotoxins. Although tetrodotoxin (this is the toxin from pufferfish) is somewhat commonly known, I’m guessing the most prominent neurotoxin is Botox.

Toxin? Yep. Botox is the botulinum toxin. It comes from the Clostridium botulinum bacteria and ranks with tetrodotoxin as one of the most toxic substances out there.

The botulinum toxin has become popular in the medical world because of its ability to paralyze cells. It’s used in minute amounts for cosmetic treatment.

Load up on Botox before a poker game!

Last year the U.S. Food and Drug Administration (FDA) approved Botox shots for treatment of chronic migraine condition. Here’s a NY Times article about the FDA approval.

I’m inserting my opinion into this paragraph before I return to the science of Botox. I have mixed feelings about Botox treatment: it’s my frenemy. I am a migraine sufferer, and thus very well understand the plight of chronic migraine sufferers.

I sometimes have luck with pharmaceuticals (i.e. prescribed drugs) and sometimes do not. The appeal of a Botox shot to curb a persistent, debilitating migraine is, thus, not lost upon me. However, Botox is a toxin, and if given incorrectly, could paralyze me. However, here’s a NY Times article from 2009 (pre-FDA approval) that makes me want to try Botox. FRENEMY!

Here’s how Botox works. Let’s say I go to the doctor complaining of a wrinkle in my forehead. The doctor injects a tiny amount of Botox directly into my forehead. She aims to hit the weak muscle underneath my wrinkle. (If the muscle weren’t weak, there would be no wrinkle!)

The toxin, once inside my body, travels to the nerve cell responsible for controlling the weakened muscle. The toxin plugs that nerve cell’s sodium channel. This prevents the nerve cell from talking to its neighbors.

Sound familiar? This is exactly how tetrodotoxin works.

As a result, the cell loses its ability to function. No longer controlled by a functional nerve cell, the muscle relaxes and my wrinkle disappears.

This procedure is an art form. Too little toxin and the wrinkle stays. Too much toxin and we have a repeat performance of what happens from eating pufferfish.

But not all toxins are neurotoxins. In the plant kingdom a toxin works differently.

The black walnut tree produces the drug-like toxin juglone. Juglone is made in the tree’s roots, bark and leaves. Juglone acts as an herbicide to nearby plants. The toxic zone is expansive, extending 50 feet from the base of the tree in every direction.

This is a black walnut tree. Toxic things are soooo pretty! Source: http://www.tree-pictures.com

The juglone toxin wipes out everything in its path. It hits alfalfa plants, tomato plants, apple trees, and [insert your favorite plant or tree]. The attacked plants and trees wilt, and their leaves darken and wither away. The black walnut tree can now eat like a king: it has no competition.

Toxins are carried in a liquid form, either as venom or poison.

If an animal is venomous, the animal will inject venom directly into its prey by biting or stinging.

If an animal is poisonous, the toxin is harmful only if we touch it or eat it or inject it ourselves.

    The pufferfish? It’s poisonous. It’s not going to bite us; we have to touch it or eat it.

    A scorpion? It’s venomous. It’s sure as heck going to sting us.

    The black mamba snake? Venomous. Bite away, snake.

    The botulinum bacteria? Poisonous. Ever seen a bacterial cell with teeth? Nope. And no, Dad, Pac-Man does not count.

    CHOMP CHOMP CHOMP. I am good at draw-ring.

    The black walnut tree’s toxin juglone? Is that poison or venom? Post a comment with your answer!

For those animals that are venomous, mostly scorpions and snakes, our medical advances provide us with anti-venom. The anti-venom protects us from the toxic effects of the venom, and we can avoid getting sick.

What is anti-venom? It’s an antibody to the venom, thanks to the use of research animals. Researchers inject animals, often horses, with venom that harms humans (but not horses). The horse’s body mounts an immune response to the venom, producing antibodies.

Medical researchers then collect the horse’s blood, isolate the antibodies, and voila – anti-venom.

The anti-venom will help snake and scorpion bites. It’s useless against the pufferfish toxin. Don’t. eat. pufferfish.

Don’t eat pufferfish

Nature is chock full of toxins. Toxins come from all five kingdoms of life — bacteria, fungi, protists, plants and animals. Although the toxins span a broad range of shapes, sizes, and potencies, they’re all produced for the same reason: warfare.

Toxins come in two main flavors: as proteins and as small organic molecules. The protein toxins are both big and small. The small organic molecule toxins are very small.

What’s a small organic molecule? You probably know it as a (prescription) drug. Check out the image below:

A dizzying array of small organic molecules.

This image is a compilation of pills your doctor prescribes to treat a variety of ailments. Inside each colorful little package is one type of small organic molecule.

So a toxin can take drug form or protein form, both of which can enter your body and reek havoc.

The tropical pufferfish, especially prevalent in Japan, carries a small organic molecule toxin — the very small drug kind.

Here’s an adorable, cuddly pufferfish:

Source: Steven Hunt/Getty Images

The drug-like toxin found in pufferfish is called tetrodotoxin. An interesting little technicality is: the pufferfish itself does not make the toxin, but rather bacteria living inside the pufferfish produce it!

Tetrodotoxin is one of the most potent toxins out there. If you eat the equivalent of a grain of salt, you’re a goner. One tenth of that has the same result. One hundredth of that: same result.

Tetrodotoxin affects a cell’s sodium channel. If you haven’t read my last post, “Your potassium channel,” now would be the time.

The sodium channel has the same functionality as the potassium channel. The difference is only the type of stuff the channel flushes out and takes in. For a potassium channel, the type of stuff is potassium. For a sodium channel, the type of stuff is sodium.

We’ve learned that we don’t want to mess with these channels, because messing with the channels inhibits the cells from communicating with each other. And, just like with potassium, cells use sodium to talk. For example:

    Cell 1: “Hey, did you see the latest episode of ‘Glee?’”
    Cell 2: “Yeah, those New Horizons kids totally nailed it!”

I jest. Cells don’t talk about “Glee.” (Although they should.)

Most toxins affect the cells of the nervous system. So the type of cell that’s of interest here is the nerve cell. On a normal day, the nerve cell opens and closes its sodium channel, flushing out sodium, taking in sodium, all the while transmitting electrical signals to its neighbor cells.

Let’s say I have a hankering for pufferfish. I eat one. I now have tetrodotoxin loose inside my body. The very, very tiny tetrodotoxin finds its way to the sodium channels in my nerve cells.

A tetrodotoxin molecule plops itself down in a channel’s opening. That channel can no longer open or close. The sodium inside the cell cannot get out. The sodium outside the cell cannot get in.

Now that poor nerve cell can’t communicate; it has lost its ability to regulate itself. It dies. The cells around it die, too. Soon, enough cells have died that I’m paralyzed. Oops.

Another toxin that plugs a cell’s sodium channel is called batrachotoxin. This drug-like toxin is produced by the poison dart frog. How cute is this little guy?

A yellow poison dart frog. More than a hundred kinds exist -- all beautiful. Click the frog to learn more.

Besides sodium channel toxins, nature has potassium and calcium channel toxins, too. Scorpions, for example, produce protein toxins targeting the potassium channel of a nerve cell. Whew. I’d hate for the poor sodium channel to be singled out for destruction.

The black mamba snake, the largest venomous snake in Africa, produces a large protein toxin called calciseptine. Calciseptine targets the calcium channel, as you may have guessed from its similar name. This particular toxin is such effective warfare that the black mamba snake eats like a king.

Here’s a black mamba snake eating some unfortunate rodent:

Yummy! Click on me!

Don’t eat black mamba snakes. Also, don’t eat scorpions. Also, don’t. eat. pufferfish.

Your potassium channel

Ask a biologist what the basic building block of life is, and she will tell you it’s a cell. Ask a chemist this question and she will tell you it’s an atom. Ask a physicist and she will tell you that it’s something even smaller, some miniscule particle with a weird name.

For the purposes of this story we’ll adopt the biologist’s definition: a cell.

If you search for a Google image of a cell, this guy pops up:

The cartoon character called "Cell."

Not exactly what I had envisioned. Let’s go with this one:

This image is from the Nobel Prize website. Click on the cell to learn why!

If you’re human (a quick check in the mirror should clear that up) your body has more than one trillion cells. One trillion! This is 10 to the 12th power, or 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10, or 1,000,000,000,000.

I’m thankful someone else figured this out, because I’m not the type to sit still long enough to count that many cells. Here’s how it would play out:

    Curious child: “How many cells are inside my body?”
    Sarah: “Hmmm, I will count them. Let’s start with your skin cells. Stick your hand under the microscope and I’ll start counting. One, two, three, four…”
    [Five minutes later]
    Sarah [visibly bored of this activity]: “Yeah, so, Google it is…”

Each of your trillion cells has a cell membrane. The membrane is a protective covering around the cell, to keep the good stuff in and the bad stuff out. Good stuff: DNA, nutrients, water. Bad stuff: foreigners (a virus, a toxin).

Science teachers often use an egg analogy for cell biology. Hard-boil an egg and you have a pretty good model of a cell. The eggshell is the cell membrane. The white part is the inside of the cell. The yellow yolk is the nucleus.

The cell membrane (the eggshell) has several gates to let stuff in and out. It’s vital that your cell has exactly what it needs; nothing less and nothing more. The gates help ensure this.

With the egg analogy it’s hard to simulate the gates, so just imagine them. The gates are called channels, and the cell membrane has different channels, one for each type of stuff. There’s a channel for water, a channel for sodium, a channel for potassium, a channel for calcium, and so on.

You might be wondering what a channel is or what it looks like. A channel is a big protein and it looks like a bunch of ribbons. Below is a close-up of the potassium channel:

Source: Brookhaven National Laboratory

The “intracellular” portion is what’s inside the cell (the white part of the egg). The “membrane” portion is lodged in the cell membrane (the eggshell). The “extracellular” piece hangs out of the cell (outside the eggshell).

That potassium channel regulates how much potassium goes in and out of the cell. If the cell has too much potassium, the channel opens and flushes the potassium out. If the cell has just the right amount of potassium the channel closes and stays closed.

If the cell changes its mind, it re-opens and thieves the potassium back.

These channels constitute a vast communication network among the cells in your body. Cells release potassium to talk to other cells. Seriously. It’s not like they have [insert your favorite type of social media here].

The talking is in the form of electrical signals. One cell’s potassium channel opens and the cell releases potassium. A nearby cell’s potassium channel opens and the cell takes the potassium in. Thanks, potassium channels! You just transmitted an electrical signal!

Since the channels control the communication between cells, if you mess with a channel you have a major problem: cells can no longer talk to each other. The solution is simple: leave the channels alone.

Easier said than done. Channels are the major targets of toxins.