You are currently browsing the tag archive for the ‘biology’ tag.
Steve Reppert at UMass Medical School in Worcester has just come out today with two very exciting new papers on the circadian clock of the monarch butterfly. They’re both published through PLoS so they’re free for the looking online. Check them out here and here. I wrote my MIT thesis on Reppert’s work so I must admit I have a soft spot for this stuff. Below, I’m bringing you an excerpt from said thesis, discussing the work that’s now culminated in these two papers.
[For quick background: Each fall, billions of monarch butterflies funnel from the Eastern US and Canada into a handful of tiny pine groves in central Mexico. As they’ve never made the trip before and they have no parents to lead the way, they must rely on genetic memory to get where they’re going. The mechanism they use to pull this off is called a time-compensated sun compass. They use the sun as a guidepost, but they must constantly recalibrate their internal compass to compensate for the fact that the sun appears to move across the sky throughout the day. The timepiece they use for this recalibration is the circadian clock. Okay, now for that excerpt.]
Instead of studying in meticulous detail the circadian clocks of every living being, scientists focus on representatives of particular groups. For example, the mouse circadian clock is often used as a model for how mammalian clocks are built. Similarly, the fruit fly clock has long been a stand-in for insect clocks in general. Circadian biologists could safely assume that the monarch clock would resemble that of the fruit fly more than that of the mouse, because the monarch is more closely related to the fruit fly. The fruit fly is much easier and cheaper to study than the monarch; its long history as a so-called model organism means that there are many well-established tools and procedures for working with it. So it seemed like a reasonable, and practical, approximation.
In the fruit fly, as in most organisms, the clock resides in individual timekeeping cells. It works by manufacturing and then destroying certain proteins in a feedback loop that takes about 24 hours to complete. This feedback loop can sustain itself indefinitely, which is why the clock keeps working even in constant darkness. When the fly encounters daylight, though, a specialized protein in the timekeeping cell absorbs the light; it tells the clock that the sun is out by feeding into the loop. This specialized protein is CRY, the fruit fly version of the protein that illuminated the possible clock-compass connection. CRY is how sunlight sets the fruit fly’s clock.
But Reppert wanted to figure out how the monarch’s time-compensated sun compass works, so he couldn’t rely on the fruit fly model—fruit flies don’t use a sun compass, time-compensated or otherwise. He decided he needed to take a closer look at the monarch clockwork, to see how the butterfly clock works. Read the rest of this entry »
Like penicillin, it all started with an accident.
In 1997 a Japanese researcher named Masaru Okabe was looking for a way to track sperm development. His thought was to cram a jellyfish gene encoding a glowing protein — green fluorescent protein, or GFP — into a mouse’s sperm. Then the sperm cells would literally light up when exposed to a certain wavelength of light, allowing him to track them as they developed. But instead, he wound up with the inverse: nearly everything but the sperm glowed. He had a full-on fluorescent green mouse.
The mistake was fortuitous. Glowing mice aren’t just seriously cool; they’re also medically relevant. For instance, other researchers have similarly tagged human cancer cells with a glowing red protein and injected them into glowing green mice (engineered to be fur-less as well, so that the glow is visible). Then they can track the cancer as it grows and spreads, differentiating it from healthy cells by color alone.
(Left: Fluorescent red cancer cells lined with the fluorescent green blood vessels of a fluorescent green mouse. Right: Fluorescent red tumor in a fluorescent green mouse. Both images from here.)
Below the fold: glowing fishies, bunnies, and kitties…
Finger-painted by a kindergartener? Think again: foot-painted by a cockroach.
“Eleven Steps” by Steven R. Kutcher
Hissing Cockroach (Gromphadorhina portentosa)
With gouache on paper, 2003.
Please check out his website at BugArtBySteven.com
This is what the artist looks like: Read the rest of this entry »
Picked up on this one over at Living the Scientific Life. The photo really speaks for itself:
(Photo of Lil’Bit the two-faced cat pinched from the Daily Mail.)
Not only does this cat have two faces — because his faces can sneeze, eat, and sleep separately, his veterinarians think Lil’Bit has two independently functioning brains.
At seven months old, he seems to be faring pretty well, considering his condition. He does have some trouble with the litter box, but his (very obliging) owner has solved that problem with diapers designed for premature babies.
I know most of us have visions of turkey dancing in our heads right now, but picture instead a lobster. Just your average run-of-the-mill fresh-from-the-pot dinner lobster. Now picture a lobster twice that size — say a foot and a half long. Now picture a lobster claw that’s a foot and a half long. Can you visualize the lobster it would belong to?
University of Bristol researchers recently stumbled upon a 1.5-foot-long fossilized claw from an ancient sea scorpion — a giant aquatic arthropod that roamed the floors of lakes and rivers 400 million years ago. The lobster analogy actually doesn’t properly convey this thing’s hugeness, because sea scorpion claws are proportionately smaller than lobster claws. Based on the size of the claw, and the relatively constant claw to body length ratio among sea scorpions, they were able to infer that the scorpion was about 8 feet 2 inches long.
An 8’2″ scorpion. Eesh. That’s just 9 inches short of the world’s tallest man.
“They would probably lie in wait,” Simon Braddy, one of the researchers, told Nature News. “When another animal went in front of it, it would lurch forward and capture it. … These things would tear their prey to shreds and then eat the little pieces.”
They’re calling it Jaekelopterus rhenaniae, and it’s the largest arthropod ever. For now.
Here’s a photo of the claw, from Nature News:
One of the joys of being a scientist — particularly in a field that’s exploding — is that you get to name the things you discover. Maybe if I’d lingered longer in the lab before fleeing to a writerly career there would be a Jocelynetensium ricensis bacterium flagella-whipping its way across some bio student’s glass slide. But alas. Now my only option is to hound some generous scientist and make him like me so much that he wants to name something after me. Something really important.
In the meantime, here’s a roundup of scientific whatnots with names — some eponymous, some not — that make you stop and ask, really? They got away with that?
The list of asteroid names reads, for the most part, like a mashup between a phone book, a history of science textbook, and an encyclopedia of Greek and Roman mythology. But nestled in among the Aphrodites and Persephones, the Fouriers and Feynmans, the 52 names starting with “David,” “Dave,” or “Davy” and the 20 starting with “Bob,” are a few odd nuggets:
- Adamcarolla and Drewpinsky. These two dispensed raunchy advice that I found both riotously funny and Very Important… when I was 13. But I’m not sure any of it — or even all of it combined — is worth an asteroid.
- Bacon. Okay wait. Are we talking Sir Francis Bacon? Kevin Bacon? Or greasy sizzling strips of porky goodness? If it’s the latter, I’m completely on board.
- Forbes. Can an asteroid be sponsored? What if that asteroid then collides with earth? Is the sponsor held resposible?
- GNU. All hail recursive acronyms. What about ASTEROID, for Asteroids Still Terrify Everyone Regardless Of Improbable Destruction?
Read the rest of this entry »
I’m too lazy to write a useful new post because I just spent 3 hours going through a messy divorce with iWeb and moving all my furniture and possessions to the house of my rebound boyfriend, WordPress. So here, instead, is a half-wet elephant. Or maybe it’s two-thirds wet. Wait, are we talking volume or surface area? What’s the surface area of an elephant, anyway?
(Photo by Jeremy Tucker, who has a whole website full of gorgeous photographs: check it out.)
EDIT: Er, it looks like someone (okay, two someones: K.P. Sreekumar and G. Nirmalan) has actually published scholarly research on how to estimate the surface area of an elephant. The paper is called “Estimation of the total surface area in Indian elephants” and it ran in a 1990 issue of Veterinary Research Communications. Their formula is:
S = -8.245 + 6.807H + 7.073FFC
Where S is surface area in square meters, H is shoulder height in meters, and FFC is forefoot circumference in meters. The BBC tells us that Indian elephants have a shoulder height of 2.5 to 3 meters — let’s go with 2.75. And a PBS classroom resource tells us that forefoot circumference is equal to about half of an elephant’s height, so we’ll call it 1.375. That works out to about 20 square meters, or 215 square feet.
So I guess that’s my answer. An average Indian elephant has a surface area (albeit crudely estimated) of 215 square feet.
ANOTHER EDIT: My tape measure says that’s twice the size of my bedroom.
I took this scanning electron micrograph of a spider head back at Smith. It’s a little bleached-out-looking (I hadn’t really mastered the instrument) but nonetheless gorgeous and creepy.
Before you image a biological specimen, you have to dry it using a gizmo called a critical point drier. Simply evaporating off the water doesn’t do the trick, because the surface tension at the interface between water and air damages the spider as it dries out and you end up with a wrinkly specimen — not so pretty. If you bring water to its so-called critical point, where the density of water and air are the same, you can avoid the surface tension issue. But then you have a really-dangerous-conditions issue: the critical point for water occurs at 374 degrees C (705 degrees F) and 3,212 psi (about 219 times the atmospheric pressure at sea level). The poor little arachnid corpse isn’t likely to make it through that experience intact. Read the rest of this entry »
It was the spring of 1977, and New Englanders had monsters on their minds. In Dover, Massachusetts, three high-school boys spotted a creature with orange eyes and a melon-shaped head. Meanwhile, in Hollis, New Hampshire, a father driving with his two sons encountered a nine-foot-tall hairy behemoth.
Arnold Vellucci, mayor of Cambridge, Massachusetts, took notice when the Boston Herald-American reported these mysterious sightings in side-by-side articles. But he wasn’t worried about aliens or Bigfoot, the usual suspects in paranormal sightings. Vellucci worried instead that the peculiar beings had escaped from a molecular biology lab at either Harvard or MIT.
On the same day that the Herald-American articles were published, Vellucci penned a letter to Philip Handler, president of the National Academy of Sciences. Vellucci politely requested that the NAS investigate the matter. “I would hope as well,” he added, “that you might check to see whether or not these ‘strange creatures,’ (should they in fact exist) are in any way connected to recombinant DNA experiments taking place in the New England area.” Read the rest of this entry »
“Physics envy. The lure of reducing complex problems to basic physical principles has dominated the philosophy of science since Descartes’s failed attempt some four centuries ago to explain cognition by the actions of swirling vortices of atoms dancing their way to consciousness. Such Cartesian dreams provide a sense of certainty, but they quickly fade in the face of the complexities of biology. We should be exploring consciousness at the neural level and higher, where the arrow of causal analysis points up toward such principles as emergence and self-organization. Biology envy.”