Fatty diet leads to fat-loving brain cells

Cheeseburgers pack on the pounds, but in mice a high-fat diet also packs on new nerve cells in the brain. More brain cells may seem like a good thing, but these newly sprouted cells appear to trigger weight gain in the animals, a new study finds.
The results offer insight into how the brain controls weight. If the same thing happens in humans, these nerve cells may be a target for anti-obesity treatments.
“This kind of work will definitely inform how we think about the underlying factors that relate to obesity,” says endocrinologist Jeffrey Flier of Harvard Medical School in Boston. There’s increasing interest, he says, in how long-term changes in brain circuitry — like new nerve cell production — affect eating and hunger. “That is going to be a very interesting frontier.”

 A special brain cell called a tanycyte (green) was caught in the process of giving birth to a new neuron (red, marked with a white arrow) in a brain region called the median eminence. A high-fat diet spurs tanycytes to make new nerve cells in the brain, a new study finds.

With some key exceptions, most regions in the adult brain don’t make new nerve cells. But in a small sliver of brain tissue called the median eminence, new nerve cells are born throughout life, neuroscientist Seth Blackshaw of Johns Hopkins University School of Medicine and colleagues report online March 25 in Nature Neuroscience. The median eminence is part of the brain’s metabolism hub known as the hypothalamus.
And one signal to step up production in the median eminence, the team found, is a diet high in fat.
In the study, mice that ate the rodent version of a steady stream of Big Macs gained weight. This unhealthy diet also kicked nerve cell production into high gear, the scientists found. After eating a fatty diet for several weeks, adult mice pumped out about four times as many new nerve cells in the median eminence as mice that ate regular chow.
To see whether these newborn nerve cells were up to no good, Blackshaw and his team shut down production with a carefully targeted laser. Even while continuing to gorge on a high-fat diet, these mice started moving around more and didn’t gain as much weight as mice on a high-fat diet that could still make the new nerve cells. Take away the steady stream of new nerve cells, and the pounds didn’t pile on as fast.
The newborn cells’ parents turn out to be a mysterious kind of brain cell that resides in the median eminence. Both mice and people have these cells, called tanycytes, but no one knew what their role was. “There’s been a lot of speculation about what their function may be,” says Blackshaw.
The scientists don’t yet know how these newborn nerve cells can influence metabolism. Other studies, including those by Flier, have found that a high-fat diet actually reduces nerve cell turnover in other parts of the hypothalamus.
Blackshaw cautions that it’s too soon to say whether a similar thing could be going on in people. “This is the very first step in trying to understand this process,” he says. “We’re a long way from realizing whether this is relevant to human obesity.”

Why the Man in the Moon is Always 'Looking' at Earth

"The man in the moon came down too soon,
and asked his way to Norwich,
They sent him south and he burnt his mouth
By eating cold pease-porridge."

It's human nature to see shapes and patterns all around us, and ascribe a meaning to what is actually just a random coincidence. The phenomenon is called pareidolia, and includes things like seeing the Virgin Mary in a piece of burnt toast, for example.
But some examples are more persistent than others -- like the Man in the Moon. It's not a real face, of course, just a quirk of how the dark areas (the lunar maria, or "seas") and lighter highlands of the lunar surface are arranged. Yet the illusion is powerful enough to have a Western mythology dating back thousands of years, inspiring all manner of nursery rhymes and literary references.

       
 And there's some interesting physics at work here as well, at least according to a new paper in the journal Icarus. See, the Man in Moon is always staring at us here on Earth -- or, if you want to be all science-y about it, those particular features of the lunar surface always face Earth.
It happens because the moon is locked in what's known as a "synchronous orbit": for every orbit it completes around the Earth, the moon also rotates exactly one time. So we always see that face.
But it didn't necessarily have to be that way; why is this side of the moon, and not the other, the one that faces Earth? There had to be a 50/50 chance of it being one way or the other. Or so astronomers have thought -- until now.

Two Caltech astronomers, along with an Israeli colleague, think that there's a perfectly good explanation why the Man in the Moon always faces us -- and it's not due to the proverbial coin toss. Rather, Oded Aharanson, Peter Goldreich, and Re'em Sari propose that it's due to the fact that the Moon spun around its axis much faster in the past than it does today. And the rate at which it gradually slowed its pace could explain why it eventually became locked in the current orientation.

 ANALYSIS: It's Alive! There's Magma on the Moon
When the moon formed some four billion years ago, it was a blob of hot molten stuff. The Earth's gravitational pull stretched it a bit, elongating it like a football, and that shape stuck when the Moon cooled off. The Man in the Moon is at one of those oblong ends.

Back then -- about a couple billion years ago -- any inhabitants of Earth would have seen varying sides of the moon, not just the fixed face. But that relentless gravitational pull from Earth eventually slowed down the Moon's rate of spin on its axis, and tidal forces created yet another bulge, one that moved around in such a way that it always pointed toward Earth.
And this is where the physics starts to get interesting. So far, so good, but it still seems like a bit of a coin toss when it comes to which side of the moon faces Earth. The Caltech team ran a series of computer simulations, plugging in many different rates of slowing, and found they could "load" the coin however they wanted, so that either side of the moon would always face the Earth when it hit that locking point -- depending on that rotational energy dissipation rate.

ANALYSIS: Today in History: Shepherd Golfs on the Moon
For instance, there really would be a 50/50 chance of the current orientation if the rate of dissipation had been, say, 100 times faster. Instead, that rate was much slower, so there would be two-to-one odds that the Man in the Moon would find himself always facing Earth. This assumes, of course, that the properties of the present-day moon were similar to those in its distant past.
Not every culture sees a Man in the Moon. There are myths and legends based on perceiving a woman, a rabbit, a frog, a moose, a buffalo, or even a dragon in the full moon. But since those illusion arise from the same patterns of light and dark shadows, one assumes the same analysis would apply.

The bulge continued to point toward Earth as the moon rotated through it, causing the moon's interior to squish and flex as the bulge changed position. The internal friction from this flexing acted as a brake that slowed the moon's spinning until its rotation rate matched its revolution rate, when it settled into a synchronous orbit.

In this way, as a result of Earth's gravity, the moon became locked into an orientation with its long axis pointing toward our planet.

How Do You Start a Fire With Ice?

Winter is full of opportunities for outdoor fun in many forms: Skiing, sledding, skijoring, ice climbing, winter camping, and more. But conditions can grow dangerous quickly when you’re exposed to plummeting temperatures and gusting winds.

So, why not take the opportunity to sharpen your winter survival skills before your next outdoor adventure?
To that end, the video above offers instructions for starting a fire with ice. What you’ll need is a frozen lake, a sharp knife, warm hands and some dry leaves or wood. A sunny day is also necessary.
Find the clearest ice you can find. Carve out a big chunk of it. Then, shape the ice into a disk, and use the warmth of your hands to melt it into a smooth, round lens. Finally, just like you used to use a magnifying glass to set ants on fire, adjust the angle of the ice disk until rays of sunlight shine through it. Focus the sunbeam onto a spot on the ground where you’ve placed some tinder. And voila – fire!