Firmicute Gut Bacteria make you fatter - Nature magazine

reposted from: Nature Podcast: 21 December 2006
from Nature Podcast / Original audio source
Nature Video: http://www.nature.com/nature/videoarchive/gutmicrobes/index.html
my highlights / edits

In "Conclusion" (3rd video) Jeff Gordan says: "The study of the coevolution of microbes with human cells may help to treat obesity. Which human genes are manipulated by microbes? The number of calories in food is determined in the lab but the total caloric yield may differ between individuals depending on the ratio of Bacteroidetes and Firmicutes.

This is a transcript of the 21 December edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (http://www.nature.com/nature/podcast), which also contains details on how to subscribe to the Nature Podcast for FREE, and has troubleshooting top-tips. Send us your feedback to mailto:podcast@nature.com

Transcript reposted: http://www.nature.com/nature/podcast/v444/n7122/nature-2006-12-21.html

Chris Smith: This week, should we think of ourselves as passengers in our own bodies? Well, Jeff Gordon says we should.

Jeff Gordon: A human being is not composed only of human cells. In fact, as adults we contain ten times more microbial cells on our body surfaces than human cells.

Chris Smith: And those very same bugs make a huge difference to whether we're fat or thin;

Hello, Merry Christmas, I'm Chris Smith, welcome to this week's show. First up, who would have thought that bacteria living in your gut could make a big difference to your body weight? Here's Jeff Gordon and his team, Peter Turnbaugh and Ruth Ley who've found that a bulging waistline in mice and humans is associated with a big change in intestinal flora. Nature 444, 1009–1010 (21 December 2006) ; Nature 444, 1022–1023 (28 December 2006) ; Nature 444, 1027–131 (21 December 2006)

Jeff Gordon: We're very interested in the alliances between microbes in humans. A human being is not composed only of human cells. In fact, as adults we contain ten times more microbial cells on our body surfaces than human cells. These partnerships are mutually beneficial. We're very interested in the role of microbes in our gut and one of the attributes that they provide is the capacity to digest otherwise indigestible components of our diet. So the question we had here was do the microbes in our gut influence our energy balance?

Chris Smith: So how did you try and explore that?

Jeff Gordon: We started out with mice and looked at the microbial communities of obese mice. They're obese because they had a genetic mutation that caused them to reliably develop obesity while they were young adults, and compared their community structure to their litter mates who didn't have this mutation and therefore were lean.

Chris Smith: So, Peter Turnbaugh, you're the lead author on this paper, when you actually did this, what did you find?

Peter Turnbaugh: We were able to take advantage of really the revolution that's going on in sequencing technology and so here at Wash U we have the genome sequencing centre, we were able to directly isolate DNA from the mouse gut and take that DNA and use them high throughput shotgun sequencing techniques to try to look at what genes were present in the bacterial community of obese mice and what we found was that there seemed to be more genes in the obese community for harvesting energy from the diet, so breaking down complex sugars that we might eat that the human or the mouse can't normally digest.

Chris Smith: So these guys have got a richer microbial flora effectively?

Peter Turnbaugh: First, originally, when we looked at who's there, we saw that there's two major groups of bacteria, the Firmicutes and the Bacteroidetes, and we saw them in the obese mouse, there was a shift in the relative abundance of these two groups so there were more Firmicutes and less Bacteroidetes.

(From Wikipedia: Researcher Jeffery Gordon and his colleagues found that obese humans and mice had a lower percentage of a family of bacteria called Bacteroidetes and more Firmicutes. But they are not sure if Firmicutes cause obesity or if people who are obese grow more of that type of bacteria.)

Chris Smith: Is the trait transmissible, in other words, can you take that different spectrum and confer it upon another animal and make that animal gain weight because that surely is the way to prove wholeheartedly that this is underlining why they're so fat?

Peter Turnbaugh: Right, exactly, so what we were able to do is harvest the microbial community from an obese mouse, or a lean mouse, and then directly colonize germ-free mice with either the obese flora or the lean flora and what we saw was the mice that were exposed to the microbes from an obese mouse actually gained more fat over the course of the experiment than the mice that were given lean microbial community.

Chris Smith: So that's mice, but actually happens if you look in humans who are too fat, are they, too, carrying an abnormal spectrum of bacteria in their intestines? Ruth Ley is the first author on a second paper which sits next to this one in this week's Nature. Ruth, what did you find in humans?

Ruth Ley: We found that the obese humans did actually have exactly the same shift in their ratio of Firmicutes to Bacteroidetes that we'd seen in the mice.

Chris Smith: How did you actually do the study? Can you tell us a bit about that?

Ruth Ley: We had 12 subjects that were randomly assigned to two different diets, one was a fat restricted diet and the other one was a low calorie diet and these people were on a diet for a year and we collected a stool sample from them before they started the diet and then three times over the course of the year, and just using the same techniques we used for the mice, we extracted DNA from their stool and we sequenced the 16 S genes for the bacteria, which was the one that tells you what kinds of bacteria are present. So we generated a very large amount of sequence for this kind of study and from that we were able to see that first of all before the diet the obese people had a skewed ratio of Firmicutes to Bacteroidetes compared to lean people so we also had some lean controls and then as they lost weight, the amount of Bacteroidetes increased and began to resemble what you would see in a normal lean person, and the amount of the increase was proportional to the amount of fat that they actually lost over time.

Chris Smith: So what do you think is going on? Why should just losing weight change the bugs that you have growing in your intestine?

Ruth Ley: Well, that's a mystery at the moment. We know that there's some kind of link, some sort of dynamic linkage between the fat that's carried on the body, we know that fat cells produce hormones and there could be some signaling between the adipose tissue in the body and the kinds of bugs that are in the intestine but at this point we don't understand the mechanism.

Chris Smith: Ruth, thanks, very much. Back to Jeffrey Gordon, Jeffrey, what are the implications of what you found?

Jeffrey Gordon: Well, surely a key element that determines the amount of fat that we store in our bodies is the amount of energy that we consume and the amount of energy that we expend through exercise and work. What this study shows is that there's also a microbial component to determining how much adipose tissue you might have and that they microbes in the gut are part of the equation that affects predisposition to, or the patho-physiology of obesity.

Chris Smith: So now you can blame your gut bacteria as well as a slow metabolism for the extra stone or two that you're carrying around your middle. That was Jeff Gordon, Peter Turnbaugh and Ruth Ley. They're all from Washington University in St Louis and they found that being overweight is associated with a big shift in the types of bacteria found living in our intestines.

Evangelical Scientists Refute Gravity With New 'Intelligent Falling' Theory

reposted from: http://richarddawkins.net/article,535,n,n
my highlights / edits

Will Kansas schools be teaching Flying Spaghetti Monsterism & Intelligent Falling?

by The Onion

Thanks to Mark for the link to this classic Onion piece (It's a joke).

Reposted from:
http://theonion.com

KANSAS CITY, KS—As the debate over the teaching of evolution in public schools continues, a new controversy over the science curriculum arose Monday in this embattled Midwestern state. Scientists from the Evangelical Center For Faith-Based Reasoning are now asserting that the long-held "theory of gravity" is flawed, and they have responded to it with a new theory of Intelligent Falling.


Rev. Gabriel Burdett explains Intelligent Falling.

"Things fall not because they are acted upon by some gravitational force, but because a higher intelligence, 'God' if you will, is pushing them down," said Gabriel Burdett, who holds degrees in education, applied Scripture, and physics from Oral Roberts University.

Burdett added: "Gravity—which is taught to our children as a law—is founded on great gaps in understanding. The laws predict the mutual force between all bodies of mass, but they cannot explain that force. Isaac Newton himself said, 'I suspect that my theories may all depend upon a force for which philosophers have searched all of nature in vain.' Of course, he is alluding to a higher power."

Founded in 1987, the ECFR is the world's leading institution of evangelical physics, a branch of physics based on literal interpretation of the Bible.

According to the ECFR paper published simultaneously this week in the International Journal Of Science and the adolescent magazine God's Word For Teens!, there are many phenomena that cannot be explained by secular gravity alone, including such mysteries as how angels fly, how Jesus ascended into Heaven, and how Satan fell when cast out of Paradise.

The ECFR, in conjunction with the Christian Coalition and other Christian conservative action groups, is calling for public-school curriculums to give equal time to the Intelligent Falling theory. They insist they are not asking that the theory of gravity be banned from schools, but only that students be offered both sides of the issue "so they can make an informed decision."

"We just want the best possible education for Kansas' kids," Burdett said.

Proponents of Intelligent Falling assert that the different theories used by secular physicists to explain gravity are not internally consistent. Even critics of Intelligent Falling admit that Einstein's ideas about gravity are mathematically irreconcilable with quantum mechanics. This fact, Intelligent Falling proponents say, proves that gravity is a theory in crisis.

"Let's take a look at the evidence," said ECFR senior fellow Gregory Lunsden."In Matthew 15:14, Jesus says, 'And if the blind lead the blind, both shall fall into the ditch.' He says nothing about some gravity making them fall—just that they will fall. Then, in Job 5:7, we read, 'But mankind is born to trouble, as surely as sparks fly upwards.' If gravity is pulling everything down, why do the sparks fly upwards with great surety? This clearly indicates that a conscious intelligence governs all falling."

Critics of Intelligent Falling point out that gravity is a provable law based on empirical observations of natural phenomena. Evangelical physicists, however, insist that there is no conflict between Newton's mathematics and Holy Scripture.

"Closed-minded gravitists cannot find a way to make Einstein's general relativity match up with the subatomic quantum world," said Dr. Ellen Carson, a leading Intelligent Falling expert known for her work with the Kansan Youth Ministry. "They've been trying to do it for the better part of a century now, and despite all their empirical observation and carefully compiled data, they still don't know how."

"Traditional scientists admit that they cannot explain how gravitation is supposed to work," Carson said. "What the gravity-agenda scientists need to realize is that 'gravity waves' and 'gravitons' are just secular words for 'God can do whatever He wants.'"

Some evangelical physicists propose that Intelligent Falling provides an elegant solution to the central problem of modern physics.

"Anti-falling physicists have been theorizing for decades about the 'electromagnetic force,' the 'weak nuclear force,' the 'strong nuclear force,' and so-called 'force of gravity,'" Burdett said. "And they tilt their findings toward trying to unite them into one force. But readers of the Bible have already known for millennia what this one, unified force is: His name is Jesus."

"Doomsday Clock" moves to 5 minutes before midnight.

Scientists have adjusted the "Doomsday Clock" to account for climate change as well as nuclear war. The clock now shows five minutes to midnight - two minutes closer than previously. BBC Video

Climate change is as great a threat to humankind as nuclear annihilation, scientists have warned. Professor Stephen Hawking explained why the world's "Doomsday Clock" was being moved two minutes closer to midnight. BBC Video