Science Corner

Read in Nature, vol. 444, issue no. 7122, page 982:
Climate change is allowing subordinate male [seals] on a remote Scottish island a chance to mate. Higher temperatures and lower rainfall mean that female grey seals forage over a wider range, making it more difficult for the top male to keep an eye on them all.

(Ambiguous references provided, so no source. Take it or leave it.)

ADDED: One of my favorite subjects of late is on the cover, the role of gut microbes in obesity.
"Although there is no doubt that human genetics plays a large part in determining body weight, it is equally undisputed that the increase in prevalence of obesity over the last 25 years cannot be attributed to changes in the human genome. The inference is that other factors are responsible, such as the availability of calorically dense foods, or the reduction in human activity in our daily lives. [Other work] raises the possibility that our gut bacteria are another factor that contributes to differences in body weight among individuals."

Two reports in this issue describe studies that suggest obesity alters the composition of intestinal microbiota. Of the trillions of bacteria that live in healthy human intestine, two groups dominate: the Firmicutes and the Bacteroidetes. It turns out the guts of obese people have a higher ratio of Firmicutes to Bacteroidetes than do the guts of lean people.

When two groups of obese people--one group eating a carbohydrate-restricted diet, and the other a fat-restricted diet--lost weight over the course of a year, both experienced a decrease in the ratio of Firmicutes to Bacteroidetes. That is, the composition of their intestinal microbiota became more like that of lean people. That's interesting, because how do the bacteria know whether they're living inside obese people or lean people?

It gets more interesting when those results are considered along with results from two studies in mice.

First, the scientists found the Fermicutes/Bacteroidetes situation in mice to be similar to that in humans.

Then they did a controlled experiment where they transferred obese mouse microbiota into the guts of lean, microbe-free mice.
Over a two-week period, mice [receiving] microbiota from obese mice extracted more calories from their food and had a modest fat gain that was statistically greater than that of mice receiving microbiota from lean mice. [T]hese data suggest that differences in the efficiency of caloric extraction from food may be determined by the composition of the microbiota, which, in turn, may contribute to differential body weights.

How did the researchers determine that mice receiving 'obese microbiota' extracted more calories from their food than the control group (who received 'lean microbiota')? They measured and compared calories left over in feces.

Interesting that 'obese microbiota' extract calories more efficiently than 'lean microbiota'. Lean hosts are the ones who need to extract calories most efficiently; obese hosts have stored calories to burn.

The authors note that questions about how and why gut microbiota is regulated should be answered before manipulating the microbiota to effect changes in obesity.

You know, it took the medical community almost twenty years to fully accept the idea that bacteria can cause gastric ulcers. Now everyone's heard of Helicobacter pylori. But that idea was a hard sell for a long time. Today we hear about viruses causing cancer and all kinds of things previous generations didn't connect. There's a long way to go before concluding bacteria cause obesity, but it shouldn't be deemed too far-fetched to consider.

Why does this interest a whoreticulturist?

When plants depend on soil microbes to fix life-sustaining nitrogen in nitrogen-poor soils and absorb minerals that are otherwise unavailable, and when those microbes depend in turn on the plant for food and whatever else, where does the plant end and the microbe begin? Separate the two and both fail. So it is with human life, going all the way back to the very beginning.

P.S. Mark my words: I predict we'll be hearing a lot about Fermicutes in the near future, just like we hear about good and bad cholesterol and trans fats.


lisa said...

Gut microbes? And all this time I thought I needed a "friendly tapeworm" to help me lose some weight! :) Actually, I need to eat less and move around more...but it's very interesting that scientists are discovering these things. Just goes to show that cause and effect is a bitch, and there is no one single thing that will magically change one's body, but the sum of several factors working together. Even if I didn't change a thing with my diet and only lifted weights a couple times a week, the increased muscle mass would increase my resting metabolism, which would help me burn more calories just sitting on my ass! Cause and effect...just like drinking more beer makes me more buzzed, making me feel happier about everything-including my overly bodacious booty! Now there's cause and effect for ya!

Jenn said...

On Seals -

If true, it's an interesting view on how nature creates more genetic diversity in times of climate stress. With more genes entering the pool, the chances are higher of a strain to emerge that can adapt to the new climate.

anile said...

Here's an article that's getting a lot of blog circulation. The writer is trying to tie-in the microbe findings to environmental factors. I like this kind of connecting the dots thinking....

anile said...

More thoughts- in eastern and holistic circles, obesity is linked to lower pH in the body- and acidic pH is caused by exposure to environmental and dietary toxins, chemicals, pesticides. They also believe (I say "believe" because I have no scientific references to cite) fat stores these toxins, therefore more toxins=more fat=more toxins. I wonder if Fermicutes bacteria increase as pH lowers? And perhaps they survive less successfully in a more basic environment?

chuck b. said...

If you're interested in this, you may have already Googled Firmicutes and found this article:


If not, it's very good for a general audience.