Bugs and weight

It's 6:45am and I'm writing a post in my blog. I need my head examined!

Actually there's a reason for the early hour. I needed to come into work quite early to work up some slides so that the results would be ready by 9am so that a coworker would know how to handle her part of the experiment. Since her leg is going to take around 8 hours she was understandably reluctant to wait until noon to see the results. Thus, I had to come in 3 hours early at 6am. Right now my coverslips are in a one hour incubation with fluorescent labeled secondary antibody. So here I am complaining about it! :-)

Onto the subject of this post, bugs. More accurately bacteria. And weight. Not their weight, mind you. Our weight.

According to a news release from the Mayo Clinic (that always reminds me of that scene in the movie Airplane), bacteria have an affect on our weight. Here's an excerpt from the press release:

Known as gut microbiota, the trillions of bacteria that populate the human gastrointestinal tract perform a variety of chores. These "friendly" microbes help extract calories from what we eat, help store these calories for later use, and provide energy and nutrients for the production of new bacteria to continue this work.

According to John DiBaise, M.D., a Mayo Clinic Arizona gastroenterologist and lead author of the Mayo Clinic Proceedings article, several animal studies suggest that gut microbiota are involved in regulating weight and that modifying these bacteria could one day be a treatment option for obesity.

Now this isn't very surprising. Bacteria are very much intertwined with everything we are and do. And doo-doo, for that matter. (ewwww!)

Within each of us there's about 10 times more bacteria cells than human cells. Kinda weird, huh? In terms of numbers, we're ten times more bacterial than we are human. Of course the bacterial cells are a lot smaller so in terms of weight the mammalian cells do tip the balance but just the thought of all those tens of trillions of bacteria wandering about our gut, skin, blood, and organs is staggering.

Anyway, it's often observed that since our blood is quite closely related chemically to seawater so it's like we're still carrying around with us that ancient sea in which we first evolved. When you consider all the bacteria we have within us, we're still carrying around all the critters that were swimming in those ancient waters as well.

But why is that? Do we carry around the bugs to our detriment? Is that why we get sick so often?

Nope. While it's true that some bacteria make us sick, most bacteria totally ignore us. We're just not of interest to them. And then there's the hundreds of bacterial strains that make their home either on us or in us. Some so specialized that they can't live anywhere else. These bacteria usually don't affect us in any way--like the bacteria that make their home on our skin and eat dead skin cells--but we're just a convenient surface for them to live on. Terra humana.

More importantly however, many of the bacteria we carry with us help us out. For example the bacteria in our gut help us digest food. Going back to the press release:

Young, conventionally-reared mice have a significantly higher body fat content than a laboratory-bred, germ-free strain of mice that lack these bacteria, even though they consumed less food than their germ-free counterparts. When the same research group transplanted gut microbiota from normal mice into germ-free mice, the germ-free mice experienced a 60 percent increase in body fat within two weeks, without any increase in food consumption or obvious differences in energy expenditure. Another animal study reviewed by the authors focused on the gene content of the gut microbiota in mice. Finding more end products of fermentation and fewer calories in the feces of obese mice led researchers to speculate that the gut microbiota in the obese mice help extract additional calories from ingested food.

So the mix of bacteria in the gut is different from mouse to mouse (and person to person, of course) and the specific mix has metabolic consequences. With the right mix, an organism can survive on a lot less food. At a cost, probably, but that's not indicated in the Mayo Clinic article.

This isn't surprising since bacteria were the original denizens of the planet and are still the only occupants in myriad environments on Earth. Since all animals developed from bacteria, way back when, it's not surprising that some bacteria hitched a ride with their more developed former brethren. I think most people are aware that the chloroplasts in plants and the mitochondria in all our cells were originally bacteria---without these organelles advanced life wouldn't exist.

Oops. My incubation is nearly over so it's back to work.