Japanese Guts Are Made For Sushi

cremeglace writes "Americans don't have the guts for sushi. At least that's the implication of a new study, which finds that Japanese people harbor enzymes in their intestinal bacteria that help them digest seaweed, enzymes that North Americans lack. What's more, Japanese may have first acquired these enzymes by eating bacteria that thrive on seaweed in the open ocean."

Comments

I must have the enzyme for french fries.

[ipquickly]

Is it not obvious that if you regularly eat a certain type of food, you will eventually have bacteria that thrive in your gut because of the regularity of what you eat?

What would really surprise me is if they find that an American living in Japan and eating a 'local' diet would not acquire these bacteria.

I'm sure by now I've acquired bacteria that help with the digestion of french fries and poutine.

Re:I must have the enzyme for french fries.

[Cyberllama]

Not all of Europe, actually, just all of northern Europe and also East Africa and places were the populations are descended primarily of those stocks. Wikipedia has a map!

http://en.wikipedia.org/wiki/File:LacIntol-World2.png

population sample

[networkzombie]

Czjzek's team compared the microbial genomes of 13 Japanese people with those of 18 North Americans.
If I used this many test subjects in my job I would get fired.

Re:population sample

[zippthorne]

31 people, but billions of gut bacteria...

...and Americans are made for steak...

[ook_boo]

Yeah, 20 years ago there was similar pseudo-science published in Japan claiming that Americans were specially built to eat hamburgers.

Re:Am i missing something?

[leenks]

Isn't that basically what all scientific papers are though? Scientific method applied to hunches or experiences to confirm a behaviour?

babies

[thoughtsatthemoment]

The study maybe valid if they can find the enzymes in Japanese babies. Otherwise it can be said that the Japanese have the enzymes because they eat lots of sushi.

Ah!

[Superdarion]

So that's why nobody eats sushi outside of Japan!

really?

[malkien]

organisms adapt to local diet.
film at 11.

But then it makes no sense

[Moraelin]

But then it makes no sense to say they acquired it from bacteria.

Genes don't transfer from bacteria to mammals. Genes transfer between bacteria, via exchange of plasmids. (Which is one reason why antibiotic resistance spreads so fast.) But your cells don't have the mechansims to acquire such a plasmid, and wouldn't know what to do with it. You don't even have the regulating proteins or the ribosome to deal with a _circular_ DNA strand, and one outside the nucleus at that.

At this point someone will probably have the knee-jerk reaction to explain how viruses can account for horizontal gene transfer, 'cause they read that notion at some point and it sounded so smart. Not so fast. Viruses are quite specialized in what they attach to. They depend on very specific nucleotid sequences, which is why you can have a virus that attacks your upper respiratory tract, but can't affect your lungs, or viceversa. Viruses that prey on bacteria, the so called "phages", have very specialized capsids and mechanisms to inject themselves into a bacterium, and are even more specialized in what they can attach to. Which is why for example you can spray meat with a phage which destroys Lysteria, but won't destroy your intestinal flora. A virus that's suited to infect both a bacterium _and_ your gut lining and transfer genes from one to the other, is almost an impossibility, and at any rate to the best of my knowledge none was ever identified.

Re:But then it makes no sense

[jc42]

But then it makes no sense to say they acquired it from bacteria. Genes don't transfer from bacteria to mammals. Genes transfer between bacteria, via exchange of plasmids.

It's more accurate to say that we don't know of gene transfer between bacteria and mammals (or eukaryotes in general). It may happen, but it's probably not common.

But what the article is about is gene transfer between bacteria in the gut. This is something that's well understood in medical circles, but not in the general population. Our digestive system depends on a lot of bacteria to provide many of our digestive enzymes. We do produce digestive enzymes ourselves, but not nearly enough, and we'd get a lot less value from our food without the assistance of all those bacteria.

The suggestion is that the enzymes to digest seaweeds came from bacteria that were ingested along with the seaweeds, and in Japan, those bacteria exchanged some genes with the more common human digestive bacteria, so that the bacteria that are adapted to our gut picked up the seaweed-digesting enzymes. From what is known about bacterial genetics, this isn't a radical suggestion. It's what you'd expect to happen when a human population adopts some new food stuff that's difficult to digest.

It is possible that the genes that make some of those seaweed-digesting enzymes have also transferred into the human genome in Japan. But it's a lot less likely. That's the sort of job that our digestive system prefers to farm out to subcontracting bacteria.

Sample size

[crossmr]

Czjzek's team compared the microbial genomes of 13 Japanese people with those of 18 North Americans. Five of the Japanese subjects harbored the enzyme, but among the North Americans, "we didn't find a single one," says Czjzek, whose team reports its findings tomorrow in Nature.

such a big sample size, how could they possibly be wrong..

Re:Americans

[techhead79]

This is one thing I always hate to hear. anyone who doesn't really like it simply hasn't been properly introduced. I've know a few Gay men that make the suggestion about certain sexual situations...

So let me be clear, you're wrong...some things just rub people the wrong way. It's not how you were introduced to it...we are honestly that different from each other. I hate Sushi and it makes me want to throw up just looking at it.

Re:North Americans? What, like the Sioux?

[Anonymous Coward]

Right, because 200+ years of living an ocean away from our mother country and inter-mingling with natives and other colonists should have zero effect on our genetics.