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Tag: sushi

Do you have the guts for nori?

The paper I will talk about this month is from April of this year and highlights the diversity of our “gut flora” (a pleasant way to describe the many bacteria which live in our digestive tract and help us digest the food we eat). Specifically, this paper highlights how a particular bacteria in the digestive tracts of some Japanese individuals has picked up a unique ability to digest certain certain sugars which are common in marine plants (e.g., Porphyra, the seaweed used to make sushi) but not in terrestrial plants.


Interestingly, the researchers weren’t originally focused on how gut flora at all, but in understanding how marine bacteria digested marine plants. They started by studying a particular marine bacteria, Z. galactanivorans which was known for its ability to digest certain types of algae. Scanning the genome of Z., the researchers were able to identify a few genes which were similar enough to known sugar-digesting enzymes but didn’t seem to have the ability to act on the “usual plant sugars”.

Two of the identified genes, which they called PorA and PorB, were found to be very selective in the type of plant sugar they digested. In the chart below (from Figure 1), 3 different plants are characterized along a spectrum showing if they have more LA (4-linked 3,6-anhydro-a-L-galactopyranose) chemical groups (red) or L6S (4-linked a-L-galactopyranose-6-sulphate) groups (yellow). Panel b on the right shows the H1-NMR spectrum associated with these different sugar mixes and is a chemical technique to verify what sort of sugar groups are present.

These mixes were subjected to PorA and PorB as well as AgaA (a sugar-digesting enzyme which works mainly on LA-type sugars like agarose). The bar charts in the middle show how active the respective enzymes were (as indicated by the amount of digested sugar that came out):

As you can see, PorA and PorB are only effective on L6S-type sugar groups, and not LA-type sugar groups. The researchers wondered if they had discovered the key class of enzyme responsible for allowing marine life to digest marine plant sugars and scanned other genomes for other enzymes similar to PorA and PorB. What they found was very interesting (see below, from Figure 3):

What you see above is an evolutionary family tree for PorA/PorB-like genes. The red and blue boxes represent PorA/PorB-like genes which target “usual plant sugars”, but the yellow show the enzymes which specifically target the sugars found in nori (Porphyra, hence the enzymes are called porhyranases). All the enzymes marked with solid diamonds are actually found in Z. galactanivorans (and were henced dubbed PorC, PorD, and PorE – clearly not the most imaginative naming convention). The other identified genes, however, all belonged to marine bacteria… with the notable exception of Bateroides plebeius, marked with a open circle. And Bacteroides plebeius (at least to the knowledge of the researchers at the time of this publication) has only been found in the guts of certain Japanese people!

The researchers scanned the Bacteroides plebeius genome and found that the bacteria actually had a sizable chunk of genetic material which were a much better match for marine bacteria than other similar Bacteroides strains. The researchers concluded that the best explanation for this is that the Bacteroides plebeius picked up its unique ability to digest marine plants not on its own, but from marine bacteria (in a process called Horizontal Gene Transfer or HGT), most probably from bacteria that were present on dietary seaweed. Or, to put it more simply: your gut bacteria have the ability to “steal” genes/abilities from bacteria on the food we eat!

Cool! While this is a conclusion which we can probably never truly prove (its an informed hypothesis based on genetic evidence), this finding does make you wonder if a similar genetic screening process could identify if our gut flora have picked up any other genes from “dietary bacteria.”

(Image credit – Nori rolls) (Figures from paper)

Paper: Hehemann et al, “Transfer of carbohydrate-active enzymes from marine bacteria to Japanese gut microbiota.” Nature 464: 908-912 (Apr 2010) – doi:10.1038/nature08937

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Sushi and soft power

image When I was in college, I had the fortune of sitting in on a talk by Joseph Nye, a famous Harvard professor who helped popularize the concept of “soft power” in foreign policy. The idea in a nutshell is that traditional conceptions of power in foreign policy (or “hard power”) around force, coercion, and payment fail to capture all the dimensions of power that are at work on the international stage. According to Nye, it’s not just about who has the biggest army or richest bank account, it was also about who had the “softer” skills in place to motivate other countries to act without coercion through the appeal of their ideals, culture, and institutions.

While Nye was a very engaging speaker, I have to admit that, at the time, I didn’t really grasp what he was talking about. Back then, I felt that “soft power” was a a luxury by-product of “hard power.” Of course, countries like and respect you — you’re rich and powerful! It was the viewpoint of a college student who believed in objective measures of success and power, and who was not a fan of the importance of “softer” influences.

image It wasn’t until later in my college career that I developed a better appreciation for Nye’s idea. What I hadn’t understood was that soft power wasn’t about getting other nations to like or respect you through strength and wealth. It wasn’t even about winning the Miss Congeniality award in international circles (as some liberals I know have seemed to interpret it). It was far more subtle (and one could even argue, insidious). Rather than compelling China to open up a new trade corridor by threatening them with economic sanctions or military attack, soft power aims to achieve that trade corridor by creating a demand from the Chinese people for US  products or by encouraging the elite in China to want to see their country more open to contact with the US or even  by encouraging the international community to view trade with the US as a sign of economic progress. In other words, the soft power approach is a psychological one where the appeal of one’s culture and image act as the motivating force

An article in this past week’s Economist on the rise of sushi as a cuisine in Syria highlights an example of this sort of soft power influence:

For a country with no particular predilection for fish, sushi is slowly but surely conquering Syria’s capital, Damascus. Ever more foreign-food restaurants have been popping up, from Indian to Italian. But sushi, now deemed the height of sophistication, is becoming de rigueur for the capital’s middle class.

Proud and nationalistic, modern Syria has not been known for welcoming outside influences, be they political, economic or culinary. A decade or two ago Damascus offered just a handful of restaurants serving typical Syrian cuisine. But that is changing as Syria opens up to the world. The sushi boom is partly a product of economic liberalisation, which has most visibly led to a proliferation of luxury services targeting the better-off.

But as more Syrian expatriates return, they are pushing new trends and demanding the services and cuisine they have been used to outside … “The mindset is changing,” says a beady sushi restaurateur. The Syrian outlook is expanding. Flatbread and hummus may no longer do. And is Baathist socialism still tasty?

Now, obviously, this is a long shot from true economic and political liberalization or even friendly relations between Syria and Japan, but with the rise of China and the Middle East, soft power influence like this will become increasingly important tools in the foreign policy arena for the soon-to-be-questioned dominance of the US.

This isn’t to say that the US should stop investing in economic and military might — not only does the rise of a potentially hostile China and Russia suggest otherwise, but the perception of American weakening could also be a big blow to its “soft power” credibility — but it requires the US to pay greater attention to things which continue to give it a moral and cultural upper-hand:

  • Allow more foreign students/scientists to study in the US. The US has one thing where it has an undeniable lead: its schools. That most of the world’s major politicians, scientists, and businesspeople have spent at least some time in the US being educated is a testament to that. It also represents a great channel with which future world leaders and businesspeople can be influenced by American values and and culture. Why the US government doesn’t promote this further is beyond me.
  • Make it easier for skilled foreigners to get visas. This is another no-brainer to me. If there are foreign workers who would like to come to the US to voluntarily learn about US culture and ideals, get a taste for US products and services, and make US friends and, along the way, contribute to American enterprise, then why don’t we encourage them?
  • Remove barriers to cross-border collaboration. There are many foreign companies and organizations who’d love to team up with and learn from their American counterparts. This represents not only a chance to earn goodwill with foreigners, but creates productive relationships which could make it less likely that a foreign government will move in a way to jeopardize those relationships.
  • Enhance the impact of NGOs that perform humanitarian work overseas. Non-Government Organizations (NGOs) like those funded by the Bill & Melinda Gates Foundation are capable of doing a lot of good in foreign countries and thus generating a lot of goodwill towards the US, provided they are run effectively and can overcome bureaucratic hurdles. If the US government can find ways to lower these hurdles and encourage greater impact and effectiveness, they not only help NGOs do better humanitarian work, but also help create more goodwill for the US.
  • Encourage trade. The vast majority of foreigners will neither work in, nor be educated in, nor be touched by cross-border collaboration or humanitarian efforts, but they can still be touched by US soft power through trade. Being encouraged to tailor their products/services to American desires helps educate foreigners about American ideals and culture (not to mention helps to give consumers more choices and lower prices), and buying high-quality American products and brands helps create a greater desire for further contact and trade with the US. After all, one does not have to meet an American to associate the US with wealth and high quality brands.

None of these is the “silver bullet” which guarantees the US will always get what it wants in the foreign policy arena, but collectively, they help maintain the US’s strong cultural standing and influence in the world as its “hard power” relative to rising giants like China and the Middle East diminishes.

(Image credit)


The Sushi Seal of Approval

Tired of going to crappy Japanese places? Well, worry no longer. The Japanese government plans to award official seals of approval to overseas restaurants serving Japanese food that they deem of sufficient quality and authenticity (ie not Asian fusion, not a Korean/Japanese restaurant, not places that are actually Chinese or Filipino but say they serve Japanese, etc.)

From the Washington Post:

A fast-growing list of gastronomic indignities — from sham sake in Paris to shoddy sashimi in Bangkok — has prompted Japanese authorities to launch a counterattack in defense of this nation’s celebrated food culture. With restaurants around the globe describing themselves as Japanese while actually serving food that is Asian fusion, or just plain bad, the government here announced a plan this month to offer official seals of approval to overseas eateries deemed to be “pure Japanese.”

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