You 'are' what you eat. (Kai, comments requested)

[Telarus]

http://science.slashdot.org/story/11/09/21/2251238/what-you-eat-affects-your-genes

purkinje writes "Tiny bits of genetic material, called microRNAs, can make their way from the food you eat into your blood stream, and change how your genes are expressed, according to a new study. A team of Chinese scientists found tiny bits of white rice microRNA floating around in people's blood after a meal. When they looked at what was happening on a cellular level, they found that the microRNAs were changing gene expression, decreasing levels of a receptor that filters out LDL (bad) cholesterol. When the scientists gave mice both rice and a chemical to block the microRNAs, their levels of that receptor returned to normal---showing that the microRNAs weren't just swimming through the blood stream, but acting on genes in the animals' cells."

This seems like a pretty big deal. Also, this commend from Slashdot jumped out at me....

Guppy writes I'm going to have a hard time believing this, until we get a couple more labs to replicate the findings.

Just about every animal on earth, including us, produces copious amounts of RNAse, an enzyme that shreds RNA molecules. And while most enzymes are rather fragile, RNAse is unusally robust -- you can boil some RNAses for hours, and they will retain their activity. They're everywhere, on your skin, in your body -- and it's a pain in the butt when you're working with RNA (you put RNAse inhibitors in everything to keep them from chewing up your material).

It's almost as if it were being produced as some kind of defense mechanism against... hmm....

[Worm Rider]

This is the awesomest thing I've read all day. So, we knew that chemicals in our food affected our physiology. However, we did not know that some of these chemicals could do this at the level of regulating our gene expression. This makes genetically modified food a bit scarier. This also points out how shitty our knowledge of nutrition is. However, we don't need to know everything about nutrition to know that it is always a good idea to eat raw fruits and vegetables. Chances are good these things are doing you more good than harm, just like the trillions of bacteria that live in and on your body. Also, this indicates that you need to eat not simply to supply calories for cellular respiration, but also to supply regulatory molecules for proper genetic expression. I'm going to to way out on a speculative limb and say maybe americans are obese because of a lack of fruits and vegetables to properly regulate expression of genes. Perhaps hunger signals are tied to these microRNA's, and if you don't get them you tend to eat way too much. Perhaps not getting enough microRNA's makes you stupid and fat.

[Kai]

http://science.slashdot.org/story/11/09/21/2251238/what-you-eat-affects-your-genes

purkinje writes "Tiny bits of genetic material, called microRNAs, can make their way from the food you eat into your blood stream, and change how your genes are expressed, according to a new study. A team of Chinese scientists found tiny bits of white rice microRNA floating around in people's blood after a meal. When they looked at what was happening on a cellular level, they found that the microRNAs were changing gene expression, decreasing levels of a receptor that filters out LDL (bad) cholesterol. When the scientists gave mice both rice and a chemical to block the microRNAs, their levels of that receptor returned to normal---showing that the microRNAs weren't just swimming through the blood stream, but acting on genes in the animals' cells."

This seems like a pretty big deal. Also, this commend from Slashdot jumped out at me....

Guppy writes I'm going to have a hard time believing this, until we get a couple more labs to replicate the findings.

Just about every animal on earth, including us, produces copious amounts of RNAse, an enzyme that shreds RNA molecules. And while most enzymes are rather fragile, RNAse is unusally robust -- you can boil some RNAses for hours, and they will retain their activity. They're everywhere, on your skin, in your body -- and it's a pain in the butt when you're working with RNA (you put RNAse inhibitors in everything to keep them from chewing up your material).

It's almost as if it were being produced as some kind of defense mechanism against... hmm....

The actual paper for this is here: http://www.nature.com/cr/journal/vaop/ncurrent/full/cr2011158a.html

The methods are pretty standard. Exogenous (meaning, from outside the body) MicroRNAs were detected in human serum (blood without rbcs and coagulants), they were sequenced, and determined to be in a variety of different plants in the Chinese diet (because the serum was from Chinese men and women). Feeding mice in a before and after experiment determined that these are not being manufactured by the organisms and result from feeding. So, this establishes that the microRNAs are of plant origin and are in our serum due to feeding.

Now, here's where it gets more tricky for me to understand and explain. The hypothesis is that these exogenous microRNA can act as activators for RNA interference (RNAi). RNAi is one of the most important defense mechanisms that organisms have. Basically, doublestranded RNA is created, cut up into little bits of microRNA by the enzyme DICER, and binds to a molecule called RISC. Whenever RISC finds an RNA that matches the microRNA, it tears that RNA up. Still with me? The kicker is, the RNA strand has to very closely match, in sequence, the microRNA for it to work as RNAi.

So they searched around in genomics to find a gene that would match the microRNAs they were looking at. And the best match was from a portion of a gene that breaks up and exports low density lipoproteins from the circulatory system, called LDLRAP1. LDL is a cholesterol based lipid transport unit, meaning it moves fats around in the body, but because of it's low density it comes out of solution easily and is a primary cause of arterial plaque and high blood pressure. What the results section is suggesting is that one of the plant microRNAs did function to cut up LDLRAP1 RNA in living culture and decrease it's expression. They also show that the exogenous RNA could be taken up by the cells of the intestinal lining. And furthermore, they showed that continued uptake of this particular microRNA in mice leads to elevated LDL levels.

So, seems sound to me, at least in concept. I'm not very familiar with the cellular or molecular methods. As for the new hypotheses posed in the discussion section, I really am out of my league with this stuff. All I can say is, if the authors have done what they claim, they've found that exogenous short chains of RNA can actually enter blood serum and cells, and can function in RNAi complexes if there is a close sequence analogue present in the corresponding genomes, and of course (since RNAi changes levels of gene expression by cutting up the middle man) this causes corresponding changes in the corresponding gene expression. This is not, I repeat, NOT the time to run around saying that Chinese diets cause high LDL cholesterol, or that rice is bad for you, but it does strongly suggest a pathway for how diet can effect gene expression.

[Kai]

Nor is it the time to start talking about GMOs. ALL domestic plants and animals are genetically modified. We as humans have been doing active genetic manipulation for the past 10,000 years. There is no escaping it. If you want to talk the harmfulness of genetically modified organisms, you have to pose a specific organism and a specific reason. Note: there are actually very few types of GMOs (i.e. those with laboratory gene insertions) on the market, the main ones being Roundup Ready and Bt. The only difference between those and any other regular old crops is a single gene insertion that means the plant manufactures a pesticide or herbicide, which may of course have harmful effects, but because we're eating pesticides or herbacides, not because of some other pathway. Just wanted to point that out.

[Mesozoic Mister Nigel]

I thought the main concern with GMO plants is the inevitable pollen drift, and the long-term effects of insecticidal plants on pollinator biology, as well as concerns about terminator pollen (which I know has been a reported problem).

Not just eating it.

[Kai]

I thought the main concern with GMO plants is the inevitable pollen drift, and the long-term effects of insecticidal plants on pollinator biology, as well as concerns about terminator pollen (which I know has been a reported problem).

Not just eating it.

I was just responding to a statement by P_M. For Bt crops, yes, pollen and other plant debris effects on insect pollinators and other insects is the main concern, not human health. Not so for Roundup Ready crops. I believe you posted some evidence of birth defects tied to RR crops before.

[Mesozoic Mister Nigel]

I thought the main concern with GMO plants is the inevitable pollen drift, and the long-term effects of insecticidal plants on pollinator biology, as well as concerns about terminator pollen (which I know has been a reported problem).

Not just eating it.

I was just responding to a statement by P_M. For Bt crops, yes, pollen and other plant debris effects on insect pollinators and other insects is the main concern, not human health. Not so for Roundup Ready crops. I believe you posted some evidence of birth defects tied to RR crops before.

Oh, gotcha now!

[Triple Zero]

I thought the main concern with GMO plants is the inevitable pollen drift, and the long-term effects of insecticidal plants on pollinator biology, as well as concerns about terminator pollen (which I know has been a reported problem).

Not just eating it.

I thought the really main main concern is that Monsanto corp is a bunch of evil fucks. Not a very biological or scientific reason, but would it be fair to say that concern might actually pose a greater health danger than GMO ?

That, and plants that are genetically modified with quantum nanotechnology. I mean, quantum is good, right? But nanotech is bad.

[Worm Rider]

You're right, kai, the GMO thing is off topic. How else would we get glow in the dark kittens?

[Mesozoic Mister Nigel]

You're right, kai, the GMO thing is off topic. How else would we get glow in the dark kittens?

You plan to eat kittens? 

[Kai]

You're right, kai, the GMO thing is off topic. How else would we get glow in the dark kittens?

I didn't know you were /eating/ kittens. You monster.

[Triple Zero]

If they were in the supermarket next to the chicken, I'd totally eat kitten, I don't see why not.

I'd get the non-glowing variety though, because it's bound to be cheaper.

[Cain]

Oh like none of you have eaten kitten before.

You may know it by its street name "number 42, sweet and sour chicken".

[Don Coyote]

Oh like none of you have eaten kitten before.

You may know it by its street name "number 42, sweet and sour chicken".

There was a chinese restaurant across the street from a veterinary hospital in a city I used to live in.

[Mesozoic Mister Nigel]

I know the racism behind Chinese/Asian pet-eating jokes is so deeply entrenched that most people don't even recognize it as racism, but there's an excellent book on the subject called "Chop Suey". http://www.amazon.com/Chop-Suey-Cultural-History-Chinese/dp/0195331079

Impoverished Chinese will, as impoverished people always do, eat anything that has nutritional value and will keep their family alive.