Genetically modified Atlantic salmon are getting closer to our dinner table. The AquaBounty Technologies company, that has bio-engineered the fish, has passed several approval hurdles with the FDA, such that the fish may soon appear in the marketplace, though a few additional hurdles remain before the green light goes on. The genetic engineering of the fish is ingenious. These modified Atlantic salmon contain a copy of the growth hormone gene from a Chinook salmon as well as a genetic “on-switch” from another fish that turns the growth hormone gene on. Normally salmon do not make growth hormone in cold weather, but the new genetic makeup produces growth hormone all year, allowing the fish to reach market size in eighteen months rather than the usual period of three years. These genetically-altered fish do not apparently get super-sized, but merely grow faster to reach their normal adult weight. The accompanying figure, taken from the front page of today’s New York Times, shows the size of age-matched genetically modified fish at the top and the normal salmon at the bottom. What a difference a gene or two in the right place can make! The modified AquaBounty salmon eggs will be sold to salmon farms only for commercial fish development. These animals are female only and they are also sterilized, so that even if they get loose in the environment, they are incapable of species propagation, at least that’s the hope.Print This Post
Here’s the quiz: two cheeseburgers are fat, juicy, smothered with cheese, accompanied by the same accouterments, deliciously presented and mouthwatering in appearance. They both have the identical number of calories, with one cooked as medium rare and the other is well done. So, do these two cheeseburgers provide us with identical caloric gains? Intuition says yes, right?
But, the answer is NO! The medium rare cheeseburger is actually less caloric to your body. The reason for this is simply that the part of the burger that is not completely cooked, contains proteins that have not been completely denatured and denatured proteins, because they “uncurl” are easier to digest. But, the uncooked proteins that remain in their native state, retain their complex foldings and twists which characterize their natural, tertiary (3D) structure (provided largely by hydrogen bonding between neighbor regions of amino acids that come near to one another). Those uncooked proteins require more effort on the part of your digestive system, more secretion of digestive enzymes and more time and activity within the gut in order to digest proteins in their natural state. That is why the development of cooking by our ancestor’s made their food acquisition task more efficient. You simply spend more energy digesting uncooked food because the tertiary structure of the proteins is harder to work on. As a result, the medium rare cheeseburger does not give your body the same number of calories as does the well done burger, because more energy is required to break it down and absorb all the calories–it eventually happens, but not before a greater part of the caloric gain has been spent on the energy of additional digestive effort. For proteins, this is not the only factor that reduces their net caloric value, because it also takes energy to convert ammonia to urea, which is a waste product for proteins that gets generated when we break them down into their amino acid constituents. Thus, the true caloric value of the food is the number of calories we swallow minus the number of calories we spend on getting the food digested and transported to internal sites for nutritional processing. Bijai Trivedi of New Scientist has a nice article on this topic, including a little interesting history of the topic.Print This Post
While the new swine flu epidemic is causing an appropriate level of alarm, more subtle aspects of environmental failure are beginning to surface, that, in the long run, will pose a more serious problem to our food supply and very likely escalate the cost of food. Europe is far more advanced than the United States in regulating the chemical industry and several herbicides that are toxic, such as Atrazine, have been banned from use in Europe, but are still used widely in the United States. It’s ironic that the research showing Atrazine’s toxicity (it gets in the ground water and causes feminization of male frogs–if it does that to frogs what does it do to our own reproductive functions?) was done here in the United States. But, under the Bush administration, the EPA approved the use of Atrazine for United States agriculture.
As I was scanning the paper this morning, mostly focusing on reports about swine flu, I came across a more obscure but troubling article. A report in the New York Times today points out that Europe, like the United States, has a major bee problem. The currently high level of bee mortality in Europe could permanently wipe out bees in that region within 8-10 years, according to Apimondia, an international bee organization. Last year alone about 30%, or more than 13 million of Europe’s bee hives died out. The loss of bee hives was much higher in some regions, reaching 80% in southwest Germany. This problem is potentially far more serious than swine flu, since about 35% of Europe’s food supply depends on pollination and no one pollinates as effectively as bees.
We have already heard about the bee crisis in the United States where mobile bee hives have been used for farm pollination for many years. In this brave new world of our farm economy, farmers pay for massive numbers of bees brought to their farms in trucks, where they are released, sting a few people, and then serve as pollinators for the region for a set period of time before the bee keeper moves on to his next contract. The near complete absence of local bees makes this arrangement a necessity. No magic bullet seems to explain the mounting decline of bee hives, either in Europe or the United States. The cumulative effects of mite infestation, pesticides and herbicides have been blamed for this crisis, but no simple solution or cure is available. The bees leave the hives to forage and pollinate, but they don’t come back. A colleague of mine working on the problem of bee vitality here at the University of Minnesota has concluded that the bees are simply stressed by too many excesses and over stimulation from their environment. One popular idea is that the stimulation by the chemical environment leads them to spend too much energy reliably identifying their to and from path and this stress leads to infestation with mites and an early death. But, stress is one thing, early death is another.
It is alarming to see that Europe is suffering from the same problem that we have here in the United States, since they have been better about regulating their chemical industry. Indeed representatives from Europe have appeared in this country giving lectures to major manufacturing establishments to tell them what chemicals they can and cannot use if they expect to export their products to Europe. And, they are all taking careful notes, because they can’t lobby their way into avoidance, like they do here. Fortunately for us, we are still enjoying benefits of a free market economy approach to the chemical industry–if it doesn’t smell too bad, go ahead and use it. I suppose what we need are large numbers of robotic bee colonies that only have to come back to their hives to get their little lithium batteries recharged. Would a robotic bee project be a suitable challenge for the summer students at MIT? Or, should we take a stab at a biological approach? Where is the genome of the honey bee when you need it most?
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