Friday, January 27, 2006

The Enemy of My Enemy is My Friend.

This maxim holds true in most parts of the world, including the plant and animal kingdoms. One of the really fascinating things about biology is the complex relationships that organisms develop with their environment, including the neighboring organisms with whom they share a common habitat.

Lest you think I’m engaging in anthropomorphism applying this saying to organisms other than humans consider the relationship between
Spodoptera littoralis,













Cotesia marginiventris,
and Zea mays.

In my opinion, that saying is a perfect summary of their relationship.

Spodoptera littoralis is a pest of many plants including corn. Adult females like the one pictured above lay their eggs on a wide variety of plants. When the larvae emerge they begin eating the host plant that their mother has chosen to be their meal. Plants being sessile, insentient, and generally lazy for that matter ;-) can do nothing to stop the attack by the hungry larvae and are eaten alive! Oh, the horror!

But, remember, plants have been on this planet for a mighty long time. And they wouldn't have lasted this long without a trick or two up their sleaves. One of those tricks is the production of secondary metabolites that can do a range of things such as make them taste bad to their insect attackers (not something we want to encourage in our crop plants), or those secondary metabolites can serve as a signal to other organisms that: "dinner is served". When corn plants are eaten by lepidopteran larvae (moth and butterfly catterpillars), they release a complex mixture of volatile compounds. These compounds attract the adult females of parasitic wasp species such as C. marginiventris.

These parasitic wasps attack the larvae and lay a single egg in the posterior of the catterpillar.
When the wasp egg hatches, the wasp larvae burrows inside the caterpillar's body and begins to chow down on the tasty parts inside. After the wasp larvae has eaten its fill, it burrows out of the caterpillar and forms a coccoon attached securely to the caterpillar's back, in which the wasp will pupate.

This takes about 7 to 10 days for C. marginiventris.

As you can see, the whole process leaves the caterpillar somewhat worse for wear.













This exit hole only tells part of the caterpillar's the tale of woe. Most of its internal organs have been eaten by the wasp and it will die in one day.

Now, scientists have identified the particular compound that attracts this wasp to corn plants that are being attacked by insect herbivores. And they have identified the single gene in corn that is responsible for producing this chemical distress signal, or dinner invitation depending on your point of view! The gene is a terpene synthase gene, tps10, which produces "(E)-beta-farnesene, (E)-{alpha}-bergamotene, and seven additional sesquiterpene hydrocarbons" in response to lepidopteran herbivory. When this gene was transferred into the model plant Arabidpsis thaliana, it produced the appropriate sesquiterpene compounds and served as an indirect defense of Arabidopsis against insect herbivory.

Interstingly, response to the sesquiterpenes produced by TPS10 appears to be a learned behavior in C. marniventris:
Indeed, females of this species are initially not attracted to these typical induced plant signals (18) but appear to exploit them as host location cues only after associating them with the presence of hosts during an initial oviposition event (19, 20).

The associative learning ability of C. marginiventris is a critical element of this tritrophic interaction, because parasitoids without oviposition experience were not significantly attracted (18). Because TPS10 products are the only sesquiterpene hydrocarbons specifically emitted after herbivory by lepidopteran larvae, they provide a very reliable cue to the parasitoid. Other hymenopteran parasitoids rely less strongly on learning and may employ more innate responses for host finding (19, 20).
"The enemy of my enemy is my friend." This is said to be an Arab proverb. How fitting then that the common name of Spodoptera littoralis is the Egyptian Cotton Leaf Worm.

The products of a single maize sesquiterpene synthase form a volatile defense signal that attracts natural enemies of maize herbivores

Christiane Schnee *, Tobias G. Köllner *, Matthias Held {dagger}, Ted C. J. Turlings {dagger}, Jonathan Gershenzon * and Jörg Degenhardt *, {ddagger}

*Max Planck Institute for Chemical Ecology, Hans-Knöll Strasse 8, D-07745 Jena, Germany; and {dagger}Laboratory of EvolutiRoundrock Journalonary Entomology, Institute of Zoology, University of Neuchatel, Emile-Argand 11-CP2, CH-2007 Neuchatel, Switzerland

http://creatures.ifas.ufl.edu/misc/wasps/cotesia_marginiventris.htm

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Update: The Circus of the spineless is up at Pharyngula. Apparently ,it is really for anything without a spine. I had thought it was just about invertebrates. Lots of good entries, I particularly like this magnificent Agrobacterium tumefaciens Crown Gall tumor submitted by Roundrock Journal.

Thursday, January 26, 2006

Is That a Frog in your Fence Post? Or...

So, a while back, I was delivering some compostable materials to my compost pile, when I happened to look down the pole for the chain link fence dividing my yard from my neighbor's, and what do you think I saw?

At first, I thought it was some kind of alien, you know, like Yoda. All I could see was two beady little eyes looking up at me from a little green face (I used the flash to take the picture so your view is a lot better than my first glance was.)


Turns out, instead of an alien Jedi Master, it was the aptly named Green Treefrog, Hyla cinerea, you can just barely see the white lines on either side of the jaw-line beneath the eyes. As it turns out the chorus is a familiar sound in my back-yard as well. While I personally was surprised to suddenly find this specimen in my fence post, if I had been looking for Green Treefrogs this is one of the first places I should have looked. Ecologists and other researchers studying frogs have used PVC pipe as a sort of open-ended trap for localizing and counting treefrogs. Turns out it's cool, moist, and quite safe in there. (I tried to catch this one to show the kids by reaching my finger down the pipe and guess what?... the little bugger was just below my reach! How about that?)

I checked back the next day and he was gone. I'm glad he stayed long enough for me to get the camera and take this picture!

Posted to the Friday Ark.

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Sunday, January 22, 2006

Paleogenomics, the Future of Evolutionary Biology?

Last month, scientists sequenced 28 million base pairs of DNA from the genome of Mammuthus primigenius, this DNA was was found to be 98.5% sequence identical to that of Loxodonta africana. Interestingly, the wooly mammoth appears to have diverged from the Asian elephant more recently than Asian elephants and African elephants diverged from their common ancestor. All three shared a common ancestor about 5 to 6 million years ago.

The DNA from one sample, extracted from Mammoth bones frozen for 27,740 years in Siberia, was surprisingly intact and free of other (fungal, bacterial, or human) DNA contamination, indicating that it would be possible to sequence the entire nuclear genome of the woolly mammoth using such samples.

"To find the ideal sample and analytical approach for paleogenomics, we screened eight of the morphologically best preserved mammoth remains in the collections of the Mammoth Museum, a dedicated permafrost ice cave facility in the town of Khatanga in the southeastern part of the Taimyr Peninsula, Russian Federation, and maintained by Cerpolex/Mammuthus Expeditions (CME)."
Although ancient DNA such as this is always degraded due to breaks in the phosphodiester backbone of the DNA and chemical alterations of the DNA bases, the extreme conditions under which these mammoth bones were preserved, -10 C, slowed down the rate of chemical alteration and degradation of the DNA. Additionally, using PCR to amplify the DNA for sequencing would avoid some of the degraded DNA strands because they are unsuitable for complete amplification. This would allow the PCR reaction to selectively amplify the more intact molecules.

From the paper:
"Recently, a whole-genome approach was attempted from DNA of the extinct cave bear Ursus spelaeus, yielding È27,000 bp of endogenous genetic material from 1.1 to 5.8% of all DNA reads (29). We have produced 13 million bp of endogenous genetic material from 45% of all DNA reads, some 480 times as much DNA sequence and 15 times the percentage. The ability to obtain this level of genetic information from extinct species makes it possible to consider detailed analysis of functional genes and fine-scale refinement of mutation rates. A rapid identification assay of single nucleotide polymorphisms (SNPs) would be of great value for studying population genetics of Pleistocene mammals and plants, which in turn could help elucidate their responses to climate changes during late glacial and early postglacial time and ultimately shed new light on the cause and consequences of late Quaternary extinctions.

The woolly mammoth isn't the only extinct species whose genome is receiving such close attention. Initial experiments using nuclear DNA extracted from Cave Bear fossils, which are similar in age and preserved under similar conditions to Neanderthals, have suggested that a Neanderthal genome project might be successful.

The ability to reference ancient genomes as benchmarks would be a powerful tool for evolutionary biologist to study how species have changed over time, and perhaps to determine some of the genetic differences between us and our Neanderthal cousins that has allowed us to prosper while they perished.

Speaking of mammoths: This is an AWESOME fossil!

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Monday, January 16, 2006

Wild 2's "Cosmic Bootie", Stardust Probe Returns

Update: Video of Stardust's 29,000 mph reentry is here. It sort of became a comet itself!
"Already got scientific results which is great!" -- The very first particle examined is a transparent mineral grain settling discussions about whether comets do indeed contain minerals, glass, etc.

Opportunity!: The interstellar dust (not the comet tail dust) collected in the Stardust Interstellar Dust Collector is extremely small, and only about 45 specimens of interstellar dust (the dust that served as the building blocks for our solar system) are expected to be found in the SIDC's one square foot of aerogel. The collector must be searched with a high magnification microscope with an operator focussing up and down through planes of view, the only way to do this in a timely fashion is to recruit volunteers to search the collector on their home computers.

"The job is roughly equivalent to searching for 45 ants in an entire football field, one 5cm by 5cm (2 inch by 2 inch) square at a time! More than 1.6 million individual fields of view will have to be searched to find the interstellar dust grains. We estimate that it would take more than twenty years of continuous scanning for us to search the entire collector by ourselves.

That is why WE NEED YOU. Volunteers are absolutely critical to the success of this project."


You can pre-register here to help out and if you find an interstellar dust particle, your name goes on the scientific paper announcing its discovery. You'll be a co-author on a very important scientific publication.

(Getty Images)

The Stardust space probe’s capsule, containing samples of dust particles collected from the tail of the comet Wild 2, referred to as "Cosmic Booty" by NASA, returned to earth on Sunday. NASA says that after travelling 2.88 billion miles, collecting samples of the comet’s tail, snapping a few photos, and re-entering the earth’s atmosphere at 29,000 miles per hour (the fastest re-entry ever by a man-made object) the mission is a complete success.

The Stardust space probe was launched seven years ago to make a close fly-by of the comet Wild 2. In 2004 the probe approached to within 150 miles of the comet and returned these stunning images that have changed ideas about the structure of cometary nuclei.

(stereo-image-- look "through" the image so that both sides merge into one 3-D image)

In the case of Wild 2 the nucleus appears to be a solid object rather than a collection of rubble held together by gravity, which was the prevailing view of comet nuclei prior to the Stardust mission. These images also show the presence of impact craters on the comet’s surface in addition to sublimation pits due to the sublimation of ice into gas as the comet is heated during its approach towards the sun.

(NASA, JPL, CalTech)
This sublimation, observed by the Stardust probe as the gas jets released from the comet in the photo above, ejects particles from the comet that follow along behind it and create the comet's tail. Collecting these micrometer sized particles was the main goal of Stardust's mission. A time of flight mass spectrometer aboard the spacecraft analyzed the makeup of 29 particles that were encountered as the probe passed throught the comet's tail. These particles were primarily organic compounds some containing nitrogen and sulfur. Interest in these particles of cometary debris stems from the fact that comets are the left-over material from the formation of our solar system. As Llorca poetically puts it:
"Like a carpentry shop littered with wood shavings after the
work is done, debris left over from the formation of the Sun
and planets is scattered throughout the inner solar system
in the form of asteroids."
As such, they truly are stardust from stars exploded long ago. Analysis of the chemical components of these particles can tell us a great deal about the materials that were present during the earth's formation and can even shed light on the origin of life on this planet by telling us what organic molecules were present and available through bombardment of the earth by comets and asteroids. Among the compounds observed in comets and meteorites are more than 70 different amino acids, at least three of the nitrogenous bases found in RNA, and a variety of 3 to 6 Carbon sugar related molecules.

The presence of these compounds at the formation of the earth, as well as the fact that these compounds are present in objects that continue to strike earth to this day, helps to answer questions about how the first biological macromolecules may have formed on this planet. Indeed, experiments replicating the effects of amino acid containing meteorites impacting the earth has shown that di- and tri-peptides can be formed during such impacts.

Although most comets are similarly ancient in age, Wild 2 is different in many ways than previously studied comets, such as Halley's, in that it only became a resident of the inner solar system about thirty years ago when Jupiter's gravity perturbed its orbit sufficiently to keep it from departing back to the outer reaches of the solar system. Previous to this close encounter with the King of the planets, Wild 2's orbit kept it in the frigid region of the solar system between Jupiter and Uranus, this means that Wild 2 is well-preserved because it hasn't suffered through numerous passages close to the sun which cause comets to sublimate and eject materials from their surfaces. (In many ways it reminds me of fossilized shark's teeth found along the beach in some areas. Teeth that have been washed against the shore are worn have lost definintion and important features. Teeth that have just been washed out of fossil beds are much more intact and show greater definition.) So Wild 2 is a particularly good comet to study because it still retains the composition and structure it had at the time of the solar system's formation. Today, Wild 2's orbit extends from outside the orbit of Jupiter to just inside Mars' orbit, and it complete its own orbit of the sun once every 6.39 years.



The most important part of Stardust's mission was collecting samples of dust particles from Wild 2's tail to return to earth for detailed analysis. These samples were collected in the lightest material on earth Aerogel a microporous material made of silicon dioxide but consisting 99.8% of air. Aerogel's porous nature allows it to slow and capture the particles that collide with it and it has excellent insulating capacity in addition to its light weight.

(NASA)
In addition to the comet dust, Stardust also collected interstellar dust on its way out to rendevous with Wild 2.

Welcome home Stardust! I look forward to seeing what treasures you have brought home from your travels.

http://www.usatoday.com/tech/science/space/2006-01-11-stardust-return_x.htm
http://t2stardust.jpl.nasa.r3h.net/home/index.html

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Friday, January 13, 2006

PZ Meyers' Immortal Soul Barbeque Sauce!


It's Great for dipping McNuggets and,... well,... anything you like to eat!!

(It's the best I could do with my meager photoshop skills. Inspired by Stubb's, which is actually pretty good!)

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Thursday, January 12, 2006

"Some pig", "Terrific", "Radiant", "Humble",

Mild-mannered slop-swillers by day,










Cancer fighting wonder pigs by night?

These pigs from Taiwan had the Green Fluorescent Protein gene from the jellyfish aqueora victoriana ?? transformed into them prior to implantation into their mothers. Three pigs were born out of 265 embryos used for transformation.

Researchers hope to use the pigs to study human disease. The green fluorescence of the pig cells will help distinguish pig tissue from human tissue in areas such as stem cell research.

Personally, I think we should find these guys a genetically engineered rat sensai? and put them to work fighting crime.


Porkabunga!!!

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Ten Years of Biotech Crops.

The number of hectares of farm land used to grow genetically modified plants grew by 11% in 2005. That's an increase from 200 million acres in 2004 to 222 million acres planted in 2005, 60% of that cropland were planted with herbicide tolerant soybeans.



The continued adoption of biotech crops in industrialized countries is not surprising and, frankly, means very little to me except that farmers continue to view biotech seeds as a good investment. There is little chance for the "escape" of transgenes for herbicide tolerance in Soy in a country like the US, or in most other areas of the world. However, the adoption of biotech crops in developing countries is a much more interesting phenomenon to me. Particularly in those countries where a significant portion of the population is suffering from undernourishment.



The map above (click to enlarge) shows the percent of total population that suffers from undernourishment. The map below shows countries who are major adopters of biotech crops:



Some "advanced" countries like the US, Canada, Australia, and Western Europe are major adopters of transgenic plant technology who have only small problems with undernourishment in their countries. The farmers in these countries are using biotech crops because they can make a profit by reducing losses to crop pests, or by eliminating weeds in fields that compete with crops for nutrients, water, and light. Countries like China and India suffer from major problems with undernourishment in their populations. In these two countries, the first and second most populous countries in the world, the promise of biotechnology is not an additional few cents per hectare of profit for farmers, it represents an increase in the amount of food people have to eat. With the population of India expected to reach 1.6 billion by 2050 and China's expected to reach 1.4 billion, the use of biotech crops in these countries is not an option, it is a necessity. There is land of poor quality in these countries that can be converted to farm land but this land will not be as productive as the best crop land that is currently under cultivation there, and every new hectare of farmland represents a hectare of environment and habitat destruction. Even a modest shift in diet in these countries from plant based foods to meat will seriously reduce the amount of food available for the poorest individuals in these growing economies. To feed the growing populations in these countries and elsewhere in the world, there is no choice but to glean more food from the land that is currently available.

I very seriously doubt that genetically modified foods alone can produce the needed increases in food production in these countries. And I am certain that the needed increases in food production cannot be acheived without the use of genetically modified foods.

"The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race. The vices of mankind are active and able ministers of depopulation. They are the precursors in the great army of destruction; and often finish the dreadful work themselves. But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague, advance in terrific array, and sweep off their thousands and tens of thousands. Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world." --Malthus

Malthus has been proven wrong in the past, I hope he can be proven wrong in the future.


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Houston, we have a problem...

In discussions about the science of Global Warming, the earth's albedo has become an increasingly important point of discussion. The earth's albedo is the ratio of solar radiation reflected by the earth to the total amount of radiation that reaches the earth from the sun. Clouds, the polar ice caps, forests, the oceans, deserts,... all contribute to the earth's albedo by absorbing or reflecting solar radiation. If sunlight is absorbed by a body, obviously it becomes hotter, if sunlight is reflected, by clouds for instance, that energy would not be available to heat the earth's surface.

Determining the albedo of an entire planet is extremely difficult, especially from the surface of that planet. Changes to the earths's atmosphere such as increased cloud cover caused by increases in evaporation due to elevated surface temperatures may counteract or even reverse the heating effects caused by increased atmospheric CO2. Pollution, snow and ice cover, desertification, and other human activities also effect the earth's albedo contributing to, or mitigating the effects of global warming. An accurate determination of the earth's albedo at present and measuring changes in the albedo is important to determining how much, or even whether at all global warming is occurring.

In March of 1998 a proposal to build and launch the "Deep Space Climate Observatory", the sattelite in the picure above, was offered and the planned launch was set for 2001. The satellite was designed to be positioned between the earth and the sun such that the gravity of the earth would be cancelled out by the gravity of the sun creating a stable surface to observe the sunlit side of the earth continuously,

"We could get an incredible set of data" of the impact of albedo on climate, says Robert Charlson, a climate scientist at the University of Washington, Seattle.

Delays and budget cut-backs forced back the launch date, the Columbia disaster in 2003 delayed launch again, and now further cutbacks have now grounded the project for good so that a largely complete, exremely useful (whether you accept global warming or not), multi-million dollar satellite will remain on earth.

Your tax dollars at work.

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The Lord works in Mysterious ways....

My sympathies to the Discovery Institute, I know how annoying this can be.

After the Kitzmiller verdict I feel bad about this. I really do! Because, you know, I can empathize with the guys at the Discovery Institute. I mean, imagine that you have your own little thing, let’s give it a name like, I don’t know... well let’s just call it science for now. Let’s say you’ve got this gig and you’re calling it science and you and your friends who “do” science and teach science all have a set of rules describing what science is, how it is conducted, what can and cannot be considered science,... and you all call yourselves “scientists” to distinguish yourselves as people who perform or use science, and then a bunch of guys come along and say:

“Hey! We’re scientists too! We have this concept called God that we use to explain the really difficult parts of our science.”

And you say “But that’s not science. That isn’t a scientific explanation.”

And they say: “Sure it is! You’re just defining science too narrowly. You need to expand the definition of science to consider things that God does...”

“But” you reply, “we’ve already defined science and we can’t use God as an explanation because we can’t control or repeat God’s actions.”

“Your definition of science is silly and incomplete. You need to include God! We’ll just give him a different name and nobody will notice.”

Well, I think you know where that can lead, a lot of hurt feelings, some name calling, mocking and ridicule, and that was just in the judge’s ruling! (ba-dump-bump)

Well it seems that the guys at the Discovery Institute are getting a taste of their own medicine today. No, not from the verdict, that’s probably wearing off by now, but it seems that a small school district in California has begun offering a course called “Philosophy of design” as an elective in philosophy. You’d think that would be a great place for “Intelligent Design”, I mean it being a philosophical and quasi-religious endeavor and not science and all. But it seems that the designer in this course isn’t quite intelligent enough for the guys at the DI. It’s just the God of Christianity. Casey Luskin, an attorney at the Discovery Institute, sent this letter to the school district’s Superintendent saying that creationism by God described in The Bible is not an example of Intelligent Design and that the school district should either:

1. Drop all the Creationist material in the course
2. Change the name of the course so as not to associate Intelligent Design with the God of The Bible
or 3. Discontinue the course

So, um... Karma, is that a scientific concept or what?

Because I think I just saw a mighty fine example of it.

("Spasibo" to the Commissar for pointing this out.)

Update: Ed Brayton (dispatches from the culture wars) points out that the Discovery institute has at least three contradictory reactions to the El Cajon class.

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