A Blog by Carl Zimmer

The Quantum Earthworm

When things get small–like millionths-of-an-inch small–they get very interesting. The ordinary rules of physics we’re used to fade back as the oddness of quantum physics looms large. Engineers have taken advantage of this fact by fashioning tiny bits of matter, known as quantum dots, that behave in all sorts of useful ways. For example, quantum dots made from cadmium telluride will respond to ultraviolet light by giving off a flash of visible light–the color depending on their size. If you attach certain molecules to cadmium telluride quantum dots, they will latch onto certain targets, making it possible to detect trace amounts of substances ranging from pesticides to cancer cells.

As versatile as cadmium telluride quantum dots are, however, they’re not easy to make. It’s especially tedious to fashion them so that they’re not toxic to living cells, since both cadmium and tellurium are nasty metals. In the latest issue of Nature Nanotechnology, a group of scientists at Kings College London offer a remarkably easy way to make them.

In earthworms.

The scientists started with some dirt, into which they mixed cadmium chloride and sodium tellurite. Then they dropped earthworms into this polluted soil. The earthworms did what earthworms do: they sucked the dirt into their mouth and pushed it down the length of their bodies, digesting the nutrients and excreting waste out their back ends.

After eleven days, the worms were still happily grazing through the dirt, despite its Superfund-scale pollution. The scientists cut the animals open and searched for metals inside their bodies. They found that the cadmium and telluride the worms had eaten had broken away from their original molecular partners and had combined into cadmium telluride. In other words, the worms had manufacture quantum dots.

When the scientists flashed the dots with ultraviolet light, they gave off a green glow. The worm-fashioned quantum dots played nicely with living cells, the scientists found. They could use the dots to make cancer cells shine amidst a background of ordinary tissue.

Cancer cells glow green with quantum dots made by earthworms. (The blue is from a dye that stains the nuclei of cells.)

There are many things to marvel at in such a study. We can imagine engineers harvesting quantum dots from giant earthworm farms and not be considered mad. But what I marvel at most of all is the fact that the earthworms were naturally so well prepared for the challenge. They have evolved to be underground alchemists. After all, when you make a living eating dirt, you have to be prepared for all sorts of unexpected nastiness.

Earthworms can sense metals in their meals. They immediately respond by making special enzymes. Exposing a worm to cadmium, for example, causes it to produce enzymes called metallothionein in its gut. The metallothionein grabs hold of the cadmium and stores it away in special cavities inside the cells, where it undergoes chemical reactions to make it less dangerous to the worm. Then immune cells attack the cells and engulf them. The worm eventually excretes them safely out of its body.

When scientists began decipering the chemistry that the worms use, their first idea was to enlist worms to clean up heavy metal pollution. That turned out to be a failure of the imagination. It may be that in the realm of nanotechnology, earthworm may truly shine.

[Worm engraving: Florida Center for Instructional Technology]

16 thoughts on “The Quantum Earthworm

  1. It is absolutely breath taking how the Lord developed the world and the universe. How can anyone logically thinking come up with the idea that it just all happened by chance.

    [CZ: Evolution is not chance.]

  2. @Tom what Carl said is correct of course, but I think ‘chance’ is much more logical than invoking some kind of supernatural agent.

    1. I am not referring to supernatural. Try to think logically and mathematically. If you do it with open mind and proper chance mathematics, then a development of life forms etc. is not an option it would not ever happen. it is not “scientifically” acceptable to say, however the only logical answer is God’s work.

  3. @tom, I can see that my reference to a “supernatural agent” was misunderstood. But you used the term ‘Lord’ first.

    1. Yes, you are right, however my gripe is with people who claim that all o9n earth and in the universe happened “by itself”.

  4. Tom you are referring to the supernatural because God is a supernatural concept.

    And we’ve *seen* natural selection happening in decades long studies of micro-organisms. Its not “just an opinion”. Its something we know happens and we know happened in the past.

  5. Bringing in the ‘God created it’ opinion, coupled with the ‘logically thinking’ into the discussion is an unjustified use of an oxymoron! .. Most often in these back and forth arguments is the lack of apprecialtion for how much time is involved in 3.8 billion years of evolution….a process proven time and again by new age science. Suffice to say, hope will always be trumped by undeniable science but will always be respected by both sides…and so it goes.

    1. I’m happy to agree not to agree, however I cannot agree with the term oxymoron in this context as I KNOW that science and God created it is fully compatible even though some people do not see it.

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