Retired Stanford professor and West Tisbury resident Paul Levine will contribute this regular column devoted to scientific research taking place today, along with profiles of the Island’s scientists and their work and facts of scientific note on the Island.
Remember last summer’s invasion of jellyfish? There have been other invasions in the past, including those by the Portuguese man-of-war, but this beast, the small, clinging jellyfish known as Gonionemus vertens, with its vicious and venomous stinging tentacles, has come to painful prominence in our summer waters (see MVTimes story: bit.ly/MVTtinyJelly), leaving its victims with a variety of ill effects that include respiratory failure, partial paralysis, and other symptoms.
Before we condemn this small gelatinous jelly and others of their ilk, consider this: Those sticky, stinging tentacles were recently behind the idea for the synthesis of nanoscale “tentacles” that can be used to isolate certain kinds of cancer cells. This is just one of many laboratory-created biomimics by what Vineyard summer resident Donald Ingber, director of the Wyss Institute at Harvard Medical School, calls biologically inspired engineering.
But before I tell you more about jellyfish and biomimics, I must tell you about biological mimicry in the real world. Take the praying mantis, for example — that master of camouflage who, through its evolution, has come to mimic flowers, green leaves, and brown branches. Another is the peppered moth, which avoids predation because its color and pattern can mimic the bark of several kinds of trees.
One of the most interesting examples of mimicry is between the lookalike monarch and viceroy butterflies. Both are avoided by predators because each of them taste bad; the monarch, because its milkweed diet contains toxic glycosides that make it unpalatable, and the viceroy, because its diet of willow leaves that contain salicylic acid makes it taste terrible to its predators. Mimicking each other seems to double their chances of being avoided by prey.
The science of biomimicry seeks examples in nature that can serve as models not for defense but for useful functions. So let’s return to the jellyfish. The isolation of certain types of cancer cells that circulate in the bloodstream may allow the early identification of the disease, and also lead to the possibility of choosing the appropriate therapy to prevent its spread.
Because the number of these circulating cancer cells is small, most methods for their detection require relatively large volumes of blood. However, scientists at Brigham and Women’s Hospital Regenerative Medicine Center in Cambridge, and colleagues at other institutions, have developed a method that requires only about seven microliters of blood (equivalent to 0.0002 fluid ounces). They made nanofibers that mimic the sticky tentacles of jellyfish and coated them with a piece of DNA that sticks to a protein specific to the surface of leukemia cells. The fibers were placed in channels in a nanochip about 100,000 times smaller than the width of a human hair.
When the miniscule amount of blood suspected of containing leukemia cells was allowed to flow through the channels, the cells stuck to the fibers in a way that is analogous to the way prey stick to jellyfish tentacles. Further research may lead to using this technology to capture and identify other types of circulating cancer, all thanks to the much-maligned jellyfish.
If you have ever harvested mussels at any one of a number of places around our shoreline, you know how tightly they adhere to rocks and pilings, but have you ever thought about the composition of the fibers by which the mussels attach? It turns out that these fibers, called byssal fibers, attach by way of a protein called mussel adhesive proteins, or MAPs.
It has occurred to bioengineers that MAPs might have a practical application in medicine — for example, as an adhesive molecule for suturing wounds or incisions, thus reducing the risk of infection and inflammation that can occur from using stitches or staples.
Bioengineers have discovered that MAPs can be used to attach insulin-producing islet cells to the liver, thus providing diabetics with a constant supply of the optimum amount of insulin. It has also been discovered that MAPs can be used for the reattachment of ruptured fetal membranes and thus prevent premature birth. Added to the use of MAPs in medicine are the many examples for its industrial use where adhesives are essential. Give all this a thought when you next sit down to enjoy your moules marinière.
Biomimicry also finds sources of ideas for practical application in plants. Velcro fasteners are one of the best examples, modeled after the seed covering of the burdock plant. In 1948, when the Swiss engineer Georges de Mestral was on a hunting trip in the Alps, he happened to walk through a field of burdock, and emerged to find burdock seeds sticking to his trousers and to the fur of his hunting dog. When he returned home, he placed a seed under a microscope, and saw that their coats were covered with hooked-shaped barbs. Knowing that the seeds bound reversibly to clothing by their barbs, he developed two materials, one of hooks and one of soft loops that interacted just like the burdock barbs and the soft loops in clothing. He went on to develop two materials that could be used as fasteners that could be opened and closed hundreds of times.
Although not intentionally a biomimic, it is interesting that asphalt roofing shingles are laid overlapped in a pattern that mimics the cup scales of acorns.
The examples of mimicry and biomimicry that I have described here are only a few of many, and we can believe that there are many examples of mimicry in the natural world waiting to be noticed by the bioengineers of the future. To learn more, go on the web to TED Talks and search “biomimicry.” Also read “Biomimicry: Inventions Inspired by Nature,” by Dora Lee, published in 2011.
And when you take your next walk in the woods or along the beach, keep your eyes out for the next animal or plant to mimic for a useful purpose. Perhaps you will be as fortunate as de Mestral with his Velcro.