Just Google nudibranchs to find the most remarkable collection of diverse animals–all variants on the sea slug, a mollusk that lost its shell. A good example of degenerative evolution, followed by morphological innovation. At left creeps Chromodoris annae, from the collection of Sergey Parinov. Why all the bright colors? Most nudibranchs have evolved nasty-tasting substances in their skin; and the colors warn predators to back off. Some nudibranchs go farther, displaying the nematocyst stinging cells from aneomones they munch on. The nematocysts last enough to protect the nudibranch (after failing to protect the anemone? Hm.)
At right, though, the “solar-powered sea slug” Placida dendritica gets its color from the chloroplasts of digested algae. The sea slug ingeniously manages to digest only the algal cytoplasm, while leaving the chloroplasts intact for months, conducting photosynthesis.
Imagine what Popeye could do if he digested only spinach cytoplasm, while storing all the chloroplasts–Solar-powered muscles!
Have a good holiday, whether turkey or tofurkey is on your table.
Much of the world’s great outdoor art, especially marble statuary, is dissolving away through acid rain. And some microbes help it along by making acids.
But certain microbes actually consume the acids that deposit on the statues. Micro4Art is a new “product” composed of sulfate-reducing bacteria. The bacteria use sulfate (part of sulfuric acid) as an oxidant which they “breathe” instead of oxygen. They use the oxidant to respire on lactate (weak-acid product of sugar), a process yielding energy for the bacteria. So if you apply the bacteria plus lactate onto the black crusted statue, they will take the electrons and hydrogens from lactate, and combine them with sulfate to form water and hydrogen sulfide. These products evaporate or wash away.
Another story shows dramatic results in a Florentine cemetery, where sculptures of draped skulls were restored. The bacteria used are Desulfovibrio vulgaris; a microbe with a poor reputation from aquatic environments where they corrode metal, and from causing possible imbalance in the intestines of autistic children. But used in the right place, these bacteria may salvage many historical artworks.
Within an evolution lab in the shadow of the Ohio State Stadium, an NSF-sponsored group of academics and computer scientists assemble to grow the latest branches of the Tree of Life. Branches range from diatoms to dragonflies. The energy level is high. An opening session on “Learning to Detect Basal Tubules of Nematocysts” draws a stadium-worthy cheer: “The nematocyst is awesome! The most complicated thing any cell makes!” A nematocyst is a jellyfish cell that discharges a harpoon-like barb extending a basal tubule through which the cell injects venom. The visualization program, we hear, detects 60% of basal tubules in the images, and 62% of the detected tubules are correct. Exclamations of joy. “That’s even better than—an undergraduate!”
The program combines crowdsourcing (of undergrads, museum goers, etc.) with visualization tools and matrix algorithms to grow a database of everything out there, all life. One major project compiles the teeth and skulls of bats. Another group images plant leaves–the plants of North America, and the plants of China. And of course the microbes—those will come through our own MicrobeWiki. We are working with Lisa Moore at U. Southern Maine to have our classes compile the Bacteroidetes, a group of intestinal and soil bacteria that break down amazingly complex plant molecules in our gut.
Down the road, one wonders. The number of bacterial species is literally infinite. Many bacteria have open pangenomes, that is, genomes capable of incorporating an infinite variety of extra genes. Actually, on a sufficiently long timescale even our one human species has an open pangenome. And once our lentivectors get started engineering us, look out. Meanwhile, like NASA rovers rising into space, the Tree of Life project carries on.
All that plastic you’ve heard about in the North Pacific Gyre–where does it go?
Barnacles seem to eat it, according to Miriam Goldstein and Deborah Goodwin. The figure shows (A) barnacles growing all over a buoy, (B) a barnacle closeup, with its shell and muscular peduncle; (C) bits of plastic isolated from the barnacle’s gut.
Do barnacles actually digest the plastic, and obtain nutrients from it? That’s hard to say without long-term studies. Plastic does get degraded by bacteria, albeit slowly. If the barnacles do incorporate plastic into their biomass, what about toxins? What about predators that eat the barnacles? This could go up the food chain. On the other hand, with all the plastic ending up in the ocean, perhaps this will be a necessary part of the ecosystem. We may have to engineer ourselves to get used to it.
The Helix and the Hard Road presents my Wiscon interview with Mike Levy, as well as a long out-of-print piece about my first book sale back in 1979. (Quaker meets publisher–a story in itself.) Available from Aqueduct Press, the full book also includes lovely poetry from Jo Walton. My portion is now here for free (with permission) but you can help support Wiscon by purchasing the full version in print.
Once in a while we meet a neighbor creature we didn’t know existed. This praying mantis appeared tonight on our house door, at least four inches long. Its belly was emerald green, and its eyes two shiny black balls. Mantises are voracious predators; they usually capture other insects, but are known to catch lizards and even snakes.
In the past, when the Earth was warmer and oxygen levels much higher, insects grew as large as seagulls. Who knows, with impending climate change insects may once again rule the Earth.
MUST see–Smart self-assembling M-blocks that jump over each other to build a larger structure.
Daniela Rus and her students at MIT designed robotic cubes with no external parts. Inside each cube is a flywheel that throws its weight around, generating angular momentum. The momentum propels the cube in a programmed direction. But the cube has a magnet on each edge. So the edges connect, while the cube roles over and snaps into place. Or else it can jump two blocks away to snap down.
In principle, the cubes could possess their own instructions and assemble themselves into a much larger structure.
Rus is the director of MIT’s Computer Science and Artificial Intelligence Laboratory. Her group builds robots “that can tend a garden, bake cookies from scratch, cut a birthday cake, fly in swarms without human aid to perform surveillance functions — and dance with humans.”