Thursday, June 18, 2015
  Cleansing the palate

While Antichrist Francine is busy smashing civilization, science and poor people, and infinitely enriching the rich, I'll focus instead on one newly published piece of REAL AND CONSTRUCTIVE SCIENCE.

Some neuroscientists and engineers at UTAustin worked together to find the exact neuron that senses magnetic fields. Using the standard nematode C. Elegans, they began with the general assumption: All living things use all available signals and gradients to find food, shelter and mates.

More specifically, C. Elegans is known to burrow downward when it's hungry and upward when it's full. It's still not clear exactly what the worm is seeking in those directions; presumably the better food is deeper and wetter, and the better air is upward, but that may not be the true motivation.

The researchers asked: Does the worm use magnetic fields as part of its navigation? If so, how?

A long series of experiments, carefully eliminating other variables like light, smell and static fields, showed that the worm does indeed follow magnetic fields, but not as expected. The preferred path is about 132 degrees away from the North-south line.

Why? Turns out that the standard lab populations of C. Elegans are all derived from one worm caught near Bristol in England. And it turns out that the angle to a vertical field matches the inclination (dip) of the earth's field at Bristol, so that the standard worm, when hungry, goes straight downward at Bristol.

The researchers picked up worms from various other places in the Northern and Southern Hemispheres, and in each case the orientation of the field was correct for the inclination at its native location. For each location, setting the artificial magnets to the same angle as the native angle made the worm go straight down when hungry, straight up when full.

Finally they pinned down the actual sensing to one neuron, which was already considered a likely candidate. The AFD neuron, which sits in the 'nose' of the worm, is also responsible for sensing temperature ahead of the worm. Mutants with this neuron missing, or worms with this neuron physically removed, didn't respond to magnetic fields.

What's not clear yet (or at least not published yet) is how this neuron works. I don't see any mention of iron compounds, which seem to be the main ingredient of magnetic sensors in other critters.

GOOD science.

How do I know it's good science? EASY. Carver. Look about you. Take hold of the things that are here. Let them talk to you. Talk to them.

In other words: No theories. Observe, ask Nature a question, and listen carefully to the answer.

Raises several new questions: How do the worms calibrate this neuron to the correct angle? Presumably there's some epigenetic adjustment in each generation. What happens when inclination changes quickly, as it has been doing recently (i.e. the most likely cause of the "climate change" that Antichrist Francine is satanically misattributing to human activity)? Are these worms and other magnetosensing animals having more trouble in locations with fast-changing inclination? The ADF neuron has lots of open-ended dendrites that resemble a beam-steering array. Do they work like that? Does the gene specify a matrix that effectively filters or rotates the input pattern from the dendrites? Finally, a little wilder: Since all genes are purpose, and all purposes are present in all living things, do all living things adjust their genes for inclination? Is this part of 'sense of place', part of why plants and bees and humans do better when they're not arbitrarily moved around?

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Polistra was named after the original townsite of Manhattan (the one in Kansas). When I was growing up in Manhattan, I spent a lot of time exploring by foot, bike, and car. I discovered the ruins of an old mill along Wildcat Creek, and decided (inaccurately) that it was the remains of the original site of Polistra. Accurate or not, I've always liked the name, with its echoes of Poland (an under-appreciated friend of freedom) and stars. ==== The title icon is explained here. ==== Switchover: This 2007 entry marks a sharp change in worldview from neocon to pure populist. ===== The long illustrated story of Polistra's Dream is a time-travel fable, attempting to answer the dangerous revision of New Deal history propagated by Amity Shlaes. The Dream has 8 episodes, linked in a chain from the first. This entry explains the Shlaes connection.

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