Monday, January 15, 2007

What's a gene gun?

One of my friends recently got a job at a lab where they are attempting to cure congenitally deaf mice using gene therapy/stem cells. Our conversation was abbreviated, but I think I understand the general theory - the scientists inject stem cells into the cochlea of baby mice. There the stem cells, guided by the cells around them, begin to differentiate, and grow into tiny hairs. These hairs sense sound vibrations and turn them into electrical signals to be delivered to your brain by nerves (in biospeak, they are the sensory transduction apparatus of hearing). The scientists also inject genes (with a gene gun!) to help tell the stem cells what to do.

The best part? The mice glow green! Actually, just the hairs glow green, but it makes their entire heads glow. It's an easy genetic modification, and lets you see if the therapy took - but wow! Everything is more neon in the modern age ... even mice.

The next steps are
1. testing to see if the mice can hear now ("It looks like the hair cells wire up to the primary auditory cortex, but they haven't done satisfactory behavioral testing yet" says my friend).
2. Applying it to people! Since adults are much less flexible than babies, this would probably be used on embryos first, if they can get it to work at all.

This didn't answer all my questions, of course. How does a gene gun work? What do they use to inject the stem cells (it's a new invention, as far as I know)? How would one inject them into a human embryo? in utero?

I also wonder what the societal implications of this idea might be. The Deaf community is very strong, and although it's had some challenges to deal with recently, I also know that its members really value belonging to a community and don't see deafness as a problem. Some deaf parents specifically choose to have children that are deaf.

Here's an interesting study that attempted to measure some attitudes towards genetic testing for deafness among hearing people and deaf people. It found that among the Deaf, genetic testing was not of interest. I imagine a genetic "solution" would be similarly unpopular.

There is already an ongoing debate over cochlear implants - implants which allow deaf children to become part of the hearing world. Will modern medical science mean the end of Deaf culture?


ps - more topics for consideration:

ITER -and fusion! And other paths to fusion ...
What is vitamin A anyway? and is it toxic?
and more mathemagic

Friday, January 5, 2007

Construct a perfect square

Geometry and Mathemagic

I recently took up drawing and painting, so I'm learning to see the world around me as shapes and forms, colors and lines. This reminds me of a book I once read: A Beginners Guide to Constructing the Universe: The Mathematical Archetypes of Nature, Art, and Science, by Michael Schneider. In it, the author shows you how to construct perfect geometrical shapes, from a triangle to a decagon, using only a compass and a straightedge. He also discusses (and illustrates!) the roles these shapes, and the numbers 1-10 play in art, architecture, and nature.

I don't have the book in front of me, but I recall that you can make each shape, from 3 sides to 12 sides, except 7 and 11. I'm going to give it a try (using Illustrator instead of paper) and show you here if I can figure it out.

Triangle is the easiest of course. Three circles of the same size, with the edge of each one aligned with the centers of the others, gives you an equilateral triangle. If you want to try this, or other shapes, with a pencil and paper, here are the rules:

1. You can make circles and straight lines.
2. You can mark the centers of circles, the points where lines cross, and the point where a line is tangent to a circle.
3. You can use the compass to mark off distances.
4. You may not measure distances with a ruler, or angles with anything.

Go to it! I'll post my attempts as soon I complete them.

Also, if there are any mathematical minds out there, I've been wondering if there is a way to test which shapes can and cannot be drawn by this method. For example, why not seven sides? Is there a formula to tell you which would work?

- lily

Thursday, January 4, 2007

Welcome to Science Night!

Once upon a time, there was a large yellow house full of curious people, who liked to play and to discuss how the world worked. Often there was music, or politics, or art, or food, but on very special nights ... there was SCIENCE!

I don't live in that house anymore, but I still have questions about how things work, and I plan to share them here, with any curious people who stop by. My own background is in physics, but I know biologists, mathematicians, computer experts, psychologists, and more, in case a guest expert is needed.

Some topics I'd like to cover soon:

color vision, color blindness, and extra colors
geometrical mathemagic (once I learn how to get pictures on this blog)
can you freeze water when air temperature is above the freezing point?
what's a mustard plaster? does it work?