Cool Science Blog
ran into this
new Blog a few days ago and it's worth checking out.
bq. So I said I'd talk about how my research on fruit flies has a practical application. The eye of a fruit fly is very different from mammalian eyes. They are basically arrays of tiny motion detectors, designed to sense movement of a predator rather than to discern the intricacies of color and form like human eyes. The electrical responses of fruit flies are 100 times faster than those of human eyes. That's what makes them so darn hard to swat with a fly swatter.
bq. While insect vision is interesting in itself (especially if you want to be able to swat them effectively), what I'm really interested in is how nerve cells or neurons function in all animals. The photoreceptors in the fly eye are actually modified neurons. They receive an input (light) and transmit an output (histamine) at their synapses. Flies are ideal model systems to use to study neurons because they have simple nervous systems, they are easy and inexpensive to maintain, there are many mutant flies that can be tested, and you can do experiments on them that you couldn't do on humans. Yes, ripping the eyes off a human being and jabbing electrodes into the freshly dissociated eyes IS unethical and illegal in case you were wondering.
bq. The fly photoreceptor cell signals in a way that is similar to certain types of neurons in the mammalian brain. This pathway contains a receptor, the protein rhodopsin (also found in mammalian eyes) in this case, on the surface of the cell that responds to an external stimulus, light. Once light activates rhodopsin, rhodopsin then turns on a whole cascade of other signaling proteins. The proteins in the signaling cascade had different functions. Some turn on other proteins, some turn others off. Some breakdown certain biological compounds, while other synthesize new compounds. Some proteins undergo conformational changes that allow them to transport other molecules into or out of the cell. These proteins are called ion channels. The end result of light stimulating rhodopsin results in ion channels opening and allowing high concentrations of calcium from outside to rush into the cell. High amounts of calcium are eventually toxic to cells so it is then pumped out of the cell at the end of the signaling event.
Posted by DaveH at December 8, 2003 9:19 PM