*Note: One of the assignments for my Science Journalism class is to keep a blog, although strangely enough it doesn't have to be an actual blog, just a word document that has all the things we would blog about. Anyway, I have't posted here in a long time (been busy), so Jen suggested I just post my assignments. Here's the first one I wrote, hopefully it's interesting enough. I'll most likely post the others as they get written.
Of all the cells in your body, only about 10% percent belong to you.
Kind of gives you a new perspective on things, doesn't it? According to Dr. Judith Eisen, a researcher at the Institute of Neuroscience at the University of Oregon, the other 90% is made up of a conglomeration of bacteria and other microorganisms. Most of these microscopic hitchhikers are beneficial to us, which is one reason our body doesn't fight them off, and many of them live in our guts. In her laboratory at the U of O, Dr. Eisen and her team study how the nervous system another vertebrate––the tiny zebrafish––affect the population of microbes that live there.
Normally we envision bacteria and other "germs" as being detrimental to our well being, so it seems odd to think that innervation in the gut affects the microbes, and not the other way around. But this is exactly what researchers in Dr. Eisen's lab have found. During a genetic screen, a process by which animals with interesting defects are generated by randomly mutating their DNA, members of her lab found a zebrafish mutant that lacked pigment cells. Upon closer inspection, they found that it also lacked nerve cells in its intestine. The lack of nerves causes the muscles in the intestines to fire randomly, or not at all; this is in contrast to normal intestinal muscle, which have controlled rhythmic movements.
Examination of the microbes living in the gut of these mutant fish revealed that there were many types not found in normal fish. Eisen’s team hypothesized that the movement of the intestinal muscles helps move the microbes into their proper position. In order to test this, they set up a simple experiment using two different types of bacterial "food". The movement of the food through the intestine can easily be monitored, thanks to the fact that zebrafish are transparent. Normal “wild” zebrafish were initially fed green bacteria, and its movement was monitored over a stretch of several days. Then, the fish were switched to red food. Over time, it was possible to see the green food disappear, replaced by the red food. In the mutant fish, however, all of the food was trapped at the entrance to the intestine. This data helped prove that their hypothesis was correct.
The reason Dr. Eisen's lab has chosen this area of research is that it is directly applicable to human health. One disease in particular, Hirschsprung's disease, is caused by a lack of nerve cells in the intestine. The mutant zebrafish studied in her lab is a good model system in which we can study and understand this deadly affliction. Furthermore, Dr. Eisen stated in her presentation that many neurological diseases have a related gastrointestinal (GI) component. At this time, it is difficult to determine if the GI problems cause the disease, or the other way around. Hopefully, the work done by researchers like Dr. Eisen will help to clear up this conundrum.
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