|
Remember the feeling you get after having been spun around and around? Now imagine feeling like that your entire life. You would if you had a dysfunctional vestibular system. The vestibular system is what allows our bodies to orientate themselves to gravity, so you don’t have that woozy, disoriented feeling. Our vestibular system begins formation during our embryonic development. Therefore, when something is born in space their vestibular will theoretically be dysfunctional because it is deprived of a gravity stimulus. With all the new exploration into the outer limits of the universe, more and more focus is on the idea of organisms born in space.
The zebra fish and Medaka fish nervous system have become well-accepted models for developmental neurobiology studies; many scientists are now using them to test neural development theories on them. Recently NASA deployed a neural space station to study different aspects of neurobiology in outer space. Among those experiments onboard was one by Japanese scientist Dr. Kenichi Ijiri. Ijiri used four Medaka fish, each of which were allowed to mate and produce eggs to test the development of the vestibular system in space. UREKA!! The first vertebrate animal to ever be born in space. This tiny Madaka fish was put through several rigorous tests to observe its behavior in a stimulated environment. This consisted of measuring its eye movements with relation to light. The fish displayed an undistinguishable swimming pattern when illuminated from above. When illuminated from below, the fish swam dorsal surface up but also laying on its side. They corkscrewed, swam vertical loops, and occasionally even swam upside down. Post birth analysis is still continuing in Ijiri’s lab using video cameras that capture the mating and birth in space. It has become apparent that the vestibular system is severely dysfunctional in the newly born Medaka fish.
The scientists at Case Western Reserve University in Cleveland OH, under the supervision of Dr. Stephen Moorman, began asking questions about the genetic makeup of these fish that could result in the dysfunctional vestibular system. The preliminary data showed that the expression of two genes, dlx-3 and msh-c were decreased in zebra fish Danio rerio when exposed to a gravity-deprived environment. These two genes (msh-c and dlx-3) are known to be present during otolith development. Otoliths are formed on the sides of head of the fish and are an integral part of vestibular system development. These genes are also known to be prevalent during olfactory development. The zebra fish were placed in a Rotating Wall Perfused Vessel (RWPV), a bioreactor designed by NASA in order to stimulate a “zero-gravity” environment. The RWPV was initially intended to be used as a method to expose cell cultures on earth to an environment comparable to the one experienced in outer space, but upon replacing the culture media with aquarium water, it becomes ideal for maintaining zebra fish. The eggs were place in RWPV and removed at 24 and 36 hrs. They were then probed with known sequences of the two genes to illuminate areas where these two genes are concentrated at these time points. Areas of otolith development were highlighted by the genes dlx-3 and msh-c, but it was evident that in the experimental fish the expression was decreased, thus yielding a dysfunctional vestibular system. However, it still cannot be absolutely concluded that dlx-3 and msh-c are the only genes, which are impaired when deprived of a gravity stimulus. Therefore, these experiments are still being explored further and are currently being funded by NASA.
Human kind has always had a need to explore, first the exploration of the new world and now as the majority of the world has been explored and mapped, we have set our sights a bit higher. We now have a craving for the outer limits; exploration of the solar systems of other galaxies isn’t very far away. Along with exploration comes colonization. As space exploration increases, the need for colonization will come soon. We have already begun taking preliminary steps with the NASA Space Station. Hopefully the Medaka fish birth and the research on zebra fish will give us the key we need to understand how to make it possible for future vertebrate animals to be born in space.
|
