( Using genetically altered zebrafish tha...)Glow-in-the-dark zebrafish at UH hold keys to biological clocks

Gregory M. Cahill, associate professor of biology and biochemistry at UH, and Maki Kaneko, a fellow UH researcher who is now at the University of California-San Diego, presented their findings in a paper titled "Light-dependent Development of Circadian Gene Expression in Transgenic Zebrafish," appearing Feb. 1 in the Public Library of Science's PLoS Biology, an online journal that, along with PLoS Medical, is committed to making scientific and medical literature a public resource.

"By injecting the luc gene that makes fireflies glow into our zebrafish, our bottom-line finding goes back to nature versus nurture," Cahill said. "We found that these per3-luc zebrafish contain something in their genetic makeup that gets their clocks ticking without parental influence, however, we determined that it does take some sort of environmental input for the clock to start. In this case it was exposure to light/dark cycles after the fourth day of development, about the age when the fish start to swim and feed."

The researchers used zebrafish (danio rerio) because they yield such a high output of spawn, with hundreds of eggs being laid by each female per week. This gives the scientists a better chance of identifying mutant fish whose biological clocks run fast or slow, providing the ability to trace the specific genes that create the anomaly. Putting UH a bit ahead of other institutions engaged in this type of research, Cahill and his team will be able to analyze more than 2,000 zebrafish per week. The per3-luc zebrafish is the first vertebrate system available for this level of high-throughput measurement.

"Because we can test so many zebrafish at a time, the one in a thousand odds of finding a mutant are more easily and efficiently attainable," Cahill said. "Ultimately, this type of research
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Source:University of Houston