PSU Magazine Spring 2005

key Lo unlocking a cure for cancer may someday be swimming in an aquarium in a campus laborawry builL specially for assisLant biology professor Jason Podrabsky. Hundreds of fish inhabiL Lhe tighL quarters, made even tighter by Podrab– sky's small crew of graduaLe students, who squeeze past each other in the warm humidiLy LO reach for pipeLLes, claim space in front of the microscope, or collecL and label lidded glass dishes containing fish eggs. And of course they feed Lhe fish, which swim in carefully conLrolled conditions in row upon row of aquariums slacked on a sysLem of Lall meLal shelves. These are no ordinary fish. The kil– li fish, a naLive of Venezuela, possess a particular Lalent for surviving in an unforgivingly harsh environment. They live in mud puddles that can heat LO as high as 113 degrees Fahrenheit, Lhen dry up compleLely When the puddles dry, Lhe fish die, but Lheir fertilized eggs live on. ln an early sLage of development, Lhe egg embryos go dormant, encasing Lhemselves in a hard protective shell LhaL seals in all moisLUre. They stay Lhis way LhroughouL Lhe hoL, dry sum– mer, waiting in the cracked eanh. Then, when the infrcquenL rains come and the dusty depressions become ponds once again, the embryos emerge from their sLaLe of suspended anima– Lion Lo become adult fish and start the cycle anew. ln Podrabsky's lab, Lhese embryos look like Liny glass beads, which roll freely and clink together when you tip Lheir glass dish. BuL look at one under a microscope and you'll see a large eye and Lhe very beginnings of a body LhaL will evenLUally become a spotted and rather flashy-looking adult. Some 4,000 of these embryos are produced in the lab every week. hat interests Podrabsky is the mechanism within each mbryo's cell that tells it to go dormant and form a hard shell. lt's called gene expression. Under certain condiLions, some of the cell's genes are "swiLched on" Lo make more of a spe– cific protein. Genes can also Lurn off the producLion of oLher proteins to pro– duce anoLher result. ln Lhe case of Lhe killifish, environmental facLors trigger a kind of gene expression LhaL allows the fish embryos Lo live wiLhouL water for months or perhaps years al a Lime. Not much is known abouL how fac– tors such as temperaLUre differences, exposure to light, changes in oxygen levels, or dehydrmion cause the embryos to do certain Lhings. Podrab– sky is working to find those answers with funding help from the NaLional Science Foundation. Although killifish use their adapLive talents in a novel way, gene "expres– sion" is a common trail among all living things. "All organisms have iL , including us. All of us are looking for ways to adapl in our environment," says Podrabsky, who earned his bachelors degree in biology at Oregon State UniversiLy and his docLOrate al UniversiLy of Colorado in Boulder. And thaL's why his research may offer insighLs into Lhe causes of and possible cures for cancer and other dis– eases. Cancer is a disease in which Lhe mechanics of cell growLh and funcLion– ing are Lhrown off killer, ofLen by an environmental Lrigger. ln a sense, cells lose Lhe abiliLy to adapL Lo Lheir envi– ronment. Excessive exposure Lo sun– lighL can trigger skin cancer, for example. Exposure Lo the chemical benzene has been idenLified as a possi– ble Lrigger for leukemia. Environmen– tal facwrs may be Lhe only explanaLion for why one person develops cancer while his or her twin sibling doesn't. an of Podrabskys research involves Lhe cnvironmem in hich the killifish live. "We can puL the embryos in a higher incubation temperaLUre to cause them Lo bypass