A discovery that at first glance seems to be at the most basic level of genetic research might someday be used to prevent or help cure one of the deadliest human cancers -- melanoma.Scientists studying zebrafish have found a gene that can make them change their stripes. That is, a mutation in the gene changes the color of those stripes.While much more research is needed, the finding could help in the fight against melanoma, said Dr. Keith C. Cheng, an associate professor of pathology at Pennsylvania State University College of Medicine. He is leader of the research effort that appears in the Dec. 16 issue of Science.