Zebrafish populate the tank in Kathleen Whitlock's laboratory, and they decorate the T-shirts she designs for scientific conferences.Photo by Robert Barker

When Kathleen E. Whitlock needs more lab animals for her developmental genetics research, her subjects arrive in a package from the University of Oregon in Eugene, where she was a postdoctoral fellow before joining the Cornell faculty as an assistant professor of genetics and development. Whitlock breeds zebrafish, originally from Southeast Asian rivers, for research into genetic mutations that result in physical deformities and endocrine disorders. Zebrafish are externally fertilized, so they develop outside the mother. The practically transparent embryos develop so rapidly that in a single day major organs, including the nose, are clearly visible. Embryonic noses, and what subsequently becomes of them, are of great interest to Whitlock because she studies the development of nerve cells that originate in the nose area of all vertebrates and somehow grow their axons to the appropriate parts of the developing brain. These so-called neuroendocrine cells signal for the secretion of hormones, and one tragic result of insufficient secretion in humans is Kallman's Syndrome, the failure to develop secondary sexual characteristics and enter puberty.