Researchers say the discovery of how sodium ions pass through the gill of a zebrafish may be a clue to understanding a key function in the human kidney. The findings from a collaboration between Mayo Clinic and the Tokyo Institute of Technology appear in the online issue of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology . "This is significant because the fish tends to mimic the process in humans," says Michael Romero , Ph.D., a Mayo Clinic physiologist who works in nephrology. "This is the true beauty of comparative physiology--- a lot of the organs function by very similar processes, down to ionic transfer." In this video, Dr. Romero offers further insight on the study.