© 2003 National Academies of Science
Take the bully out of the schoolyard and another quickly takes his place. Only minutes after subordinate male cichlid fish sense an opportunity to become socially dominant, they display dominant characteristics such as changes in color and behavior and increasing fertility. They also express
Researchers gave subordinate fish an opportunity to ascend in a familiar environment by removing the dominant male from a tank containing two males and four females.
The researchers used in situ hybridization to analyze gene expression in the fish's brains. Ascending males had more than twice as much egr-1 expression in the anterior preoptic region as males who had remained either subordinate or dominant. The authors found an egr-1 recognition site in the gonadotropic-releasing hormone-1 (GnRH1) ...
