Meeting Abstract

P3.13  Sunday, Jan. 6  Effect of aggression and social status on gene expression in rainbow trout BALLI, S. *; DREW, R. E. ; University of Massachusetts Dartmouth; University of Massachusetts Dartmouth sballi@umassd.edu

Aggression is an agonistic and costly behavior by which individuals compete for better resources and social status. This study examined the modulation of aggressive behavior in the establishment of social status in rainbow trout (Oncorhynchus mykiss). Subsequently, gene expression in the brain as a result of aggression and social status was also examined using quantitative polymerase chain reaction (qPCR). The behavior study was conducted on 12 dyads of juvenile rainbow trout from two inbred domesticated strains, Hot Creek and Arlee. The fish were allowed to compete for food and social status for 9 days and were sacrificed to analyze gene expression in the brain. Nine of the twelve dyads developed a clear dominant and subordinate relationship. During the establishment of social status, the overall frequency of aggressive encounters decreased. However, the aggressive interactions progressed from simple chase-away to physical harm. Corticotrophin-releasing hormone (crh) and neuropeptide Y (npy) genes were differentially expressed with respect to brain region and social status. From previous studies, these genes are known to influence food intake, stress and aggression. Region-specific expression of additional genes involved in aggression and social status are currently being analyzed by qPCR and in situ hybridization. This research will aid the understanding of possible genetic variation involved in modulation of aggressive behavior social status in fish and other vertebrates.