Effect of nonylphenol on gene expression in Atlantic salmon liver, gill, hypothalamus, pituitary, and olfactory rosettes

Exposure to environmental contaminants like nonylphenol can disrupt smolt development and may be a contributing factor in salmon population declines. We used GRASP 16K cDNA microarrays to identify genes that are differentially expressed in the liver, gill, hypothalamus, pituitary, and olfactory rosettes of Atlantic salmon smolts treated with nonylphenol compared to control smolts. Nonylphenol treatment was confirmed using physiological assays: nonylphenol-treatment significantly decreased gill Na+,K+-ATPase activity and plasma cortisol and T3 levels. Microarray analyses were used to compare expression in nonylphenol-injected fish with expression in vehicle-injected fish: eight arrays each for liver, gill, olfactory rosettes, hypothalamus, and pituitary tissues. Total RNA was isolated from the tissues of eight nonylphenol-injected fish (six males and two females) and eight vehicle-injected fish (two males and six females) and reverse transcribed separately (not pooled); each slide represents a biological replicate. For each tissue, the eight arrays were balanced for dye: nonylphenol-injected fish were labeled with Alexa Fluor 555 and vehicle-injected fish were labeled with Alexa Fluor 647 on four slides, nonylphenol-injected fish were labeled with Alexa Fluor 647 and vehicle-injected fish were labeled with Alexa Fluor 555 on four slides. Liver, gill, hypothalamus, pituitary, and olfactory rosette tissues were analyzed separately.