Nitric oxide (NO) is an immune signaling molecule secreted primarily by blood cells of animals and plays a role in the inflammatory response. But NO also functions as a brain neurotransmitter and can regulate behaviors, including aggression, mating, and feeding. In mammals, NO is associated with learning, memory and social behavior; however, its role in insect behavior warrants further investigation. In insects, NO can regulate agonistic behavior, a behavior crucial for insect survival and reproduction. For example, injecting a drug into crickets that increases NO will induce male crickets to flee from other males, i.e. increased NO produces socially subordinate crickets. In our study, we employed RNA interference (RNAi) to decrease nos gene expression in Acheta domesticus crickets. NOS is the enzyme responsible for NO production. We hypothesized that decreasing nos expression would decrease NO production, leading to socially dominant crickets. Interestingly, crickets raised in social isolation exhibit decreased brain nos expression. Isolation is recognized as a potent factor shaping animal behavior, with solitary rearing often leading to behavioral phenotypes distinct from group-reared individuals. Our goal was to determine if this ‘isolation-induced’ decrease in nos expression could also produce socially dominant crickets. As predicted, nos RNAi male crickets were significantly more likely to win fights against control males (n=28 fights; 64% RNAi males dominant; Chi-square, p=0.03). Similarly, socially isolated males were also more likely to become dominant in fights against group-raised males (n=12 fights; 83% isolated males dominant; p=0.001). We are currently determining if there is a corresponding decrease in NO levels in these dominant males. These findings provide insight into the impact of NO and social isolation on animal behavior. This project has important implications for my intended career in the medical field, as it allows me to develop my skills in behavioral neuroscience and molecular biology.
Author(s): Madison A. Slosier, Hope D. Keane, Siva A. Lakshamana Vijayarajan, Kathleen A. Killian, PhD
Advisor(s): Kathleen A. Killian; Siva A. Lakshamana Vijayarajan Department of Biology
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