Genetic and molecular studies have identified a number of antagonistic neural pathways that regulate C.elegans aggregation behaviour. One of these pathways is mediated by oxygen sensing soluble guanylate cyclases expressed in the body cavity neurons AQR, PQR and URX1-3. These neurons are activated by a reduction in ambient oxygen to induce a suppression of exploratory activity (see abstract by Cheung et al.).This aerokinetic response appears to require integration of signals from both oxygen sensing and food sensing neurons, providing an opportunity to study how the nervous system integrates sensory stimuli. To study this integration, we examined mutants identified previously in the lab that suppress aggregation of
npr-1 animals. A subset of these mutants failed to suppress high locomotory activity when oxygen levels are reduced. By characterizing their aerotaxis behaviour in the absence of food we can classify these animals into those that disrupt aerotaxis and those that disrupt the food sensing pathway. We are currently identifying the molecular deficits in a subset of these mutants.The
npr-1 215V allele that is found in solitary wild isolates of C.elegans acts to suppress the activity of the AQR, PQR and URX neurons when food is present. Targeted expression of
npr-1 215V in these neurons abrogates the aerokinetic response. Interestingly, however, these transgenic animals retain substantial aggregation behaviour, suggesting that
npr-1 also acts in other neurons to regulate aggregation. To identify these neurons I am expressing cDNA for
npr-1 215V under neuron specific promoters in
npr-1 mutant animals and looking for suppression of aggregation.1Coates, J. & de Bono, M. Nature 419, 925-929 (2002); 2Cheung, B. H., Arellano-Carbajal, F., Rybicki, I. & de Bono, M. Curr. Biol. 14, 1105-11 (2004); 3Gray, J. M. et al. Nature 430, 317-322 (2004).