Conspecific cues modulate body size in Caenorhabditis elegans

Many organisms change their life history, size, and shape in response to environmental signals. Although touted as a ‘developmentally hardwired’ system, the soil-dwelling nematode C. elegans is no exception. Previous research has shown that sensory perception mutants are smaller than wild-type worms (Fujiwara et al., 2005). This suggests that sensory input from the environment can regulate the neuroendocrine functions controlling adult body size. Based on this thesis and the work in Rose et al. (2005), I propose that cues from conspecifics are one source of sensory input capable of affecting body size. Rose et al. (2005) found that worms reared in isolation have a decreased response to mechanical stimulation, a down-regulation of a pre- (snb 1) and post-synaptic (gir-1) marker in the mechanosensory neural circuit, and delayed physical development compared to worms reared in groups (colony worms). In this thesis I propose that colony worms integrate mechanosensory and chemosensory information to modulate growth in response to the presence of another worm. Using several sensory perception mutants I’ve identified the sensory neurons that are required for colony worms to grow bigger than isolated worms.Medicine, Faculty ofMedical Genetics, Department ofGraduat