Effect of interactions among individuals on the chemotaxis behaviours of Caenorhabditis elegans

Abstract

In many species, individual social animals interact with others in their group and change their collective behaviours. For the solitary nematode strain N2, previous research suggests that individuals can change the behaviour of other worms via pheromones and mechanosensory interactions. In particular, pheromones affect foraging behaviour, so that the chemotactic behaviours of individuals in a group (population) can be modulated by interactions with other individuals in the population. To investigate this, we directly compared the chemotactic behaviours of isolated (single) worms with those of individual animals within a population. We found that worms approached an odour source in a distinct manner depending on whether they were alone or in a population. Analysis of behaviours of the N2 worm and a pheromone production-defective mutant revealed that the 'pirouette' strategy was modulated by interaction of the worms via pheromones. Thus, pheromones play an important role in the characteristic collective behaviours seen in the population condition.

Food deprivation changes chemotaxis behavior in <i>Caenorhabditis elegans</i>

“…The same analysis methods in previous research were employed [12] using Matlab programs modified from parallel worm tracker [18]. If worms arrived at the high odor concentration area, their subsequent trajectories were removed from the dataset because the animals were restrained by sodium azide.…”

“…where θ i is bearing angle at time point i. Circular variance V varies from 0 to 1. The odor concentration for Figure 3 was estimated by the numerical simulation as previous research [12,20]. For calculation of the direction change (∆cosθ, Fig.…”

“…Under food deprivation, animals should explore for food efficiently. Although chemotaxis is one of the important behaviors to explore for food [9][10][11][12], effect of food deprivation on chemotaxis is largely unknown. In C. elegans, two chemotactic strategies are well known: the pirouette and weathervane strategies [12][13][14][15].…”

“…Although chemotaxis is one of the important behaviors to explore for food [9][10][11][12], effect of food deprivation on chemotaxis is largely unknown. In C. elegans, two chemotactic strategies are well known: the pirouette and weathervane strategies [12][13][14][15]. In the pirouette strategy, worms change their locomotive direction with sharp turns (pirouettes) when they detect a negative time derivative of the odor concentration (dC/dt<0) [13].…”

“…In the weathervane strategy, animals gradually migrate to higher concentration regions [14,15]. These strategies have been investigated well [12][13][14][15]; however, the change of the chemotactic strategy by food deprivation is still unknown.…”