A gene involved in nematode feeding behaviour

摘要

Recent studies on feeding behaviour in the soil nematode Caenorhabditis elegans provide a striking illustration of how genetic and environmental influences together mould complex behaviour. C. elegans worms inhabit decaying organic matter in the soil and feed on different species of bacteria. Cassada first noted in 1987 that in the presence of food, wild strains of C. elegans exhibit one of two distinct feeding behavioural patterns, known as 'solitary' and 'social'. Since then, this has been confirmed in the case of every one of 17 natural isolates from all over the world (de Bono and Barg-mann 1998). Solitary feeders forage alone on a bacterial lawn (figure 1A). The common laboratory strains N2 (originally isolated from England) and TR403 (from Wisconsin, USA) belong to this category. In contrast, social feeders tend to clump with each other while feeding (figure 1B). Some isolates from Hawaii, Australia, Germany and England show such social feeding. In one instance, social and solitary wild strains were isolated from the same sod of soil (de Bono and Bargmann 1998). It must be emphasized that the two classes of isolates differ in their feeding behaviour only under conditions of a plentiful supply of food bacteria, underlining the importance of the environment in determination of this behaviour. Also, the aggregation behaviour is enhanced by an increased density of worms (de Bono et al 2002).