Fig. 7. The nph-1 and nph-4 single and nph-1;nph-4 double mutants exhibit defects in chemotaxis toward volatile attractants. Comparison of chemotaxis indices for the wild-type N2 and the nph mutants in response to (A) benzaldehyde and (B) diacetyl indicate that both single mutants and the double mutant exhibit abnormal response to these attractants. To demonstrate that the phenotypes were the result of mutation of the nph genes, the chemotaxis defect in nph-1 and nph-4 mutants was rescued by expression of nph-1::CFP and nph-4::YFP, respectively. Both the nph-1 and nph-4 rescued lines exhibited a strong chemotactic response to (A) benzaldehyde or (B) diacetyl similar to that obtained for wild-type controls. Error bars represent the standard deviation and n refers to the number of independent experiments with an average of 100 worms on each plate being evaluated.