Worm Breeder's Gazette 15(2): 23 (February 1, 1998)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The Netherlands Cancer Institute, Division of Molecular Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
We are studying avoidance of repulsive stimuli to ask how a general avoidance mechanism is generated and controlled in C. elegans. With a forward mutagenesis screen we are now trying to identify genes involved in this sensory pathway, using copper ions as an aversive chemical (De Vries et al. WM97 p.585). As a source of mutations we use a mut-7 strain to isolate tranpsoson insertion alleles with the mutant phenotype. The copper aversion assay is performed by placing the worms on one side of a Petri dish, an attractive odorant on the other side and a thin line of copper sulphate in between. Mutants that pass through the copper barrier are isolated and allowed to produce self progeny. We are now using the transposon insertion display technique (Van Luenen and Plasterk (1996) WBG 40:20) to genetically analyse the aversion mutants. The first gene to be identified is the dynein heavy chain 1b-isotype. This gene also shows up in a screen for mutants that fail to chemotax to ammonium acetate (Wicks and Plasterk WM97 p.169). In the chemoaversion screen a Tc1 insertion was found in this gene and in the chemoattraction screen both a Tc1 and a Tc3 insertion was found. The transposons are both inserted in a small conserved region of the gene. Dynein heavy chain is a member of a large ATPase superfamily of motor proteins. It was found to be allelic to the existing che-3 mutant in which the cilia of the sensory neurons have an abnormal morphology. By expressing GFP under the control of a chemosensory neuron specific promotor (gpa-13) in the dynein heavy chain mutant background, we have shown that the ciliated processes of these neurons are shortened and swollen. The chemotaxis defect caused by disruption of the dynein heavy chain gene is probably due to disruption of ciliary structural integrity in the sensory endings.