Influence of lectins on female sex pheromone reception byHeterodera schachtii (Nematoda: Heteroderidae) males

Effect of the sulphydryl reagent, mersalyl acid, on sex pheromone reception by Heterodera schachtii (Nematoda: Heteroderidae) males

Female sex pheromone reception was inhibited in a bioassay by treating males of the beet cyst nematode, Heterodera schachtii, with the sulphydryl reagent, mersalyl acid. This effect was blocked by the sulphydryl group protectant, dithiothreitol, indicating the occurrence of sulphydryl groups in the receptor molecules and a role for sulphydryl groups in pheromone reception.

In vitro studies on the behaviour of second-stage juveniles of Heterodera schachtii (Nematoda: Heteroderidae) in response to host plant root exudates

The behaviour of Heterodera schachtii second-stage juveniles in response to mustard (Sinapis alba) rooxudates was observed and analysed under aseptic conditions in a standardized bioassay. Aggregation of juveniles on an agarose layer occurred within less than 30 min in the area where root exudates had been applied and persisted for several hours. Analysis of time-lapse video recordings showed that the aggregation did not result from a directed orientation of the juvenile towards the root exudate. This was supported by an orientation assay using single juveniles. Aggregated juveniles showed pre-infection exploratory behaviour, including stylet thrusting and head-end bending, while staying at rest for several minutes.

Chemoreception in plant parasitic nematodes

The role and functioning of the anterior chemosensory organs of plant parasitic nematodes is examined, with particular emphasis on the amphids. The morphology of the amphids is discussed primarily in the context of the changes in the ultrastructure associated with different life stages. The involvement of amphidial secretions in chemoreception and the behavioral and electrophysiological analyses of nematode responses to semiochemicals are discussed with special reference to research on sex pheromones. These research techniques, combined with the use of lectins and antibodies, provide information on nematode sensilla that may lead to novel control strategies for economically important plant parasitic nematodes based on perturbing nematode sensory perception to prevent host or mate location.

Tissue treatment for whole mount internal lectin staining in the nematodes Caenorhabditis elegans, Panagrolaimus superbus and Acrobeloides maximus

Four different fixation schemes, using ten fluorescent-labelled lectins, were investigated for whole mount internal staining of three rhabditid nematodes: Caenorhabditis elegans, Panagrolaimus superbus and Acrobeloides maximus. Acetone-only fixation was found to give strong and reproducible staining, which could be prevented either by periodate treatment of the organisms or by specific inhibitory sugars of the lectins under investigation. Whereas the use of either phosphate or TRIS buffers had no effect on the staining pattern or the fluorescence intensity, the incubation time as well as the incubation temperature affected the staining reaction. The best results were obtained upon overnight incubation at 4 degrees C: the lectin staining could be inhibited in all cases, except for the intestinal brush border of C. elegans by the lectin of Lens culinaris.