Earthworm chemoattractant wash

Wang, D., Chen, R, and Halpern, M. (1987). Further isolation and purification of the garter snake chemoattractant in earthworm wash. Chemical Senses 12,706. 

The vomeronasal system has been strongly implicated in detection of the chemical prey washes that snakes respond to by either increased tongue flicks, attack or trailing (Burghardt and Hess, 1968 Burghardt and Pruitt, 1975 Chiszar et al., 1981 Halpern and Frumin, 1979 Kahmann, 1932 1934 Kubie and Halpern, 1979 Naulleau, 1966 Wilde, 1938). As part of our continuing efforts to understand the vomeronasal system and contrast it to the olfactory system, we have attempted to isolate and characterize the active components in the chemoattractant portion of the wash of one prey of snakes, the common earthworm, Lumbricus terrestris. 

Earthworm wash (EWW) is normally prepared by placing 6 gms of clean earthworms in 20 cc of 60° dH20 for one or two minutes (our earlier studies used one minute, our current studies use two minutes). This is the standard (IX) concentration of EVJW. The temperature at which EWW is prepared is critical to the production of the chemoattractant (Halpern et al., 1984 Sheffield et al., 1968). At temperatures lower than 40°C, no discriminable chemoattractant is produced (Fig. 1). 

The chemoattractant material in EWW absorbs at 280nm and 230 nm, contains carbohydrate, is ninhydrin-positive, gives positive Bradford and Lowry test for protein and is precipitated by 90% - 100% saturated ammonium sulfate (Halpern et al., 1984). Earthworm wash retains its chemoattractant properties after dialysis through 50,000 molecular weight (MW) cut off tubing, and lyophilization. However, repeated lyophilization, freeze-drying and thawing, do diminish and eventually destroy the chemoattractant in EWW (Table 1). 

To determine if earthworms that had been decuticlized could be used to produce chemoattractant, we removed the cuticles of 50 worms by placing the worms in anhydrous ether for 15 minutes and then stripping the cuticles from the worms (Watson, 1958). The decuticlized worms were placed in 60 C H2O for 2 minutes, discarded, and the wash water centrifuged. The supernatant was tested for chemoattractant activity as described above and found to have no chemoattractant activity. 

Chemoattractant for the garter snake Characterization of vomero-nasally-mediated response-eliciting components of earthworm wash III, Comp. Biochem. Physiol., in press. 

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