Worm Breeder's Gazette 8(2): 52
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.
Soil samples (200-300 gms) from the Adelaide area were collected from leafy compost, cultivated garden plots, orchards and open areas at 17 locations. The soil samples were placed over funnel collectors in a misting chamber overnight and the filtrate was collected in 90 ml test tubes. Most of the water was removed by suction, and the remainder was allowed to settle in a conical centrifuge tube. This sediment of worms and debris about 0.1-0.2 ml in volume was transferred to the surface of a 8.5 cm diameter NGM agar petri plate spread with E. coli. After three days incubation at room temperature (24 C), worms which grew and reproduced on the E. coli were selected. Worms morphologically similar to C. elegans were transferred to fresh plates at hourly intervals, 2 to 3 times in succession. These repeated transfers removed contaminating soil microbes. The worms were cloned, and those animals capable of self-fertilization were then mated with C. elegans N2 males. Generally, no more than four clones were made from any soil sample, and two hermaphrodite progeny from each clone were mated with four males on a petri plate. When F1 males (usually 30-60) issued from such a cross, the maternal clone was tentatively identified as C. elegans. Final confirmation was obtained by backcrossing the F1 hybrid males with hermaphrodites from the cloned soil isolate. The appearance of F1 males in this latter cross demonstrated that the hybrid males were fertile. The 17 soil samples produced four new C. elegans isolates: one from Alan Bird's garden (AB1), one from the Australian Wine Research Institute grounds (AB2), and two from Waite Agricultural Research Institute nursery plots. The samples containing C. elegans were moist, well-aerated, and near the surface where decaying vegetable matter provided ground cover. We conclude from these preliminary results that C. elegans may be widespread in the Adelaide area, and perhaps in other areas of Australia as well. Stocks of AB1, AB2, AB3 and AB4 were repeatedly sub-cloned to ensure that a genetically true- breeding stock was obtained. To determine the male bursa morphology exhibited by an Australian C. elegans strain, spontaneous males were picked from a large population (approx. 50,000 worms) of the AB1 clone, and subsequently propagated by mating with AB1 hermaphrodites. The pattern of bursal rays was identical to that previously described for C. elegans isolates from England and France. Southern hybridizations with AB strain genomic DNA using a Tc1 probe (kindly provided by Brad Rosensweig) showed that each of the AB strains is of the low copy number (N2) type, although the AB1 pattern differs slightly from the other three, and they all differ slightly from N2.