Worm Breeder's Gazette 4(1): 16
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.
For many biochemical and cytological experiments on development it is useful to have populations of worms of a uniform age. Like several other workers we are interested in obtaining uniform populations by filtration. Here is our best method: About 100 ml worm suspension containing about 5 g of worms, grown in 1.5L liquid culture containing 20g E. coli NA 22/1, are freed of bacteria and debris by settling in 30% sucrose as described by Sulston and Brenner (1974). The worms in 100 ml S Medium are poured over a 40 m-pore nylon net (35 mm in diameter) fitted on a Sartorius-filter- unit. The suspension containing all developmental stages of worms is allowed to pass through the net very slowly (2 ml/min) and after this the retentate is washed three times with 5 ml of S Medium, to remove any remaining juvenile stages. Taking the filtrate the procedure is repeated successively with 30 m, 10 m and 5 m nets with the following results: [See Figure 1] The L1's obtained from the 5 m filtrate are allowed to settle at 6 C. Synchronous cultures can be started from these within the next three days. The most successful method is to let them grow on NGM-plates. Good synchrony is retained until adulthood. In liquid culture results are not as good. One difficulty during filtration is that sometimes the nets are blocked by a thick layer of worms. To overcome this, gentle swirling of the whole filter unit helps. Also gentle suction speeds up elution. From small amounts of worms, pure L1's are obtained by using the 5 m net directly on the debris freed culture. Addresses of the companies where the nets and filter-units can be MOnyl-nets: HYDRO-BIOS, Apparatebau GmbH, Am Jagersberg 7, 2300 Kiel 16, Federal Republic of Germany Filter-unit No. 16510: SARTORIUS-Membranfilter GmbH, Weender Landstr. 94-108, 3400 Gottingen, Federal Republic of Germany