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.

A Method for Fractionating C. elegans Populations by size using Filtration through Nylon Nets

U. Certa

Figure 1

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 
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 
[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 
Filter-unit No.  16510: SARTORIUS-Membranfilter GmbH,
Weender Landstr.  94-108, 3400 Gottingen,
Federal Republic of 

Figure 1