Worm Breeder's Gazette 8(1): 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.
1. Re-using small plates. One small plate is cheap, but ten thousand plates are expensive. For many genetic purposes, a plate need only last for four days or so, and only a few worms on each plate need to be examined. I have adopted the following procedure for reusing small (5cm) plates. Take used plates that are not too old or mushy or contaminated, and flip out the agar with a spatula. Incubate the empty plastic dishes at 65 C overnight to kill off any residual worms and to reduce bacterial contamination. Spread large (9cm) NGM plates with uniform lawns of OP50, and allow to grow up; then cut each plate into 16 approximately square blocks with a scalpel. Each little agar block is transferred to a separate dish using a scalpel or spatula. Worms can then be inoculated onto the agar in the usual manner. They almost always stay in the agar blocks, usually on the top (spread) surface, and produce broods that are easily scored. The scoring is qualitative only, because complete broods cannot be counted. Worms will also mate efficiently on the blocks. The main problem with the technique is desiccation: the agar becomes seriously dried out after more than a few days unless precautions are taken, so it is best to use fairly fresh large plates for making the blocks. Small plates may be reused several times in this way, more or less until there is no space left to write on the plastic. 2. Picking up lots of worms at once. It is convenient to be able to pick up many worms on one worm pick, especially when picking males for many parallel crosses. I have found chilling worms to be helpful. Place the plate to be picked from on ice for 20-30 minutes. The worms become completely torpid. Scoop up a sticky gob of bacteria on the end of a platinum wire worm pick, and pick up the torpid worms by adherence to this gob. When the mass of worms and bacteria is placed in contact with agar at room temperature, the worms instantly recover their mobility and swim off, having suffered no ill effects. It is possible to pick up and transfer as many as 100 wild-type males at once by this means.