of tube as a white mass then the cells have
already reached stationary phase and these
cells will not be of optimal quality for cryopreservation.
2. Ice tubes of cells until they detach from the
culture tube. Concentrate cells by centrifugation for 5 min at 600g and 4°C.
3. Decant spent medium and add 2 ml of room
temperature FM per cell pellet (from 15 ml
starting culture). Resuspend cells briefly in
FM, and then transfer immediately to a cryo
tube (i.e. sterile Nunc 1 ml tube, Nalgene
Nunc International). All manipulations need
to be done under sterile conditions.
4. Place cryo tube into a room temperature
Nalgene Cryo 1°C Freezing Container (Cat.
# 5100-0001; be sure to fi ll tank to line with
isopropanol as instructed by manufacturer)
and put at –80°C for at least 24 h. Move cryo
tubes containing Giardia to a liquid nitrogen tank for long-term storage.