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Freezing of Protozoa (Toxoplasma) - (Dec/13/2011 )

I am trying to freeze my parasites, apparently *toxoplasma gondii*, I have been using the freezing media of 10% DMSO 90% FBS. I spin them down, resuspend with the freezing media and straight away into the -80oC.

Freshly thawed parasites have very low viability (10%~), I realized gradual freezing is important.

But my lab does not have the machine (for gradual freezing -1oC per minute). Is there other way to achieve gradual freezing ?

Thanks in advance for the help.

Please advise with your professional opinion.

Many Thanks!!!


no experience with toxoplasma, but I usually first cool sensitive samples on ice for a few hours, then freeze samples for one day at -20°C and then put them to -80°C, got good results with bacteria and fungi.
This slow freezing is not as effective than controlled gradual freezing, but the cells should survive better this way than putting them straight to -80°C.....


Perhaps the cysts are more robust to freezing? Though I've no idea if you can produce them at all in the lab.


Thanks~ Gebirgsziege! I am trying your method now, previously I just chuck them into -80oC, most likely rapid freezing could have killed them ;)


hope it works :) would be great if you could let me know!


ok sure!!! i will i just wanna thaw them after a week and see hows the viability! HAHA thanks! ;) take care!


may i know what is the best way to thaw it? since thawing also affect the toxoplasma..thanks~^^


Hi sorry for the late reply I hope this still answer your question Jannaiem:

I just thaw normally like how to thaw cells.. but u have to infect the toxo immeadiately into mice intraperitoneally.. cos for me.. reinfection in cells doesnt work at all.. hope it works!!