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" Press ring down on base of dish to spread grease" ? - (Mar/20/2005 )

In the selection of a colony, i use a ring to isolate it from the dish. The protocol says; " Press ring down on base of dish to spread grease?" What does it mean with "grease"?

And what is conditioned media?

Thanks for any input.


The grease in your protocol can be vacuum grease, you know, that kind of silicone which is used on ultracentrifuge rotors to seal them from the vacuum on the rotor chamber. What I do is to spread some of this grease on the bottom of a glass petri dish and autoclave it so as to make it sterile. Then, working under the hood, I press the bottom end of my cloning cylinders (also sterile) over this grease. This will ensure that the cloning cylinder will adhere to your tissue culture plate when you press it around the colony you wish to select. Then you can add the trypsin to it without it leaking out of the cylinder.
As for conditioned media, I'm not 100% sure, but I understand for it a media which has been incubated in the presence of a determined cell line and which as a consequence of that incubation now has some products secreted by those cells, such as grow factors.
Hope that it helps!