The Mycoplasma Menace

Stanbridge (1971) has thoroughly reviewed the problems intrinsic to mycoplasmic contamination of cell cultures. Following such contamination we have found that our cultures acquire a number of unusual traits, most of which are predictable in accordance with Stanbridge (1971). Briefly stated, these are the following  

Infected TK-competent cultures fail to grow in THMG-supple-mented medium but continue to grow well indefinitely in unsupplemented medium. 

Infected TK-competent cells fail to remove H-TdR at low concentrations from the growth medium (Fiop), whereas noninfected TK-competent cells rapidly incorporate H-TdR. This inability to utilize exogenous thymidine serves to explain the failure of infected cultures to grow in THMG medium. 

Infected TK-competent cultures have normal TK activity in cell-free extracts, implying that their inability to take up low concentrations of thymidine from the medium results either from a transport problem or from an interaction between the PPLO and the added thymidine. 

Infected TK - cultures cannot be mutagenized i.e., no BUdR-resistant colonies can be recovered from such cultures either 

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