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Mycoplasmas produce double-stranded ribonuclease
1Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269-3044.
Abstract:
Mycoplasmas (Mollicutes) constitute a constant threat as insidious contaminants of animal cell cultures. They are responsible for myriad biochemical reactions associated with the cells they infect, and undoubtedly have been the source of metabolic and physiological activities attributed to their hosts. In an attempt to demonstrate a dsRNA-inducible double-stranded ribonuclease (dsRNase) in mammalian cells, comparable to that reported in avian cells, we discovered high levels of dsRNase "induced" by a particular stock of vesicular stomatitis virus. We now report that the double-stranded ribonuclease resulted from the activity of a contaminant in that stock--a "noncultivable" Mycoplasma hyorhinis. This report demonstrates the ubiquitous distribution of dsRNase among mycoplasmas, presents some characteristics of the enzyme and its production, and implicates once again mycoplasmas as contaminants of cell culture and potential perturbers of cellular physiology.
Insights
Contaminating Mycoplasma hyorhinis, not mammalian cells, produced the double-stranded ribonuclease (dsRNase) activity initially observed. This study highlights mycoplasmas as common cell culture contaminants and significant disruptors of cellular functions.
Area of Science:
- Cell Biology
- Microbiology
- Molecular Biology
Background:
- Mycoplasmas (Mollicutes) are known contaminants in animal cell cultures.
- These contaminants can cause biochemical reactions attributed to host cells.
- Previous research suggested a double-stranded ribonuclease (dsRNase) inducible in mammalian cells.
Purpose of the Study:
- To investigate the source of an observed dsRNA-inducible dsRNase in mammalian cells.
- To identify the specific agent responsible for dsRNase activity.
- To characterize the dsRNase and its production by the identified agent.
Main Methods:
- Investigating dsRNase activity in mammalian cell cultures.
- Analyzing vesicular stomatitis virus stocks for contaminants.
- Isolating and identifying microbial contaminants.
- Characterizing the enzymatic activity and production of the contaminant.
Main Results:
- A specific stock of vesicular stomatitis virus contained a contaminant responsible for high dsRNase levels.
- The contaminant was identified as Mycoplasma hyorhinis.
- Mycoplasmas were found to ubiquitously distribute dsRNase.
- Characteristics of the enzyme and its production by mycoplasmas were presented.
Conclusions:
- Mycoplasma hyorhinis, not mammalian cells, was the source of the investigated dsRNase activity.
- Mycoplasmas are widespread contaminants in cell cultures.
- Mycoplasmas can significantly alter cellular physiology and experimental results.