TK6 cells have a doubling time of around 14h, so samples for micronucleus scoring could just be taken following this to assure that all cells have divded. Are there any benefits to using cytochalasin B in these cases?
Yes, there are advantages to using cytochalasin B for micronucleus assay in cells with short doubling times.
The micronucleus assay is a widely used method to evaluate chromosomal damage in cells. It involves the induction of micronuclei, which are small, extra-nuclear bodies containing fragments or whole chromosomes that are not incorporated into the daughter nuclei during cell division. The assay is usually performed on cells that have completed one or more cell cycles, and cytochalasin B is often used to prevent the formation of daughter cells by inhibiting cytokinesis.
In cells with short doubling times, such as rapidly dividing cancer cells, the use of cytochalasin B can be advantageous for several reasons:
Be careful, the cell doubling time of TK6 may be ~14 hours in untreated cells, but as soon as you expose to a chemical that is toxic then the doubling time will increase. If you sample at 14 hours then you risk missing any clastogenic effects. Read the OECD 487 test guideline to get guiddance on methodology, most people harvest the cells after at least 1.5 to 2.0 cell cycles.
The main value of using Cyto-B is that if you score only the binucleate cells for MN then you can be certain that these cells have completed a full cell cycle and passed through mitosis since treatment.
Also, I am not sure that I agree with point 2 of the answer of Vinay. TK6 cycle at ~14 hours and this is pretty much their maximum rate and cannot be reduced. In addition, Cyto-B has some toxicity, so likely the doubling time will increase a little in any case.
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