Technical information
What is genotoxicity?
Genotoxicity is the ability of a chemical or physical agent to directly or
indirectly induce genetic damage in cells. Compounds or agents that
test positive in genotoxicity assays have the potential to be
carcinogens or mutagens. The FDA and the EPA require that drugs
and other chemicals must be tested for genotoxicity if humans will be
exposed to them.
What assays are used for genotoxicity?
Several different assays exist, including the Ames Assay and the
Mouse Lymphoma Assay (MLA). We have developed an alternative
assay that is even more sensitive than the MLA to a wide variety of
genotoxic agents and yet can be done much more rapidly and is less
labor intensive. Our assay is known as the Flow Cytometry Mutation
Assay (FCMA) The assay is based on a Chinese hamster hybrid cell
line (CHO AL) that was derived over 30 years ago by fusing a CHO cell
with a normal human cell. Eventually the CHO AL cell line was
established which contained the normal hamster chromosomes and
one copy of human chromosome 11. This human chromosome
encodes several genes that express surface proteins on the CHO
plasma membrane that would not normally be expressed, the most
important of which is CD59. Mutations in CD59 lead to the loss of the
CD59 surface protein which is detected by monoclonal antibodies. Of
major importance, since chromosome 11 is unnecessary for the
survival of the CHO AL cell, mutations ranging from a point mutation to
loss of nearly the entire chromosome can be detected without killing
the cell. Thus our mutation assay based on the CHO AL cells is more
sensitive than any other mammalian cell mutation assay, including the
MLA (see Scientific Results). Furthermore, we use flow cytometry to
measure the presence or absence of CD59 on the surface with
monoclonal antibodies. This avoids the time needed for colony
growth, thus reducing the time for analysis approximately in half
compared to the MLA or other clonogenic assays.
What is genotoxicity?
Genotoxicity is the ability of a chemical or physical agent to directly or
indirectly induce genetic damage in cells. Compounds or agents that
test positive in genotoxicity assays have the potential to be
carcinogens or mutagens. The FDA and the EPA require that drugs
and other chemicals must be tested for genotoxicity if humans will be
exposed to them.
What assays are used for genotoxicity?
Several different assays exist, including the Ames Assay and the
Mouse Lymphoma Assay (MLA). We have developed an alternative
assay that is even more sensitive than the MLA to a wide variety of
genotoxic agents and yet can be done much more rapidly and is less
labor intensive. Our assay is known as the Flow Cytometry Mutation
Assay (FCMA) The assay is based on a Chinese hamster hybrid cell
line (CHO AL) that was derived over 30 years ago by fusing a CHO cell
with a normal human cell. Eventually the CHO AL cell line was
established which contained the normal hamster chromosomes and
one copy of human chromosome 11. This human chromosome
encodes several genes that express surface proteins on the CHO
plasma membrane that would not normally be expressed, the most
important of which is CD59. Mutations in CD59 lead to the loss of the
CD59 surface protein which is detected by monoclonal antibodies. Of
major importance, since chromosome 11 is unnecessary for the
survival of the CHO AL cell, mutations ranging from a point mutation to
loss of nearly the entire chromosome can be detected without killing
the cell. Thus our mutation assay based on the CHO AL cells is more
sensitive than any other mammalian cell mutation assay, including the
MLA (see Scientific Results). Furthermore, we use flow cytometry to
measure the presence or absence of CD59 on the surface with
monoclonal antibodies. This avoids the time needed for colony
growth, thus reducing the time for analysis approximately in half
compared to the MLA or other clonogenic assays.
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| Genes on chromosome 11 |
| CHO AL Cell with chromosome 11 (arrow) |
| Cytomation GTX, Inc. |
| Flow Cytometry histogram of the mutants and non-mutants |
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