A comparison of the agar cloning and microtitration techniques for assaying cell survival and mutation frequency in L5178Y mouse lymphoma cells

Evaluation of the mouse lymphoma tk assay (microwell method) as an alternative to the in vitro chromosomal aberration test

“…The MLA quantifies genetic alterations affecting expression of the thymidine kinase (TK) gene (tk). This assay was developed by Drs D.Clive and M.Moore (Clive and Spector, 1975;Clive et al, 1979;Moore-Brown et al, 1981) and the protocol has been optimized Moore and Howard, 1982;Cole et al, 1983;Turner et al, 1984;Majeska and Matheson, 1990). Some TK-deficient mutants in the MLA exhibit not only point mutations but also gross structural and numerical changes at the chromosomal level (Hozier et al, 1982;Moore et al, 1985;Blazak et al, 1989;Clive et al, 1990;Combes et al, 1995;Zhang et al, 1996), thus the MLA can detect a wide range of genetic damage, including gene mutations, larger scale chromosomal changes, recombination, aneuploidy and others.…”

1,4-Dioxane is not mutagenic in five in vitro assays and mouse peripheral blood micronucleus assay, but is in mouse liver micronucleus assay

“…Negative data were reported for the induction of sex-dioxane is due to genotoxic or nongenotoxic mechanisms has been extensively discussed [Stott et al, 1981; Stott linked recessive lethal mutations in Drosophila [Yoon et al, 1985], DNA damage in rat liver [Stott et al, 1981], andWatanabe, 1982;Kitchin and Brown, 1990;Goldsworthy et al, 1991;Jackson et al, 1993;. DNA repair in rat liver or nasal cavity [Stott et al, 1981;Goldsworthy et al, 1991], micronuclei in mouse periph-Positive findings from in vivo assays raise the possibility that 1,4-dioxane might be a weak genotoxic carcinogen eral blood or bone marrow in B6C3F1 [McFee et al, 1994], CD-1 [Morita, 1994], C57BL and CBA mice [Tin- [Kitchin and Brown, 1990;. The mouse liver micronucleus assays conducted in this study and well and .…”

“…Data from the mouse erythMost carcinogens that show genotoxic activity in vivo also show it in vitro. Recently, standardization of genorocyte micronucleus assay, however, remain equivocal [Morita et al, 1997] because of mixed results and a failure toxicity test procedures has brought about improved assay protocols so that genotoxins are detected more efficiently to confirm the positive result reported by Mirkova [1994] [ McFee et al, 1994;Morita, 1994;Tinwell and Ashby, [Galloway, 1994;ICH, 1997;OECD, 1997]. We therefore reevaluated the genotoxic potential of 1,4-dioxane in five 1994].…”

The mouse lymphoma assay in the wake of ICH4where are we now?

“…In order to overcome the latter problem, a protocol variation that had initially been validated using L5178Y wild-type cells (Cole et al, 1983) involving cloning cells in liquid medium in 96-well microtitre trays instead of in soft agar in Petri dishes was successfully applied to tk ϩ/-cells (Cole et al, 1986). A detailed comparison of cloning tk ϩ/-cells in agar and microtitre trays showed that under optimal conditions the two methods gave essentially similar results when both sets of plates were scored by eye so that all small colonies were counted (J.…”

“…The mouse lymphoma assay (MLA) has been widely used for many years for determining the potential for chemicals to cause the full broad spectrum of mutational damage Mitchell et al, 1997). Substantial research has been conducted to understand the capabilities (and limitations) of the assay, its proper conduct and the appropriate interpretation of test data (Clive et al, 1979(Clive et al, , 1990Hozier et al, 1981Hozier et al, , 1982Hozier et al, , 1989Moore-Brown, 1981;Cole et al, 1983Cole et al, , 1990Cole et al, , 1991Turner et al, 1984;Moore et al, 1985aMoore et al, ,b, 1989Blazak et al, 1986;Doerr et al, 1989;Applegate et al, 1990;Moore and Doerr, 1990;Liechty et al, 1993Liechty et al, , 1994Liechty et al, , 1996Zhang et al, 1996;Mitchell et al, 1997;Clark et al, 1998).…”