Cytogenetic assays

Structural and Numerical Alterations. The basic principles underlying in vivo cytogenetic assays are the same as those for in vitro assays, discussed above (Section 25.3.4b). The cell types that are available for the analysis of chromosome alterations are those that are cycling cell populations, such as bone marrow and spermatogonial cells. For acute exposures, analysis of metaphase cells at their first metaphase after S-phase treatment and analysis of all aberration types is appropriate for hazard evaluation. For chronic exposures, it is inappropriate to analyze unstable aberration types the informative approach is to analyze stable types (e.g., reciprocal translocations and inversions) using FISFI. 

For numerical chromosomal alterations, it is possible to analyze interphase cells using FISH with whole chromosome paints, or chromosomal specific probes. Thus, it is feasible to assess nondisjunctional events in any cell type, including target cells for tumorigenesis. Other fluorescence-based methods described in the section on in vitro methods (Section 25.3.4b) can be used in vivo, but they are of rather limited value for basic mutagenicity assays. 

A micronucleus assay can be conducted with bone marrow cells, peripheral lymphocytes or germ cells (spermatids) of mice. Rats can be used for micronucleus assays with bone marrow or spermatogenic cells but the use of peripheral lymphocytes requires surgical removal of the spleen, since this is the predominant site of removal of micronucleated erythrocytes in rats. 

---

In vitro cytogenetic assay using mouse lymphomas tk cells Chromosome Mammalian In vitro... 

Assays for Chromosomal and Genomic Mutations In vitro cytogenetic assay [OECD 473] / ... 

The in vitro cytogenetic assay is a short-term mutagenicity test for detecting chromosomal damage in cultured mammalian cells. 

Natarajan, A.T. and Obe, G. (1982). Mutagenicity testing with cultured mammalian cells cytogenetic assays. In Mutagenicity, New Horizons in Genetic Toxicology, (Heddle, J.A., Ed.). Academic Press, New York, pp. 172-213. 

Richardson, C., Williams, D.A., Allen, J.A., Amphlett, G., Changer, D.O. and Phillips, B. (1989). Analysis of data from in vitro cytogenetic assays. In UKEMS Sub-committee on Guidelines for Mutagenicity Testing. Report. Part III. Statistical Evaluation of Mutagenicity Test Data. (Kirkland, D.J., Ed.). Cambridge University Press, pp. 141-154. 

Thompson, E.D. (1986). Comparison of in vivo and in vitro cytogenetic assay results. Environ. Mutagen. 8 753-767. 

Topham, J., Albanese, R., Bootman, J., Scott, D. and Tweats, D. (1983). In vivo cytogenetic assays. In Report ofUKEMS Sub-committee on Guidelines for Mutagenicity Testing. Parti (Dea, B., Ed.), pp. 119-141. 

Liang JC, Hsu TC, Henry JE. 1983. Cytogenetic assays for mitotic poisons. The grasshopper embryo system for volatile liquids. Mutat Res 113 467-479. 

Mackay JM, Fox V, Griffiths K, et al Trichloroacetic acid Investigation into the mechanism of chromosomal damage in the in vitro human lymphocyte cytogenetic assay and the mouse bone marrow micronucleus test. Carcinogenesis 16(5) 1127-1133, 1995... 

Hazleton Labs. 1988a. Mutagenicity tests on o-, m-, and p-cresol in an ivitro cytogenetic assay measuring chromosomal aberration frequencies in CHOcells. Unpublished data submitted to EPA/OTS. Fiche no. OTS0517691. 

Hazleton Labs. 1989c. Mutagenicity test on cresol program panel sample 2 meta-cresol in the mouse bone marrow cytogenetic assay. HLA study no. 10002-0- 451. Unpublished data submitted to Chemical Manufacturers Association,Washington, DC. 

In vivo cytogenetic assay In vivo cytogenetic assay integrated into 28 d rodent toxicity study, provided it is adequate to support dinical trials and sampling within a day of last day of dosing In vivo cytogenetic assay and a 2nd in vivo endpoint, integrated wilh 28 d rodent assay and 1st in vivo endpoint if possible... 

Warr, T.J., Parry, E.M. Parry, J.M. (1993) A comparison of two in vitro mammalian cell cytogenetic assays for the detection of mitotic aneuploidy using 10 known or suspected aneugens. Mutat. Res., 287, 29-46... 

Lowe, K.W., Holbrook, C.J., Linkous, S.I. Roberts, M.R. (1987) Preliminary comparison of three cytogenetic assays for genotoxicity in mouse bone-marrow cells (Abstract No. 160). Environ. Mutag.. 9 (Suppl. 8), 63... 

The disadvantages of cytogenetic assays are that they are time-consuming and that negative results indicate only that further studies must be conducted with S-9 activation and with multiple fixations to account for possible different sensitivities of stages of the cell cycle. Furthermore, the scoring of 300 cells per point for chromosomal and chromatid aberrations is very difficult, requires much expertise, and is necessary to establish an accurate result. 

No rodent bioassay Not genotoxic (Ames, in vitro cytogenetic assay in human lymphocytes)... 

This in vitro cytogenetic test is a clastogenicity test system for the detection of chromosomal aberrations in cultured mammalian cells or primary cultures. Chromosomal aberrations may be either structural or numerical. However, because cytogenetic assays are usually designed to analyze cells at their first posttreatment mitosis and numerical aberrations require at least one cell division to be visualized, this type of aberration is generally not observed in a routine cytogenetic assay. The best estimate of aberration frequency is the first cell division after the start of treatment. Structural aberrations are of two types chromosome or chromatid aberrations. 

Natarajan AT, Boei JJ (2004) Formation of chromosome aberrations insights from FISH. Mutation Res 544 299-304 OECD Guideline 475 (1997) Mammalian Bone Marrow Chromosome Aberration Test. Adopted July 21 Preston RJ, Dean BJ, Galloway S, Holden H, McFee AF, Shelby M (1987) Mammalian in vivo cytogenetic assays Analysis of chromosome aberrations in bone marrow cells. Mutation Res 189(2) 157-165... 

---