Hprt assay

Graves, R.J. Green, T. (1996) Mouse liver glutathione S-transferase mediated metabolism of methylene chloride to mutagen in the CHO/HPRT assay. Mutat. Res., 36il, 143-150... 

In Vivo Gene Mutation Assays Mouse (Coat) Spot Assay Mouse Retinoblast (Eye Spot) Assay Hprt Assay... 

The genotoxicity of TNT s known metabolites has also been investigated. In the CHO HPRT assay, 4,4 -AZT, 2, 4,6,6 -tetranitro-2,4 -azoxytoluene (2,4 -AZT), and triaminotoluene (TAT) were found to be directly mutagenic and 4-ADNT and 2, 4-AZT were mutagenic following metabolic (S9) activation [32], The positive... 

DNT under anaerobic conditions produced 2-amino-4-nitrotoluene and 4-amino-2-nitrotoluene as well as azoxy compounds. Subsequently, the same team reported that technical grade 2,4-DNT as well as pure 2,4-DNT, 3,4-DNT and 2,6-DNT (at concentrations up to 2 mM) were nonmutagenic using standard conditions in the CHO-HPRT assay [42], Both 2,4-DNT and 2,6-DNT isomers gave negative results in the HGPRT-V79 assay when tested in absence of metabolic activation [43],... 

Kennel SJ et al., Mutation analyses of a series of TNT-related compounds using the CHO-HPRT assay, J. Appl. Toxicol., 20, 441, 2000. 

Exposure to ultraline Ti02 particles at 130 p-g/mL was used to assay cytotoxicity (tetrazohum MMT) and population growth, as well as for comet assay (58a). There was an increase in the in vitro mutation rate as indicated by the comet assay and hypox-anthine guanosine phosphoribosyl transferase (HPRT) assays of 2.5- to 5-fold relative to controls, suggesting that mutations had occurred from the nanoparticle exposure. 

MICRO HPRT ASSAY IN FIBROBLASTS AND HAIR FOLLICLES... 

HPRT assays wer performed on RBC and WBC lysates with excess PRPP (2.5 X 10 M). Intact leukocytes were incubated with hypox-... 

TK or HPRT forward mutation assays in cultured mammalian ceils Drosophila sex-linked recessive lethal assay... 

The assay was described by Clive and co-workers (Clive et al. 1972) as a mutational assay system using the TK locus in mouse lymphoma cells. In the following years, he and his collaborators undertook a large-scale of investigation of the potential and optimal conduct of the assay. This included the use of the above mentioned TFT to select tk mutants, a comparison of the hypoxanthine guanine phosphoribosyl transferase (hprt) and tk loci, an analysis of the best expression time for tk mutant selection and a description of distinct large and small colony tk mutants. 

CD-I mice were exposed to purified air or benzene by inhalation at 0.04, 0.1, or 1.0 ppm for 22 hours per day, 7 days per week for 6 weeks (Ward et al. 1992). The effects of in vivo exposure to benzene were evaluated by using an autoradiographic assay to determine the frequency of mutants which represent mutations at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus in spleen lymphocytes. At the end of the six weeks exposure period, lymphocytes were recovered from the spleens of the mice and cryopreserved prior to assay. Mutant cells were selected on the basis of their ability to incorporate tritiated thymidine in the presence of 6-thioguanine. The increased frequencies of mutant spleen lymphocytes were significant at the low and mid, but not the high dose, and the method does not take into account possible clonal expansion. Further evaluation of the induction of gene mutation at these dose levels seems warranted. 

Point mutation tests have been developed also for cultured mammalian cells (de Marini et al, 1989). These tests are based on the mutational resistance to otherwise cytotoxic agents (i.e. TKor HPRT mutations, conferring resistance to trifluorothymidine and 6-thioguanine, respectively). Compared to the Ames test and other bacterial assays they are, however, more laborious and time consuming. 

Dimethyl ether is inactive in genetic tests including the Salmonella assay (with and without metabolic activation in at least four strains), HPRT reversion in CHO cells, DNA repair/synthesis in rat liver cells, and the sex-linked recessive lethal test in the fruit fly. 

Johnson GE (2012) Mammalian cell HPRT gene mutation assay test methods. Methods Mol Biol 817 55-67... 

In Lesch-Nyhan patients, all tissues are devoid of HPRT. The disorder thus can be detected by an assay for HPRT in erythrocytes and by cultured fibroblasts. The former test has been used in detection of the heterozygous state. HPRT is a 217-amino-acid cytosolic enzyme coded for by a single gene on the X chromosome. 

Mutation spectrum for some assays (e.g., transgenic models, hprt). 

The mouse lymphoma assay or HPRT locus test is required as part of the EC Base Set if the Ames test... 

---