Ulrich Wahnschaffe, Annette Bitsch, Janet Kielhorn, Inge Mangelsdorf
Fraunhofer Institute of Toxicology and Experimental Medicine ITEM, Department of Chemical Risk Assessment, Nikolai-Fuchs-Str. 1, 30625 Hannover, Germany
| Date of Submission | 19-May-2004 |
| Date of Acceptance | 27-Jan-2005 |
| Date of Web Publication | 27-Jan-2005 |
Correspondence Address:
Janet Kielhorn
Fraunhofer Institute of Toxicology and Experimental Medicine ITEM, Department of Chemical Risk Assessment, Nikolai-Fuchs-Str. 1, 30625 Hannover
Germany.
Source of Support: None, Conflict of Interest: None
DOI: 10.1186/1477-3163-4-4
Abstract
The mouse spot test, an in vivo mutation assay, has been used to assess a number of chemicals. It is at present the only in vivo mammalian test system capable of detecting somatic gene mutations according to OECD guidelines (OECD guideline 484). It is however rather insensitive, animal consuming and expensive type of test. More recently several assays using transgenic animals have been developed. From data in the literature, the present study compares the results of in vivo testing of over twenty chemicals using the mouse spot test and compares them with results from the two transgenic mouse models with the best data base available, the lacI model (commercially available as the Big Blue® mouse), and the lacZ model (commercially available as the Muta™ Mouse). There was agreement in the results from the majority of substances. No differences were found in the predictability of the transgenic animal assays and the mouse spot test for carcinogenicity. However, from the limited data available, it seems that the transgenic mouse assay has several advantages over the mouse spot test and may be a suitable test system replacing the mouse spot test for detection of gene but not chromosome mutations in vivo.
| How to cite this article: Wahnschaffe U, Bitsch A, Kielhorn J, Mangelsdorf I. Mutagenicity testing with transgenic mice. Part II: Comparison with the mouse spot test. J Carcinog 2005;4:4 |
| How to cite this URL: Wahnschaffe U, Bitsch A, Kielhorn J, Mangelsdorf I. Mutagenicity testing with transgenic mice. Part II: Comparison with the mouse spot test. J Carcinog [serial online] 2005 [cited 2021 Oct 15];4:4. Available from: https://carcinogenesis.com/text.asp?2005/4/1/4/42209 |
Background
This is the second presentation from a project for the International Programme on Chemical Safety (IPCS) evaluating the possible use of transgenic animal mutagenicity assays in toxicity testing and mechanistic research. Part I, preceeding this article, discussed comparison of effects of chemicals using certain transgenic assays with results using the bone marrow micronucleus test.
The assessment of the potential genotoxicity of chemicals in vivo is important for both the verification and confirmation of intrinsic mutagenicity and for establishing the mode of action of chemical carcinogens. Although the present trend is to reduce animal testing, in vitro data must be confirmed by testing in in vivo conditions which take into account whole animal processes like absorption, tissue distribution, metabolism and excretion of the chemical and its metabolites, and overall toxicity [1]. In the mid 1980s, the mouse spot test [2] was suggested as a complementary in vivo test to the bacterial mutagenicity assay for detection of mutagenic substances and as a confirmatory test for the identification of carcinogens [3]. The mouse spot test has been used to assess a number of chemicals (see e.g. , see separate file). It is at present the only in vivo mammalian test system capable of detecting somatic gene mutations according to OECD guidelines (OECD guideline 484 [4]). However to achieve an acceptable sensitivity, a large number of animals are necessary and it is therefore an expensive type of test and seldom used. More recently assays using transgenic animals have been developed for testing in vivo gene mutagenicity. The two transgenic mouse models with the best data base available are the lacI model (commercially available as the Big Blue® mouse), and the lacZ model (commercially available as the Muta™ Mouse). The present study compares the results of in vivo testing of a number of chemicals using the mouse spot test and compares it with results from these two transgenic mouse models.
Descriptions of test systems
Mouse spot test
In the spot test, mouse embryos which are heterozygous for different recessive coat colour genes, are treated in utero at gestation day 9-11 with the test substance. The exposed embryo at gestation day 10 contains about 150-200 melanoblasts and each melanoblast has 4 coat colour genes under study [2,5]. The in utero exposure may result in an alteration or loss of a specific wild-type allele in a pigment precursor cell resulting in a colour spot in the coat of the adult animal. The frequency of spots is compared with the frequency in sham-exposed controls [2,4].
In the mouse spot test there are 4 possible mechanisms by which the recessive coat-colour alleles can be expressed: 1) gene mutation in the wild-type allele, 2) deficiency (large or small) of a chromosomal segment involving the wild-type allele, 3) nondisjunctional (or other) loss of the chromosome carrying the wild-type allele and 4) somatic recombination (marker gene then homozygous) [5]. Gene mutagenic but also clastogenic effects are detected by this test system.
Transgenic mouse models
The transgenic mutation test systems the lacI model (Big Blue® mouse), and the lacZ model (Muta™ Mouse) are described in detail in the preceding article: Mutagenicity testing with transgenic mice. Part I: Comparison with the mouse bone marrow micronucleus test
Methods
Data presented in this documentation are the results of an extensive literature research. Concerning data on transgenic mouse assays only primary literature was used. Data on the mouse spot test were extracted from reliable reviews on this item or from primary literature. For all other data informations from secondary literature or data banks were used.
Results and Discussion
Comparison of the mouse spot test with transgenic mouse model systems
In the literature search chemicals have been identified that had been tested using the spot test and the Muta™ mouse assay (n = 20) or the Big Blue® mouse assay (n = 9) or both transgenic mutation assays (n = 8). The results (including references) are given in .
The results on 15 out of 20 substances (2-acetylaminofluorene, acrylamide, benzo[ a ]pyrene, 1,3-butadiene, cyclophosphamide, ethylmethanesulfonate, N -ethyl- N -nitrosourea, N -methyl- N ‘-nitro- N -nitrosoguanidine, N -methyl- N -nitrosourea, 4-nitroquino-line-1-oxide, N -nitrosodiethylamine, N -nitrosodimethylamine, procarbazine, 4-acetylaminofluorene and N -propyl- N -nitrosourea) showed agreement between the Muta™ mouse and the mouse spot test. No agreement was seen with 5 out of 20 substances (4-acetylaminofluorene, 2-amino-3-methylimidazo(4,5-f)quinoline (IQ), hydrazine, mitomycin C, trichloroethylene).
The positive results obtained with the Big Blue® mouse assay agreed with results in the mouse spot test for 7 out of 9 substances (2-acetylaminofluorene, benzo[ a ]pyrene, 1,3-butadiene, cyclophosphamide, N -ethyl- N -nitrosourea, N -methyl- N -nitrosourea, N -nitrosodimethylamine); one (di-(2-ethylhexyl)phthalate) was negative in both test systems and only one (methyl methanesulfonate) showed no agreement between the two test systems.
With two exceptions, 4-acetylaminofluorene and N-propyl-N-nitrosourea (discussed later), all of the tested substances showed also clearly positive results in in vitro gene mutation assays (exception of 1,3-butadiene, negative results) and in the majority of in vivo studies on this endpoint. Further they induced carcinogenic effects in long-term studies on mice.
Although no data on carcinogenicity on mice is available on N -propyl- N -nitrosourea, this substance might also be included in the category mentioned above, since carcinogenic effects were reported in rats [113] and in vitro gene mutation assays revealed clearly positive results.
The following substances did not show agreement between results in the mouse spot test and transgenic mouse assays or negative results were reported in both test systems (see ). These are therefore discussed in more detail here; for references see Additional file .
4-Acetylaminofluorene
This substance showed mutagenic activity in the Muta™ mouse assay [19] but negative results in the mouse spot test [12,13]. No data on carcinogenicity are available on 4-acetylaminofluorene. However, data on two in vitro test systems indicated gene mutagenic activity supporting results in the transgenic assay [15-18].
2-Amino-3-methylimidazo(4,5-f)quinol (IQ)
IQ is mutagenic in the Muta™ mouse assay [28] but negative results were obtained in the mouse spot test [29]. This negative result in the mouse spot test is in contrast to all other in vivo gene mutation assays on rodents and insects which revealed positive results [27]. Furthermore, gene mutagenic activity was detected in in vitro test systems and carcinogenic effects were observed in long-term studies on mice [27]. The results in the Muta™ mouse assay are in accordance with these data.
Di-(2-ethylhexyl)phthalate
Negative results in the mouse spot test [51] are in agreement with the negative Big Blue® assay [11]. Furthermore no gene mutagenic or questionable activity was reported in in vitro tests and in tests on Drosophila. Carcinogenic effects were obtained in studies on mice but nongenotoxic mechanisms are presumed.
Hydrazine
This substance induced mutagenic effects in the mouse spot test [72] but negative results were observed in the Muta™ mouse assay [71]. Other in vivo as well as in vitro test systems revealed gene mutagenic effects [70]. Increased tumor incidences were observed in carcinogenicity studies on mice. Overall, the mouse spot test but not the Muta™ mouse assay reflects data on genotoxicity and carcinogenicity. However, a single exposure was used in the Muta™ mouse assay [71]. Studies on other in vivo genotoxicity endpoints have shown generally negative results after single exposure but genotoxic activity after repeated application, for example the mouse bone marrow micronucleus assay was positive [20]. It is possible that positive results may be found using another experimental design in the Muta™ mouse assay e.g. repeated exposure.
Methyl methanesulfonate
Only weak mutagenic effects were observed in the Muta™ mouse [19, 57, 75-77] and negative results in the Big Blue® mouse [63-65,78]. In the mouse spot test this carcinogenic substance is mutagenic [3] as well as in other gene mutation assays in vitro and in vivo [73,74]. However, there is evidence that the chromosome mutagenic activity is detectable at much lower doses than the gene mutagenic activity. Tinwell et al. [19] have shown in Muta™ mice a weak gene mutagenic effect in the liver but no effect in the bone marrow. The same dose induced in these animals a significant increase in bone marrow micronuclei indicating clear clastogenic activity. However, the transgenic mutation assay is less suitable for detection of these effects [1].
Mitomycin C
No mutagenic activity was observed in the Muta™ mouse assay after single application and ambiguous results after repeated exposure [93] but positive results were obtained with the mouse spot test [2,3] and other gene mutation assays in vitro and in vivo with this carcinogenic substance [90-92]. The reason for this discrepancy is similar to that presumed for methyl methanesulfonate above. Clastogenicity in bone marrow but no gene mutagenic activity in liver and bone marrow has been shown in the same animals in the Muta™ mouse assay combined with a micronucleus assay [93]. However, using another experimental design for detection of gene mutations in the Muta™ mouse assay (dose level up to the MTD, repeated exposure) positive results might be obtained.
Trichloroethylene
Also with this carcinogenic substance, no mutagenicity was detected in the Muta™ mouse assay [117], the mouse spot test was positive [3], but this result is possibly related to contaminations with epoxides [116]. Further in vitro and in vivo assays on gene mutation resulted in weak positive, questionable, or negative effects [116]. Results in chromosome mutation assays are equivocal. However, a further (simple) reason for this discrepancy between the Muta™ mouse assay and the mouse spot test might be that the MTD was not reached in the Muta™ mouse assay presented by Douglas et al. [117].
In general, from the studies on genotoxic carcinogens given above, the results do not seem to give a preference for either the spot test or transgenic mouse model system.
However, considering the mechanisms of action of specific substances there is some evidence, that the mouse spot test detects gene mutations as well as chromosome mutations whereas the transgenic mouse assays are restricted to gene mutations. Evidence for this hypothesis has been shown with the examples methyl methanesulfonate, mitomycin C, and trichloroethylene. In the mouse spot test, there are four possible mechanisms by which the recessive coat-colour alleles can be expressed (see introduction) including gene and chromosome mutations. Although the chromosome mutations have to survive several mitoses to cause the expression of the recessive allele [118], there is evidence that also predominantly clastogenic substances might result in a positive mouse spot test. In contrast, the transgenic mutation assays detected point mutations and maximal small deletions and insertions [1].
Predictivity of the transgenic animal assays and the mouse spot test for carcinogenicity
The sensitivity, specificity and predictivity of carcinogenicity for the transgenic mouse model (Muta™ mouse assay and the Big Blue® mouse assay combined) and the mouse spot test are documented in [Table 1]. Data on 18 substances (see ) are available on carcinogenicity in mice and mutagenic effects in transgenic mice as well as mutagenic effects in the mouse spot test (trichloroethylene not included because of inconclusive results in the mouse spot test).
Although the data pool is not sufficient for a comprehensive comparison, there is some indication, that no significant differences were detectable between the two test systems.
Advantages and disadvantages of both test systems
Sensitivity of the test system
In comparison to models using endogenous genes like the target genes in the mouse spot test, the spontaneous mutant frequency in transgenic animals is relatively high. This might be due to the fact that bacterial DNA is the target gene (high methylation rate) and/or the transgene is silent and no transcription related repair occurs as in endogenous genes which are more efficiently repaired [1]. However, comparing the number of cells and genes at risk at the time of exposure, the mouse spot test is numerical inferior to the transgenic mouse mutation assays. In the mouse spot test, the exposed embryo at gestation day 10 contains about 150-200 melanoblasts and each melanoblast has 4 coat colour genes under study [2,5]. In the transgenic Big Blue® mouse, for example, 30-40 copies of the target gene (the constructed λLIZα shuttle vector) are integrated on chromosome 4 of each cell of the animal [1].
Other factors
To achieve an acceptable sensitivity, a large number of animals are necessary in the mouse spot test. Many pregnant dams have to be in one treatment group to get a sufficient number of surviving F1-animals, since the test substance may induce maternal and developmental toxicity. Fahrig [2] suggested that 30-40 pregnant mice are needed per treatment group for evaluation of spots in the progeny. At least 150 F1-mice are recommended for the concurrent vehicle control [5] and at least two dose groups are used (OECD guideline 484 [4]). Therefore, the mouse spot test is an expensive type of in vivo test.
In contrast, in transgenic mutation assays ca. 20 animals (3 dose groups and 1 concurrent vehicle control group in laboratories which already established this test system) are recommended per species and gender [119-121].
In the mouse spot test the discrimination between spots of mutagenic and non-mutagenic origin may be problematic [2].
A comparison of both test systems is presented in [Table 2].
Conclusions
Although the mouse spot test is a standard genotoxicity test system according to the OECD guidelines, this system has seldom been used for detection of somatic mutations in vivo in the last decades. This is partly due to considerations of cost effectiveness and number of animals needed for testing but also for toxicological considerations. The usefulness of the mouse spot test in toxicology is limited by restrictions in toxicokinetics, sensitivity, target cell/organ, and molecular genetics. From the limited data available, it seems that the transgenic mouse assay has several advantages over the mouse spot test and may be a suitable test system replacing the mouse spot test for detection of gene but not chromosome mutations in vivo .
Author’s contributions
UW was the main author. The other authors were involved in the discussions, writing small parts of text and in final preparation of the manuscript.
Acknowledgements
This paper is based on work performed by the authors in preparation of an Environmental Health Criteria document on ‘Transgenic Animals in Mutagenicity Testing’ for the International Programme on Chemical Safety (IPCS). However, opinions expressed in this paper are the sole responsibility of the authors. We acknowledge the financial support of the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.[122]
References
| 1. | RIVM: Mutagenicity of chemicals in genetically modified animals. RIVM Report no. 650210 002, TNO Report no. V99.1097 . Bilthoven: National Institute of Public Health and the Environmenta (RIVM); 2000.  |
| 2. | Fahrig R: The mammalian spot test (Fellfleckentest) with mice. Arch Toxicol 1977, 38: 87-98. |
| 3. | Styles JA, Penman MG: The mouse spot test. Evaluation of its performance in identifying chemical mutagens and carcinogens. Mutat Res 1985, 154: 183-204. |
| 4. | OECD: OECD 484; Genetic toxicology: mouse spot test; OECD guideline for testing of chemicals . 1986. |
| 5. | Russell LB, Selby PB, von Halle E, Sheridan W, Valcovic L: Use of the mouse spot test in chemical mutagenesis: interpretation of past data and recommendations for future work. Mutat Res 1981, 86: 355-379. |
| 6. | Shephard SE, Sengstag C, Lutz WK, Schlatter C: Mutations in liver DNA of lacI transgenic mice (Big Blue) following subchronic exposure to 2-acetylaminofluorene. Mutat Res 1993, 302: 91-96. |
| 7. | Hazardous Substances Data Bank (HSDB) 2003, 2-Acetylaminofluorene, CAS: 53-96-3 |
| 8. | National toxicology programm (NTP) 2001, 2-Acetylaminofluorene, Factsheet CAS: 53-96-3 |
| 9. | Brooks TM, Szegedi M, Rosher P, Dean SW: The detection of gene mutation in transgenic mice (Muta Mouse) following a single oral dose of 2-acetylaminofluorene. Mutagenesis 1995, 10: 149-150. |
| 10. | Ross JA, Leavitt SA: Induction of mutations by 2-acetylaminofluorene in lacI transgenic B6C3F1 mouse liver. Mutagenesis 1998, 13: 173-179. |
| 11. | Gunz D, Shephard SE, Lutz WK: Can nongenotoxic carcinogens be detected with the lacI transgenic mouse mutation assay? Environ Mol Mutagen 1993, 21: 209-211. |
| 12. | Hüttner E, Braun R, Sch φneich J: Mammalian spot test with the mouse for detection of transplacental genetic effects induced by 2-acetylaminofluorene and 4-acetylaminofluorene. In Evaluation of short-term tests for carcinogens: Report of the International Programme on Chemical Safety’s collaborative study on in vivo assays . Edited by: Ashby J. Cambridge: Cambridge University Press; 1988:164-167. |
| 13. | Fahrig R: Positive response of 2-Acetylaminofluorene, negative response of 4-Acetylaminofluorene in the mammalian spot test. In Evaluation of short-term tests for carcinogens . Cambridge: Cambridge University Press; 1988:159-163. |
| 14. | Gocke E, Wild D, Eckhardt K, King MT: Mutagenicity studies with the mouse spot test. Mutat Res 1983, 117: 201-212. |
| 15. | Schinz HR, Fritz-Niggli H, Campbell TW, Schmid H: Krebsbildung durch Aminofluorene und verwandte K φrper. Oncologia 1955, 8: 233-245. |
| 16. | Morris HP, Velat CA, Wagner BP, Dahlgard M, Ray FE: Studies of carcinogenicity in the rate of derivates of aromatic amines related to N-2-fluorenylacetamide . J Natl Cancer Inst 1960, 24: 149-180. |
| 17. | Genetic Toxicology (GENETOX) 1998, 4-Acetylaminofluorene, CAS: 28322-02-3 |
| 18. | Chemical carcinogenesis research information system (CCRIS) 1995, 4-Acetylaminofluorene, CAS: 28322-02-3 |
| 19. | Tinwell H, Lefevre PA, Ashby J: Relative activities of methyl methanesulphonate (MMS) as a genotoxin, clastogen and gene mutagen to the liver and bone marrow of Muta Mouse mice. Environ Mol Mutagen 1998, 32: 163-172. |
| 20. | Morita T, Asano N, Awogi T, Sasaki Y, Sato S, Shimada H, Sutou S, Suzuki T, Wakata A, Sofuni T, Hayashi M: Evaluation of the rodent micronucleus assay in the screening of IARC carcinogens (groups 1, 2A and 2B) the summary report of the 6th collaborative study by CSGMT/JEMS MMS. collaborative study of the micronucleus group test. mammaliam mutagenicity study group. Mutat Res 1997, 389: 3-122. |
| 21. | IARC: Acrylamide. In Some Industrial Chemicals. Monographs on the Evaluation of Carcinogenic Risks to Humans, No. 60 . Lyon: International Agency for Research on Cancer (IARC); 1994:389-433. |
| 22. | Chemical Carcinogenesis Research Info System (CCRIS) 1996, Acrylamide, CAS: 79-06-1 |
| 23. | Myhr B: Validation studies with muta mouse: a transgenic mouse model for detecting mutations in vivo. Environ Mol Mutagen 1991, 18: 308-315. |
| 24. | Hoorn AJW, Custer LL, Myhr BC, Brusick D, Gossen J, Vijg J: Detection of chemical mutagens using Muta Mouse: a transgenic mouse model. Mutagenesis 1993, 8: 7-10. |
| 25. | Krebs O, Favor J: Somatic and germ cell mutagenesis in lambda lacZ transgenic mice traeted with acrylamide or ethylnitrosourea. Mutat Res 1997, 388: 239-248. |
| 26. | Neuhδuser-Klaus A, Schmahl W: Mutagenic and teratogenic effects of acrylamide in the mammalian spot test. Mutat Res 1989, 226: 157-162. |
| 27. | IARC: IQ (2-Amino-3-methylimidazo[4,5-f]quinoline. In Some Naturally Occuring Substances: Food Items and Constituents, Heterocyclic Aromatic Amines and Mycotoxins. IARC Monographs on the Evaluation on Carcinogenic Risks to Humans, No.56 . Lyon: International Agency for Research on Cancer (IARC); 1993:165-195. |
| 28. | Davis CD, Dacquel EJ, Schut HAJ, Thorgeirsson SS, Snyderwine EG: In vivo mutagenicity and DNA adduct levels of heterocyclic amines in Muta Mice and c-myc/lacZ double transgenic mice. Mutat Res 1996, 356: 287-296. |
| 29. | Wild D, Gocke E, Harnasch D, Kaiser G, King MT: Differential mutagenic activity of IQ (2-Amino-3-methylimidazo(4,5-F)quinoline) in Salmonella Typhimurium strains in vitro and in vivo, in Drosophila, and in mice. Mutat Res 1985, 156: 93-102. |
| 30. | WHO: Selected Non-heterocyclic Polycyclic Aromatic Hydrocarbons . International Programme on Chemical Safety, Environmental Health Criteria 202, Geneva: World Health Organization; 1998. |
| 31. | Chemical carcinogenesis research information system (CCRIS) 2003, Benzo(a)pyrene, CAS: 50-32-8 |
| 32. | Hakura A, Tsutsui Y, Sonoda J, Kai J, Imade T, Shimada M, Sugihara Y, Mikami T: Comparison between in vivo mutagenicity and carcinogenicity in multiple organs by benzo[a]pyrene in the lacZ transgenic mouse (Muta Mouse). Mutat Res 1998, 398: 123-130. |
| 33. | Hakura A, Tsutsui Y, Sonoda J, Mikami T, Tsukidate K, Sagami F, Kerns WD: Multiple organ mutation in the lacZ transgenic mouse (Muta Mouse) 6 months after oral traetment (5 days) with benzo[a]pyrene. Mutat Res 1999, 426: 71-77. |
| 34. | Kohler SW, Provost GS, Fieck A, Kretz PL, Bullock WO, Putman DL, Sorge JA, Short JM: Analysis of spontaneous and induced mutations in transgenic mice using a lambda ZAP/lacI shuttle vector. Environ Mol Mutagen 1991, 18: 316-321. |
| 35. | Kohler SW, Provost GS, Fieck A, Kretz PL, Bullock WO, Sorge JA, Putman DL, Short JM: Spectra of spontaneous and mutagen-induced mutations in the lacI gene in transgenic mice. Proc Natl Acad Sci U S A 1991, 88: 7958-7962. |
| 36. | Skopek TR, Kort KL, Marino DR, Mittal LV, Umbenhauer DR, Laws GM, Adams SP: Mutagenic response of the endogenous hprt gene and lacI transgene in benzo[a]pyrene-treated Big Blue B6C3F1 mice. Environ Mol Mutagen 1996, 28: 376-384. |
| 37. | Shane BS, Lockhart AM, Winston GW, Tindall KR: Mutant frequency of lacI in transgenic mice following benzo[a]pyrene treatment and partial hepatectomy. Mutat Res 1997, 377: 1-11. |
| 38. | Shane BS, de Boer J, Watson DE, Haseman JK, Glickman BW, Tidall KR: LacI mutation spectra following benzo[a]pyrene treatment of Big Blue mice. Carcinogenesis 2000, 21: 715-725. |
| 39. | IARC: 1,3-butadiene. In Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide (part one). Monographs on the evaluation of carcinogenic risks to humans, No. 71 . Lyon: International Agency for Research on Cancer (IARC); 1999:109-225. |
| 40. | Recio L, Bond JA, Pluta LJ, Sisk SC: Use of transgenic mice for assessing the mutagenicity of 1,3-butadiene in vivo . IARC (Int Agency Res Cancer) Sci Pub 1993, 127: 235-243. |
| 41. | Sisk SC, Pluta L, Bond JA, Recio L: Molecular analysis of lacI mutants from bone marrow of B6C3F1 transgenic mice following inhalation exposure to 1,3-butadiene. Carcinogenesis 1994, 15: 471-477. |
| 42. | Recio L, Meyer KG, Pluta LJ, Moss OR, Saranko CJ: Assessment of 1,3-butadiene mutagenicity in the bone marrow of B6C3F1 lacI transgenic mice (Big Blue): a review of mutational spectrum and lacI mutant frequency after a 5-day 625 ppm 1,3-butadiene exposure. Environ Mol Mutagen 1996, 28: 424-429. |
| 43. | Adler I-D, Cao J, Filser JG, Gassner P, Kessler W, Kliesch U, Neuhδuser-Klaus A, Nüsse M: Mutagenicity of 1,3-butadiene inhalation in somatic and germinal cells of mice. Mutat Res 1994, 309: 307-314. |
| 44. | IARC: Cyclophosphamide. In Some antineoplastic and immunosuppressive agents. Monographs on the evaluation of the carcinogenic risk chemicals to humans, No. 26 . Lyon: International Agency for Research on Cancer (IARC); 1981:165-202. |
| 45. | IARC: Cyclophosphamide (Group 1). In Overall evaluations of carcinogenicity: An updating of IARC MOnographs volumes 1 to 42. Monographs on the evaluation of carcinogenic risks to humans, Suppl. 7 . Lyon: International Agency for Research on Cancer (IARC); 1987:182-184. |
| 46. | Gorelick NJ, Andrews JL, de Boer JG, Young R, Gibson DP, Walker VE: Tissue-specific mutant frequencies and mutational spectra in cyclophosphamide-treated lacI transgenic mice. Environ Mol Mutagen 1999, 34: 154-166. |
| 47. | Walker VE, Andrews JL, Upton PB, Skopek TR, deBoer JG, Walker DM, Shi X, Sussman HE, Gorelick NJ: Detection of cyclophosphamide-induced mutations at the Hprt but not the lacI locus in splenic lymphocytes of exposed mice. Environ Mol Mutagen 1999, 34: 167-181. |
| 48. | Hoyes KP, Wadeson PJ, Sharma HL, Hendry JH, Morris ID: Mutation studies in lacI transgenic mice after exposure to radiation or cyclophosphamide. Mutagenesis 1998, 13: 607-612. |
| 49. | Hart J: The mouse spot test: results with a new cross. Arch Toxicol 1985, 58: 1-4. |
| 50. | DFG: Di(2-ethylhexyl)phthalat (DEHP). In Gesundheitsschδdliche Arbeitsstoffe: toxikologisch-arbeitsmedizinische Begründung von MAK-Werten. Gase, Dδmpfe, Aerosole; Diazinon bis N,N-Dimethylanilin . Edited by: Henschler D. Weinheim: Verlag Chemie; 2002:1-81. |
| 51. | Fahrig R, Steinkamp-Zucht A: Co-recombinogenic and anti-mutagenic effects of diethylhexylphthalate, inactiveness of pentachlorophenol in the spot test with mice. Mutat Res 1996, 354: 59-67. |
| 52. | IARC: Ethyl methanesulfonate. In Some anti-thyroid and related substances, nitrofurans and industrial chemicals. Monographs on the evaluation of the carcinogenic risk of chemicals to man, No. 7 . Lyon: International Agency for Research on Cancer (IARC); 1974:245-251. |
| 53. | DECOS (Dutch expert committee for occupational standards): Health-based recommended occupational exposure limits for Ethyl Methanesulphonate (EMS) and Methyl Methanesulphonate (MMS) . Voorburg: Directorate-General of Labour; 1989. |
| 54. | Chemical Carcinogenesis Research Info System (CCRIS) 2001, Ethyl methanesulphonate, CAS: 62-50-0 |
| 55. | Genetic toxicology (GENETOX) 1995, Ethyl methanesulphonate, CAS: 62-50-0 |
| 56. | Suzuki T, Hayashi M, Wang X, Yamamoto K, Ono T, Myhr BC, Sofuni T: A comparison of the genotoxicity of ethylnitrosourea and ethyl methanesulfonate in lacZ transgenic mice (Muta Mouse). Mutat Res 1997, 395: 75-82. |
| 57. | Suzuki T, Hayashi M, Sofuni T: Initial experiences and future directions for transgenic mouse mutation assays. Mutat Res 1994, 307: 489-494. |
| 58. | Mientjes EJ, Luiten-Schuite A, van der Wolf E, Borsboom Y, Bergmanns A, Berends F, Lohman PHM, Baan RA, van Delft JHM: DNA adducts, mutant frequencies, and mutation spectra in various organs of lacZ mice exposed to ethylating agents. Environ Mol Mutagen 1998, 31: 18-31. |
| 59. | IARC: N-Nitroso-N-Ethylurea. In Some N-Nitro Compounds. Monographs on the evaluation of carcinogenic risk of chemicals to humans, No. 17 . Lyon: International Agency for Research on Cancer (IARC); 1978:191-215. |
| 60. | Genetic Toxicology (GENETOX) 1998, 1-Ethyl-1-Nitrosourea, CAS: 759-73-9 |
| 61. | JEMS/MMS: Organ variation in the mutagenicity of ethylnitrosourea in Muta Mouse: results of the collaborative study on the transgenic mutation assay by JEMS/MMS. Environ Mol Mutagen 1996, 28: 363-375. |
| 62. | Douglas GR, Jiao J, Gingerich JD, Gossen JA, Soper LM: Temporal and molecular characteristics of mutations induced by ethylnitrosourea in germ cells isolated from seminiferous tubules and in spermatozoa of lacZ transgenic mice. Proc Natl Acad Sci U S A 1995, 92: 7485-7489. |
| 63. | Gorelick NJ, Andrews JL, Gibson DP, Carr GJ, Aardema MJ: Evaluation of lacI mutation in germ cells and micronuclei in peripheral blood after treatment of male lacI transgenic mice with ethylnitrosourea, isopropylmethane sulfonate or methylmethane sulfonate. Mutat Res 1997, 388: 187-195. |
| 64. | Putman D, Penn Ritter A, Carr GJ, Young RR: Evaluation of spontaneous and chemical-induced lacI mutations in germ cells from lambda/lacI transgenic mice. Mutat Res 1997, 388: 137-143. |
| 65. | Winegar RA, Carr G, Mirasalis JC: Analysis of the mutagenic potential of ENU and MMS in germ cells of male C57BL/6 lacI transgenic mice. Mutat Res 1997, 388: 175-178. |
| 66. | Katoh M, Horiya N, Valdivia RPA: Mutations induced in male germ cells after treatment of transgneic mice with ethylnitrosourea. Mutat Res 1997, 388: 229-237. |
| 67. | Zimmer DM, Harbach PR, Mattes WB, Aaron CS: Comparison of mutant frequencies at the transgenic lambda LacI and cII/cI loci in control and ENU-treated Big Blue mice. Environ Mol Mutagen 1999, 33: 249-256. |
| 68. | Provost GS, Short JM: Characterization of mutations induced by ethylnitrosourea in seminiferous tubule germ cells of transgenic B6C3F1 mice. Proc Natl Acad Sci U S A 1994, 91: 6564-6568. |
| 69. | Skopek TR, Kort KL, Marino DR: Relative sensitivity of the endogenous hprt gene and lacI transgene in ENU-treated Big Blue B6C3F1 mice. Environ Mol Mutagen 1995, 26: 9-15. |
| 70. | BUA (Beratergremium für umweltrelevante Altstoffe): Hydrazin, Hydrazinhydrat und Hydrazinsulfate. BUA Stoffbericht 205 . Stuttgart: S. Hirzel Wissenschaftliche Verlagsgesellschaft; 1996. |
| 71. | Douglas GR, Gingerich JD, Soper LM: Evidence for in vivo non-mutagenicity of the carcinogen hydrazine sulfate in target tissues of lacZ transgenic mice. Carcinogenesis 1995, 16: 801-804. |
| 72. | Neuhδuser-Klaus A, Chauhan PS: Studies on somatic mutation induction in the mouse with isoniazid and hydrazine. Mutat Res 1987, 191: 111-116. |
| 73. | IARC: Methyl methanesulfonate. In Re-evaluation of some organic chemicals, hydrazine and hydrogen peroxide. Monographs on the evaluation of carcinogenic risks to humans, No. 71/3 . Lyon: International Agency for Research on Cancer (IARC); 1999:1059-1079. |
| 74. | IARC: Methyl methanesulphonate. In Some anti-thyroid and related substances, nitrofurans and industrial chemicals. Monographs on the evaluation of the carcinogenic risk of chemicals to man, No. 7 . Lyon: International Agency for Research on Cancer (IARC); 1974:253-260. |
| 75. | Renault D, Brault D, Thybaud V: Effect of ethylnitrosourea and methyl methanesulfonate on mutation frequency in Muta™ Mouse germ cells (seminiferous tubule cells and epididymis spermatozoa). Mutat Res 1997, 388: 145-153. |
| 76. | Brooks TM, Dean SW: The detection of gene mutation in the tubular sperm of Muta™ Mice following a single intraperitoneal treatment with methyl methanesulphonate or ethylnitrosourea. Mutat Res 1997, 388: 219-222. |
| 77. | Itoh S, Miura M, Shimada H: Germ cell mutagenesis in lacZ transgenic mice treated with methyl methanesulfonate. Mutat Res 1997, 388: 223-228. |
| 78. | Mirsalis JC, Provost GS, Matthews CD, Hamner RT, Schindler JE, O’Loughlin KG, MacGregor JT, Short JM: Induction of hepatic mutations in lacI transgenic mice. Mutagenesis 1993, 8: 265-271. |
| 79. | IARC: N-methyl-N’-nitro-n-nitrosoguanidine. In Some aromatic amines, hydrazine and related substances, N-nitroso compounds and miscellaneous alkylating agents. Monographs on the evaluation of the carcinogenic risk of chemicals to man, No. 4 . Lyon: International Agency for Research on Cancer (IARC); 1974:183-195. |
| 80. | IARC: N-methyl-N’-nitro-N-nitrosoguanidine. In Genetic and related effects: an updating of selected IARC monographs from volumes 1 to 42. Monographs on the evaluation of carcinogenic risks to humans, Suppl. 6 . Lyon: International Agency for Research on Cancer (IARC); 1987:394-398. |
| 81. | IARC: N-methyl-N’-nitro-N-nitrosoguanidine (Group 2B). In Overall evaluations of carcinogenicity: an updating of IARC Monographs Volume 1 to 42. Monographs on the evaluation of carcinogenic risks to humans, Suppl. 7 . Lyon: International Agency for Research on Cancer (IARC); 1987:248-250. |
| 82. | Brooks TM, Dean SW: Detection of gene mutation in skin, stomach and liver of Muta Mouse following oral or topical treatment with N-methyl-N’-nitro-N-nitrosguanidine or 1-chloromethylpyrene: some preliminary observations. Mutagenesis 1996, 11: 529-532. |
| 83. | Brault D, Bouilly C, Renault D, Thybaud V: Tissue-specific induction of mutations by acute oral administration of N-methyl-N’-nitro-N-nitrosoguanidine and -propiolactone to the Muta Mouse: preliminary data on stomach, liver and bone marrow. Mutat Res 1996, 360: 83-87. |
| 84. | IARC: N-nitroso-n-methylurea. In Some n-nitroso compounds. Monographs on the evaluation on carcinogenic risk of chemicals to humans, No. 17 . Lyon: International Agency for Research on Cancer (IARC); 1978:227-255. |
| 85. | Genetic Toxicology (GENETOX) 1998, 1-Methyl-1-Nitrosourea, CAS: 684-93-5 |
| 86. | von Pressentin MdM, Kosinska W, Guttenplan JB: Mutagenesis induced by oral carcinogens in lacZ mouse (Muta Mouse) tongue and other oral tissues. Carcinogenesis 1999, 20: 2167-2170. |
| 87. | Shephard SE, Gunz D, Schlatter C: Genotoxicity of agaritine in the lacI transgenic mouse mutation assay: evaluation of the health risk of mushroom consumption. Food Chem Toxicol 1995, 33: 257-264. |
| 88. | Provost GS, Kretz P, Hamner RT, Matthews CD, Rogers BJ, Lundberg KS, Dycaico MJ, Short JM: Transgenic systems for in vivo mutation analysis. Mutat Res 1993, 288: 133-149. |
| 89. | Monroe JJ, Kort KL, Miller JE, Marino DR, Skopek TR: A comparative study of in vivo mutation assays: analysis of hprt, lacI, cII/cI as mutational targets for N-nitroso-N-methylurea and benzo[a]pyrene in Big Blue mice. Mutat Res 1998, 421: 121-136. |
| 90. | IARC: Mitomycin C. In Some naturally occuring substances. Monographs on the evaluation of the carcinogenic risk of chemicals to man, No. 10 . Lyon: International Agency for Research on Cancer (IARC); 1976:171-179. |
| 91. | Chemical Carcinogenesis Research Info System (CCRIS) 2002, Mitomycin C, CAS: 50-07-7 |
| 92. | Genetic Toxicology (GENETOX) 1998, Mitomycin C, CAS: 50-07-7 |
| 93. | Suzuki T, Hayashi M, Sofuni T, Myhr BC: The concomitant detection of gene mutation and micronucleus induction by mitomycin C in vivo using lacZ transgenic mice. Mutat Res 1993, 285: 219-224. |
| 94. | Genetic toxicology (GENETOX) 1998, 4-Nitroquinoline 1-Oxide, CAS: 56-57-5 |
| 95. | Chemical carcinogenesis research information system (CCRIS) 2003, 4-Nitroquinoline 1-Oxide, CAS: 56-57-5 |
| 96. | Nakajima M, Kikuchi M, Saeki K, Miyata Y, Terada M, Kishida F, Yamamoto R, Furihata C, Dean SW: Mutagenicity of 4-nitroquinoline 1-oxide in the Muta Mouse. Mutat Res 1999, 444: 321-336. |
| 97. | IARC: N-Nitrosodiethylamine. In Some N-Nitro Compounds. Monographs on the evaluation of the carcinogenic risk of chemicals to humans, No. 17 . Lyon: International Agency for Research on Cancer (IARC); 1978:83, 89-106. |
| 98. | Chemical Carcinogenesis Research Info System (CCRIS) 2003, N,N-Diethylnitrosamine, CAS: 55-18-5 |
| 99. | Genetic Toxicology (GENETOX) 1998, Diethylnitrosamine, CAS: 55-18-5 |
| 100. | Okada N, Honda A, Kawabata M, Yajima N: Sodium phenobarbital-enhanced mutation frequency in the liver DNA of lacZ transgenic mice treated with diethylnitrosamine. Mutagenesis 1997, 12: 179-184. |
| 101. | Suzuki T, Hayashi M, Myhr B, Sofuni T: Diethylnitrosamine is mutagenic in liver but not in bone marrow of lacZ transgenic mice (Muta Mouse). Honyu Dobutsu Shiken Bunkakai Kaiho 1995, 3: 33-39. |
| 102. | IARC: N-nitrosodimethylamine. In Some N-Nitroso Compounds. Monographs on the evaluation of the carcinogenic risk of chemicals to humans, No. 17 . Lyon: International Agency for Research on Cancer (IARC); 1978:125-175. |
| 103. | Genetic toxicology (GENETOX) 1995, Dimethylnitrosamine, CAS: 62-75-9 |
| 104. | Schmezer P, Eckert C, Liegibel U, Klein R, Bartsch H: Use of transgenic mutational test systems in risk assessment of carcinogens. Arch Toxicol 1998, (Suppl 20) : 321-330. |
| 105. | Ashby J, Short JM, Jones NJ, Lefevre PA, Provost GS, Rogers BJ, Martin EA, Parry JM, Burnette K, Glickman BW, Tinwell H: Mutagenicity of o-anisidine to the bladder of lacI- transgenic B6C3F1 mice: absence of 14C or 32P bladder DNA adduction. Carcinogenesis 1994, 15: 2291-2296. |
| 106. | Cunningham ML, Hayward JJ, Shane BS, Tindall KR: Distinction of mutagenic carcinogens from a mutagenic noncarcinogen in the Big Blue transgenic mouse. Environ Health Perspect 1996, 104: 683-686. |
| 107. | Shane BS, Smith-Dunn DL, de Boer JG, Glickman BW, Cunningham ML: Mutant frequencies and mutation spectra of dimethylnitrosamine (DMN) at the lacI and cII loci in the livers of Big Blue transgenic mice. Mutat Res 2000, 452: 197-210. |
| 108. | IARC: Procarbazine hydrochloride. In Some Antineoplastic and Immunosuppressive Agents. Monographs on the evaluation of the carcinogenic risk of chemicals to humans, No. 26 . Lyon: International Agency for Research on Cancer (IARC); 1981:311-339. |
| 109. | IARC: Procarbazine hydrochlorine (Group2A). In Overall evaluations of carcinogenicity: an updating of IARC Monographs Volumes 1 to 42. Monographs on the evaluation of carcinogenic risks to humans, Suppl. 7 . Lyon: International Agency for Research on Cancer (IARC); 1987:327-328. |
| 110. | Suzuki T, Uno Y, Idehara K, Baba T, Maniwa J, Ohkouchi A, Wang X, Hayashi M, Sofuni T, Tsuruoka M, Miyajima H, Kondo K: Procarbazine genotoxicity in the Muta Mouse; strong clastogenicity and organ-specific induction of lacZ mutations. Mutat Res 1999, 444: 269-281. |
| 111. | Pletsa V, Valavanis C, van Delft JHM, Steenwinkel M-JST, Kyrtopoulos SA: DNA damage and mutagenesis induced by procarbazine in lacZ transgenic mice: evidence that bone marrow mutations do not arise primarily through miscoding by O6-methylguanine. Carcinogenesis 1997, 18: 2191-2196. |
| 112. | Neuhδuser A: Die Wirksamkeit von Natulan im Fellflecken-Test mit der Maus. GSF-Ber B 1977, 798: 42-44. |
| 113. | Chemical Carcinogenesis Research Info System (CCRIS) 2000, N-Propyl-N-nitrosourea, CAS: 816-57-9 |
| 114. | Genetic Toxicology (GENETOX) 1992, N-Propyl-N-nitrosourea, CAS: 816-57-9 |
| 115. | Hara T, Hirano K, Hirano N, Tamura H, Sui H, Shibuya T, Hyogo A, Hirashio T, Tokai H, Yamashita Y, Kura K: Mutation induction by N-propyl-N-Nitrosourea in eight Muta Mouse organs. Mutat Res 1999, 444: 297-307. |
| 116. | DFG: Trichloroethylene. In Occupational toxicants. Critical data evaluation for MAK values and classification of carcinogens, Volume 10 . Deutsche Forschungsgemeinschaft (DFG). Weinheim: Wiley-VCH; 1996:201-244. |
| 117. | Douglas GR, Gingerich JD, Soper LM, Potvin M, Bjarnason S: Evidence for the lack of base-change and small-deletion mutation induction by trichloroethylene in lacZ transgenic mice. Environ Mol Mutagen 1999, 34: 190-194. |
| 118. | Fahrig R: Genetic effects of dioxins in the spot test with mice. Environ Health Perspect 1993, 101 (Suppl 3) : 257-261. |
| 119. | Mirsalis J, Monforte J, Winegar R: Transgenic animal models for detection of in vivo mutations. Annu Rev Pharm Toxicol 1995, 35: 145-164. |
| 120. | Heddle JA, Dean S, Nohmi T, Boerrigter M, Casciano D, Douglas GR, Glickman BW, Gorelick NJ, Mirsalis JC, Martus H-J, Skopek TR, Thybaud V, Tindall KR, Yajima N: In vivo transgenic mutation assays. Environ Mol Mutagen 2000, 35: 253-259. |
| 121. | Thybaud V, Dean S, Nohmi T, de Boer J, Douglas GR, Glickman BW, Gorelick NJ, Heddle JA, Heflich RH, Lambert I, Martus HJ, Mirsalis JC, Suzuki T, Yajima N: In vivo transgenic mutation assays. Mutat Res 2003, 540: 141-151. |
| 122. | Nohmi T, Suzuki T, Masumura K-I: Recent advances in the protocols of transgenic mouse mutation assays. Mutat Res 2000, 455: 191-215. |
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