Toluene chromosomal

In the degradation of toluene, the plasmid-borne genes encode enzymes for the oxidation to benzoate, whereas those that are chromosomally borne encode ring 2,3-dioxygenation. 

The pathways for the aerobic biodegradation of alkylated benzenes have been elncidated in extensive investigations and have been discussed in Chapter 8, Part 1, so that only salient featnres are briefly snmmarized here. The genes for the degradation of toluene may be either chromosomal or... 

Metabolism and genetic toxicity have been reported to differ with the isomer of nitro-toluene. p-Nitrotoluene was not mutagenic in bacterial assays, but it did increase sister chromatid exchange frequencies and chromosomal aberrations in vitro-, in vivo it did not increase the frequency of micronuclei in bone marrow of treated rodents. Similar findings were reported for the ortho isomer, except that it did not induce chromosomal aberrations in vitro. Only the ortho isomer induces DNA excision repair in the in vivo-in vitro hepatocyte unscheduled DNA synthesis assay. Furthermore, ort/jo-nitrotoluene binds to hepatic DNA to a much greater extent than meta- or para-nitrotoluene, and investigators suggest that it may act similarly to the rodent hepatocarcino-gen 2,6-dinitrotoluene. ... 

Chromosomal aberrations in peripheral lymphocytes were also reported in a study of about 40 workers who had been occupationally exposed to trace quantities of 2-butanone (methyl ethyl ketone), butyl acetate, toluene, cyclohexanone and xylene in addition to dimethylfonnamide. Blood samples were taken at two Ibur-nionth intervals, when exposure was to an average of 180 and 150 mg/nr dimethylformamide, respectively. The frequencies of chromosomal aberrations were 3.82% and 2.74% at these two sampling times. Subsequent sampling at tliree six-month intervals, when average dimethylformamide exposures were to 50, 40 and 35 mg/m- , gave lower aberration frequencies of 1.59%, 1.58% and 1.49%. Aberration frequencies in two control groups were 1.61% and 1.10% (Koudela Spazier, 1981). 

The frequency of chromosomal aberrations in 20 employees exposed mainly to toluene in various printing inks at a rotogravure plant was no different from that in 23 control workers an increased frequency was observed in smokers in both groups (Pelclova etal., 1987). 

Toluene did not induce sex-linked recessive lethal mutations or translocations, but did induce sex-chromosome loss and nondisjunction in male Drosophila melanogaster and induced mitotic arrest (C-mitosis) in embryos of the grasshopper, Melanoplus sanguinipes. 

Bauchinger, M., Schmid, E., Dresp, J., Kolin-Gerresheim, J., Hauf, R. Suhr, E. (1982) Chromosome changes in lymphocytes after occupational exposure to toluene. Mutat. Res., 102, 439-445... 

Forni, A., Pacifico, E. Limonta, A. (1971) Chromosome studies in workers exposed to benzene or toluene or both. Arch, environ. Health, 22, 373-378... 

Maki-Paakkanen, J., Husgafvel-Pursiainen. K., Kalliomaki, P.-L., Tuominen, J. Sorsa, M. (1980) Toluene-exposed workers and chromosome aberrations. J. Toxicol, environ. Health, 6.775-781... 

Rodriguez Amaiz, R. Villalobos-Pietrini, R. (1985a) Genetic effects of thinner, benzene and toluene in Drosophila melanogaster. 1. Sex chromosome loss and non-disjunction. Contam. amb., 1, 35-43... 

Toluene diisocyanate did not induce unscheduled DNA synthesis in rat primary hepatocytes. 2,4-Toluene diisocyanate induced mutations in mouse lymphoma L5178Y cells at the tk locus in the presence of exogenous metabolic activation and increased the frequency of sister chromatid exchanges but not chromosomal aberrations in Chinese hamster ovary cells. 2,6-Toluene diisocyanate induced gene mutations in L5178Y cells in the presence of an exogenous metabolic activation system and induced sister chromatid exchanges and chromosomal aberrations in Chinese hamster ovary cell cultures. 

In human lymphocyte cultures prepared from a male donor, toluene diisocyanate induced DNA single-strand breaks and chromosomal aberrations, but not sister chromatid exchanges. 

Maki-Paakkanen, J. Norppa, H. (1987) Chromosome aberrations and sister-chromatid exchanges induced by technical grade toluene diisocyanate and methylenediphenyl diisocyanate in cultured human lymphocytes. Toxicol. Lett., 36, 37-4.3... 

Pseudomonas putida FI (which contains a chromosomally encoded tod operon for toluene degradation) was genetically modified by the introduction of tod-lux CDABE into the chromosome yielding the biosensor Pseudomonas putida TVA8 (Applegate et al., 1998). The tod operon is induced when exposed to several compounds such as benzene, toluene, ethylbenzene and xylene (Shingleton et al., 1998). 

Applegate, B.M., Kehrmeyer, S.R., and Sayler, G.S., A chromosomally-based tod-luxCDABE whole-cell reporter for benzene, toluene, ethylbenzene, and xylene (BTEX) sensing, Ann. Environ. Microbiol., 64, 2730-2735, 1998. 

The degradation of toluene In this example, different pathways are used by the plasmid and chromosomally borne genes — side-chain oxidation to benzoate and ring 2,3-dioxygenation, respectively (Chapter 6, Section 6.2.1). 

For monoalkylated benzenes, there are two additional factors (1) the genes may be either chromosomal or carried on plasmids and (2) oxidation may be initiated either on the aromatic ring or at the alkyl substituent. For example, toluene may be degraded by several different pathways. 

Angenendt P, Glokler J, Konthur Z, Lehrach H, Cahill DJ (2003) 3D protein microarrays performing multiplex immunoassays on a single chip. Anal Chem 75(17) 4368 372 Applegate BM, Kehrmeyer SR, Sayler GS (1998) A chromosomally based tod-luxCDABE wholecell reporter for benzene, toluene, ethybenzene, and xylene (BTEX) Sensing. Appl Environmental Microbiol 64(7) 2730-2735... 

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