Mutagenicities of nitrofuran derivatives on a bacterial tester strain with an R factor plasmid

Many nitrofuran derivatives are known to be mutagenic on Escherichia coli WP2 but not on Salmonella typhimurium TA1535, TA1536, TA1537 or TA1538. Ames and coworkers recently obtained a new tester strain of S. typhimurium, TA100, by putting an R factor plasmid, pKM101, into TA1535. We found that all the mutagenic nitrofuran derivatives previously found to be mutagenic on E. coli WP2 were mutagenic on this new strain (TA100).     

The mutagenic activity of 4-chloromethylbiphenyl (4CMB) and Benzyl Chloride (BC) in the bacterial/microsome assay

The mutagenic activity of 4CMB was investigated in agar layer cultures of Salmonella typhimurium TA1535, TA1537, TA1538, TA98 and TA100, and Escherichia coli WP2 and WP2 uvrA. The mutagenic activity of BC was investigated in the Salmonella strains only. Assays were performed both in the absence and in the presence of S9 microsomal fraction obtained from a liver homogenate from rats pretreated with Aroclor 1254.     

Mutagenicity of butadiene and butadiene monoxide.

Incubation of $\text{S. typhimurium}$ strains TA1530 and TA1535 in the presence of gaseous butadiene increased the number of his⁺ revertants/plate. This mutagenic effect occured in absence of fortified S-9 rat liver fraction. In its presence, the mutagenic effect seemed to be dependent on its composition. With butadiene monoxide, a reversion to histidine prototrophy was obtained without metabolic activation with strains TA1530, TA1535 and TA100. Butadiene monoxide might be a possible primary metabolite of butadiene.     

High mutagenicity and toxicity of a diol epoxide derived from benzo[a]pyrene

(±)-7β,8α-Dihydroxy-9β,10β-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BP 7,8-diol-9,10-epoxide) is a suspected metabolite of benzo[a]pyrene that is highly mutagenic and toxic in several strains of $\text{Salmonella}\text{typhimurium}$ and in cultured Chinese hamster V79 cells. BP 7,8-diol-9,10-epoxide was approximately 5, 10 and 40 times more mutagenic than benzo[a]pyrene 4,5-oxide (BP 4,5-oxide) in strains TA 98 and TA 100 of $\text{S.}\text{typhimurium}$ and in V79 cells, respectively. Both compounds were equally mutagenic to strain TA 1538 and non-mutagenic to strain TA 1535 of $\text{S.}\text{typhimurium}$. The diol epoxide was toxic to the four bacterial strains at 0.5–2.0 nmole/plate, whereas BP 4,5-oxide was nontoxic at these concentrations. In V79 cells, the diol epoxide was about 60-fold more cytotoxic than BP 4,5-oxide.     

Mutagenic evaluation of the monocyclic aromatic amine N-methylamino-2-nitro-4-N′,N′-bis(2-hydroxyethyl)aminobenzene in the Salmonella typhimurium/mammalian microsome test

The hair-dye component N-methylamino-2-nitro-4-N′,N′-bis(2-hydroxyethyl)aminobenzene was investigated for mutagenic activity in Salmonella typhimurium strains TA1535, TA100, TA1537, TA1538 and TA98. The testing was performed in the absence and in the presence of a rat-liver microsomal activation system induced by Aroclor 1254. Our results indicate that N-methylamino-2-nitro-4-N′,N′-bis(2-hydroxyethyl)aminobenzene does not induce mutations in Salmonella typhimurium strains, either in the absence or in the presence of the metabolic activation system. The purity of the compound was controlled by utilizing high-pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC).     

Mutagenicity of glycerol chlorohydrines and of their esters with higher fatty acids present in protein hydrolysates

3-Chloro-1,2-propanediol and 1,3-dichloro-2-propanol caused base substitutions in Salmonella typhimurium TA1535 both with and without metabolic activation. Metabolic activation seemed to act mainly by decreasing the toxicity of these compounds. A difference in the growth of the wild-type and repair-deficient strains of Escherichia coli was observed only for 1,3-dichloro-2-propanol with S9 mix. Esters of both chlorohydrines with fatty acids had smaller mutagenic effects than unesterified compounds.     

The origin of the carbon chain in the thiazole moiety of thiamine in Escherichia coli: incorporation of deuterated 1-deoxy-D-threo-2-pentulose

Non growing washed cells of Escherichia coli, derepressed for the biosynthesis of thiamine, have been incubated in the presence of glucose and either 1-deoxy-$\text{D}$-threo-2-pentulose $\text{1}$ or 1-déoxy-$\text{D}$-erythro-2-pentulose $\text{2}$ trideuterated on the methyl group. The incorporation of deuterium into the thiazole moiety of thiamine was measured by mass spectrometry. The label of the threo-compound was found in more than 40% of the thiazole biosynthesized in its presence; the label of the erythro-compound in less than 5%. Hence it is likely that the carbon chain of 1-deoxy-$\text{D}$-threo-2-pentulose is the precursor of the five carbons chain of the thiazole moiety of the thiamine molecule in E. coli.     

UKEMS trial compounds: In vitro bacterial mutagenicity

4CMB, 4HMB and BC were examined in the Ames test using Salmonella typhimurium TA1535, TA1537, TA1538, TA98 and TA100. 4CMB was mutagenic for all of the indicator strains, 4HMB was inactive and BC was weakly mutagenic for TA100 only.     

The occurrence of pili associated with a plasmid of the W compatibility group

Using electron microscopy, it was found that the acquisition of the W group drug resistance plasmid S-a by normally pilusless bacterial strains was associated with the appearance of pili. The loss of drug resistance markers in presumed R^? revertants was accompanied by a loss of pili. The numbers of pili present on transconjugant strains of the three bacterial species tested were 3.2 pili/cell for $\text{Salmonella typhimurium}$, and 0.19 pili/cell for both $\text{Escherichia coli}$ and $\text{Pseudomonas aeruginosa}$. Negatively stained pili were about 12 nm thick and varied in length from 23 nm to 3,370 nm.     

Outer membrane of gram-negative bacteria. XVII. Secificity of transport process catalyzed by the lambda-receptor protein in Escherichia coli.

The outer membrane of Gram-negative bacteria contains (a) “porin” proteins that form transmembrane channels and allow diffusion of various hydrophilic, small molecules (Nakae, J. Biol. Chem., 251, 2176–2178, 1976), and (b) proteins which catalyze the specific transport of unique classes of compounds, e.g. the λ-receptor protein facilitates the diffusion of maltose and maltotriose (Szmelcman et al., Eur. J. Biochem., 65, 13–19, 1976). When strains of $\text{Escherichia coli}$, $\text{B}\text{r}$ and K-12 containing the λ-receptor but not porin were constructed and compared with those containing neither of them, it was found that in the former strains the transmembrane diffusion of glucose and lactose, but not of histidine and 6-aminopenicillanic acid, was significantly accelerated. These results suggest that λ-receptor may facilitate the diffusion of sugars other than maltose.     

Behavioral comparisons of the stereoisomers of tetrahydrocannabinols

The potencies of (?)-$\text{trans}$-Δ⁹-THC, (+)-$\text{trans}$-Δ⁹-THC, (+)-$\text{cis}$-Δ⁹-THC, (?)-$\text{trans}$-Δ⁸-THC and (+)-$\text{trans}$-Δ⁸-THC were compared in several different species. (?)-$\text{trans}$-Δ⁹-THC was 100 times more potent than (+)-$\text{trans}$-Δ⁹-THC in depressing schedule-controlled responding in monkeys. The (+)-$\text{trans}$ isomers were less effective than their corresponding (?)-$\text{trans}$ isomers in the dog static-ataxia test, but potency ratios could not be determined due to a lack of dose-responsiveness of the (+)-$\text{trans}$ isomers. However, it appeared that their potency differed by at least ten fold. The potency of (+)-$\text{cis}$-Δ⁹-THC in the dog static-ataxia test was comparable to that of (+)-$\text{trans}$-Δ⁹-THC. The hypothermia in mice produced by the (?) isomers of $\text{trans}$-Δ⁹-THC and $\text{trans}$-Δ⁸-THC were 9.1 and 30.4 times greater than that produced by their respective (+)-isomers. Also, the potency ratio of the (+)- and (?)-$\text{trans}$-Δ⁹-THC was 5.6 as measured by depression of spontaneous activity in mice. The magnitude of the potency ratios of the THC stereo-isomers is dependent upon the species and the pharmacological test used.     

Mutagenicity of nitrofuran drugs in bacterial systems

The mutagenic activity of 5 nitrofuran drugs (furadantin, furoxon, furacin, benzazon VII and lampit) was tested on strainsSalmonella typhimurium TA 100, TA 1535, TA 1538 andEscherichia coli WP2uvra ⁺ and WP2uvr A. All nitrofurans tested had a marked mutagenic effect on strain TA 100 and, partially, on strain TA 1535 except for furoxon which was strongly toxic for this strain. No significant mutagenic effects of the drugs were observed with strain TA 1538. With the exception of lympit, all drugs exerted a mutagenie action onE.coli WP2uvrA but no on WP2 uvrA⁺ which has an intact excision repair system. The only drug exerting a mutagenie effect on the latter strain was furoxon. All five nitrofurans exhibited a positive repair rest. The results support the notion that the nitrofuran mutagens under study induce single base substitutions.     

Application of the Salmonella typhimurium microsome test to the study of 25 drugs belonging to 5 chemical series

25 active-principle forms of pharmaceutical drugs belonging to 5 chemical series have been tested for mutagenic activity. To screen these drugs we used the Salmonella typhimurium assay on 5-histidine-requiring strains, with and without microsomal activation. Only the 3 nitroimidazole derivatives were mutagenic for strains TA100, TA1535 and TA98.     

Mutagenicity of styrene and styrene oxide

Incubation of S. typhimurium strain TA 1535 with styrene increased the number of his⁺ revertants/plate in presence of a fortified S9 rat-liver fraction. Styrene was also highly cytotoxic for Salmonella cells. Styrene oxide, the presumed first metabolite, had a mutagenic effect towards strains TA 1535 and TA 100 both with and without metabolic activation. Styrene is probably mutagenic because it is metabolized to styrene oxide.     

Mutagenicity to Salmonella typhimurium of some Aspergillus and Penicillium mycotoxins

17 mycotoxins produced by various Aspergillus and Penicillium species were screened for their mutagenic activity to Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537, both with and without metabolic activation. Austdiol, austocystins A and D, kojic acid and viridicatumtoxin were found to be mutagenic after metabolic activation, while austdiol was also mutagenic per se. Aflatoxin B₁, sterigmatocystin and versicolorin A, which were used as positive controls were also mutagenic. No mutagenic activity was evident in the case of citrinin, cyclopiazonic acid, fumitremorgen B, griseofulvin, luteoskyrin, O-methylsterigmatocystin, mycophenolic acid, ochratoxin A, patulin, penicillic acid, secalonic acid D and TR₂-toxin.A good relationship was found between the mutagenic activity, or lack of it, of most of the mycotoxins with existing data on carcinogenicity. Inadequate information on the carcinogenicity of austdiol, austocystins A and D, kojic acid and viridicatumtoxin precluded correlations with mutagenicity to S. typhimurium. The relationship between chemical structure and mutagenicity of the mycotoxins is discussed.     

Evaluation of the mutagenic potential of mycotoxins using Salmonella typhimurium and Saccharomyces cerevisiae

The mutagenic effects of fifteen mycotoxins on Salmonella typhimurium strains TA1535, TA1537 and TA1538 and Saccharomyces cerevisiae strain D-3 were tested. Only aflatoxin B₁ and sterigmatocystin were mutagenic. Both were active against S. typhimurium strain TA1538 and S. cerevisiae strain D-3; however, both required activation by the hepatic S-9 enzyme preparation. A positive correlation between the other mycotoxins reported to be carcinogenic and the two in vitro test systems employed was not demonstrated in our hands.     

DNA synthesis during the division cycle of three substrains of Escherichia coliBr

The relationship between chromosome replication and the bacterial division cycle has been examined in three substrains of Escherichia coli$\text{B}\text{r}$ obtained from different sources and designated $\text{B}\text{r}$ A, $\text{B}\text{r}$ F and $\text{B}\text{r}$ K. At growth rates greater than 1.0 doubling per hour (μ > 1.0), the time for a round of chromosome replication (C) was 42 minutes in all three substrains, but the time between the end of a round and cell division (D) was 22 minutes in $\text{B}\text{r}$ A, 16 minutes in $\text{B}\text{r}$ F and 14 minutes in $\text{B}\text{r}$ K. At slower growth rates C and D increased, but to significantly different extents in the three substrains. When μ = 0.5, C and D were approximately 80 and 40 minutes in $\text{B}\text{r}$ A, 60 and 20 minutes in $\text{B}\text{r}$ F, and 70 and 20 minutes in $\text{B}\text{r}$ K.As a consequence of the lengths of the C and D periods in the three stocks of E. coli$\text{B}\text{r}$, the patterns of chromosome replication during the division cycle differed. The most obvious difference was that E. coli$\text{B}\text{r}$ F and E. coli$\text{B}\text{r}$ K possessed periods devoid of DNA synthesis at both the beginning and the end of the division cycle during slow growth, whereas E. coli$\text{B}\text{r}$ A contained only one period devoid of DNA synthesis at the end of the cycle.     

Evaluation of the mutagenic properties of the coccolithophorePleurochrysis carterae (Haptophyceae) as a potential human food supplement

The mutagenicity of the algaPleurochrysis carterae for use as human food was tested by the Ames method with the modification of pre-incubation, by usingSalmonella typhimurium TA98, TA100, TA1535, TA1537 andEscherichia coli WP2uvrA. The freeze-dried powder ofP. carterae was not mutagenic to any strain either with or without S9 mix. In view of the absence of adverse effects ofP. carterae in this mutagenicity study, it is suggested thatP. carterae is safe for human consumption as a human food supplement.Author for correspondence     

Comparative mutability of the Ames tester strains of Salmonella typhimurium by ultraviolet radiation and by 4-nitroquinoline 1-oxide

A standard method for determining mutant frequencies per survivor was used to study the detailed kinetics of reverse mutations of Ames tester strains of Salmonella typhimurium induced by UV and by 4N1O. After UV irradiation, strain TA1538 was non-mutable, but its plasmid-containing derivative TA98 was mutable, whereas TA1535 was mutable and its plasmid-bearing derivative TA100 was about 10-fold more mutable. After treatment with 4NQO, TA98 was less mutable than TA1538, whereas TA100 was more mutable than TA1535 by a factor of 10–50. TA1537 was slightly less mutable than TA1535 by either UV or 4NQO. The differential mutabilities of these strains are briefly discussed in relation to the “hot spot” base sequences for reversion and the nature of DNA damage caused by UV and 4NQO.     

Bacterial mutagenicity tests on 4-chloromethylbiphenyl and 2 structural analogues

4CMB, 4HMB and BC were tested in 5 strains of S. typhimurium and 2 strains of E. coli without S9. 4HMB was negative in all strains. 4CMB was a strong positive mutagen in TA1535, TA1537, TA1538, TA98, TA100 and WP2uvrA⁻(pKM101), and BC was a weak mutagen in TA100 and WP2uvrA⁻(pKM101). Positivity was determined as a dose response over 3 or more points, in repeat experiments, giving a significant correlation coefficient.