DNA staining with the fluorochromes EtBr, DAPI and YOYO-1 in the comet assay with tobacco plants after treatment with ethyl methanesulphonate, hyperthermia and DNase-I.

We applied the alkaline version of the single-cell gel electrophoresis (comet) assay to roots and leaves of tobacco (Nicotiana tabacum var. xanthi) seedlings or isolated leaf nuclei treated with: (1) the alkylating agent ethyl methanesulphonate, (2) necrotic heat treatments at 50 degrees C, and (3) DNase-I. All three treatments induced a dose-dependent increase in DNA migration, expressed as percentage of tail DNA.

Polyclonal antibodies to a recombinant coat protein of Potato virus A.

Specific mouse antibodies against a recombinant coat protein (CP) of Potato virus A (PVA) were produced. The PVA CP gene was cloned in an expression vector pMPM4omega. After expression in Escherichia coli the presence of the expressed CP was proved by Western blot analysis using polyclonal and monoclonal antibodies (MAbs).

Monitoring the genotoxicity of soil extracts from two heavily polluted sites in Prague using the Tradescantia stamen hair and micronucleus (MNC) assays.

We have taken soil samples from two sites in Prague, the capital of the Czech Republic, that are heavily polluted by motor vehicles. As a negative control, soil samples from a recreational site in Prague with no motor vehicle traffic were used. Soil samples from these sites were extracted with water or 5% dimethylsulphoxide (DMSO) for 24 h and cuttings of Tradescantia clone 4430 were immersed for 12 h at 25 degrees C in the extraction solutions.

[Evaluation of diet in a sample of Czech mothers six months after delivery].

Background: Health care of nursing mothers and their infants is an important priority of primary preventive care. The mother's diet plays an important role in this respect. The objective of the presented investigation was to assess the adequacy of the dietary intake of lactating mothers during the sixth month after delivery.

Mutagenic synergy between paraoxon and plant-activated m-phenylenediamine or 2-acetoxyacetylaminofluorene.

Paraoxon (diethyl-p-nitrophenylphosphate) is the toxic, but non-mutagenic metabolite of the organophosphorus ester insecticide parathion. Although this agent has been used as a deacetylase inhibitor in many studies, we discovered a mutagenic synergy when paraoxon was incubated with plant-activated m-phenylenediamine (mPDA) or with direct-acting 2-acetoxyacetylaminofluorene (2AAAF) and S. typhimurium tester strains.

Environmental monitoring for genotoxicity with plant systems. Results and recommendations.

In the first phase of a collaborative study by the International Programme on Chemical Safety (IPCS), four coded chemicals, i.e. azidoglycerol (AG, 3-azido-1,2-propanediol), methyl nitrosourea (MNU), sodium azide (NaN3) and maleic hydrazide (MH), and ethyl methanesulfonate (EMS) as a positive control were tested in four plant bioassays, namely the Arabidopsis embryo and chlorophyll mutation assay, the Tradescantia stamen hair assay (Trad-SH assay), the Tradescantia micronucleus assay (Trad-MCN), and the Vicia faba root tip assay.

Arabidopsis assay for mutagenicity.

Four laboratories, two in the Czech Republic (Brno and Prague) and two in the CIS (Moscow and Duschanbe), participated in the International Programme on Chemical Safety's (IPCS) collaborative study to evaluate the utility of the most commonly used plant test systems, including the Arabidopsis thaliana assay, for assessing the mutagenic potential of environmental agents. Out of the five compounds evaluated in the Arabidopsis assay, three compounds, i.e.

Environmental monitoring for genotoxicity with plant systems. An introduction and study design.

Under the sponsorship of the International Programme on Chemical Safety (IPCS), 17 laboratories from diverse regions of the world participated in evaluating the utility of four plant bioassays for detecting genetic hazards of environmental chemicals. The bioassays included in this collaborative study were: Arabidopsis thaliana embryo and chlorophyll assay and Tradescantia stamen hair assay, Tradescantia paludosa micronucleus assay and Vicia faba root tip assay. Four to six laboratories participated in the performance of each of the bioassays.

An E. coli ada transgenic clone of Nicotiana tabacum var. Xanthi has increased sensitivity to the mutagenic action of alkylating agents, maleic hydrazide and gamma-rays.

Two transgenic clones X3 and X15 of Nicotiana tabacum var. Xanthi, heterozygous in two genes (a1 and a2) for chloroplast differentiation and transformed with the E. coli DNA repair gene ada cloned downstream from the 1' direction of the dual mas promoter, differed in the expression of the ada gene, in the number of copies of integrated T-DNA and in the response to the mutagenic action of alkylating and non-alkylating agents.

Mutagenicity of 3-azido-1,2-propanediol and 9-(3-azido-2-hydroxypropyl)-adenine in repair deficient strains of Escherichia coli.

The mutagenicity of two non-aromatic organic azido compounds, 3-azido-1,2-propanediol (AG) and 9-(3-azido-2-hydroxypropyl)-adenine (AHPA), was studied in E. coli repair deficient strains uvrA6, uvrA6 + umuC36, uvrA6+ umuC122::Tn5, polA1, tagA1+ alkA1, ada and dam3. The mutagenicity of both agents was markedly enhanced by defects of UvrABC excinuclease (uvrA6) and was independent of umuC function of the SOS error-prone pathway.

Inhibitory effects of acetaminophen, 7,8-benzoflavone and methimazole towards N-nitrosodimethylamine mutagenesis in Arabidopsis thaliana.

The metabolic inhibitors acetaminophen, 7,8-benzoflavone, and methimazole significantly reduced the mutagenicity of the promutagen N-nitrosodimethylamine in the higher plant Arabidopsis thaliana. In contrast, these metabolic inhibitors had no effect on the mutagenicity of the direct-acting mutagen N-methyl-N'-nitro-N-nitrosoguanidine.

Increased resistance to the toxic effects of alkylating agents in tobacco expressing the E. coli DNA repair gene ada.

The protein coding region of the E. coli gene ada has been transferred to tobacco plants by a leaf disc transformation procedure involving an Agrobacterium tumefaciens Ti plasmid. Transformed plants were shown to be transgenic for the ada message and had increased levels of O6-alkylguanine DNA alkyltransferase activity.

Mutagenic activity of 6-azido deoxyhexoses and azido alcohols in Salmonella typhimurium and its inhibition by a structure-similar carbon source in the medium.

6-Azido-6-deoxy (AZd) derivatives of D-glucose, D-mannose, D-altrose, D-allose, L-idose, D-galactose, D-galactonic acid and D-galactitol, 3-azido-1,2-propanediol (azidoglycerol), 3,1-diazido-2-propanol (diazidoglycerol) and (at much higher doses) 2-azidoethanol were mutagenic in Salmonella typhimurium strains TA100 and TA1535. The mutagenic response was similar to that induced by sodium azide, i.e.

UV-irradiation potentiates the antimutagenicity of p-aminobenzoic and p-aminosalicylic acids in Salmonella typhimurium.

UV-irradiation (254 nm, 10 or 20 J/cm2) of p-aminobenzoic acid (PABA) and p-aminosalicylic acid (NaPAS) potentiated their antimutagenicity towards N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis in Salmonella typhimurium. Their inhibitory action towards the formation of the mutagen N-methyl-N-nitrosourea from the nitrosation mixture of N-methylurea and nitrite was also increased by UV-irradiation. In contrast, UV-irradiated PABA exhibited no inhibitory effects towards the mutagenicity of sodium azide or 3-azidoglycerol.

The mutagenicity of azido derivatives of monosaccharides and alcohols and of N-(3-azido-2-hydroxypropyl) derivatives of purines and pyrimidines in Arabidopsis thaliana and in Salmonella typhimurium.

The azido derivatives of alcohols (3-azido-1,2-propandiol and 1,3-diazido-2-propanol) and monosaccharides (6-azido-6-deoxy-beta-D-glucose and 6-azido-6-deoxy-beta-D-galactose), as well as the proximal mutagenic product of sodium azide metabolism beta-azido-L-alanine, exhibited a high mutagenic activity in a higher plant Arabidopsis thaliana and in Salmonella typhimurium. In contrast, 11 N-(3-azido-2-hydroxypropyl) derivatives of purines and pyrimidines (adenine, thymine, uracil, cytosine, 2-amino-6-chloropurine, 6-chloropurine, 2,6-diaminopurine, 6-methylthiopurine, 4-O-methylthymine, 4-O-methyluracil and 7-deaza-8-azaadenine) were mutagenic in the Ames assay but ineffective in the Arabidopsis mutagenicity assay.

[Microcirculation in the subcutaneous layer and in muscles in diabetes mellitus].

The work is focused on the possibility of early diagnosis of diabetic microangiopathy. The authors used examination of microcirculation by the method of tissue clearance of Na 131I. In a group of 106 patients with diabetes thus the microcirculation of the lower extremities in the subcutaneous layer and the calf muscle was examined.

[Diagnosis of diabetic macroangiopathy of the lower extremities using rheography].

Rheography (impedance plethysmography) makes it possible to differentiate the normal condition of arteries of the lower extremity from functional and organic affections. The examination of a group of 325 patients with diabetes mellitus revealed that without the use of rheography, i.e.

Effects of humic acids, para-aminobenzoic acid and ascorbic acid on the N-nitrosation of the carbamate insecticide propoxur and on the mutagenicity of nitrosopropoxur.

Nitrosation of the carbamate insecticide propoxur at pH 3 and 37 degrees C was determined colorimetrically and found to be time- and sodium nitrite concentration-dependent. Nitrosated propoxur was mutagenic when exposed to the seeds of the higher plant Arabidopsis thaliana but the formation of nitrosopropoxur, the presumed mutagen, was inhibited by humic acids, para-aminobenzoic acid and ascorbic acid. These agents also reduced the mutagenicity of preformed nitrosopropoxur.

Repair of bleomycin-induced DNA double-strand breaks in Vicia faba.

As detected by neutral DNA elution, bleomycin induced at the concentrations tested (5, 10 and 50 micrograms/ml) DNA double-strand breaks (dsbs) in in vitro cultured embryos of V. faba. Most of these breaks were repaired during a 4-h incubation period after treatment.

Humic acids inhibit the formation but not the mutagenicity of N-methyl-N-nitrosourea.

Humic acids in the form of potassium humate (KH), at concentrations exerting a strong inhibitory effect on the formation of N-methyl-N-nitrosourea (MNU) when present during the nitrosation of N-methylurea (MU) at pH 3, did not reduce the mutagenicity of preformed MNU in Tradescantia, clone 4430. The inhibitory effect of 20 mg/ml KH corresponds approximately to that of 3.75 mM (0.

Mechanisms of inhibition of N-nitroso compounds-induced mutagenicity.

In this review we describe the mechanisms of the inhibitory effects of various chemical agents towards the mutagenicity of N-nitroso compounds, including direct-acting mutagens such as N-nitroso derivatives of alkylureas, alkylnitroguanidines and alkylurethanes, and promutagenic nitrosamines. Possible mechanisms by which the inhibitors may exert their effects outside and inside the target cells include chemical and enzymatic deactivation of the mutagen, inhibition of metabolic activation of nitrosamines, scavenging mutagenic products, inhibition of cellular uptake, induction of detoxifying mechanisms, protecting nucleophilic centers in DNA and modulating DNA repair.