Mutagenicity of drinking water detected by the Tradescantia micronucleus test

Spring Lake reservoir of Macomb, Illinois, is a typical model of the drinking water supply of some midwestern towns of the United States. Water samples collected periodically in 1980 and 1981 from this lake were tested for mutagenicity using the Tradescantia micronucleus (Trad-MCN) test, a highly sensitive mutagen-detecting bioassay. Water samples from 1981 were also analyzed chemically. The micronucleus (MCN) frequency peaked (12-14 MCN/100 tetrads) in mid-July in both years, as compared with the average frequency (5 MCN/100 tetrads) of the base-line control that was maintained in nutrient solution (prepared with distilled water and pure chemicals). Drinking water from the tap was tested in parallel with lake water, and its mutagenicity tended to fluctuate with the mutagenicity of the lake water.     

Removal of Cr(VI) from ground water by Saccharomyces cerevisiae

Chromium can be removed from ground water by the unicellular yeast, Saccharomyces cerevisiae. Local ground water maintains chromium as CrO₄ ^2- because of bicarbonate buffering and pH and E _h conditions (8.2 and +343 mV, respectively). In laboratory studies, we used commercially available, nonpathogenic S. cerevisiae to remove hexavalent chromium [Cr(VI)] from ground water. The influence of parameters such as temperature, pH, and glucose concentration on Cr(VI) removal by yeast were also examined. S. cerevisiae removed Cr(VI) under aerobic and anaerobic conditions, with a slightly greater rate occurring under anaerobic conditions. Our kinetic studies reveal a reaction rate (V_max) of 0.227 mg h^-1 (g dry wt biomass)^-1 and a Michaelis constant (Km) of 145 mg/l in natural ground water using mature S. cerevisiae cultures. We found a rapid (within 2 minutes) initial removal of Cr(VI) with freshly hydrated cells [55–67 mg h^-1 (g dry wt biomass)^-1] followed by a much slower uptake [0.6–1.1 mg h^-1 (g dry wt biomass)^-1] that diminished with time. A materials-balance for a batch reactor over 24 hours resulted in an overall shift in redox potential from +321 to +90 mV, an increase in the bicarbonate concentration (150–3400 mg/l) and a decrease in the Cr(VI) concentration in the effluent (1.9-0 mg/l).     

Assessment of the genotoxicity of mine-dump material using the Tradescantia-stamen hair (Trad-SHM) and the Tradescantia-micronucleus (Trad-MCN) bioassays.

The Tradescantia-stamen hair (Trad-SHM) and -micronucleus (Trad-MCN) bioassays were used to determine the genotoxicity of two eluates derived from mine tailings. The goal was to test the suitability of the Tradescantia bioassays as screening tools for this kind of waste material. Leachates obtained using the current standard German leaching test methods (S4 eluate) as well as leachates obtained using a new eluation method (pHstat4) were tested and compared. Concentration of heavy metals in the pHstat4 eluate were much higher than in the S4 eluate. The chemical analysis corresponded well with the results of the bioassays. Exposure to solutions containing more than 1% pHstat4 eluate caused a significantly higher number of micronuclei. The Trad-SHM bioassay also showed an increased pink mutation rate when plants were exposed to 8 or 16% eluate solutions. In contrast, the S4 eluate only caused increased mutation rates when solutions containing more than 32% eluate were used. The low pH of the pHstat4 eluate was not responsible for the genotoxicity observed using both bioassays, as indicated by the lack of significant mutation rates in the nitric acid controls. This demonstrates that the Tradescantia bioassays can be used as tools to assess the genotoxic potential of environmental samples with a wide range of pH values, without the need for sample modification.     

On the fauna of chironomidae (Diptera) of the Hrazdan Basin (Armenia)

A faunistic review of larvae and pupae of chironomid midges (Diptera, Chironomidae) from 15 habitats in the Hrazdan River valley (Armenia) is presented. The revealed fauna includes 40 species from 20 genera and 6 families and tribes. Diploid chromosome numbers are specified for 24 species from 13 genera and 4 subfamilies; 23 species from 14 genera and 4 subfamilies are reported from the region for the first time. Predominant oligotrophic status is confirmed for most of the reservoirs studied.     

Mutagenicity of cooked hamburger is reduced by addition of onion to ground beef

Addition of onion effectively reduced mutagenicity of cooked hamburger when tested on Salmonella typhimurium TA98 strain with metabolic activation. The components of onion that participated in the reduction of mutagenicity were sugars. Addition of starch or glucose to ground beef the amount equivalent to that in onion reduced the mutagenicity of cooked hamburger. Addition of onion may cause imbalance of the sugar content of ground beef that effectively produces mutagenicity. Mutagenicity of the heated model mixture of glucose/glycine/creatinine in diethyleneglycol–water was reduced by an excessive amount of glucose. Hence, Japanese cooking-style with addition of onion can reduce mutagenicity of hamburger.     

On simulation of air temperature curve near the ground in presence of frosts in Valley of Perote (Mexico)

An exponential of the time function was used in order to model the air temperature curve near the ground after frost in the Valley of Perote (Mexico). From January to March 1989 air temperature was recorded with a telethermograph, and data from 22 frosts were used to adjust and evaluate the exponential function.     

Mutagenicity on chlorination of products formed by ozonation of naphthoresorcinol in water

The mutagenicity of products formed by chlorination after ozonation of naphthoresorcinol in aqueous solution was assayed with Salmonella typhimurium strains TA98 and TA100 in the presence and absence of S9 mix from phenobarbital- and 5,6-benzoflavone-induced rat liver. Ozonated and subsequently chlorinated naphthoresorcinol was directly mutagenic, as was ozonated naphthoresorcinol, in both strains tested. The mutagenic activity at chlorination with 8 equivalents of chlorine per mole of naphthoresorcinol after ozonation was markedly higher than that at only ozonation. Of the identified ozonation products of naphthoresorcinol, muconic acid, after chlorination with 2 or 4 equivalents of chlorine per mole of the compound, induced direct mutagenicity against TA98 and TA100. The chlorination of glyoxal with 0.5 and 1 chlorine equivalents per mole of the compound was shown to produce direct mutagenicity toward TA98. The identification of the chlorination products of these compounds is also discussed.     

Mutagenicity of (p-nitrophenyl)adenines in Salmonella typhimurium

Adenine derivatives having a p-nitrophenyl group at position 2, 8, or 9 were directly mutagenic towards Salmonella typhimurium strains TA98 and TA100, whereas N6-(p-nitrophenyl)adenine was not mutagenic. 2,9- And 8,9-bis-(p-nitrophenyl)adenines were also mutagenic, but N6,9-bis-(p-nitrophenyl)adenine was not. The study on 13 (p-nitrophenyl)adenine derivatives for their Salmonella mutagenicity indicates that only those having a p-nitrophenyl ring directly linked to the purine ring are mutagenic, implying the importance of the coplanar character of the nitrophenyl and the purine rings. The nitro group seems essential for the mutagenicity, as shown from the results of assays using nitroarene-sensitive and -insensitive Salmonella strains. The mutagenic potency of this class of compounds is high, comparable to that of 2-nitrofluorene.     

Karyotypes of some Cypriniform fishes from the water bodies of Armenia

Karyotypes of six species of Cypriniformes from the water bodies of Armenia—blackbrow Acanthalburnus microlepis, white bream Blicca bjoerkna transcaucasica, chub Leuciscus cephalus orientalis, stone moroco Pseudorasbora parva, mursa Barbus mursa, and Angora stone loach Barbatula angorae were studied. The karyotype of A. microlepis is represented by 50 chromosomes (2n = 50), 10M + 28SM + 12STA, NF = 88; of B. bjoerkna transcaucasica, by 2n = 50, 12M + 24SM + 14STA, NF = 86; of L. cephalus orientalis, by 2n = 50, 12M + 18SM + 20STA, NF = 80; of P. parva, by 2n = 50, 8M + 16SM + 26STA, NF = 74; of B. mursa, by 2n = 100, 6M + 36SM + 58STA, NF = 142; and of B. angorae, by 2n = 50, 8M + 24SM + 18STA, NF = 86. The intraspecific and interspecific chromosome polymorphism of species of the genera Blicca, Leuciscus and Pseudorasbora is described.     

Mutagenicity background monitoring of the River Don delta water

The mutagenicity of 14 samples of Don river delta water was studied by the Ames test and the technique of estimation of Drosophila dominant lethals. Experiments revealed that mutagenic pollution of Don river delta water was total at least in April--May 1989.     

Demonstration of prostaglandin activity in lungs of the rainbow lizard (Agama agama) by bioassay

Extracts and perfusate effluents of lungs of the rainbow lizard (Agama agama) were assayed for prostaglandin-like activity. Results of differential bioassay and thin-layer chromatography suggested that the prostanoid was predominantly PGE2-like. The mean PGE2-like content of 10 lizard lung extracts was 2.9 micrograms g-1 wet weight compared with 146 ng g-1 in rat lungs. Mechanical pressure applied to the lung during perfusion through the pulmonary vasculature provoked the release of large quantities of PGE2-like material. This release was blocked by fatty acid cyclooxygenase inhibitors. Compared with guinea-pig and rat lungs, lizard lungs exhibited a markedly low capacity for inactivating PGE2. In view of an apparently high prostaglandin-forming and a low inactivating capacity, we speculate that under certain circumstances, lizard lungs may release vasoactive substances into the circulation.     

Nitrate and nitrite microgradients in barley rhizosphere as detected by a highly sensitive denitrification bioassay.

A highly sensitive denitrification bioassay was developed for detection of NO3- and NO2- in rhizosphere soil samples. Denitrifying Pseudomonas aeruginosa ON12 was grown anaerobically in citrate (30 mM) minimal medium with KClO3 (10 mM) and NaNO2 (3 mM), which gave cells capable of NO2- reduction to N2O but incapable of NO3- reduction to NO2-. Growth on citrate minimal medium further resulted in the absence of N2O reduction. When added to small soil samples in O2-free vials, such cells could be used to convert the indigenous NO2- pool to N2O, which was subsequently quantified by gas chromatography. Cells grown in KClO3-free citrate medium with 10 mM NaNO3 as the electron acceptor were capable of reducing both NO3- and NO2-, and these cells could subsequently be added to the sample to convert the indigenous NO3- pool to N2O. Concentrations of both NO3- and NO2- were thus determined as N2O, with a detection limit of approximately 10 pmol of N. The bioassay could be used to determine NO3- and NO2- pools in 10-mg soil samples taken along a microgradient in the rhizosphere of field-grown barley plants. At both low (10%, wt/wt) and high (18%, wt/wt) water content, relatively high levels of NO2- were found in the rhizosphere compared with bulk soil. Under dry conditions, NO3- was also more abundant in the rhizosphere than in the bulk soil, whereas such a difference was not observed at the high water content. The roles of plant metabolism and bacterial nitrification and denitrification processes for NO3- and NO2- availability in the rhizosphere are discussed.     

Nitrate and nitrite microgradients in barley rhizosphere as detected by a highly sensitive denitrification bioassay.

A highly sensitive denitrification bioassay was developed for detection of NO3- and NO2- in rhizosphere soil samples. Denitrifying Pseudomonas aeruginosa ON12 was grown anaerobically in citrate (30 mM) minimal medium with KClO3 (10 mM) and NaNO2 (3 mM), which gave cells capable of NO2- reduction to N2O but incapable of NO3- reduction to NO2-. Growth on citrate minimal medium further resulted in the absence of N2O reduction. When added to small soil samples in O2-free vials, such cells could be used to convert the indigenous NO2- pool to N2O, which was subsequently quantified by gas chromatography. Cells grown in KClO3-free citrate medium with 10 mM NaNO3 as the electron acceptor were capable of reducing both NO3- and NO2-, and these cells could subsequently be added to the sample to convert the indigenous NO3- pool to N2O. Concentrations of both NO3- and NO2- were thus determined as N2O, with a detection limit of approximately 10 pmol of N. The bioassay could be used to determine NO3- and NO2- pools in 10-mg soil samples taken along a microgradient in the rhizosphere of field-grown barley plants. At both low (10%, wt/wt) and high (18%, wt/wt) water content, relatively high levels of NO2- were found in the rhizosphere compared with bulk soil. Under dry conditions, NO3- was also more abundant in the rhizosphere than in the bulk soil, whereas such a difference was not observed at the high water content. The roles of plant metabolism and bacterial nitrification and denitrification processes for NO3- and NO2- availability in the rhizosphere are discussed.     

Mutagenicity of glyceryl trinitrate (nitroglycerin) in Salmonella typhimurium

The recent finding that the clinical nitrovasodilator, glyceryl trinitrate (GTN), is mutagenic in Salmonella typhimurium strain TA1535 has been examined in closer detail, with emphasis on its mechanism of action. GTN increased the number of His⁺ revertants to a maximum of 4 times over background at a GTN dose of 5 μmol/plate. Hamster liver S9 depressed the toxicity of high GTN doses and increased the maximum number of revertants to 5 times over background at 10 μmol/plate. GTN did not cause significant reversion in any of the six other S. typhimurium strains tested (TA1975, TA102, TA1538, TA100, TA100NR, YG1026), although signs of toxicity were observed. Therefore, the mutagenicity of GTN was manifest only in the repair-deficient (uvrB and lacking in pKM101) strain which is responsive to single base changes. Oligonucleotide probe hybridization of TA1535 revertants showed that virtually all of the GTN-induced mutants contained C → T transitions in either the first or second base of the hisG46 (CCC) target codon, with a preference for the latter. A similar mutational spectrum was seen previously with a complex of spermine and nitric oxide (NO) which releases nitric oxide. This suggests that NO, which can be derived from GTN via metabolic reduction, may be responsible for GTN's mutagenic action. The known NO scavenger oxymyoglobin did not substantially alter the dose response of GTN, indicating that extracellular NO was not mediating reversion. The data are consistent with the hypothesis that intracellular nitric oxide is responsible for the observed mutations.     

Microscopic examination of bacteria in Fe(III)-oxide deposited from ground water

Ochreous sludge deposited in the course of aeration of ground water contained an assortment of bacterial forms and structures which were investigated by light microscopy, scanning electron microscopy, and transmission electron microscopy. Bacterial structures were often covered by iron deposition which could be removed by acidification of the samples. Sulfuric acid treatment was consistently better than hydrochloric acid to dissolve iron without a considerable damage to the bacterial cells. Partial dissolution of amorphous ferric iron was achieved by acidifying the samples with oxalic acid or citric acid prior to the preparation for electron microscopy.     

New species of ixodid ticks (Ixodidae) for the fauna of Armenia

Two species of ixodids , Ixodes arboricola Schulze et Schlottke and I. frontalis ( Panzer ), new for the fauna of Armenia are given. Larvae and nymphs of these ticks were found on birds in the forest zone and gardens.     

Non-MHC alloantigenic system in pigs (SLC) detected by leucoagglutination

Two cell membrane leucocyte alloantigens were detected in pigs by simple direct agglutination tests. Family studies showed that the locus controlling these antigens was not identical, or in close linkage, with the SLA major histocompatibility complex, SLB leucocyte locus or with the A, E , and N blood group loci. In the studied population, the locus termed SLC (Swine Leucocyte C locus) has two alleles controlling mutually exclusive antigens SLC-1 and SLC-2. The frequency of SLC¹ and SLC² alleles is 0.10 and 0.90, respectively. The antigens have not been detected on erythrocytes and thrombocytes but are well determined on granulocytes, peritoneal macrophages, mononuclears from different sources (thymus, spleen, bone marrow, lymph nodes) and enriched T and B cells from peripheral blood.