Mutagenicity

All sorts of pollution on the planet can be traced back to development of
industries and the most important among them is water pollution. Clean
technologies, management practices and regular monitoring of effluents could be
helpful to minimize the contamination of watersheds. Allium cepa (A. cepa) has
been recognized as a promising genetic model to detect the toxicity of industrial
wastewater, contaminated soil, river water, nuclear contamination and even for
those systems which are considered non toxic. A. cepa is distinguished as a low
cost test, easy to handle and sensitive to both in vivo and in vitro models. It offers
the detection of damages in genetic material quantitatively and the results can be
generalized for other biological and ecological systems. Moreover, the pollutants
can be classified on the basis of this test present in industrial effluents and their
mechanism of action on genetic material. This review focuses on the studies
undertaken to evaluate the toxicity of industrial wastewater, contaminated river
and soils.

Yablokov A.V., Ostroumov S.A.  Molecular-Genetic Level. In: Conservation of Living Nature and Resources. Springer, Berlin, Heidelberg, (1991) pp 18-38;
(Chapter 2);
About this chapter
Cite this chapter as:
Yablokov A.V., Ostroumov S.A. (1991) Molecular-Genetic Level. In: Conservation of Living Nature and Resources. Springer, Berlin, Heidelberg. pp 18-38;  https://doi.org/10.1007/978-3-642-75376-3_3
https://www.academia.edu/71478685/ ;
• DOI: 10.1007/978-3-642-75376-3_3
• pp 18-38; Chapter length: 21 pages;

• DOI https://doi.org/10.1007/978-3-642-75376-3_3

• Publisher Name Springer, Berlin, Heidelberg;

• Print ISBN 978-3-642-75378-7

• Online ISBN 978-3-642-75376-3

• eBook PackagesSpringer Book Archive



DOI https://doi.org/10.1007/978-3-642-75376-3_12 ;

• Publisher Name Springer, Berlin, Heidelberg;

• Print ISBN 978-3-642-75378-7;

• Online ISBN 978-3-642-75376-3;
Chapter 2;

Conservation of Living Nature and Resources, pp 18-38;
Molecular-Genetic Level;
• Alexey V. Yablokov, 
• Sergey A. Ostroumov,

Moscow State University, Faculty of Biology, Moscow 119991; Russia;

, Abstract (Chapter 2):
Abstract
Many problems of conservation occur at the molecular-genetic level of life systems. The elementary units at this level are genes represented by segments of DNA (or RNA in some viruses); the elementary events at this level are convariant reduplications of genes. Processes of realization of information stored in DNA involve the functioning of the biochemical machinery of the cell.
Keywords
Genes, DNA, RNA, cell, Sewage Sludge, Anthropogenic Factor, Aryl Hydrocarbon Hydroxylase, Biochemical Machinery, Redox Chain,




Lot of info on the entire book is here:
https://www.academia.edu/45623432/;

https://rd.springer.com/book/10.1007/978-3-642-75376-3



About this chapter
Cite this chapter as:
Yablokov A.V., Ostroumov S.A. (1991) Molecular-Genetic Level. In: Conservation of Living Nature and Resources. Springer, Berlin, Heidelberg. pp 18-38;  https://doi.org/10.1007/978-3-642-75376-3_3
• DOI: 10.1007/978-3-642-75376-3_3
• pp 18-38; Chapter length: 21 pages;

• DOI https://doi.org/10.1007/978-3-642-75376-3_3

• Publisher Name Springer, Berlin, Heidelberg;

• Print ISBN 978-3-642-75378-7

• Online ISBN 978-3-642-75376-3

• eBook PackagesSpringer Book Archive



DOI https://doi.org/10.1007/978-3-642-75376-3_12 ;

• Publisher Name Springer, Berlin, Heidelberg;

• Print ISBN 978-3-642-75378-7;

• Online ISBN 978-3-642-75376-3;
Chapter 2;

Conservation of Living Nature and Resources, pp 18-38;
Molecular-Genetic Level;
• Alexey V. Yablokov, 
• Sergey A. Ostroumov,

Moscow State University, Faculty of Biology, Moscow 119991; Russia;

, Abstract (Chapter 2):
Abstract
Many problems of conservation occur at the molecular-genetic level of life systems. The elementary units at this level are genes represented by segments of DNA (or RNA in some viruses); the elementary events at this level are convariant reduplications of genes. Processes of realization of information stored in DNA involve the functioning of the biochemical machinery of the cell.
Keywords
Genes, DNA, RNA, cell, Sewage Sludge, Anthropogenic Factor, Aryl Hydrocarbon Hydroxylase, Biochemical Machinery, Redox Chain,




Lot of info on the entire book is here:
https://www.academia.edu/45623432/;

https://rd.springer.com/book/10.1007/978-3-642-75376-3 ;

The present study has been carried out to investigate the possible mutagenic effects of the synthetic food preservative Prague powder on meristematic cells of Allium cepa roots. Prague powder was evaluated at the dose of (I don’t fucking know) at the exposure time of 24 hours in root tip cells of Allium cepa. Slides were prepared and cells were analyzed for cellular aberrations totaling (I don’t fucking know) cells for each dose evaluated. The mitotic index was calculated, and statistical analysis was performed using the Chi-squared test (p < 0.05). The obtained results indicated that the synthetic food preservative Prague powder had the ability to cause different mitotic changes varying from chromosome bridges and stickiness to formation of laggards. These changes appeared in varying degrees depending on the applied concentration and duration of treatment. The types of abnormalities produced were stickiness at metaphase, anaphase bridges, stickiness at anaphase, and telophase with laggard. Further genotoxity studies should be conducted for additional results and a proper evaluation of the effect of prague powder on a cellular level.

Resumen Context: Sunlight ultraviolet (UV) radiation constitutes a significant physical carcinogen in nature. It could induce direct and indirect DNA damage, which if not properly repaired may generate mutations. Plants in the genus Phyllanthus (Phyllanthaceae) are widely used in traditional medicine and known as natural sources of antioxidant compounds. Recent investigations support their genoprotective activity against chemical and physical mutagens, among them UV radiation. Aims: To compare the antioxidant, photoprotective and antimutagenic activity of aqueous extracts obtained from three Cuban endemic Phyllanthus species: P. chamaecristoides Urb., P. microdictyus Urb., and P. williamioides Gr. Methods: DPPH radical scavenging assay was use for quantify the in vitro antioxidant capacity. Genoprotection against UVC radiation was measured at two levels: structural DNA damage and mutations, by means of the SOS Chromotest, Survival assay, and Rif R mutagenicity test in Caulobacter crescentus cells. Results: P. chamaecristoides extract showed the highest antioxidant capacity (IC50 = 0.032 mg/mL), and together with P. microdictyus exhibited the greatest bioantimutagenic effects (RMF ≤ 5%), diminishing UVC-induced DNA damage in three and five times, respectively. Conclusions: The reduction in DNA damage is not founded in a Phyllanthus aqueous extracts desmutagenic effect. It is possible that the genoprotective activity detected could be due to modulation of DNA repair mechanisms, diminishing SOS response and related mutagenicity induced by UVC radiation. Moreover, high antioxidant capacity could also decrease UV radiation oxidative-damage. Altogether, these outcomes validate future pre-clinic research regarding Phyllanthus photoprotective capacities.

The cytogenetic effects exerted by the systemic fungicide mefenoxam and copper hydroxide (the active ingredients of Ridomil Gold Plus 42,5 WP fungicide) were studied in root tips of Allium cepa L. A progressive concentration- and time-related inhibition of the mitotic activity of meristematic cells was observed. The mitotic index was minimum (3.38%) at the highest concentration (1500 ppm) of the fungicide tested. The genotoxicity of the fungicide was measured by using the frequency of chromosomal aberrations. The highest percent of abnormal cells (8.39%) were determined for the lowest concentration of 100 ppm of Ridomil. The high frequency of sticky chromosomes, laggard and multipolarity indicated that the investigated fungicide caused abnormal DNA condensation, abnormal chromosome coiling and inactivation of the spindles, having an aneugenic potential.

This essay traces a long trajectory starting in the 1920s in the breeding facilities of the German Research Foundation, the basis for the first German research programme in comparative
medical genetics. The journey from the Berlin comparative
genetics project into the atomic energy programme proceeded from the use of radiation and radioisotopes for phenogenetic problems, to the genetics of radiation effects. The transition from this phase to the third phase of mass testing of chemical compounds was facilitated by knowledge of old-school comparative genetics and the provision of useful genetic strains for standard mutagenesis testing.  The story ends with the foundation of the German Mouse Clinic in 2001. It underscores the continuity of a specific research tradition, from early agricultutal genetics to today's genomics. This continuity, did not manifest itself in terms of a linear progress, but involved the many breaks and contingent configurations common to the development of new research fields.

Invasive alien species are a global threat to biodiversity that affects protected areas around the world. The occupation of new environments by these plants is a problem to be solved and it is essential to investigate all the aspects that allow this successful to find solutions to this question, such as its mutagenic effects. Thus, this study aimed to evaluate the mutagenic effect of leaves extracts of Acacia mangium Willd, Artocarpus heterophyllus Lam and Eriobothrya japonica (Thunb.) Lindl through Allium cepa bioassay. For this, A. cepa seeds were submitted to continuous and discontinuous (acute and chronic) treatments in medium with water (negative control) or four concentration of each extract (1, 5, 10 and 50 mg/mL). The mitotic index was affected at all concentrations of three extracts tested in all treatments, continuous and discontinuous. Aneugenic effects were not related to any treatment tested. E. japonica extract induced clastogenic effects at 1, 5 and 10 mg/mL in continuous treatment, 5 and 10 mg/mL in acute discontinuous treatment and at 10 mg/mL in chronic discontinuous treatment. Clastogenic effect was also observed at 10 mg/mL of A. heterophyllus extract in continuous and acute discontinuous treatments.

Supplied water in semiarid region was analyzed concerning heavy metals, cyanobacteria and radiation. Indoor radon and gamma emitters (U, K and Th) concentrations were measured. High radon levels are present inside urban residences. It was found high frequencies of micronuclei and nuclear alterations in human oral mucosa. High background radioactivity could explain the observed mutagenic effect observed. a b s t r a c t Lucr ecia city, known to harbor a high cancer rate, is located in a semiarid region characterized by the presence of mineral reservoirs, facing a high exposure to metal and natural radioactivity. The present study aimed to assess the environmental scenario at a semiarid region located in Northeastern Brazil. Metal concentration, alpha and beta radiation, and cyanobacteria content in tap water along with indoor radon and gamma emitters (U, K and Th) concentrations were measured. In addition, mutagenic and nuclear instability effects were assessed using buccal micronucleus cytome assay. The study included five samplings corresponding to a period between 2007 and 2009. Drinking water from Lucr ecia city presented levels of Mn, Ni and Cr along with cyanobacteria in concentrations one to four times higher than regulatory guidelines considered. Furthermore, high levels of all the tested radionuclides were found. A high percentage of the houses included in this study presented indoor radon concentrations over 100 Bq m À3. The mean annual effective dose from Lucr ecia houses was six times higher than observed in a control region. The levels of exposure in most of the Lucr ecia houses were classified as middle to high. A significant mutagenic effect, represented as an increase of micronuclei (MN) frequency and nuclear abnormalities as nuclear buds (NB), binucleated cells (BN), and pyknotic cells (PYC) were found. The results obtained highlight the role of high background radioactivity on the observed mutagenic effect and could help to explain the exacerbated cancer rate reported in this locality.

This paper brings together the history of risk and the history of DNA repair, a biological phenomenon that emerged as a research field in between molecular biology, genetics, and radiation research in the 1960s. The case of xeroderma pigmentosum (XP), an inherited
hypersensitivity to UV light and, hence, a disposition to skin cancer will be the starting point to argue that, in the 1970s and 1980s, DNA repair became entangled in the creation of new models of the human body at risk – what is here conceptually referred to as the vulnerability
aspect of body history – and new attempts at cancer prevention and enhancement of the body associated with the new flourishing research areas of antimutagenesis and anticarcinogenesis. The aim will be to demonstrate that DNA repair created special attempts at disease prevention: molecular enhancement, seeking to identify means to increase the self-repair abilities of the body at the molecular level. Prevention in this sense meant enhancing the body’s ability to cope with the environmental hazards of an already toxic world. This strategy has recently been adopted by the beauty industry, which introduced DNA care as a new target for skin care research and anti-aging formulas.

Interaction between Vitamin C (VitC) and transition metals can induce the formation of reactive oxygen species (ROS). VitC may also act as an ROS scavenger and as a metal chelant. To examine these possibilities, we tested in vivo the effect of two doses of VitC (1 and 30 mg/kg of mouse body weight) on the genotoxicity of known mutagens and transition metals. We used the alkaline version of the comet assay to assess DNA damage in peripheral white blood cells of mice. Animals were orally given either water (control), cyclophosphamide (CP), methyl methanesulfonate (MMS), cupric sulfate or ferrous sulfate. A single treatment with each VitC dose was administered after treatment with the mutagens or the metal sulfates. Both doses of VitC enhanced DNA damage caused by the metal sulfates. DNA damage caused by MMS was significantly reduced by the lower dose, but not by the higher dose of VitC. For CP, neither post-treatment dose of VitC affected the DNA damage level. These results indicate a modulatory role of Vitamin C in the genotoxicity/repair effect of these compounds. Single treatment with either dose of VitC showed genotoxic effects after 24 h but not after 48 h, indicating repair. Double treatment with VitC (at 0 and 24 h) induced a cumulative genotoxic response at 48 h, more intense for the higher dose. The results suggest that VitC can be either genotoxic or a repair stimulant, since the alkaline version of the comet assay does not differentiate “effective” strand breaks from those generated as an intermediate step in excision repair (incomplete excision repair sites). Further data is needed to shed light upon the beneficial/noxious effects of VitC.

A novel microbiological mutagenicity assay, based on bioluminescence of a marine bacterium Vibrio harveyi mutant strain, potentially suitable for monitoring and assessment of mutagenic pollution of marine environment, has been described recently. Here, we tested the use of this assay, in combination with either mussels (Mytilus sp.) or semipermeable membrane devices (SPMDs), in assessment of accumulation of mutagens in marine water (samples of Baltic Sea water were tested). Either similar results were obtained in both systems or higher signals in the SPMD-based system were detected, depending on the tested water samples. We conclude that the use of both mussels and SPMDs in combination with the V. harveyi bioluminescence mutagenicity assay is a method suitable for monitoring and assessment of accumulation of mutagenic pollutants in marine environment, but in some cases the SPMD-based system may provide a more sensitive test.

Abstract. In Rajasthan state particularly, textile mills represent an important economic sector. Pali district in Rajasthan has got largest number of textile industries in the State i.e.989 units, mostly engaged in cotton and synthetic textile printing and dyeing. These industries liberate a variety of chemicals, dyes, acids and alkalis besides other toxic compounds like heavy metals, which are known for their hazardous properties. However, excessive and indiscriminate use of dyestuffs has become increasingly a subject of environmental concern. These dyes can enter the environment through the industrial effluents of dye manufacturing plants and from textile dyeing and printing operations, as wastewater effluents. Assessment of genotoxicity of dyes is therefore of utmost importance. Short-term genetic bioassays have proved to be an important tool in such studies because of their simplicity, sensitivity to genetic damage, speed, low cost of experimentation and small amount of sample r...

Regulation and the prevention of danger are among the main characteristics of the modern state. However, the idea and the conceptualization of what danger is have changed over time. The genealogy of these changes shows that the history of social change and the history of knowledge are well connected. The 1970s marked the start of a social transformation of Western industrialized societies. This article proposes that this transformation was connected with basic epistemic reconfigurations and that the genealogy of risk played a significant role. This thesis is explored through the example of DFG advisory politics. Beginning in the 1960s, the DFG expert commissions that had been established to make policy and regulation recommendations began to focus more and more on the health effects of environmental pollution. The Commission for Questions of Mutagenicity played a particularly interesting role because its recommendations resulted in the foundation of a research institution run by the...

The mutagenic and antimutagenic activities of triterpene betulinic acid {3b-3-hydroxy-lup-20(29)-en-28-oic} isolated from the roots of Scoparia dulcis (Scrophulariaceae) were analyzed using the somatic mutation and recombination test (SMART) in the wings of Drosophila melanogaster. The mutagenic potential of betulinic acid was evaluated at 3 different concentrations (1.64, 3.28, and 6.57 mM). Antimutagenic activity evaluation was performed by co-treatment trials in which the flies received betulinic acid at 3 different concentrations in addition to 10 mM pro-mutagenic urethane. The results demonstrated that betulinic acid was not capable of causing DNA damage. However, the frequency of small single spots, large spots, and twin spots was significantly reduced. In the high bioactivation cross, betulinic acid was significantly active and exerted enhanced antimutagenic activity, possibly as a desmutagen.

The induction of forward mutations to L-arabinose resistance (AraR) and of reversions to histidine prototrophy (His+) can be quantitatively compared in Salmonella typhimurium BA strains. The BA bacteria carry the araD531 allele required for the Ara assay and a his auxotrophy (hisD3052 or hisG46) required for the His assay. In this study, 2 new sets of BA indicator strains have been constructed in order to combine the Ara forward and the His reverse mutation assays of S. typhimurium with deficiency, or overproduction, in either classical nitroreductase or O-acetyltransferase for mutagenicity testing of nitro-containing chemicals. Nine mutagens with different chemical structures were tested to compare the specific mutagenic sensitivities of the new constructions with those of the parental and of the conventional TA indicator bacteria. The Ara test, which responded with high sensitivity to all chemicals tested, revealed important differences between the standard tester strains TA98 and TA100 with respect to the activation of mutagens considered to be dependent on classical nitroreductase activity. Total correspondence was found between the specific mutagenic sensitivities of the defective and the overproducing bacteria in the genetic background of TA98 but not in that of TA100. In the genetic background of TA100, chemicals such as nitrofurantoin and nitrofurazone displayed 10-fold reduced mutagenicity to the “classical nitroreductase” defective strain without increasing mutagenicity to the corresponding overproducing bacteria. This discrepancy might be attributed to the greater nitroreduction capability of strain TA100 (68.12 nmole/min/mg protein) as compared to TA98 (24.42 nmole/min/mg protein), by assuming that nitrofurantoin and nitrofurazone are such good substrates for classical nitroreductase that the additional enzyme activity produced from the corresponding overexpressing plasmid when present in TA100 no longer affected their metabolic activation. We propose that the Ara forward mutation test carried out in the set of overproducing bacteria constructed in the genetic background of TA98 might play a role for routine testing of large number of samples. The isogenic defective strains could be used in cases of uncertain results with the corresponding overproducing bacteria. Finally, the reversion of the his alleles accompanying the Ara assay in the BA strains could play a role in assessing the presence of mixtures of chemicals with different mutagenic specificity in samples of environmental relevance such as urban air, foods, and water.

Nanotechnology globally represents a new direction within scientific development, where the atomic and electronic properties of molecules are used in a unique fashion to produce and construct new and exotic materials and products. The specific scientific issue of fullerenes (Bucky balls, C60) constitute a particular group within the field of nanotechnology. Its key applications are within medicine, industrial chemistry and electronics. There are several unanswered questions about fullerenes and their toxicological properties however. Most toxicological studies on fullerenes evolve around the in vitro and in vivo aspects of pristine C60 along with chemically modified C60 molecules.

We reviewed several toxicology-reports on C60 and also opposing studies. The major points ate that as a new turn of the debate, we add a critical and challenging evaluation of the electronic and quantum properties of C60 molecules in context with the implications on cellular factors and metabolites. The evaluation shows that the reactivity and quantum chemical properties of C60 can have unexpected effects in the cell, by principally absorbing metabolites, such as OH- and H+ ions and alter its reactivity based on the interaction with these. We thus challenge the present view of C60 solely based on empirical studies, based on the electronic properties of C60 that vary considerably with their size and reaction-path. A further example of this is the absorption of divalent zinc ions, which shows an increase in reactivity of the C60 that presents an important pattern of chemical state, reactivity and toxicological potential.

The results supplied herein evaluate the toxicological potential of C60 from a different angle than conventional, by applying a blend of critical review of the findings on C60 toxicity, their chemical and electronic properties.

Mutagenic pollution of the natural environment, including marine waters, is a very serious ecological problem. However, since chemical mutagens usually occur and act at low concentrations, their detection and identification is technically difficult, laborious and time-consuming. Therefore, preliminary detection of mutagenic pollution is commonly based on biological mutagenicity assays. On the other hand, triolein-containing semi-permeable membrane devices (SPMDs) provide a method for concentration of hydrophobic organic contaminants, including a large fraction of the mutagens. Combinations of SPMDs with microbiological toxicity and mutagenicity assays have already been described, but only SPMD-derived extracts, prepared with various organic solvents, were tested in such a way to date. We found that the presence of these solvents could interfere with the Vibrio harveyi bioluminescence-based mutagenicity assay. Moreover, preparation of the extracts from SPMD takes usually at least 48h. Here, we propose a modified procedure, based on direct addition of tester bacteria cultures into SPMD. We found that this procedure is significantly (at least two times) more rapid and several times more sensitive than that based on testing the extracts. This optimization is presented in this report. Moreover, we have performed preliminary studies on samples of marine waters. Positive results (i.e. detection of mutagenic activity) were obtained when test samples came from a region known to be highly contaminated by industrial pollution, while negative results were observed in the case of samples from a region supposed to be of low risk for mutagenic pollution.

The induction of forward mutations to L-arabinose resistance (AraR) and of reversions to histidine prototrophy (His+) can be quantitatively compared in Salmonella typhimurium BA strains. The BA bacteria carry the araD531 allele required for the Ara assay and a his auxotrophy (hisD3052 or hisG46) required for the His assay. In this study, 2 new sets of BA indicator strains have been constructed in order to combine the Ara forward and the His reverse mutation assays of S. typhimurium with deficiency, or overproduction, in either classical nitroreductase or O-acetyltransferase for mutagenicity testing of nitro-containing chemicals. Nine mutagens with different chemical structures were tested to compare the specific mutagenic sensitivities of the new constructions with those of the parental and of the conventional TA indicator bacteria. The Ara test, which responded with high sensitivity to all chemicals tested, revealed important differences between the standard tester strains TA98 and TA100 with respect to the activation of mutagens considered to be dependent on classical nitroreductase activity. Total correspondence was found between the specific mutagenic sensitivities of the defective and the overproducing bacteria in the genetic background of TA98 but not in that of TA100. In the genetic background of TA100, chemicals such as nitrofurantoin and nitrofurazone displayed 10-fold reduced mutagenicity to the “classical nitroreductase” defective strain without increasing mutagenicity to the corresponding overproducing bacteria. This discrepancy might be attributed to the greater nitroreduction capability of strain TA100 (68.12 nmole/min/mg protein) as compared to TA98 (24.42 nmole/min/mg protein), by assuming that nitrofurantoin and nitrofurazone are such good substrates for classical nitroreductase that the additional enzyme activity produced from the corresponding overexpressing plasmid when present in TA100 no longer affected their metabolic activation. We propose that the Ara forward mutation test carried out in the set of overproducing bacteria constructed in the genetic background of TA98 might play a role for routine testing of large number of samples. The isogenic defective strains could be used in cases of uncertain results with the corresponding overproducing bacteria. Finally, the reversion of the his alleles accompanying the Ara assay in the BA strains could play a role in assessing the presence of mixtures of chemicals with different mutagenic specificity in samples of environmental relevance such as urban air, foods, and water.

The induction of forward mutations to L-arabinose resistance (AraR) and of reversions to histidine prototrophy (His+) can be quantitatively compared in Salmonella typhimurium BA strains. The BA bacteria carry the araD531 allele required for the Ara assay and a his auxotrophy (hisD3052 or hisG46) required for the His assay. In this study, 2 new sets of BA indicator strains have been constructed in order to combine the Ara forward and the His reverse mutation assays of S. typhimurium with deficiency, or overproduction, in either classical nitroreductase or O-acetyltransferase for mutagenicity testing of nitro-containing chemicals. Nine mutagens with different chemical structures were tested to compare the specific mutagenic sensitivities of the new constructions with those of the parental and of the conventional TA indicator bacteria. The Ara test, which responded with high sensitivity to all chemicals tested, revealed important differences between the standard tester strains TA98 and TA100 with respect to the activation of mutagens considered to be dependent on classical nitroreductase activity. Total correspondence was found between the specific mutagenic sensitivities of the defective and the overproducing bacteria in the genetic background of TA98 but not in that of TA100. In the genetic background of TA100, chemicals such as nitrofurantoin and nitrofurazone displayed 10-fold reduced mutagenicity to the “classical nitroreductase” defective strain without increasing mutagenicity to the corresponding overproducing bacteria. This discrepancy might be attributed to the greater nitroreduction capability of strain TA100 (68.12 nmole/min/mg protein) as compared to TA98 (24.42 nmole/min/mg protein), by assuming that nitrofurantoin and nitrofurazone are such good substrates for classical nitroreductase that the additional enzyme activity produced from the corresponding overexpressing plasmid when present in TA100 no longer affected their metabolic activation. We propose that the Ara forward mutation test carried out in the set of overproducing bacteria constructed in the genetic background of TA98 might play a role for routine testing of large number of samples. The isogenic defective strains could be used in cases of uncertain results with the corresponding overproducing bacteria. Finally, the reversion of the his alleles accompanying the Ara assay in the BA strains could play a role in assessing the presence of mixtures of chemicals with different mutagenic specificity in samples of environmental relevance such as urban air, foods, and water.

There is considerable epidemiological evidence indicating an association between diets rich in fresh fruit and vegetables and a decreased incidence of cancers. Methyl methanesulfonate (MMS) and cyclophosphamide (CP) are alkylating agents that differ in their mode of action. MMS is a directly-acting, monofunctional agent, while CP is a bifunctional agent that requires metabolic activation to a reactive metabolite. To evaluate if orange juice could reduce DNA damage induced by these alkylating agents, mice were treated orally (by gavage) with MMS and CP, prior to and after treatment with orange juice. DNA damage was evaluated by the comet assay in peripheral white blood cells. Under these experimental conditions, orange juice reduced the extent of DNA damage caused by both mutagens. For MMS, the antigenotoxic effect of the orange juice was both protective (orange juice pre-treatment) and reparative (orange juice post-treatment); for CP, the effect was reparative only. The components of orange juice can have several biological effects, including acting as targets of toxicants and modulating metabolization/detoxification routes. Considering the different mechanisms of the action of the two drugs, different protective effects are suggested. These results demonstated the ability of the in vivo comet assay to detect in vivo modulation of MMS and CP mutagenicity by orange juice

Stratospheric ozone depletion due to pollution has long been recognised as a threat to human health as well as to the earth's ecosystem. UV-B radiation being a part of solar electromagnetic radiations reaches earth's surface at an elevated level due to ozone depletion thereby imparting its ill impacts on flora and fauna. Hence, keeping UV-B as an important key of environmental factors inducing stress and disturbance on biodiversity the present experimental work has been designed to study the effect of UV-B on chromosomal organisation and biochemical contents of Coriandrum sativum L. Four sets have been maintained viz. set A for control, set B for 20 minutes treatment, set C for 40 minutes and set D for 60 minutes. All sets, excluding A, were irradiated with supplemental UV-B radiation along with visible lights for 1 st , 2 nd and 3 rd day treatment after seed germination. For cytological study, irradiated germinated seeds of each set (B, C and D) were fixed in carnoy's fixative along with control (set A). For biochemical study few germinated irradiated seeds of each set (A, B, C and D) were transplanted in field for further growth and development. It was found that lower doses are stimulatory in its action while as the treatment time along with duration was increased, the rate of Mitotic Index (MI %) were decreased and Total Abnormality Percentage (TAB %) was increased in all the treated sets as compared to control set. Regarding biochemical constituents, the proline content was increased while photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoid) and total carbohydrate contents were declined at higher treatment doses. Hence, it was concluded that low levels of UV-B exposures are not inhibitory in its action and promote metabolic processes on the way in contrary high levels of elevated UV-B radiation are genotoxic and causes cell disruptions by inducing chromosomal aberrations increasing TAB (%), declined MI (%), decreased photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoid) and carbohydrates while in response to stress, Coriandrum adapts protective mechanism thereby elevated proline accumulation.

Pesticides can cause acute or chronic effects on human health. Many pesticides can cause damage to genetic material. These changes in genetic information have been associated with an increased risk of cancer. The objective of this study is to investigate damage to genetic material in a population of children potentially exposed to pesticides in the environment. The study design was observational and cross sectional. We studied 48 children potentially exposed to pesticides and 46 unexposed children. Samples of the oral mucosa were obtained to determine damage to genetic material using micronucleus frequency (MN).Higher average micronucleus counts were found in the group potentially exposed to pesticides (5.1±2.9 vs. 1.8±2.0, p &lt;0.0001), along with a higher average of binucleate cells (3.5±2.7 vs. 1.4±1.4 p &lt;0.0001), higher frequency of karyorrhexis (18.2±18.4 vs. 5.8± 18.4, p &lt;0.004) and pyknosis (24.8±18.0 vs. 17.1±8.3; p &lt;0.03).Of the children potentially exposed to pes...

We introduce skypattern cubes and propose an efficient bottom-up approach to compute them. Our approach relies on derivation rules collecting skypatterns of a parent node from its child nodes without any dominance test. Non-derivable skypatterns are computed on the fly thanks to Dynamic CSP. The bottom-up principle enables to provide a concise representation of the cube based on skypattern equivalence classes without any supplementary effort. Experiments show the effectiveness of our proposal.