bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA sequence analysis of X‐ray induced Adh null mutations in Drosophila melanogaster
Authors: Mahmoud J. , Fossett N. G. , Arbour‐Reily P. , McDaniel M. , Tucker A. , Chang S. H. , Lee W. R. , Aaron C. S. 
Published: February 2007

AbstractThe mutational spectrum for 28 X‐ray induced mutations and 2 spontaneous mutations, previously determined by genetic and cytogenetic methods, consisted of 20 multilocus deficiencies (19 induced and 1 spontaneous) and 10 intragenic mutations (9 induced and 1 spontaneous). One of the X‐ray induced intragenic mutations was lost, and another was determined to be a recombinant with the allele used in the recovery scheme. The DNA sequence of two X‐ray induced intragenic mutations has been published. This paper reports the results of DNA sequence analysis of the remaining intragenic mutations and a summary of the X‐ray induced mutational spectrum. Only one of the X‐ray induced mutations is a single base change, a C to G transversion (AdhnLA80). Therefore, the mutational spectrum of X‐ray induced mutations consists predominantly of deletions that are observed to range in size from two base pairs to deletions of a large number of loci as determined by genetic complementation analysis. The combination of DNA sequence analysis with genetic complementation analysis shows a continuous distribution in size of deletions rather than two different types of mutations consisting of deletions and “point mutations.” Sequencing is shown to be essential for detecting intragenic deletions. Of particular importance for future studies is the observation that all of the intragenic deletions consist of a direct repeat adjacent to the breakpoint with one of the repeats deleted.
Enumeration of 6‐thioguanine‐resistant T‐lymphocytes in the peripheral blood of nonhuman primates (cynomolgus monkeys)
Authors: Zimmer D. M. , Aaron C. S. , O'Neill J. P. , Albertini R. J. , Carver J. H. , Hoffman G. R. 
Published: February 2007

AbstractWe have investigated the use of cynomolgus monkeys (Macaca fascicularis) as a model of somatic cell mutagenesis in non‐human primates. Using techniques described by Albertini (Mutation Research 150:411–422, 1985) for similar studies in humans, the frequency of TG‐resistant T‐lymphocytes in the peripheral blood was determined in animals that were either untreated or treated with ethylnitrosourea. The frequency of TG‐resistant cells in untreated males was (mean ± 5D) 6.0 ± 5.9 per 106 cells and for untreated females was 2.9 ± 2.7 per 106 cells. The spontaneous frequency of TG‐resistant cells for all animals was 4.2 ± 4.44 per 106 cells. Maximum frequency of TG‐resistant cells for two animals treated with a single I.P. dose of ENU was 45.1 and 77.9 per 106 cells. Substantial increases in frequencies of TG‐resistant cells were not seen until at least 63 days after treatment. The TG‐resistant phenotype of clones isolated in the assay was stable after growth for 2 weeks in the absence of selective agent. Many of the TG‐resistant clones selected were frozen for future molecular analysis.
Relationship between DNA adduct formation and unscheduled DNA synthesis (UDS) in cultured mouse epidermal keratinocytes
Authors: Gill Rosalynn D. , Butterworth Byron E. , Nettikumara Anusha N. , Digiovanni John , Landolph J. R. 
Published: February 2007

AbstractPrimary cultures of mouse epidermal keratinocytes from SENCAR mice were treated with 7,12‐dimethylbenz(a)anthracene (DMBA), benzo(a)pyrene [B(a)P], (±)7β‐8α‐dihydroxy‐9α,10α‐epoxy‐7,8,9,10‐tetrahydrobenzo(a)pyrene [(±)anti‐BPDE], and (±)7β,8α‐dihydroxy‐9β,10β‐epoxy‐7,8,9,10‐tetrahydrobenzo(a) pyrene [(±)syn‐BPDE] to examine the relationship between DNA adduct formation and the induction of unscheduled DNA synthesis (UDS). DNA adducts were measured as pmol hydrocarbon bound per mg of DNA, and UDS was quantitated autoradiographically as net grains per nucleus. A good correlation was observed between the levels of UDS detected and the amount of DNA adducts present in the cell population when comparing similar compounds within the linear dose‐response range of 0.005 μg/ml‐0.25 μg/ml. A higher rate of UDS for a given level of DNA adducts was interpreted as an increased efficiency of DNA repair. In some cases, an increase in the efficiency of DNA excision repair correlated with lower tumor‐initiating activity.For this family of PAH, the concentration below which UDS could no longer be detected was approximately 0.01 μg/ml. However, DNA adducts were measurable at concentrations of 0.01 and 0.005 μg/ml. The limits of detection of the current UDS assay in the SENCAR MEK culture system occurred at hydrocarbon adduct levels of approximately 10 pmol/mg DNA, or approximately 1 adduct per 3 × 105 bases. Additionally, the UDS assay was unable to detect DNA repair induced by the weakly carcinogenic PAHs, dibenz(aj)anthracene and 7‐methyl‐dibenz(aj)anthracene. The UDS assay did detect DNA repair by the more strongly carcinogenic PAH, 6‐methylcholanthrene. These results suggest that the present UDS assay with MEKs is a useful assay for the rapid screening of potential genotoxic agents. However, the limits of sensitivity are such that the current assay may be unable to detect a low level of DNA damage induced by some weakly genotoxic (carcinogenic) agents. In addition, while the limits of sensitivity determined in these experiments apply to the polycyclic aromatic hydrocarbon class, other classes of genotoxic compounds such as alkylating agents or crosslinking agents may exhibit different thresholds of detection.
Antimutagenic activities of naturally occurring polyamines in Chinese hamster ovary cells in vitro
Authors: Cozzi Renata , Perticone Paolo , Bona Roberta , Polani Stefania , Casciano D. A. 
Published: February 2007

AbstractSpermine and spermidine, ubiquitous polyamines present in bacteria and animal cells, are also involved in cell growth. Since they interact with the double helix, they can stabilize the DNA molecule.Recent evidence of the antimutagenic and anticarcinogenic capacity of spermine has focused attention on the mechanism(s) by which such agents can protect cells from induced damages.In the present paper we show the ability of spermine and spermidine to decrease the level of sister chromatid exchanges induced in Chinese hamster ovary cells cultivated in vitro, by treating them with Psoralen + UVA irradiation (able to induce mainly monoadducts and DNA cross‐links).Two different mechanisms of polyamine action can be invoked to explain the preservative activity of this class of agents.
Genotoxic effects of gossypol acetic acid on cultured murine erythroleukemia cells
Authors: Majumdar Shyamal K. , Daly Eileen P. , Kleemeyer Katherine M. , Daehler Curtis C. , Baker Michelle A. , Tice R. R. 
Published: February 2007

AbstractGossypol acetic acid, a male anti‐fertility drug, was evaluated for its effects on cell multiplication, chromosomes, scheduled and unscheduled DNA synthesis, and the surface ultrastructure in cultured murine erythroleukemia cells (clone 6A11A). Gossypol treatments inhibited cell multiplication at 10 and 20 μg/ml concentrations and this inhibitory effect increased with elevated dosage and prolonged treatment. Gossypol significantly depressed the mitotic index but did not alter chromosome numbers or increase the frequency of chromosomal structural abnormalities. Cell fraction techniques revealed that gossypol induced a negative effect on cellular DNA synthesis at concentrations as low as 3.3 μg/ml after 24 hr of treatment. The number of cells undergoing DNA synthesis decreased with increasing dosages and durations of drug exposure. An unscheduled DNA synthesis assay (UDS) found gossypol to be an active UDS‐inducing agent at certain dose levels and treatment times, as measured by increase in net nuclear gain and percentage of UDS cells (ANOVA, Bonferroni test, P < 0.05). A scanning electron microscope study revealed that 10 μg/ml treatment with gossypol caused changes in mouse erythroleukemia cell surface ultrastructure characterized by general balding and the appearance of holes, often after 48 hr of treatment.
Rapid localization of point mutations in PCR products by chemical (HOT) modification
Authors: Tindall Kenneth R. , Whitaker Richard A. 
Published: February 2007

AbstractOur studies of mutational mechanisms in mammalian cells use the AS52 Chinese hamster avary cell line. AS52 mutants can be selected as 6‐thioguanine resistant colonies and mutations are studied at a chromosomally integrated gpt locus. Mutant gpt sequences are amplified using the polymerase chain reaction (PCR) to distinguish deletions from putative point mutations. PCR is efficiently performed from a few thousand lysed cells or from isolated genomic DNA. Amplified mutant PCR fragments carrying putative point mutations are further characterized by localizing the site of the mutation using chemical modification. A heteroduplex molecule consisting of one wild‐type and one mutant DNA strand is generated. A base mismatch will be produced at the site of the mutation. Mismatched cytosine or thymine residues are sensitive to modification by hydroxylamine or osmium tetroxide, respectively. The modified DNA heteroduplex is then sensitive to piperidine cleavage. If one strand is 32P‐end labeled, then the cleavage product can be separated on a denaturing acrylamide sequencing gel and visualized using autoradiography. Thus, the site of a mutation can be localized to a specific region of the gene, thereby simplifying the DNA sequence analysis and facilitating the rapid generation of mutational sequence spectra.
Detection of DNA sequence polymorphisms in carcinogen metabolism genes by polymerase chain reaction
Authors: Bell Douglas A. 
Published: February 2007

AbstractThe glutathione transferase mu gene (GST1) and the debrisoquine hydroxylase gene (CYP2D6) are known to be polymorphic in the human population and have been associated with increased susceptibility to cancer. Smokers with low lymphocyte GST mu activity are at higher risk for lung cancer, while low debrisoquine hydroxylase activity has been correlated with lower risk for lung and bladder cancer. Phenotypic characterization of these polymorphisms by lymphocyte enzyme activity (GST) and urine metabolite ratios (debrisoquine) is cumbersome for population studies. Recent cloning and sequencing of the mutant alleles of these genes has allowed genotyping via the polymerase chain reaction (PCR). Advantages of PCR approaches are speed, technical simplicity, and minimal sample requirements. This article reviews the PCR‐based methods for detection of genetic polymorphisms in human cancer susceptibility genes.
DNA sequence mapping by fluorescence in situ hybridization
Authors: Brandriff B. F. , Gordon L. A. , Trask B. J. 
Published: February 2007

AbstractVarious types of DNA probes, such as total genomic DNA, repetitive sequences, unique sequences, and composites of chromosome‐specific DNA probes, can be used with fluorescence in situ hybridization (FISH) techniques to address research questions having to do with localization, mapping, and distribution of DNA in situ. FISH involves the formation of a heteroduplex between such DNA probes and chromatin targets on a microscope slide, which can be visualized with fluorescent reporter molecules. Three chromatin targets—metaphase chromosomes, somatic interphases, and zygote interphases‐offer increasingly extended states of chromatin which can be strategically selected, individually or in combination, to address specific research questions of interest.
Molecular analysis of chromosomal rearrangements using pulsed field gel electrophoresis and somatic cell hybrids
Authors: Davis Lisa M. 
Published: February 2007

AbstractMany human genetic diseases, including some cancers, are characterized by consistent chromosome abnormalities, such as deletions and translocations. Analyses of these mutations often prove crucial to the eventual cloning and characterization of the gene(s) responsible for the disease. Two methods for analyzing these chromosome abnormalities have been developed in recent years: somatic cell hybridization and pulsed field gel electrophoresis (PFGE). Somatic cell hybridization is a technique for segregating an aberrant chromosome from its normal homologue in a cell derived from an unrelated species, which is usually a rodent. Panels of such hybrids dividing a given chromosomal region into increasingly smaller units can be constructed and used specifically to map DNA probes into those units. PFGE can then be used to define precise physical distances between such an array of chromosome abnormalities. Demonstrations of these analytic techniques are presented, using as an example chromosomal abnormalities involving human chromosome band 11p13, the locus for the Wilms' tumor, anirdia, genitourinary abnormality, and mental retardation (WAGR) syndrome.
Overview: Industrial perspectives on existing in vivo gene mutation assays
Authors: Li A. P. , Kier Larry D. 
Published: February 2007

AbstractIn vivo gene mutation assays are considered the most definitive for the evaluation of human health risks. Suggestions are provided here for the critical evaluation of the application of established in vivo gene mutation assays and alternative approaches in the evaluation of industrial chemicals. Objective evaluation of the assays and approaches based on sound science and practical issues will allow better application of the existing assays. Such an evaluation may also help illuminate areas of improvement, as well as help guide the development of future assays.
The biochemical specific‐locus test and a new multiple‐endpoint mutation detection system: Considerations for genetic risk assessment
Authors: Lewis Susan E. 
Published: February 2007

AbstractThe importance of studying the generation of mutations in mouse germ cells is emphasized, and the utility of the biochemical specific‐locus test in detecting germinal mutations is described. All experiments performed to date using this test are listed. The relevance of dominant mutations to human genetic risk is also discussed. Finally, the value of using multiple tests for the study of in vivo germinal mutations is discussed, and the design for a new multiple‐endpoint system is presented.
Direct‐acting mutagenic activity in white, rosé, and red wines with the ara test of salmonella typhimurium
Authors: Ariza Rafael R. , Serrano Angeles , Pueyo Carmen 
Published: February 2007

AbstractThirty‐two commercially produced white, rosé, and red wines from Spain were assayed for genotoxicity. The Ara forward mutagenicity assay with Salmonella typhimurium served as the test system. All the wines were mutagenic in the absence of mammalian microsomal activation (S9 mix) and/or glycosidase activities with the exception of one rosé wine which gave a clear dose‐response relationship, although its mutagenic potency was considered statistically nonsignificant. The mutagenic activity covered nearly a 30‐fold range. Compared to white and rosé wines, red wines showed the highest levels of mutagenicity; this wine type included four “very potent” (>3,000 AraR mutants/ml) mutagenic wines. The level of wine mutagenicity did not correlate with either the region or the year of production (vintage). Individual winery methods are suggested as primarily responsible for variations in mutagenic activity. The present study with the Ara test supports the possibility that wine components other than the flavonols quercetin and rutin are the major putative mutagens: (1) white wines, as well as roé or red wines, were detected as being mutagenic; (2) in no case was activation required for the detection of mutagenicity; (3) mutagen(s) were detected mainly (red wine) when not exclusively (white and rosé wine) in the polar fraction from XAD‐2 chromatography. The high sensitivity of the Ara test has allowed the screening of the mutagenicity of a variety of wines with no previous process of extraction or concentration. The comparison of the mutagenic activity of the entire complex mixture to that of its lyophilized residue has revealed a positive synergistic role for ethanol in the mutagenicity of certain wines. Finally, this work suggests that the Ara test is a useful tool for mutagenicity screening in wines. Thus, this test might play an important role in elucidating the genotoxic mechanism of action of alcoholic beverages, and for studying optional production methods to decrease the mutagenicity of commercial wines.
Conversion of excision‐repairable DNA lesions to micronuclei within one cell cycle in human lymphocytes
Authors: Fenech M. , Neville S. 
Published: February 2007

AbstractThe human lymphocyte micronucleus (MN) assay is relatively insensitive to genotoxic agents that predominantly induce excision‐repairable lesions such as adducts and abasic sites. In this study we have explored the possibility of using cytosine arabinoside (ARA) to convert excision‐repairable DNA lesions to micronuclei (MN) within one cell cycle. The system consisted of human lymphocytes as target cells, the cytokinesis‐block (CB) method for identifying cells that had completed one nuclear division only, and X‐rays, methylnitrosourea (MNU), and ultraviolet light (UV) as mutagens. With each mutagen we have observed significant increments in induced MN in the cultures that had also been treated with ARA during G1. The slope of the dose‐response curves for induction of MN was increased by a factor of approximately 1.8 for X‐rays and 10.3 for UV and significant MNU induction of MN was only achieved in the cultures treated with ARA. Furthermore, a 24‐hr gap between mutagen exposure and the start of the assay did not abolish the increased sensitivity in the cultures treated with ARA. These observations suggested that the combined ARA and cytokinesis‐block micronucleus (CBMN) method may enhance the detection of exposure to genotoxic agents that predominantly induce excision‐repairable lesions.
Quantitative structure‐activity relationship investigation of the role of hydrophobicity in regulating mutagenicity in the Ames test: 2. Mutagenicity of aromatic and heteroaromatic nitro compounds in Salmonella typhimurium TA100
Authors: Debnath Asim Kumar , Lopez Compadre Rosa L. , Shusterman Alan J. , Hansch Corwin 
Published: February 2007

AbstractA quantitative structure‐activity relationship (QSAR) has been derived for the mutagenic activity of 117 aromatic and heteroaromatic nitro compounds acting on Salmonella typhimurium TA100. Relative mutagenic activity is bilinearly dependent on hydrophobicity, with an optimal log P of 5.44, and is linearly dependent on the energy of the lowest unoccupied molecular orbital of the nitro compound. The dependence of mutagenic activity on hydrophobicity and electronic effects is very similar for TA98 and TA100. Mutagenic activity in TA100 does not depend on the size of the aromatic ring system, as its does in TA98. The effect of the choice of assay organism, TA98 versus TA100, on nitroarene QSAR is seen to be similar to the effect previously found for aminoarenes. Lateral verification of QSARs is presented as a tool for establishing the significance of a new QSAR.
Metal, mutagenicity, and biochemical studies on bivalve molluscs from Spanish coasts
Authors: Rodriguez‐Ariza Antonio , Abril Nieves , Navas José I. , Dorado Gabriel , López‐Barea‐Ariza Juan , Pueyo Carmen 
Published: February 2007

AbstractThree species of marine bivalve molluscs (Chamelea gallina, Ruditapes decussatus, and Crassostrea gigas) have been studied in order to evaluate the levels of pollution on the South Atlantic Spanish littoral. Several transition metals (Cu, As, Cd, Sn, Hg, Pb) were determined as a general index of total contamination. Animals from putative contaminated areas exhibited higher metal contents than those from cleaner waters. C. gigas showed 5–20‐fold higher total metal content than the other two species. The mutagenicity of ethanolic extracts was assayed by using both the His reversion and the Ara forward mutation tests. Mollusc tissues from the three species did not contain genotoxins active on TA98 (frameshift mutations) or TA100 (mainly G:C base‐pair substitutions), but did contain direct‐acting genotoxins of a polar nature and oxidative type. This was based on the following observations: 1) mammalian metabolic activation was not required for mutagenicity, 2) mutagens were eluted with the polar fraction from XAD‐2 columns, and 3) mutagenic responses were observed with Salmonella typhimurium TA102 (A:T base‐pair substitutions; sensitive to oxidative damages) and Escherichia coli catalase‐deficient (AraR forward mutations) strains. No relevant differences were found in the mutagenicity of mollusc extracts from areas with different pollution levels. Otherwise, our data suggest that, in general, animals living in contaminated environments had fewer genotoxins of oxidative type than those from less polluted areas. Such a result might be explained by the observation of increased levels of a number of detoxifying and antioxidant enzymes, such as glutathione‐S‐transferase, glutathione‐peroxidase, catalase, and superoxide dismutase. Thus, contaminated animals seem to be better protected against the oxidative damages induced by metals, in agreement with their lower malondialdehyde levels. To what extent the responsible mutagenic compounds are of endogenous origins, or “Nature's pesticides” (the major toxic chemicals ingested by phytoplankton filterfeeders), and/or the result of human activities remains to be determined.
Conditions for detecting the mutagenicity of divalent metals in Salmonella typhimurium
Authors: Pagano Dennis A. , Zeiger Errol 
Published: February 2007

AbstractThe mutagenesis of metals in bacteria, as reported in the literature, can best be described as inconsistent. We report that cobalt chloride (Co++), ferrous sulfate (Fe++), manganese sulfate (Mn++), cadmium chloride (Cd++), and zinc chloride (Zn++) could be reproducibly detected as mutagens in Salmonella strain TA97 when preincubation exposures were made in sterile, distilled, deionized water, or in Hepes buffer in NaCl2/KCl2, rather than the standard sodium phosphate buffer. Co++ was also mutagenic under standard preincubation conditions. The individual components of Vogel‐Bonner medium, i.e., potassium and ammonium phosphates, citrate, and magnesium sulfate, inhibit mutagenesis by these metals. The phosphates and the citrate probably inhibit by chelating the metals, while data are presented to suggest that Mg++ inhibition of metal mutagenesis is due to competitive inhibition for active transport via the magnesium active transport system in Salmonella. The chelator, diethyldithiocarbamate, inhibited the mutagenicity of Co++, Fe++, Zn++, and Mn++, but enhanced the mutagenicity of Cd++. The results presented show that divalent metals can be detected as mutagens in Salmonella, and that their lack of detection as mutagens is not due to an inherent insensitivity of Salmonella but to their interaction with media components and/or passive and active transport processes.
Phenobarbital: Does the positive result in TA1535 indicate genotoxic properties?
Authors: Albertini S. , Gocke E. 
Published: February 2007

AbstractThe liver carcinogen phenobarbital (PB) causes a weak but reproducible increase of the mutant frequency in the Ames test, strain TA1535, without S9. Since there is no obvious chemical basis for a “DNA reactivity” of this compound experiments were performed to obtain information about possible indirect mechanisms of enhancing the number of spontaneous mutant colonies. In the course of the study strong synergistic and comutagenic effects of PB when given in combination with Na‐azide or 2‐aminoanthracene (2AA) were observed. Not only TA1535 but the complete set of tester strains was responsive. However, PB did not enhance the effects of other mutagens such as 4‐nitroquinoline N‐oxide or 2‐nitrofluorene. It is argued that in strain TA1535 the fixation and expression of spontaneously occurring DNA lesions is amenable to modulation by PB similar to that of Na‐azide or 2AA induced lesions. Thus in the usual sense, PB is not genotoxic in the Ames test. Methapyrilene, another liver carcinogen with an assumed non‐genotoxic mode of action, showed almost identical properties in these experiments.