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D J Kowbel

Publications and source records attributed to D J Kowbel.

At least 19 recordsLinked to original sources
PubMed1990

Nucleotide sequence of nine protein-coding genes and 22 tRNAs in the mitochondrial DNA of the sea star Pisaster ochraceus.

We have cloned and sequenced over 9 kb of the mitochondrial genome from the sea star Pisaster ochraceus. Within a continuous 8.0-kb fragment are located the genes for NADH dehydrogenase subunits 1, 2, 3, and 4L (ND1, ND2, ND3, and ND4L), cytochrome oxidase subunits I, II, and III (COI, COII, and COIII), and adenosine triphosphatase subunits 6 and 8 (ATPase 6 and ATPase 8). This large fragment also contains a cluster of 13 tRNA genes between ND1 and COI as well as the genes for isoleucine tRNA between ND1 and ND2, arginine tRNA between COI and ND4L, lysine tRNA between COII and ATPase 8, and the serine (UCN) tRNA between COIII and ND3. The genes for the other five tRNAs lie outside this fragment. The gene for phenylalanine tRNA is located between cytochrome b and the 12S ribosomal genes. The genes for tRNA(glu) and tRNA(thr) are 3' to 12S ribosomal gene. The tRNAs for histidine and serine (AGN) are adjacent to each other and lie between ND4 and ND5. These data confirm the novel gene order in mitochondrial DNA (mtDNA) of sea stars and delineate additional distinctions between the sea star and other mtDNA molecules.

Adenosine Triphosphatases↗
PubMed1989

The genomic nucleotide sequences of two differentially expressed actin-coding genes from the sea star Pisaster ochraceus.

The genomic sequences of two differentially expressed actin genes from the sea star Pisaster ochraceus are reported. The cytoplasmic actin gene (Cy) is expressed in eggs and early development. The muscle actin gene (M) is expressed in tube feet and testes. Both genes contain an 1125-nucleotide coding region interrupted by three introns at codons 41, 121 and 204. Gene M contains two additional introns at codons 150 and 267. The intron position at codon 150, although present in higher vertebrate actins, has not been reported in actin genes from invertebrates. The M gene coding region has 89.5% nucleotide homology to the Cy gene, and differs from the Cy actin gene in 13 of 375 amino acids (aa), 11 of which are found in the C-terminal half of the gene. The C-terminal half of the M gene contains a significant number of muscle isotype codons. Even though there is only 1 aa change in the first 150 codons, there have been limited substitutions at many four-fold degenerate sites which may indicate selection pressure upon the secondary structure of the mRNA and/or a biased codon usage. Variant CCAAT, TATA, and poly(A)-addition signals have been identified in the 5' and 3' flanking regions. The presence of 5' and 3' splice junction sequences in the 5' flanking region of the Cy gene suggests the potential for an intron there.

Actins↗
PubMed1989

Gene arrangement in sea star mitochondrial DNA demonstrates a major inversion event during echinoderm evolution.

The mitochondrial (mt) DNA from the sea star Pisaster ochraceus has been isolated, restriction-mapped, and cloned into plasmid vectors. Both ribosomal RNA genes, the genes for 12 of the 13 mitochondrial proteins, and 11 of the tRNA genes have been localized by DNA sequence analyses. The sequence arrangement of the genes is markedly different from that seen in sea urchin mitochondrial DNA. A segment of the DNA molecule extending from tRNA(pro), including the tRNA cluster, ND1, ND2, and 16S genes, is inverted in relation to the sea urchin genome. The resulting gene order in the sea star is 12S, 16S, ND2, tRNA cluster, COI. As a result of the inversion, the transcriptional polarity of ND1, ND2, and 16S genes are opposite to that of the 12S and COI genes. The arrangement and transcriptional polarity of the other genes mapped here is the same as seen in urchin.

Animals↗
PubMed1986

Mutagenicity studies in Salmonella: residues of ozonated and/or chlorinated water fulvic acids.

Aqueous residues of ozonated, chlorinated, and ozonated/chlorinated water fulvic acids (WFA) were tested for induction of His+ reversion in Salmonella typhimurium strain TA100 in fluctuation tests for mutagenicity. The data suggest that ozonation of natural organics present in sources of drinking water can prevent subsequent formation of by-products of chlorination that are mutagenic in bacteria. Ozonation of the WFA at different pH and at varying dose levels produced residues that were not or were only weakly mutagenic. Chlorination of WFA or of previously ozonated WFA led to residues that were highly mutagenic. However, mutagen formation in the ozonated/chlorinated residues could be prevented, depending upon the pH of the WFA solutions during ozonation-mutagenicity decreased as pH increased. This decrease in mutagenicity is associated with previous observations of enhanced ozone decomposition into its highly reactive oxidant species at higher pH. Since ozonation seems to be more effective at alkaline pH, alkaline raw water sources seem to be the best candidates for water treatment that involves ozonation.

Benzopyrans↗
PubMed1986

The effect of 2-micron DNA on survival and mutagenesis in Saccharomyces cerevisiae.

Strains of Saccharomyces cerevisiae, with and without endogenous 2-microns DNA, were studied in experiments designed to determine the effect of this plasmid on survival and mutagenesis in yeast. Comparison of the two strains exposed to ultraviolet light, 4-nitroquinoline oxide, or methyl methanesulfonate (MMS), revealed that the presence of 2-microns DNA slightly enhanced survival after exposure to each agent. Spontaneous frequencies of mutations (histidine reversion, canavanine resistance, and mitochondrial petites, but not adenine auxotrophy) were reduced by the presence of 2-microns DNA. MMS-induced His+ reversion was weak, and both strains responded similarly. No difference was found between the two strains when induced forward mutation to canavanine resistance was examined. The extent of induction of mitochondrial petites was about the same in both strains. Therefore, it appears that under these experimental conditions with these mutagens, 2-microns DNA has an effect on spontaneous mutation and survival after DNA damage but not on induced mutagenesis in S. cerevisiae.

4-Nitroquinoline-1-oxide↗
PubMed1985

Solvent interactions with test compounds and recommendations for testing to avoid artifacts.

Reports in the literature describing artifactual results owing to interactions of test materials with solvents are becoming more frequent. The present study was initiated to examine possible interactions of 1,1,3-trichloro-, 1,1,3,3-tetrachloro-, pentachloro- and hexachloroacetones with different solvents, since certain solvent effects with the last compound have been shown previously. Quantitative differences in levels of mutagenic potency were found for tri-, tetra-, and pentachloroacetone, dissolved in acetone or dimethyl sulfoxide (DMSO). On the other hand, hexachloroacetone without solvent was mutagenic, and this activity was enhanced when it was dissolved in DMSO; in acetone it was not mutagenic. A time-dependent reaction of hexachloroacetone with DMSO was the only test material-solvent interaction found in this study. The results show clearly that DMSO is not an appropriate solvent for hexachloroacetone. On the basis of these and previous results, we recommend consideration of the following strategy to help prevent reporting of artifactual results owing to interaction with solvents: Results from initial screening experiments should be confirmed in repeat experiments using a different solvent; and a different solvent should be used in confirming the findings of other investigators. Differences in results would indicate a need for further study.

Acetone↗
PubMed1984

Chlorination of ozonated soil fulvic acid: mutagenicity studies in Salmonella.

Samples of soil fulvic acid (SFA) were ozonated and subsequently chlorinated under acidic or slightly basic conditions. The residues were tested for His+ reversion in a fluctuation assay, using Salmonella typhimurium TA100 as the tester strain. The ozonated/chlorinated samples were mutagenic, but activity was dependent on the amount of ozone utilized and the pH of the reaction medium. Although increases in cell concentrations were also induced by some mutagenic samples, this alone did not account for the mutagenicity observed. Unchlorinated samples displayed insignificant activity.

Benzopyrans↗
PubMed1984

Mutagenicity in a modified Salmonella assay of fabric-protecting products containing 1,1,1-trichloroethane.

Methyl chloroform (1,1,1-trichloroethane) was identified as a major component in two fabric-protector spray products. Mutagenic effects were determined at several dosage levels for the two products and some of the identified components. Levels of organics in the air of sealed desiccators, used as exposure chambers in modified Salmonella reversion assays, were measured by a gas chromatographic technique. Both fabric protectors and two samples of trichloroethane were mutagenic in strain TA 1535 and one of each was mutagenic in strain TA 100. Other constituents, such as petroleum distillate and p-dioxane, were nonmutagenic at the tested exposure levels.

Aerosols↗
PubMed1983

Genotoxic activity of pulp mill effluent in Salmonella and Saccharomyces cerevisiae assays.

An XAD-2 resin concentrate of chlorination-stage pulp mill effluent was found to induce mutations in Salmonella typhimurium strains TA1535, TA100 and TA98 but not in strains TA1537 or TA1538. The presence of either S9 mix, S9 mix without cofactors, or heat-inactivated S9 mix, reduced the mutagenic effects. Dose-related increases in gene conversion, mitotic recombination and aberrant colony formation in Saccharomyces cerevisiae strain D7 also were found.

Canada↗
PubMed1983

Suitability of the modified fluctuation assay for evaluating the mutagenicity of unconcentrated drinking water.

Filter-sterilized, unconcentrated tap water induced mutagenic responses (p less than 0.01) in Salmonella strain TA100 in fluctuation assays, usually with dose-related increases in positive tubes. Additional experiments were performed to study possible artifacts that could lead to falsely positive results. Determinations of bacterial survival revealed that cell populations in the tubes containing tap water were larger than in the controls. Since spontaneous mutation is a function of cell generation, the increased numbers of bacteria appeared to be responsible for the higher numbers of mutants observed. Therefore, the positive responses must be regarded as artifactual. This study suggests that survival determination should be a routine part of this method, and care should be exercised in the interpretation of positive results.

Cell Division↗
PubMed1982

Differential survival as an indicator of potential mutagenicity using repair deficient strains of Saccharomyces cerevisiae and Schizosaccharomyces pombe.

A method is presented to screen chemicals for potential mutagenicity on the basis of their ability to cause more killing in cells of repair-deficient yeast than in wild type cells. Two species were chosen in the event that one might be more sensitive to certain chemicals. The strains used were RAD+ and rad6 derivatives of Saccharomyces cerevisiae and RAD+ and rad3 derivatives of Schizosaccharomyces pombe. This report describes the test system and results for 12 known, direct-acting mutagens (i.e., not requiring mammalian metabolic activation). These compounds showed more lethality in one or both of the repair-deficient strains, indicating that they induce damage to DNA which is subject to repair in wild type cells. Advantages of this system include the use of eukaryotic yeast cells which can be manipulated as easily as bacteria, and that exogenous enzymes (S9) can be added for metabolic activation. Growing yeast cells can activate certain promutagens, and preliminary experiments showed positive responses for diethylnitrosamine and 2-acetylaminofluorene without the addition of S9.

Ascomycota↗
PubMed1981

Mutagenic activity of diallate and triallate determined by a battery of in vitro mammalian and microbial tests.

Diallate and Triallate are carbamate herbicides used mainly for the pre-emergence control of wild oats in various crops. The genetic activity of these compounds was studied using a battery of microbial and mammalian in vitro tests. In the Salmonella/mammalian-microsome assay, Diallate and Triallate show dose-related increases without metabolic activation in strains TA1535, TA100 and TA98, indicating that these compounds cause both frameshift and base-substitution mutations. Mutagenicity of both herbicides was enhanced greatly by incubation with Aroclor 1254 induced rat-liver S9. Genetic activity in mammalian cells was determined using a number of in vitro tests with Chinese hamster ovary (CHO) cells combined with metabolic activation as described above. Both Diallate and Triallate caused dose-related decreases in colony-forming ability, with concomitant dose-related increases in the frequencies of cells with chromosome damage and in the number of sister-chromatid exchanges. However, only Diallate caused a reduction in DNA molecular weight as determined by alkaline sucrose gradient (ASG) sedimentation. DNA damage was negligible even at concentrations of Triallate that reduced colony-forming ability to zero. This suggests that the lesions in DNA detected by the ASG technique are not necessarily related to those that produce chromosomal damage. These data, taken together, strongly implicate both Diallate and Triallate as capable of causing mutations in mammals. However the risk to man in terms of inherited disease or cancer remains to be established by appropriate in vivo methodology.

Animals↗
PubMed1981

Mutagenicity of paint removers containing dichloromethane.

A volatile component of commercially available paint and varnish removers was mutagenic in strains of Salmonella typhimurium TA1535, TA100 and TA98. Levels of dichloromethane in exposure chambers were determined by gas chromatography and were related directly to mutational dose-effect curves observed for the products.

Environmental Exposure↗
PubMed1981

Mutagenicity in Salmonella of dyes used by defence personnel for the detection of liquid chemical warfare agents.

Paper strips containing indicator dyes have been developed by defence scientists to change color upon exposure to certain agents but not to common solvents. As a preliminary step in studies on their possible genetic or carcinogenic hazard, 6 dyes used in these detection papers were tested with the Salmonella/mammalian-microsome assay. The 3 nitro arenes tested were found to be mutagenic. Two of them, Orasol Navy Blue 2RB (without metabolic activation) and Eastman Fast Blue B-GLF (with metabolic activation), induced higher yields of mutations in the frameshift revertible strains, but base substitution mutations also were found. The third nitro arene, ethyl-bis-(2,4-dinitrophenyl) acetate, induced only frameshift reversions, the greatest yields without metabolic activation. Because of weak but consistent mutagenic activation. Because of weak but consistent mutagenic effects with a fourth dye, thiodiphenyl-4,4'-diazo-bis-salicylic acid, fluctuation tests using Salmonella strain TA98 were performed, and dose-related, statistically-significant mutagenic responses were observed. Two remaining dyes, Fluorescent Brilliant Yellow R and 2,5,2',5'-tetramethyltriphenylmethane-4,4'-diazo-bis-beta-hydroxynaphthoic anilide, were not mutagenic in experiments using doses extending into the toxic range. Spot tests were performed on different paper strips containing the dyes. When the papers were eluted with dimethyl sulfoxide, responses were found to be qualitatively similar to those in the plate tests. Although microbial test results cannot be used to assess risk in man, these results indicate a potential mutagenic or carcinogenic hazard for individuals exposed to these dyes, especially the nitro aromatics.

Animals↗
PubMed1981

Genetic activity of actinomycin D in Saccharomyces cerevisiae but not in Escherichia coli.

The potential of actinomycin D for induction of forward mutation (ADE-), reversion (TRP+), gene conversion, and mitotic recombination, was examined using haploid and diploid strains of yeast Saccharomyces cerevisiae. No increase in forward or reverse mutations or gene conversion was detected, but actinomycin D induced up to 13-fold increases in mitotic recombinants and a 2-fold increase in numbers of aberrant colonies, in a non-selective assay for genetic activity. Actinomycin D was non-mutagenic in a fluctuation test using Escherichia coli strain WP2 UvrA-. This furnishes an example of a mutagen which is negative in bacteria but has genetic activity in yeast, emphasizing the need for using a battery of microbial tests for determining the genetic activity of any given chemical.

Dactinomycin↗
PubMed1980

Short-lived mutagen in Salmonella produced by reaction of trichloroacetic acid and dimethyl sulphoxide.

A chemical reaction occurs when trichloroacetic acid (TCA) is dissolved in dimethyl sulphoxide (DMSO), with the production of a short-lived mutagenic derivative which was detected using the Salmonella/mammalian-microsome plate overlay assay. Other interactions between test chemicals and solvents are discussed. Choice of proper solvents in mutagenicity testing is emphasized.

Dimethyl Sulfoxide↗