Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 93-105).

Thesis (Ph. D.)--Illinois State University, 1991. / Title from title page screen, viewed December 8, 2005. Dissertation Committee: Herman E. Brockman (chair), Radheshym K. Jayaswal, Alan J. Katz, David F. Weber, Brian J. Wilkinson. Includes bibliographical references (leaves 113-125) and abstract. Also available in print.

Mutagenic heterocyclic amines are produced during the ordinary cooking of meats and fish. When metabolically activated, heterocyclic amines will form covalent adducts with DNA, which, if not repaired, may affect the flow of genetic information in a cell. It has been proposed previously that heterocyclic amine mutagens contribute to the incidence of dietary-related cancers because they cause somatic cell mutations and induce tumors in rodents and nonhuman primates. Recent work has shown that some cooked food mutagens preferentially produce DNA damage in heart cells, DNA adduct levels are directly related to dose and duration of mutagen exposure, the dietary damage persists for long intervals in cardiac tissue, and mitochondrial DNA is more vulnerable than nuclear DNA to these mutagens. Because cardiac myocytes are terminally differentiated cells that have lost their ability to divide, the capacity to repair DNA damage is a critical factor in the proper function of cardiomyocytes, and cardiac myocytes seem to have limited DNA repair capabilities. DNA damage formed by dietary components, such as heterocyclic amines, might accumulate with time because of inefficient repair and thereby affect heart cell function or viability. The possibility that dietary habits play a role in idiopathic cardiomyopathies and congestive heart disease should be explored in greater depth.

Photoactivated psoralens and other agents that form DNA interstrand crosslinks are highly cytotoxic and are useful in treating a range of diseases, including vitiligo, psoriasis, and some forms of cancer. Unlike many lesions that damage only one strand of the duplex DNA, DNA interstrand crosslinks form covalent bonds with both strands. Thus, repairing these lesions is complicated both by the lack of an undamaged strand to serve as a template for resynthesis following excision, as well as the potential to form double strand breaks if both strands are incised. A number of models have proposed that repair is likely to couple nucleotide excision repair with other repair pathways such as recombination, and/or translesion synthesis. However, several aspects of these models remain speculative, and how these medically relevant lesions are repaired by cells still remains elusive. In this study, I use Escherichia coli as a model organism to characterize which gene products contribute to survival in the presence of psoralen-induced DNA interstrand crosslinks. In Chapter II, I demonstrate that although nucleotide excision repair initiates repair, not all subunits contribute equally to survival. Notably, uvrC is less sensitive to psoralen-induced damage than either uvrA or uvrB. I found that Cho, an alternative endonuclease, accounts for the increased resistance of uvrC mutants and contributes to survival in the presence of UvrABC. Cho was not required following angelicin treatment, a psoralen derivative that only forms monoadducts, suggesting that Cho function is specific for interstrand crosslink repair. However, Cho, by itself, is not required for the initial incision and only modestly enhances the rate that psoralen crosslinks are incised in vivo. Following incision, many of the intermediates in the repair process remain speculative. In Chapter III, I examine how recombination and translesion synthesis mutants contribute to survival of psoralen-induced damage. I show that both recBC and recF contribute to survival, but that neither mutant is as hypersensitive as recA, potentially suggesting that pathways involving either single strand gaps or double strand break intermediates can occur during repair. Finally, I show that Polymerase V is responsible for the translesion synthesis that contributes to survival in the case of psoralen-induced damage in E.coli.

In the present study DNA damage was measured in peripheral blood lymphocytes from polyposis coli and colorectal cancer patients, treated with different dietary and environmental compounds and compared with lymphocytes from healthy individuals. In addition, confounding factors such as age, gender, alcohol intake and smoking habits were taken into consideration. The assays used in this study included the Comet assay, the Micronucleus assay, the Micronucleus ¿ FISH assay and the sister chromatid exchange assay. The food mutagens, PhIP and IQ, as well as titanium dioxide nanoparticles (TiO2 NPs) induced a dose dependent increase in the DNA damage and chromosomal abnormalities in all tested groups regardless of confounding factors. Prior to experiments physicochemical characterisation of nanoparticles was conducted. In the presence of the flavonoids, quercetin and rutin that were acting in an antioxidant manner, the DNA damage resulting from the highest doses of food mutagens was significantly reduced. Thus, dietary supplementation with flavonoid-rich vegetables and fruits may prove very effective in protection against oxidative stress. The polyposis coli and colon cancer patients were more susceptible to food mutagens, PhIP and IQ, as well as TiO2 NPs, and in the majority of cases had a higher level of DNA damage in the Comet assay and higher cytogenetic damage in the Micronucleus assay. In the final project, twelve frequently encountered (NewGeneris) chemical compounds were evaluated to establish their damaging potential in lymphocytes and spermatozoa from healthy donors. The highest damage was produced by DNA reactive aldehydes, food mutagens and benzo[a]pyrene when assessed with the neutral and alkaline Comet assay with and without metabolic activation. / EU NewGeneris Programme and United Kingdom - India Education and Research Initiative (UKIERI)

Yes / In vivo tests for male reproductive genotoxicity are time consuming, resource-intensive and their use should be minimised according to the principles of the 3Rs. Accordingly, we investigated the effects in vitro, of a variety of known, phase-specific germ cell mutagens, i.e. pre-meiotic, meiotic, and post-meiotic genotoxins, on rat spermatogenic cell types separated using Staput unit-gravity velocity sedimentation, evaluating DNA damage using the Comet assay. N-ethyl-N-nitrosourea (ENU), N-methyl-N-nitrosourea (MNU) (spermatogenic phase), 6-mercaptopurine (6-MP) and 5-bromo-2'-deoxy-uridine (5-BrdU) (meiotic phase), methyl methanesulphonate (MMS) and ethyl methanesulphonate (EMS) (post-meiotic phase) were selected for use as they are potent male rodent, germ cell mutagens in vivo. DNA damage was detected directly using the Comet assay and indirectly using the TUNEL assay. Treatment of the isolated cells with ENU and MNU produced the greatest concentration-related increase in DNA damage in spermatogonia. Spermatocytes were most sensitive to 6-MP and 5-BrdU while spermatids were particularly susceptible to MMS and EMS. Increases were found when measuring both Olive tail moment (OTM) and % tail DNA, but the greatest changes were in OTM. Parallel results were found with the TUNEL assay, which showed highly significant, concentration dependent effects of all these genotoxins on spermatogonia, spermatocytes and spermatids in the same way as for DNA damage. The specific effects of these chemicals on different germ cell types matches those produced in vivo. This approach therefore shows potential for use in the detection of male germ cell genotoxicity and could contribute to the reduction of the use of animals in such toxicity assays.

In vitro genetic toxicity tests using cultured bacterial or mammalian cells provide a cost- and time-effective alternative to animal tests. Unfortunately, existing in vitro assays are not always reliable. This is in part due to the limited metabolic capacity of the cells used, which is often critical to accurately assess chemical genotoxicity. This limited metabolic capacity necessitates the use of exogenous sources of mammalian metabolic enzymes that can simulate in vivo mammalian metabolic activation reactions. In response to this, and other limitations, alongside the worldwide trend to reduce animal testing, there is an acute need to consider various strategies to improve in vitro mutagenicity assessment. This thesis first examined the utility of exogenous metabolic activation systems based on human hepatic S9, relative to conventional induced rat liver S9, for routine genetic toxicity assessment. This was accomplished by critically evaluating existing literature, as well as new experimental data. The results revealed the limitations of human liver S9 for assessment of chemical mutagenicity. More specifically, the analyses concluded that, due to the increased risk of false negative results, human liver S9 should not be used as a replacement for induced rat liver S9. To address the limitations of conventional mammalian cell genetic toxicity assays that require exogenous hepatic S9, the thesis next evaluated the utility of an in vitro mutagenicity assay based on metabolically-competent primary hepatocytes (PHs) derived from the transgenic MutaMouse. Cultured MutaMouse PHs were thoroughly characterized, and found to temporarily retain the phenotypic attributes of hepatocytes in vivo; they express hepatocyte-specific proteins, exhibit the karyotype of typical hepatocytes, and maintain metabolic activity for at least the first 24 hours after isolation. Preliminary validation of the in vitro MutaMouse PH gene mutation assay, using a panel of thirteen mutagenic and non-mutagenic chemicals, demonstrated excellent sensitivity and specificity. Moreover, inclusion of substances requiring a diverse array of metabolic activation pathways revealed comprehensive metabolic competence. Finally, the thesis further investigated the applicability domain of the in vitro MutaMouse PH assay by challenging the assay with selected azo compounds. Comparison of these results with those obtained using the in vivo MutaMouse TGR (transgenic rodent) assay revealed that MutaMouse PHs can carry out some forms of reductive metabolism. Overall, this thesis demonstrated that a gene mutation assay based on MutaMouse PHs holds great promise for routine assessments of chemical mutagenicity.

Submitted by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2017-06-12T14:17:48Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) JONATHALINE APOLLO DUARTE.pdf: 1033426 bytes, checksum: 65249cf69187d253ce4462e7152ce8db (MD5) / Approved for entry into archive by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2017-06-12T14:18:00Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) JONATHALINE APOLLO DUARTE.pdf: 1033426 bytes, checksum: 65249cf69187d253ce4462e7152ce8db (MD5) / Made available in DSpace on 2017-06-12T14:18:00Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) JONATHALINE APOLLO DUARTE.pdf: 1033426 bytes, checksum: 65249cf69187d253ce4462e7152ce8db (MD5) Previous issue date: 2016 / O emprego de produtos naturais para o tratamento, cura ou prevenção de doenças pela população é datada desde os tempos mais remotos, e apesar dos inúmeros avanços na ciência, o uso de plantas com finalidade medicinal, ainda representa na maioria das vezes o único recurso terapêutico de muitas comunidades e de diversos grupos étnicos.Atualmente é possível verificarmos que apesar de todos os avanços nas indústrias farmacêuticas para a produção de fármacos sintéticos, a população ainda recorre às plantas medicinais.Entretanto, existe uma infinidade de plantas que ainda não são conhecidos os seus possíveis efeitos farmacológicos e/ou toxicológico. Diante desse contexto, a Schinus molle L. (Anacardiaceae), popularmente conhecida como anacauíta, é uma planta rica em óleo essencial, a qual vem sendo usada como uma opção de tratamento para diversas enfermidades, e apesar de seu amplo emprego na medicina popular, a literatura carece de informações voltadas para seu perfil imutoxicologico. Assim, investigouse os efeitos do óleo essencial frente a parâmetros citotóxico, mutagênico e genotoxico em cultura de linfócitos e macrófagos humanos. Inicialmente, determinaramse as DL50 para ambas as células estudadas, através do teste de proliferação celular, para então desenvolver os demais testes. As DL50 encontradas foram de 30.07μg/mL para linfócitos humanos e de 42.07μg/mL para macrófagos humanos, assim, foram definidas as concentrações a serem testadas, sendo essas DL50, DL50/10, DL50/100, DL50/1000 e DL50/10000 para as células em questão, e foi constatado que o óleo essencial foi capaz de promover citotoxicidade em concentrações superiores a DL50/1000, para ambas as células testadas. Entretanto, o mesmo proporciona efeito genotóxico em culturas de macrófagos, somente para as duas concentrações maiores e quando avaliado os frente a parâmetros mutagênicos, constatouse que, o mesmo não promove alterações cromossômicas assim como, também não alterou o índice de divisão celular, embora tenha sido capaz de proporcionar frequência de micronúcleo concentração dependente nos macrófagos. Contudo, é importante salientar a importância de conhecimento dos constituintes do óleo essencial da Schinus molle L., para maiores esclarecimentos referente a sua toxicidade, uma vez que, essa planta é amplamente empregada na medicina popular para as diversas finalidades. Dessa forma, os resultados encontrados nesse trabalho, tem a contribuir com a literatura. Para tanto, estudos complementares são necessários para auxiliar na construção completa do perfil toxicológico do óleo essencial da planta em estudo, buscando a segurança da população que a utiliza. / The use of natural products for the treatment, cure or prevention of disease by population is dated from the earliest times, and despite the numerous advances in science, the use of plants for medicinal purposes, yet is most often the only therapeutic resource many communities and various ethnic groups. It is currently possible to see that despite all the advances in the pharmaceutical industry for the production of synthetic drugs, people still make use of medicinal plants. However, there is a multitude of plants that are not yet known its possible pharmacological effects and / or toxicology. In this context, the Schinus molle L.(Anacardiaceae), popularly known as anacauíta, is a plant rich in essential oil, which has been used as a treatment option for various diseases, and despite its widespread use in therapy, the literature lacks information geared to your immunotoxicology profile. Thus, we investigated the effects of essential oil cytotoxic front parameters, mutagenic and genotoxic in cultured human lymphocytes and macrophages. Initially, the LD50 were determined for both the cells studied by the cell proliferation assay, and then to develop other tests. The LD50 was found to 30.07μg/ml for human lymphocytes and 42.07μg/ml for human macrophages, thus the concentrations to be tested have been identified and these LD50, LD50/10, LD50/100 LD50/1000 and LD50/10000 to the cells in question, and it was found that the essential oil was able to promote cytotoxicity at concentrations above LD50/1000, for both test cells, however, it provides genotoxic effects in macrophage cultures, only the two concentrations and larger when measured against the mutagens parameters, it was found that it does not promote chromosomal abnormalities as well as, did not alter the rate of cell division, although it was able to provide frequency micronucleus concentration dependent on macrophages. However, it is important to stress the importance of knowledge of essential oil constituents of Schinus molle L., for further information regarding its toxicity, since this plant is widely used in folk medicine for a variety of purposes. Thus, the results found in this work, is to contribute to the literature. Therefore, further studies are needed to help complete construction of the toxicological profile of the essential oil of the plant under study, seeking the safety of the population makes use of this. / Schinus molle L

Made available in DSpace on 2014-08-20T13:44:39Z (GMT). No. of bitstreams: 1 tese_enrique_parachu_moliterno.pdf: 1249954 bytes, checksum: 934585fa055374ac866ea4a1bfb4b4e1 (MD5) Previous issue date: 2008-02-28 / Seed dormancy is a trait shown by a large variety of weedy plants, which helps the purpose of perpetuating the species through space and time by delaying germination until specific environmental cues happen. Black oat, a temperate forage grass, is widely used for pasture and as a cover crop in minimum tillage systems in Southern Brazil. However, the largest portion of the seed sown belongs to an old variety, which has no genetic identity, contributing to the appearance of undesirable agronomic traits in a crop species such as seed dormancy. This trait is hold responsible for turning black oat into a potential weedy species in areas sown to other cool season cereals, such as wheat and barley. Three methods were used to screen and select for black oat genotypes expressing low seed dormancy, i.e. screening of lines collected throughout different agricultural regions of the state of Rio Grande do Sul; subjecting a specific line of the species to the effects of two chemical and one physical mutagens and crossbreeding between selected lines and commercial cultivars of the species. All three methods were undertaken under a glasshouse environment (without temperature control), and since there are no known vegetative morphological traits associated to seed dormancy the procedure consisted on selecting seedlings from non dormant seeds. These were grown in the glasshouse environment and their progeny seeds tested for germinability, thus repeating the cycle. Genetic progress was slow for all three methods and cross breeding resulted the most difficult way for the creation of new genotypes, as only less than 8% of all pollinated flowers yielded hybrid seeds. Differences in germinability percentage among seeds of the first and second selection cycles were largest for the line- screening method, less for mutant seed phenotypes and minimum for the crossbreeding method, in which only F1 seeds were tested for germinability. On average, mutant seed treatments yielded 15% germinability after the first selection cycle, increasing to 20% germinability by the end of the second selection cycle. The screening of black oat lines yielded an initial 7% germinability, which increased to 36% germinability by the end of the second cycle. A common trend for all three methods was that seed germinability was highest during the first half of the standard germination test period for oat species, which implies that seedling selection was exercised for two traits simultaneously, i.e. absence of seed dormancy and seed vigor. The identification of several genotypes producing seeds expressing both traits increases the opportunity for genetic progress in this species. / A dormência de sementes é um caráter de muitas espécies de plantas invasoras de culturas agrícolas modernas, a qual tem por objetivo preservar a multiplicação da espécie através da germinação de suas sementes ao longo do tempo e o espaço. Aveia-preta é uma gramínea forrageira temperada muito semeada para produção de forragem e proteção do solo como cultura de cobertura, em sistemas de plantio direto. Porém, a maior parte da semente utilizada para semear a espécie pertence a uma variedade que praticamente não tem sido melhorada desde sua introdução, produzindo sementes com níveis variáveis de dormência. Esse caráter tem gerado problemas na área agrícola ocupada por essa espécie, tornado-a invasora potencial de outras culturas de estação fria. Com o objetivo de contribuir à melhora do caráter dormência de sementes quanto de outros de interesse numa espécie forrageira, foram aplicados três métodos de seleção de genótipos produtores de sementes com baixo nível de dormência: avaliação de genótipos fixos (linhagens) provenientes de diferentes regiões edafoclimáticas do estado de RS, indução a mutação de um genótipo fixo por dois agentes mutagênicos químicos e um físico e hibridações artificiais entre catorze genitores (linhagens e cultivares comerciais). Conforme a influência do ambiente num caráter quantitativo como a dormência de sementes, e o fato de não ter associação conhecida com caracteres morfológicos vegetativos, a estratégia adotada foi de multiplicar as sementes de cada tratamento sob ambiente de casa de vegetação e avaliar sua germinabilidade logo após a colheita. Os progressos na expressão do caráter de interesse foram lentos para os três métodos empregados, sendo que a hibridação artificial resultou o método mais difícil desde que o porcentual de sementes hibridas obtidas em relação ao número de polinizações efetuadas foi inferior a 8%. A diferença entre a germinabilidade das sementes oriundas do primeiro ciclo de seleção em relação às seguintes foi mais marcante para as linhagens do que para aqueles genótipos mutantes. Já, no caso dos híbridos, a avaliação só abrangeu a geração F1 por causa da baixa quantidade de sementes produzidas. Enquanto o progresso para o conjunto de tratamentos com mutagênicos foi relativamente baixo, com germinabilidade inicial média de 15% e final de 20%, as linhagens iniciaram em média com 7% de germinabilidade e logo do primeiro ciclo de seleção finalizaram a avaliação com 36% germinabilidade. Um aspecto comum aos três métodos empregados foi o fato da germinabilidade das sementes ser expressa em níveis mais importantes na primeira metade do período padrão da análise de germinação para a espécie. Isso implica em que a seleção de plântulas foi feita considerando dois caracteres, ausência de dormência e vigor de sementes em forma conjunta. A obtenção de vários genótipos no presente experimento produzindo sementes com ambos os caracteres abre boas perspectivas de progresso genético em aveia preta.

Dietary factors have been implicated in the etiology of colon cancer. The salient components of high-risk diets are thought to be high intakes of meat, especially beef, and fat, especially animal fat, and low intakes of fiber. Low-risk diets are thought to be high in fiber, and low in meat and animal fat. The present study examines the effects of short-term consumption of diets hypothesized to increase or decrease the risk for colon cancer on mutagenic activity of feces. Whether the fecal mutagens responsible for the mutagenic activity observed in the study are directly involved in the etiology of colon cancer is not known. However, most known mutagens are potentially carcinogenic, and fecal mutagenic activity may be an indicator of risk for colon cancer. Six healthy adult subjects consumed the following diets in sequence a baseline diet for one week, a low-risk lacto-ovo vegetarian, high fiber diet for two weeks, and a high-risk, high meat, low fiber diet for two weeks. Quantitative daily food intake records were kept, and daily bowel habits were recorded. Fecal samples were collected at the end of each diet period. Analyses were performed of the diets for food and nutrient intake, and of feces for percent dry weight and pH. Mutagenic activity of the fecal samples was assayed using the fluctuation test for mutagens. The subjects' habitual diets, although omnivorous, were found to closely resemble a low-risk diet pattern. Analysis of the vegetarian and high meat diets confirmed that the subjects had consumed foods which respectively represented the components of high-risk and low-risk diets. The overall fecal mutagenic activity obtained with samples on the high meat diet was higher than with the vegetarian or baseline diets using Salmonella typhimurium TA 98 and TA 100. The trend towards higher mutagenicity on the high meat diet over the vegetarian diet was consistent for all six subjects using TA 100, and for five of the six using TA 98. The vegetarian and baseline diets resulted in similar overall mutagenic activity. Analysis of the fecal sample parameters using the Kruskal-Wallis one-way analysis of variance showed no significant differences among fecal samples from the three diet periods with respect to wet weight, dry weight, percent dry weight, pH or number of daily bowel movements. However, a sign-test analysis showed a significant trend (p<0.05) towards fewer bowel movements on the high meat diet than on the vegetarian diet. There were significant differences among subjects for all of the fecal sample parameters (p<0.01 or p<0.001). Spearman rank correlations were significantly positive between mutagenic activities using bacterial strains Salmonella typhimurium TA 98 and TA 100 for the baseline diet (p<0.01) and the vegetarian diet (p<0.05). There were also significant positive correlations (p<0.001) between pH and fecal mutagenicity on the high meat' diet using tester strain TA 100, and between wet weight and dry weight. The results of this study indicate that the overall mutagenic activity of human feces can be increased over a period of two weeks by the consumption of a diet high in meat and low in fiber, which is considered to be a high-risk diet for colon cancer. / Land and Food Systems, Faculty of / Graduate