Insights into the modes of action (MoAs) of xenobiotics are of utmost importance for the definition of adverse outcome pathways (AOPs), which are essential for a mechanism-based risk assessment. A well-established strategy to reveal MoAs of xenobiotics is the use of omics. However, often an even more comprehensive approach is needed, which can be achieved using multi-omics. Since the immune system plays a central role in the defense against foreign substances and pathogens, with the innate immune system building a first barrier, we systematically reviewed multi-omics studies investigating the effects of xenobiotics on macrophages. Surprisingly, only nine publications were identified, combining proteomics with transcriptomics or metabolomics. We summarized pathways and single proteins, transcripts, or metabolites, which were described to be affected upon treatment with xenobiotics in the reviewed studies, thus revealing a broad range of effects. In summary, we show that macrophages are a relevant model system to investigate the toxicological effects induced by xenobiotics. Furthermore, the multi-omics approaches led to a more comprehensive overview compared to only one omics layer with slight advantages for combinations that complement each other directly, e.g., proteome and metabolome.

Bisphenols are used in the process of polymerization of polycarbonate plastics and epoxy resins. Bisphenols can easily migrate out of plastic products and enter the gastrointestinal system. By increasing colonic inflammation in mice, disrupting the intestinal bacterial community structure and altering the microbial membrane transport system in zebrafish, bisphenols seem to interfere with the gut microbiome. The highly abundant human commensal bacterium Bacteroides thetaiotaomicron was exposed to bisphenols (Bisphenol A (BPA), Bisphenol F (BPF), Bisphenol S (BPS)), to examine the mode of action, in particular of BPF. All chemicals caused a concentration-dependent growth inhibition and the half-maximal effective concentration (EC50) corresponded to their individual logP values, a measure of their hydrophobicity. B. thetaiotaomicron exposed to BPF decreased membrane fluidity with increasing BPF concentrations. Physiological changes including an increase of acetate concentrations were observed. On the proteome level, a higher abundance of several ATP synthase subunits and multidrug efflux pumps suggested an increased energy demand for adaptive mechanisms after BPF exposure. Defense mechanisms were also implicated by a pathway analysis that identified a higher abundance of members of resistance pathways/strategies to cope with xenobiotics (i.e., antibiotics). Here, we present further insights into the mode of action of bisphenols in a human commensal gut bacterium regarding growth inhibition, and the physiological and functional state of the cell. These results, combined with microbiota-directed effects, could lead to a better understanding of host health disturbances and disease development based on xenobiotic uptake.

The urinary excretion of D-glucaric acid (DGA) has been used as a nonspecific measure of the induction of hepatic enzymes associated with drug metabolism in man. A survey of 124 nonmedicated men (18-56 years of age), who kept a 5-day food and beverage intake record and collected their total urinary output for the last three days of the five, was conducted to assess the relationship between DGA excretion and various dietary factors. Eighteen nonmedicated, healthy women collected the same data, but started recording on the eighth day from the commencement of menstruation. DGA was determined by an enzymatic assay and recorded as micromoles D-glucaro-1,4-lactone/gm creatinine. There was a positive association between total DGA excreted and the use of marijuana, caffeine, and tobacco products, the heaviest users excreting significantly higher levels of urinary DGA than the moderate or low users of the same substance. Analysis of variance of mean DGA excretion also revealed significant differences between females (17.0±3.7) and males (14.3±5.2): male vegetarians (17.4±5.5) and nonvegetarians ( 13.9±5.1) ; and female vegetarians (19.8±4.6) and nonvegetarians (16.2±3.1). Alcohol consumption and family history of cancer incidences were not significantly related to DGA excretion in either sex. Multiple regression analyses revealed that consumption were the two vegetarianism and caffeine strongest predictors of DGA excretion, while alcohol and marijuana consumption affected DGA the least. These results indicate that dietary and environmental factors can exert a significant effect on DGA excretion, and these associations may identify dietary inducers of hepatic enzymes associated with xenobiotic biotransformations in humans. / Master of Science

Les champignons saprophytes sont les acteurs principaux du recyclage de la matière organique morte au sein des écosystèmes forestiers. Ces microorganismes possèdent la capacité unique de dégrader la totalité des polymères constitutifs du bois. L'analyse de la structuration des communautés durant les stades initiaux de la colonisation du bois par séquençage à haut débit a révélé que celui-ci influence la distribution et la dynamique des communautés qui lui sont associées. A l'échelle de l'organisme, les différents groupes écologiques de champignons décomposeurs du bois possèdent des systèmes de dégradation extracellulaires reflétant cette complexité chimique. Le séquençage du génome d'un grand nombre de ces organismes a permis l'identification de superfamilles d'enzymes impliquées dans les mécanismes de résistance et de détoxication des composés toxiques exogènes. Parmi elles, la superfamille des glutathion transférases présente une extension de classes spécifiques au sein des champignons décomposeurs du bois. La détermination des propriétés biochimiques et structurales d'une isoforme, issue d'une de ces classes spécifique (les Etherase-like), présente chez Phanerochaete chrysosporium a révélé des caractéristiques particulières. Cette enzyme possède un mode de dimérisation atypique ainsi que la capacité à séquestrer des composés phénoliques toxiques via une propriété ligandine unique. La comparaison des propriétés de plusieurs isoformes de cette classe d'enzymes appartenant aux champignons C. cinereus et P. chrysosporium a démontré que celle-ci exhibe une grande versatilité intra- et interspécifique, de leurs activités enzymatiques et de leur propriété ligandine / Saprophytic fungi are key players of dead organic matter recycling in forest ecosystems. These microorganisms possess the unique ability to degrade the integrality of wood constitutive polymers by secretion of complex oxydative and hydrolytic enzymatic systems. Communities structuration analysis during the initial stages of wood colonisation by high throughput sequencing revealed that the latter beyond being a source of nutrients, influences the distribution and dynamic of communities by its broad chemical variability. At the organism level, the different ecological groups of wood decomposing fungi possess extracellular degradation systems reflecting this chemical complexity. Genome sequencing of these organisms allowed the identification of enzymes superfamilies involved in resistance and detoxification mechanisms towards exogenous toxic compounds. Among them, the glutathione transferases superfamily exhibit extension of specific classes in wood decaying basidiomycetes. Biochemical and structural properties determination of one isoform belonging to one of these specific classes (the Etherase-like), found in Phanerochaete chrysosporium revealed unusual characteristics. This enzyme possesses an atypical dimerization mode as well as the ability to sequestrate toxic phenolic compounds resulting from wood degradation through a unique ligandin property. Properties comparison of several isoforms from this class belonging to C. cinereus and P.chrysosporium demonstrated a huge intra- and interspecific versatility of their enzymatics activities and ligandin property in response to environmental constraints arising from the great chemical heterogeneity of wood composition

Phanerochaete chrysosporium est un champignon forestier faisant partie des organismes saprophytes capables de recycler la matière organique morte. Grâce à l'excrétion de nombreuses enzymes de dégradation, en particulier des lignine peroxydases, il est capable de décomposer la matière végétale dont la lignine, un polymère complexe de composés phénoliques très résistant. L'élimination de la lignine permet la libération des autres composants du bois tels que la cellulose et l'hémicellulose qui peuvent être utilisés dans l'industrie papetière ou pour la production de bioéthanol de deuxième génération. La structure des intermédiaires et produits de dégradation de la lignine est souvent proche de celle denombreux polluants, d'où l'intérêt biotechnologique de P. chrysosporium dans les processus de bioremédiation. Cependant, les systèmes de dégradation engendrent des composés plus ou moins toxiques pour le champignon et contre lesquels il doit faire face. C'est pourquoi il possède un système de détoxication impliquant des enzymes telles que les cytochrome P450 monooxygénases ou encore les glutathion transférases (GST). Les Ure2p forment une classe de GST étendue chez Phanerochaete et d'autres basidiomycètes saprophytes. Leur étude par des approches phylogénétiques, biochimiques, structurales et transcriptomiques a permis de mieux comprendre les mécanismes d'évolution que peut subir une classe d'enzymes potentiellement soumises à une forte pression de sélection / Phanerochaete chrysosporium is a forest fungus being part of saprophytic organisms able to recycle dead organic matter. Thanks to the excretion of numerous wood decaying enzymes, and especially lignin peroxidases, this fungus is able to break down plant material including lignin, a complex polymer of phenolic compounds. Lignin removal allows the release of other wood components such as cellulose and hemicellulose, which can be further used in paper industry or to produce second generation bioethanol. The structure of intermediates and products from lignin decomposition is close to that of numerous pollutants making P. chrysosporium biotechnologically interesting for bioremediation purposes. Moreover, the fungus has to deal with more or less toxic compounds created by degradation mechanisms. It thus presents a detoxification pathway involving enzymes including cytochrome P450 monooxygenases and glutathione transferases (GST). Ure2p enzymes belong to an extended GST class in Phanerochaete genus as well as in other saprophytic basidiomycetes. Their study based on phylogenetic, biochemical, structural and transcriptomic approaches provides a better understanding of evolution mechanisms of a class of enzymes potentially subject to strong selection selection pressure

Made available in DSpace on 2016-08-10T10:55:03Z (GMT). No. of bitstreams: 1 ANA KAROLINA LOPES.pdf: 9734532 bytes, checksum: 4203439893759543f5fa8773dd844696 (MD5) Previous issue date: 2016-03-11 / The oral cancer is considered a public health problem worldwide. Are estimated for the biennium 2016-2017, in Brazil, 15,490 new cases of this disease that is the result of interactions between genetic and environmental factors, therefore, considered to be multifactorial. Genes related to the carcinogen detoxification process can influence the risk of developing cancer of the oral cavity. The objective of this study was to evaluate the relationship between tobacco risk factor, polymorphisms of GSTM1 and GSTT1 and the risk for oral cancer. The series consisted of 100 cases of patients diagnosed with oral cavity cancer, in 2005 and 2006, in the Hospital Araújo Jorge, Goiânia - GO and 70 control individuals without cancer. After DNA extraction from paraffin material from the group of cases and peripheral blood for the control group, the samples were analyzed by PCR and separated by electrophoresis. The frequency of null polymorphisms for the case group was 28.0% for GSTM1 and 49.0% to GSTT1. Among the control group, the frequency of null polymorphism was 31.5% for GSTM1 and 44.3% to GSTT1. The results showed that the GSTM1 and GSTT1 null genotypes were not associated with oral cancer in the population studied, as well as no significant association of polymorphisms with smoking status has not been established. The overall survival of patients with oral cavity cancer included in this study was 51,71%, however, the prognosis of this disease were not significantly associated with the GSTT1 and GSTM1 polymorphisms. The oral cancer was more correlated whith risk factors than genetic factors. Further studies correlating other xenobiotics metabolizing genes, must be performed in order to elucidate the influence of genetic polymorphisms in increasing the risk for cancer of the oral cavity and other cancers induced by toxic agents. / O câncer de cavidade oral é considerado um problema de saúde pública em todo o mundo. Estimam-se para o biênio 2016-2017, no Brasil, 15.490 novos casos dessa patologia que é resultado de interações entre fatores genéticos e fatores ambientais, portanto, considerada como multifatorial. Genes relacionados com o processo de detoxificação de carcinógenos podem interferir no risco para o desenvolvimento de câncer de cavidade oral. Este estudo objetiva avaliar a relação entre o fator de risco tabaco, os polimorfismos de GSTM1 e GSTT1 e o risco para o câncer de cavidade oral. No estudo, foram incluídos 100 casos de pacientes diagnosticados com câncer de cavidade oral, nos anos de 2005 e 2006, no Hospital Araújo Jorge, Goiânia-GO e 70 controles de indivíduos sem história de câncer. Após extração de DNA do material parafinado do grupo de casos e de sangue periférico para grupo controle, as amostras foram avaliadas por técnica de PCR e separação por eletroforese. A frequência de polimorfismos nulos para o grupo de casos foi de 28,0% para GSTM1 e 49,0% para GSTT1. No grupo controle, a frequência dos polimorfismos nulos foi de 31,5% para GSTM1 e de 44,3% para GSTT1. Não foi possível estabelecer uma associação significativa entre os polimorfismos dos genes GSTM1 e GSTT1 e o aumento do risco para o câncer de cavidade oral, bem como não foi estabelecida nenhuma associação significativa dos polimorfismos com o hábito tabagista. A sobrevida global dos pacientes com câncer de cavidade oral incluídos neste estudo foi de 51,71%, porém, os fatores prognósticos desta patologia não foram significativamente associados aos polimorfismos de GSTT1 e GSTM1, correlacionando o câncer de cavidade oral mais a fatores de risco do que a fatores genéticos. Novos estudos, que correlacionem outros genes metabolizadores de xenobióticos, precisam ser realizados a fim de elucidar a influência dos polimorfismos genéticos no aumento do risco para o câncer de cavidade oral e demais cânceres induzidos por agentes tóxicos.

O melanoma é uma lesão maligna da pele, com alta taxa de mortalidade cuja incidência vem aumentando nos últimos anos. Os principais fatores de risco são a história familial da doença, presença de nevos benignos múltiplos ou nevos atípicos e melanoma prévio. Imunossupressão, sensibilidade ao sol e exposição intermitente e intensa à radiação UV da luz solar, sem proteção, são fatores de risco adicionais. O objetivo deste estudo caso-controle de base hospitalar foi avaliar a contribuição de polimorfismos de genes de metabolização de xenobióticos (CYP1A1/MspI, CYP2E1/PstI, GSTM1, GSTT1 e GSTP1/Bsma), de genes de reparo do DNA (XRCC1/MspI, XRCC3/NcoI e XPD/PstI) e do gene do receptor de vitamina D (VDR/FokI e VDR/TaqI) no risco de melanoma. Consentiram em participar 193 pacientes com melanoma (49,7% homens e 50,3% mulheres, média de 52 ± 14,28 anos) e 208 controles (51,4% homens e 48,6% mulheres, média de 48 ± 15,24 anos) que após responderem a um questionário detalhado sobre hábitos e tipos de exposição a fatores de risco cederam amostras biológicas para análsie do DNA por PCR-RFLP. Os principais fatores de risco para o melanoma foram ascendência européia (p<0,001), cor de olhos claros (p<0,001), presença de nevos (p<0,001), histórico de queimadura grave na adolescência (p<0,001), falta de filtro solar (p<0.034) e exposição à lâmpadas fluorescentes (p=0,001). Quanto à análise dos polimorfismos de genes de metabolização de xenobióticos somente o GSTT1 nulo revelou associação inversamente positiva com o risco de melanoma maligno (OR ajustado = 0,60; IC95% = 0,37-0,97). Entretanto, essa associação não se manteve após a análise de regressão múltipla escalonada. Os polimorfismos VDR/FokI e VDR/TaqI não modificaram a susceptibilidade ao melanoma maligno na comparação entre os grupos. Na análise conjunta do fenótipo-genótipo, indivíduos com olhos verdes e genótipo VDR/FokI polimórfico, apresentaram risco praticamente seis vezes maior de melanoma (OR ajustado = 5,93; IC95% = 1,49-23,59). A associação entre os polimorfismos em pelo menos um dos alelos dos genes de reparo do DNA, XRCC3/NcoI e XPD/PstI aumentou praticamente duas vezes o risco de melanoma tanto na análise estatística multivariada (OR ajustado = 1,84; IC95% = 1,08-3,14) quanto na regressão logística múltipla escalonada (OR ajustado = 2,32; IC95% = 1,01-5,36). Na interação genemeio ambiente a falta do uso de filtro solar dobrou o risco de melanoma em indivíduos com polimorfismo XPD/PstI (OR ajustado = 2,17; IC95% = 1,12- 4,17). A identificação de polimorfismos genéticos associados com doenças multifatorias como o caso do melanoma maligno devem ser estimuladas em nosso meio, principalmente por vivermos em um país tropical com alta incidência solar em praticamente todo seu território. A identificação de marcadores genéticos de susceptibilidade pode propiciar medidas precoces e eficazes de prevenção do câncer. / Melanoma is a malignant skin lesion, with high mortalitty rate and its incidence has been rising in the last years. The main risk factors are melanoma family history, presence of multiple benign or atypical nevi and previous melanoma. Immunosuppression, sun sensitivy and intermittent and intense exposure to UV sunlight radiation, without protection, are additional risk factors. The aim of this hospital based case-control study was to evaluate the contribution of genetic polymorphisms of xenobiotic metabolizing enzymes (CYP1A1/MspI, CYP2E1/PstI, GSTM1, GSTT1 and GSTP1/Bsma), DNA repair genes (XRCC1/MspI, XRCC3/NcoI and XPD/PstI) and vitamin D receptor genes (VDR/FokI and VDR/TaqI) to the risk of melanoma. All participants, including 193 melanoma patients (49.7% men and 50.3% women, mean age 52 ± 14.28 years old) and 208 controls (51.4% men and 48.6% women, mean age 48 ± 15.24 years old) gave written informed consent to participate in the study and agreed to donate a sample of bloody to analysis of DNA by PCR-RFLP and answer a questionarie regarding phenotypic characteristics, personal habits and questions regarding sun exposure that could be associated to the disease. The main risk factors to melanoma were European ancestries (p<0.001), light colored eyes (p<0.001), presence of nevi (p<0.001), history of sunburns during the adolescence (p<0.001), no use of sunblock (p<0.034) and exposure of fluorescent lamps (p<0.001). Regarding the genes polymorphisms, only GSTT1 null genotype showed as an inversely positivefactor (OR adjusted = 0.60; 95%CI = 0.37-0.97) to malignant melanoma. However, this association disappeared with multiple regression analysis. The VDR/FokI and VDR/TaqI polymorphisms did not alter the susceptibility to malignant melanoma in the comparison between groups. A joint analysis of phenotype-genotype, individuals with green eyes and polymorphic genotype VDR/FokI, presented almost six times more risk to melanoma (OR adjusted = 5.93, 95% CI = 1.49-23.59). The association between polymorphisms, in at least one polymorphic allele of DNA repair genes XRCC3/NcoI and XPD/PstI increased almost twice the risk of melanoma in the multivariate statistic analysis (OR adjusted = 1.84, 95%CI = 1.08-3.14) and in multiple logistic regression (OR adjusted = 2.32, 95%CI = 1.01-5.36). In the interaction gene-environment the lack of sunscreen doubled the risk of melanoma in individuals with polymorphisms of XPD/PstI (OR adjusted = 2.17, 95%CI = 1.12-4.17). The identification of genetic polymorphisms associated with diseases such as multi factorial case of malignant melanoma should be encouraged in our country, mainly because we live in a tropical country with high solar irradiation in almost all its territory. The identification of genetic markers of susceptibility may provide early and effective prevention of cancer.

O melanoma é uma lesão maligna da pele, com alta taxa de mortalidade cuja incidência vem aumentando nos últimos anos. Os principais fatores de risco são a história familial da doença, presença de nevos benignos múltiplos ou nevos atípicos e melanoma prévio. Imunossupressão, sensibilidade ao sol e exposição intermitente e intensa à radiação UV da luz solar, sem proteção, são fatores de risco adicionais. O objetivo deste estudo caso-controle de base hospitalar foi avaliar a contribuição de polimorfismos de genes de metabolização de xenobióticos (CYP1A1/MspI, CYP2E1/PstI, GSTM1, GSTT1 e GSTP1/Bsma), de genes de reparo do DNA (XRCC1/MspI, XRCC3/NcoI e XPD/PstI) e do gene do receptor de vitamina D (VDR/FokI e VDR/TaqI) no risco de melanoma. Consentiram em participar 193 pacientes com melanoma (49,7% homens e 50,3% mulheres, média de 52 ± 14,28 anos) e 208 controles (51,4% homens e 48,6% mulheres, média de 48 ± 15,24 anos) que após responderem a um questionário detalhado sobre hábitos e tipos de exposição a fatores de risco cederam amostras biológicas para análsie do DNA por PCR-RFLP. Os principais fatores de risco para o melanoma foram ascendência européia (p<0,001), cor de olhos claros (p<0,001), presença de nevos (p<0,001), histórico de queimadura grave na adolescência (p<0,001), falta de filtro solar (p<0.034) e exposição à lâmpadas fluorescentes (p=0,001). Quanto à análise dos polimorfismos de genes de metabolização de xenobióticos somente o GSTT1 nulo revelou associação inversamente positiva com o risco de melanoma maligno (OR ajustado = 0,60; IC95% = 0,37-0,97). Entretanto, essa associação não se manteve após a análise de regressão múltipla escalonada. Os polimorfismos VDR/FokI e VDR/TaqI não modificaram a susceptibilidade ao melanoma maligno na comparação entre os grupos. Na análise conjunta do fenótipo-genótipo, indivíduos com olhos verdes e genótipo VDR/FokI polimórfico, apresentaram risco praticamente seis vezes maior de melanoma (OR ajustado = 5,93; IC95% = 1,49-23,59). A associação entre os polimorfismos em pelo menos um dos alelos dos genes de reparo do DNA, XRCC3/NcoI e XPD/PstI aumentou praticamente duas vezes o risco de melanoma tanto na análise estatística multivariada (OR ajustado = 1,84; IC95% = 1,08-3,14) quanto na regressão logística múltipla escalonada (OR ajustado = 2,32; IC95% = 1,01-5,36). Na interação genemeio ambiente a falta do uso de filtro solar dobrou o risco de melanoma em indivíduos com polimorfismo XPD/PstI (OR ajustado = 2,17; IC95% = 1,12- 4,17). A identificação de polimorfismos genéticos associados com doenças multifatorias como o caso do melanoma maligno devem ser estimuladas em nosso meio, principalmente por vivermos em um país tropical com alta incidência solar em praticamente todo seu território. A identificação de marcadores genéticos de susceptibilidade pode propiciar medidas precoces e eficazes de prevenção do câncer. / Melanoma is a malignant skin lesion, with high mortalitty rate and its incidence has been rising in the last years. The main risk factors are melanoma family history, presence of multiple benign or atypical nevi and previous melanoma. Immunosuppression, sun sensitivy and intermittent and intense exposure to UV sunlight radiation, without protection, are additional risk factors. The aim of this hospital based case-control study was to evaluate the contribution of genetic polymorphisms of xenobiotic metabolizing enzymes (CYP1A1/MspI, CYP2E1/PstI, GSTM1, GSTT1 and GSTP1/Bsma), DNA repair genes (XRCC1/MspI, XRCC3/NcoI and XPD/PstI) and vitamin D receptor genes (VDR/FokI and VDR/TaqI) to the risk of melanoma. All participants, including 193 melanoma patients (49.7% men and 50.3% women, mean age 52 ± 14.28 years old) and 208 controls (51.4% men and 48.6% women, mean age 48 ± 15.24 years old) gave written informed consent to participate in the study and agreed to donate a sample of bloody to analysis of DNA by PCR-RFLP and answer a questionarie regarding phenotypic characteristics, personal habits and questions regarding sun exposure that could be associated to the disease. The main risk factors to melanoma were European ancestries (p<0.001), light colored eyes (p<0.001), presence of nevi (p<0.001), history of sunburns during the adolescence (p<0.001), no use of sunblock (p<0.034) and exposure of fluorescent lamps (p<0.001). Regarding the genes polymorphisms, only GSTT1 null genotype showed as an inversely positivefactor (OR adjusted = 0.60; 95%CI = 0.37-0.97) to malignant melanoma. However, this association disappeared with multiple regression analysis. The VDR/FokI and VDR/TaqI polymorphisms did not alter the susceptibility to malignant melanoma in the comparison between groups. A joint analysis of phenotype-genotype, individuals with green eyes and polymorphic genotype VDR/FokI, presented almost six times more risk to melanoma (OR adjusted = 5.93, 95% CI = 1.49-23.59). The association between polymorphisms, in at least one polymorphic allele of DNA repair genes XRCC3/NcoI and XPD/PstI increased almost twice the risk of melanoma in the multivariate statistic analysis (OR adjusted = 1.84, 95%CI = 1.08-3.14) and in multiple logistic regression (OR adjusted = 2.32, 95%CI = 1.01-5.36). In the interaction gene-environment the lack of sunscreen doubled the risk of melanoma in individuals with polymorphisms of XPD/PstI (OR adjusted = 2.17, 95%CI = 1.12-4.17). The identification of genetic polymorphisms associated with diseases such as multi factorial case of malignant melanoma should be encouraged in our country, mainly because we live in a tropical country with high solar irradiation in almost all its territory. The identification of genetic markers of susceptibility may provide early and effective prevention of cancer.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Les moustiques génèrent une nuisance importante et sont notamment contrôlés grâce à des traitements insecticides. Aujourd'hui, les gîtes où se développent leurs larves sont souvent pollués par des xénobiotiques environnementaux (hydrocarbures, herbicides, pesticides, toxines naturelles…). Jusqu'à présent, l'impact de ces xénobiotiques sur la capacité des larves de moustiques à résister aux insecticides chimiques reste méconnu. Cette thèse vise à étudier la réponse des larves de d'Aedes aegypti aux xénobiotiques environnementaux et leur impact sur leur tolérance et résistance aux insecticides chimiques. Une première étude, sur le court terme, montre que des larves exposées pendant 24h à divers xénobiotiques deviennent plus tolérantes à vis à vis de différents insecticides chimiques (Poupardin et al. 2008). Des études biochimiques et transcriptomiques suggèrent que l'induction de certaines familles d'enzymes (e.g. P450s et GSTs) par ces xénobiotiques peut être liée à l'augmentation de tolérance des larves vis-à-vis de l'insecticide. Dans le but de mieux caractériser le profil transcriptionnel des précédents gènes candidats, des expérimentations complémentaires ont été faites à différents niveaux (Poupardin et al., 2010). Cette étude a montré que de nombreux gènes étaient préférentiellement transcrits dans des tissus fortement impliqués dans la détoxication de composés exogènes, essentiellement des CYP6. Elle révèle aussi que la transcription de ces P450s varie beaucoup au cours des différents stades de développement et qu'ils étaient induits à des faibles de doses de polluants avec un pic d'induction après 48 et 72 heures d'exposition. Ces études mettent en évidence le rôle potentiel des gènes de détoxication dans la réponse à l'exposition à des xénobiotiques et dans l'augmentation de tolérance aux insecticides chimiques. Concernant l'étude sur le long terme de l'impact des polluants sur la résistance des moustiques aux insecticides, la question est de savoir si les polluants trouvés dans l'environnement influencent la sélection de la résistance aux insecticides et si oui, favorisent-ils la sélection de gènes en particulier? Pour répondre à ces questions, trois souches d'Aedes aegypti ont été sélectionnées à la perméthrine. Ces souches sont exposées ou non à différents polluants avant sélection. Après 10 générations de sélection, des bioessais montrent une résistance de ces 3 souches vis-à-vis de la perméthrine. Aucune différence significative de niveau de résistance n'est observée entre les trois souches sélectionnées pour le moment. Pour identifier les gènes différentiellement transcrits dans ces souches, la puce "Agilent Aedes chip" développée par l'école de médecine tropicale de Liverpool (LSTM) et contenant 14200 transcrits a été utilisée. Les microarrays ont révélé que la présence de polluants ou insecticides résiduels pouvait affecter la sélection des mécanismes de résistance aux insecticides chimiques, notamment par la sélection de gènes particuliers codant pour des enzymes de détoxication (Poupardin et al, en préparation). D'une manière globale, cette thèse permettra de mieux comprendre l'impact de l'environnement chimique sur la résistance des moustiques aux insecticides et fournira de nouvelles pistes afin d'optimiser les traitements insecticides utilisés en démoustication. / Mosquitoes have a major impact on public health due to their capacity to transmit human diseases such as viruses (dengue, yellow-fever, west-Nile, chikungunya…) and parasites (malaria, filariasis…). To control them, insecticides have been heavily used since the 1950's leading to the emergence of insecticide resistance. Today, wetlands where mosquito larvae develop are frequently contaminated by environmental xenobiotics (e.g. residual insecticides, agrochemicals, pollutants and plant allelochemicals) and little is known about the impact of these molecules on the capacity of mosquitoes to resist insecticides. The aim of my thesis is to study the response of mosquito larvae to xenobiotic exposures and the impact of these molecules on the tolerance (single generation) and resistance (multiple generations) of mosquitoes to chemical insecticides. A first ‘short term' study revealed that mosquito larvae exposed for few hours to sub-lethal doses of various xenobiotics become more tolerant to several chemical insecticides (Poupardin et al., 2008, Riaz et al., 2009) and that this increased tolerance is linked with an increase of detoxification enzyme activities. Thanks to the “Aedes detox chip” developed in LSTM, we showed that several detoxification genes, especially P450s, were induced by various xenobiotics which could explain the increased tolerance of mosquito larvae to insecticides. In order to better characterize these genes, their transcription profiles were studied at different life stages and in various organs (Poupardin et al., 2010). We demonstrated that several of these P450s are preferentially transcribed in gastric caeca, midgut and malpighian tubules, known to play an important role in xenobiotic metabolism. Moreover, we found that the transcription levels of these genes vary according to life stages. Finally, several genes were induced by environmental doses of xenobiotics with a maximum induction peak at 48-72h after exposure. Overall, these studies evidenced of the potential role of mosquito detoxification genes to respond to xenobiotic exposure and to affect their tolerance to chemical insecticides. The other aim of my thesis was to understand the ‘long term' (across several generations) impact of xenobiotics on the selection of insecticide resistance mechanisms in mosquitoes. In other words, ‘Do pollutants affect the selection of insecticides resistance mechanism by insecticides treatments' and if yes, ‘are particular genes favoured?' To answer these questions, three strains of the mosquito Aedes aegypti were selected with the pyrethroid insecticide permethrin. Before the selection process, larvae were exposed or not to sub-lethal dose of various pollutants. After 11 generations of selection, the three strains showed elevated resistance to permethrin compared to the susceptible strain. To identify the genes differentially transcribed in these resistant strains, we used the new ‘Agilent Aedes chip' representing more than 14,200 transcripts developed by the LSTM. Microarray results showed that the presence pollutants or residual insecticide can affect the selection of insecticide resistance mechanisms by favouring the selection of particular genes such as those encoding for detoxification enzymes (Poupardin et al., in prep). Globally, this research work will provide a better understanding of the impact of environmental factors on insecticide resistances in mosquitoes and will provide new ways to optimize the control of vectors with insecticides.