Orientador: Suzete Aparecida Lanza Destéfano / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-20T14:37:32Z (GMT). No. of bitstreams: 1 Tonin_MarianaFerreira_D.pdf: 2371085 bytes, checksum: d7c915d664efeec24397b855164c65b9 (MD5) Previous issue date: 2012 / Resumo: Espécies pertencentes ao gênero Xanthomonas são responsáveis por doenças que podem causar grandes perdas econômicas em diversas culturas. Esses fitopatógenos têm sido objeto de diversos estudos taxonômicos resultando em significativas alterações na classificação em nível inter e infraespecífico. O presente estudo teve por objetivo caracterizar taxonomicamente bactérias do gênero envolvendo: (1) diferenciação e análises filogenéticas de espécies do gênero Xanthomonas; (2) esclarecimento da posição taxonômica de linhagens classificadas como Xanthomonas sp.; (3) diferenciação de patovares da espécie X. campestris; (4) desenvolvimento de primers específicos para X. campestris, X. translucens, X. cucurbitae e X. melonis. O par de primers rpoB2F/rpoB3R, desenhado a partir de sequências do gene rpoB, foi empregado em experimentos de amplificas;ao utilizando-se DNAs de 26 espécies do gênero Xanthomonas e os produtos de amplificas;ao (800 pb) foram digeridos com diversas endonucleases. Os perfis de restrição obtidos com a utilização da enzima Hae III permitiram a diferenciação da maioria das espécies, incluindo os patógenos de mesmo hospedeiro como X. albilineans e X. sacchari (patogênicas à cana-de-açúcar); X. cucurbitae . e X. melonis (patogênicas ao melão); X. vesicatoria, X. gardneri e X. euvesicatoria/X. perforans (patogênicas ao tomateiro). Ainda, os produtos de amplificação do gene rpoB foram seqüenciados e a árvore filogenética construída a partir destas sequências também possibilitou a diferenciação das espécies do gênero, indicando que o gene rpoB pode ser considerado um marcador molecular eficiente para o estudo das relações filogenéticas de espécies do gênero Xanthomonas. Os DNAs de linhagens classificadas como Xanthomonas sp. também foram analisados por meio de experimentos de amplificação com primers específicos para a espécie X. axonopodis, de hibridizas;ao DNA-DNA, e analise de multilocus utilizando-se sequências dos genes rpoB, rpoA, atpA, recA e região espaçadora 16S-23S DNAr. Os resultados mostraram que as linhagens de X. sp. pv. viticola, X. sp. pv. betae e X. sp. pv. paulliniae pertencem a espécie X. axonopodis, entretanto, não foi possível definir a posição taxonômica das linhagens de X. sp. pv. arracaciae, X. sp. pv. esculenti e X. sp. pv. eucalypti, embora várias ferramentas tenham sido utilizadas. Assim, somente estudos complementares deverão ser conduzidos visando esclarecer a classificação dessas linhagens. Nesse estudo também foram analisadas as espécies X. campestris, X. translucens, X. cucurbitae e X. melonis. Visando a diferenciação dos patovares da espécie X. campestris, os DNAs destas linhagens foram submetidos a experimentos de PCR-RFLP do gene rpoB e as digestões duplas utilizando-se Cfo I/Mbo I. Os resultados permitiram a diferenciação dos patovares X.c. pv. raphani, X.c. pv. barbariae, X.c. pv. incanae, X.c. pv. armoraciae e X.c. pv. campestris/ X.c. pv. aberrans. Ainda, os dados obtidos nas amilises do gene rpoB permitiram o desenvolvimento de primers específicos para as espécies X. campestris, patogênicas as crucíferas (rpoB2F/xcamR) e X. translucens, patogênicas a gramíneas e cereais (trans1F/trans2R). Alem disso, amilises de sequências da região espaçadora 16S-23S DNAr possibilitaram o desenho do par de primers mecF/mecR, especifico para X. cucurbitae e X. melonis, espécies patogênicas ao melão. A especificidade destes primers foi confirmada em experimentos de amplificação utilizando-se DNAs de algumas bactérias de diferentes gêneros isoladas de mesma espécie de plantas hospedeiras. O nível de sensibilidade da técnica de PCR utilizando-se os primers desenvolvidos foi de 0,1 pg para rpoB/xcam, de 0,01 ng para trans1F/trans2R e de 1 pg para mecF/mecR / Abstract: Xanthomonas species are responsible for diseases causing economic losses in many crops. These phytopathogens have been subject of several taxonomic studies resulting in significant changes at interespecific or infraspecific level. This study aimed the taxonomic characterization of Xanthomonas species including: (1) differentiation and phylogenetic analysis of Xanthomonas species; (2) clarification of taxonomic position of strains classified as Xanthomonas sp.; (3) differentiation of the pathovars of X. campestris; ( 4) development of specific primers for X. campestris, X. translucens, X. cucurbitae and X. melonis. The rpoB2F/rpoB3R primers, designed from rpoB gene sequences, were employed in amplification experiments using DNAs from 26 species of Xanthomonas genus and the products (800 bp) were digested with different restriction enzymes. Profiles using Hae III allowed to differentiate the most species of the genus, including pathogens the affect the same plant host as X. albilineans e X. sacchari (pathogenic to sugarcane); X. cucurbitae e X. melonis (pathogenic to melon); X. vesicatoria, X. gardneri and X. euvesicatoria/X. perforans (pathogenic to tomato). Amplification products of the rpoB gene were sequenced and the phylpgenetic tree constructed from these sequences also allowed the differentiation of the Xanthomonas species, indicating that the rpoB gene can be used as an efficient molecular marker for phylogenetic relationships studies within the Xanthomonas genus. DNA of the strains classified as Xanthomonas sp. were also analysed by the amplification experiments using specific primers for X. axonopodis species, DNA-DNA hybridization and multilocus sequence analysis of the genes rpoB, rpoA, atpA, recA and intergenic spacer region 16S-23S rDNA. Results showed that the strains of X. sp. pv. viticola, X. sp. pv. betae and X. sp. pv. paulliniae belong to X. axonopodis species, however, it was not possible to define the taxonomic position of X. sp. pv. arracaciae, X. sp. pv. esculenti and X. sp. pv. eucalypti, although different approaches have been used. Thus, further studies should be conducted in order to clarify their classification. In this study X. campestris, X. translucens, X. cucurbitae and X. melonis were also analyzed. In order to differentiate the pathovars of the X. campestris specie, the DNAs of these strains were submitted to PCR-RFLP analysis of the rpoB gene and the double digestions using Cfo I/Mbo I allowed the differentiation of the pathovars X. c. pv. raphani, X.c. pv. barbariae, X.c. pv. incanae, X.c. pv. armoraciae and X.c. pv. campestris/ X.c. pv. aberrans. Also, the data obtained in the rpoB gene analysis allowed the development of specific primers for the species X. campestris, pathogenic to crucifers (rpoB2F/xcamR) and X. translucens, pathogenic to grasses and cereals (trans1F/trans2R). Furthermore, intergenic spacer 16S-23S rDNA sequences analysis enabled the development of the mecF/mecR primers, specific for X cucurbitae and X melonis, both pathogenic to melon. The specificity of these primers was confirmed by amplification experiments using DNAs from bacteria belonging to different genera pathogenic to the same plant hosts. Sensitivity level of the PCR technique using the primers developed was 0,1 pg for rpoB/xcam, 0,01 ng for trans1F/trans2R and 1 pg for mecF/mecR / Doutorado / Genetica de Microorganismos / Doutor em Genetica e Biologia Molecular

In severe cases of ulcerative colitis (UC) unresponsive to current treatment options, patients require a complete proctocolectomy, or surgical removal of the colon. Ileal pouch anal anastomosis (IPAA) has become the preferred surgical technique for patients who require surgery, as this method restores rectal function. This procedure is also used to treat colorectal cancers such as adenocarcinoma and familial adenomatous polyposis (FAP). The surgery involves an abdominal colectomy with the construction of an ileal pouch created from folded tissue recovered from the ileal portion of the small intestine. Up to 50% of patients who require IPAA surgery experience an episode of pouchitis, a non-specific inflammation of the constructed ileal pouch with unknown etiology. Several hypotheses have been proposed regarding the pathogenesis of pouchitis. Current theories include bacterial overgrowth due to fecal stasis, microbial imbalance (dysbiosis), immune alteration, genetic susceptibility, metaplasia, ischemic complications of surgery, a recurrence of UC, or even a novel form of inflammatory bowel disease. The efficacy of antibiotics and probiotics in treating pouchitis and maintaining remission underscores the importance of gut microbiota in the development of this condition. In the study, we aimed to characterize the intestinal bacterial communities that inhabit IPAA pouches of both UC and FAP patients, in an effort to investigate the hypothesis that bacterial dysbiosis is involved in the pathogenesis of pouchitis. Mucosal biopsy and stool samples were analyzed from patients with UC and pouchitis (UCP), healthy UC controls (HUC) and healthy pouches with a background of FAP (FAP). Samples were examined through analysis of terminal restriction fragment length polymorphisms (TRF) and DNA sequencing. The data presented here demonstrate that a microbial imbalance exists in pouchitis, as bacterial communities in pouchitis differ significantly from healthy UC pouches and pouches constructed for FAP. Both methods identified potential groups of organisms that may play a role in the development of pouchitis, including decreases in protective Lactobacillus and Bacteroides and increases in mucin-degrading Clostridium and Akkermansia. A better understanding of the factors driving the pathogenesis of pouchitis will not only benefit patients with this disease, but also lead to a better understanding of the complex relationship that exists between the human host and the diverse community of organisms that inhabit the gastrointestinal tract.

No description available.

Terminal restriction fragment length polymorphism (T-RFLP) analysis and pyrosequencing were used to characterize the microbiota of the tonsil of the soft palate of 126 unfit and 18 healthy pigs. The T-RFLP analysis method was first optimized for the study of the pig tonsil microbiota and the data compared with culture-based identification of common pig pathogens. Putative identifications of the members of the microbiota revealed that the phyla Firmicutes, Proteobacteria and Bacteroidetes were the most prevalent. A comparison of the T-RFLP analysis results grouped into clusters to clinical conditions revealed paleness, abscess, PRRS virus, and Mycoplasma hyopneumoniae to be significantly associated with cluster membership. T-RFLP analysis was also used to select representative tonsil samples for pyrosequencing. These studies confirmed Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and Proteobacteria to be the core phyla of the microbiota of the tonsil of the soft palate of pigs. / OMAFRA Animal Health Strategic Investment

<p>BACKGROUND: Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder caused by mutations in the gene coding for microsomal triglyceride transfer protein (MTTP).</p><p>AIM: To characterize the genetic basis of ABL in two unrelated patients.</p><p>RESULTS: In the first patient, the substitution c.1911C>T in exon 12 of the <em>MTTP</em> gene, resulting in the protein substitution p.P552L, was discovered using mutation screening. The parents are heterozygous and the proband is a homozygous carrier of this substitution. Using restriction fragment length polymorphism (RFLP), 100 control subjects were analyzed and none carried the substitution indicating that it is a novel <em>MTTP </em>mutation. Sequencing of the other ABL patient showed that the proband carried a homozygous single base insertion, at position  c.2342IVS16+2-3insT, located at the donor splice-site of intron 16 resulting in skipping of exon 16 and truncation of the protein. The proband's mother is heterozygous for the insertion while the father does not carry the insertion. Multiplex ligation-dependent probe amplification (MLPA) did not identify any deletion encompassing exon 16 in the proband, father or mother. Nonpaternity was excluded using polymorphic markers from several chromosomes. Haplotype analysis using markers spanning chromosome 4 revealed  heterodisomy (two homologous chromosomes) of 4p and the distal part of 4q, and isodisomy (duplication of one chromosome) of 4q12-4q26.</p><p>CONCLUSION: These data show that the cause of ABL in one of the patients is a missense mutation, p.P552L, while the cause of ABL in the other patient is due to uniparental disomy, probably resulting from non-disjunstion in meiosis I.</p>

BACKGROUND: Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder caused by mutations in the gene coding for microsomal triglyceride transfer protein (MTTP). AIM: To characterize the genetic basis of ABL in two unrelated patients. RESULTS: In the first patient, the substitution c.1911C&gt;T in exon 12 of the MTTP gene, resulting in the protein substitution p.P552L, was discovered using mutation screening. The parents are heterozygous and the proband is a homozygous carrier of this substitution. Using restriction fragment length polymorphism (RFLP), 100 control subjects were analyzed and none carried the substitution indicating that it is a novel MTTP mutation. Sequencing of the other ABL patient showed that the proband carried a homozygous single base insertion, at position  c.2342IVS16+2-3insT, located at the donor splice-site of intron 16 resulting in skipping of exon 16 and truncation of the protein. The proband's mother is heterozygous for the insertion while the father does not carry the insertion. Multiplex ligation-dependent probe amplification (MLPA) did not identify any deletion encompassing exon 16 in the proband, father or mother. Nonpaternity was excluded using polymorphic markers from several chromosomes. Haplotype analysis using markers spanning chromosome 4 revealed  heterodisomy (two homologous chromosomes) of 4p and the distal part of 4q, and isodisomy (duplication of one chromosome) of 4q12-4q26. CONCLUSION: These data show that the cause of ABL in one of the patients is a missense mutation, p.P552L, while the cause of ABL in the other patient is due to uniparental disomy, probably resulting from non-disjunstion in meiosis I.

Os transportadores da família ABC são proteínas transmembrânicas envolvidas com o tráfego de substâncias endógenas e exógenas do meio intracelular para o extracelular, sendo alvos de estudo na resistência celular a agentes quimioterápicos. O ABCC2 é um transportador transmembrânico que exporta ativamente fármacos aniônicos conjugados e facilita o transporte de agentes anticâncer. O ABCG2 é outro transportador transmembrânico que tem influência na farmacocinética e farmacodinâmica de certos xenobióticos e substratos endógenos; além disso, acredita-se que este gene contribui para a resistência a várias drogas. Por esses motivos identificamos por sequenciamento ou PCR-RFLP os polimorfismos dos genes ABCC2 (Val417Ile, Ser789Phe e Ala1450Thr) e ABCG2 (Val12Met, Gly126stop códon, Gly141Lys) em 90 pacientes portadores de carcinoma epidermóide de cabeça e pescoço (HNSCC) e tentamos correlacionar a presença do polimorfismo com resposta a tratamento que incluiu cisplatina em todos os pacientes. Não encontramos nenhuma correlação entre a presença de polimorfismo para Val12Met, Gly141Lys e Val417Ile, determinados em 68 pacientes tratados exclusivamente com cisplatina e radioterapia, e a resposta ao tratamento. As curvas de sobrevida, determinadas por Kaplan-Meier, considerando polimórfico os pacientes que continham pelo menos um dos alelos alterados e selvagem os que não tivessem nenhum deles, mostraram que os pacientes selvagens para o polimorfismo Val12Met tiveram tendência a uma pior sobrevida (sobrevida mediana de 18,7 meses) em relação aos pacientes polimórficos (sobrevida mediana não atingida; P=0,089 Teste de log-rank), já os pacientes selvagens para o polimorfismo Gly141Lys tiveram tendência a uma pior sobrevida (sobrevida mediana de 15,8 meses) em relação aos pacientes polimórficos (sobrevida mediana de 25,6 meses; P = 0,16 Teste de logrank). Não observamos correlação entre os outros polimorfismos e sobrevida. Quanto ao GLY126stop, somente um paciente foi identificado como polimórfico. Conclusões: No nosso estudo, a freqüência do polimorfismo Val12Met de 10% está próxima dos 18% descrito na população normal (Kobayashi 2004). Nosso trabalho foi o primeiro a correlacionar estes polimorfismos com resposta ao tratamento em pacientes com carcinoma epidermóide de cabeça e pescoço e indica que Val12Met e Gly141Lys e o gene ABCG2 como um todo são candidatos a um estudo maior / ATP binding cassette (ABC) transporters form one of the largest transmembrane protein families. These proteins use cellular ATP to drive the transport of various substrates across cell membranes including many exogenous and endogenous compounds, which includes drugs used in cancer treatment. ABCC2 is an ATP binding cassette transporter which accepts a diverse range of substrates, including glutathione, glucuronide, and sulfate conjugates of many metabolites and xenobiotics. ABCG2 is a member of the ATP binding cassette (ABC) transporters whose function is to pump out of the cell a wide variety of endogenous and exogenous compounds. Widely expressed in stem cells, ABCG2 is also recognized as a universal marker of stem cells. For these reasons we had identified the following polymorphisms of ABCC2 gene: -Val417Ile, Ser789Phe and Ala1450Thr- and of ABCG2 gene as well: -Val12Met, Gly126stop códon, Gly141Lys in 88 patients with head and neck squamous cell carcinoma (HNSCC). Methodology included PCR - RFLP and direct sequencing. Survival analysis was done using Kaplan-Meier curves and response measured by RECIST criteria. Comparisons were done between polymorphic patients in which at least one polymorphism was present as opposed to the patients without the polymorphism. Correlation with response to treatment was studied for Val12Met, Gly141Lys e Val417Il in 68 patients exclusively treated with concomitant cisplatin and radiotherapy and no correlation was found between these markers and treatment response. Patients without the Val12Met presented a trend towards shorter survival (median survival 18.7 months) as compared to polymorphic patients (median survival not reached, long rank p= 0.089). Although statistical significance was not reached, patients wild type for Gly141Lys polymorphism (median survival 15.8 months) had shorter survival than polymorphic patients (25.6 months, p=0.16). We did not observe any other correlation between other polymorphisms and survival. With respect to Gly126stop, only one patient was identified as polymorphic and survival analysis was not possible. As far as we know this is the first study to try to correlate these polymorphisms with treatment response and survival in HNSCC patients. Although we were unable to draw any definitive conclusions, our results indicate that Val12Met and Gly141Lys deserve to be further studied in the future.

Os transportadores da família ABC são proteínas transmembrânicas envolvidas com o tráfego de substâncias endógenas e exógenas do meio intracelular para o extracelular, sendo alvos de estudo na resistência celular a agentes quimioterápicos. O ABCC2 é um transportador transmembrânico que exporta ativamente fármacos aniônicos conjugados e facilita o transporte de agentes anticâncer. O ABCG2 é outro transportador transmembrânico que tem influência na farmacocinética e farmacodinâmica de certos xenobióticos e substratos endógenos; além disso, acredita-se que este gene contribui para a resistência a várias drogas. Por esses motivos identificamos por sequenciamento ou PCR-RFLP os polimorfismos dos genes ABCC2 (Val417Ile, Ser789Phe e Ala1450Thr) e ABCG2 (Val12Met, Gly126stop códon, Gly141Lys) em 90 pacientes portadores de carcinoma epidermóide de cabeça e pescoço (HNSCC) e tentamos correlacionar a presença do polimorfismo com resposta a tratamento que incluiu cisplatina em todos os pacientes. Não encontramos nenhuma correlação entre a presença de polimorfismo para Val12Met, Gly141Lys e Val417Ile, determinados em 68 pacientes tratados exclusivamente com cisplatina e radioterapia, e a resposta ao tratamento. As curvas de sobrevida, determinadas por Kaplan-Meier, considerando polimórfico os pacientes que continham pelo menos um dos alelos alterados e selvagem os que não tivessem nenhum deles, mostraram que os pacientes selvagens para o polimorfismo Val12Met tiveram tendência a uma pior sobrevida (sobrevida mediana de 18,7 meses) em relação aos pacientes polimórficos (sobrevida mediana não atingida; P=0,089 Teste de log-rank), já os pacientes selvagens para o polimorfismo Gly141Lys tiveram tendência a uma pior sobrevida (sobrevida mediana de 15,8 meses) em relação aos pacientes polimórficos (sobrevida mediana de 25,6 meses; P = 0,16 Teste de logrank). Não observamos correlação entre os outros polimorfismos e sobrevida. Quanto ao GLY126stop, somente um paciente foi identificado como polimórfico. Conclusões: No nosso estudo, a freqüência do polimorfismo Val12Met de 10% está próxima dos 18% descrito na população normal (Kobayashi 2004). Nosso trabalho foi o primeiro a correlacionar estes polimorfismos com resposta ao tratamento em pacientes com carcinoma epidermóide de cabeça e pescoço e indica que Val12Met e Gly141Lys e o gene ABCG2 como um todo são candidatos a um estudo maior / ATP binding cassette (ABC) transporters form one of the largest transmembrane protein families. These proteins use cellular ATP to drive the transport of various substrates across cell membranes including many exogenous and endogenous compounds, which includes drugs used in cancer treatment. ABCC2 is an ATP binding cassette transporter which accepts a diverse range of substrates, including glutathione, glucuronide, and sulfate conjugates of many metabolites and xenobiotics. ABCG2 is a member of the ATP binding cassette (ABC) transporters whose function is to pump out of the cell a wide variety of endogenous and exogenous compounds. Widely expressed in stem cells, ABCG2 is also recognized as a universal marker of stem cells. For these reasons we had identified the following polymorphisms of ABCC2 gene: -Val417Ile, Ser789Phe and Ala1450Thr- and of ABCG2 gene as well: -Val12Met, Gly126stop códon, Gly141Lys in 88 patients with head and neck squamous cell carcinoma (HNSCC). Methodology included PCR - RFLP and direct sequencing. Survival analysis was done using Kaplan-Meier curves and response measured by RECIST criteria. Comparisons were done between polymorphic patients in which at least one polymorphism was present as opposed to the patients without the polymorphism. Correlation with response to treatment was studied for Val12Met, Gly141Lys e Val417Il in 68 patients exclusively treated with concomitant cisplatin and radiotherapy and no correlation was found between these markers and treatment response. Patients without the Val12Met presented a trend towards shorter survival (median survival 18.7 months) as compared to polymorphic patients (median survival not reached, long rank p= 0.089). Although statistical significance was not reached, patients wild type for Gly141Lys polymorphism (median survival 15.8 months) had shorter survival than polymorphic patients (25.6 months, p=0.16). We did not observe any other correlation between other polymorphisms and survival. With respect to Gly126stop, only one patient was identified as polymorphic and survival analysis was not possible. As far as we know this is the first study to try to correlate these polymorphisms with treatment response and survival in HNSCC patients. Although we were unable to draw any definitive conclusions, our results indicate that Val12Met and Gly141Lys deserve to be further studied in the future.

Orientador: Suzete Aparecida Lanza Destéfano / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T18:58:40Z (GMT). No. of bitstreams: 1 Correa_DanieleBussioliAlves_M.pdf: 2704976 bytes, checksum: 40df9160618a30b2959f8df5ff93e585 (MD5) Previous issue date: 2011 / Resumo: A batata ocupa o quarto lugar em volume de produção mundial de alimentos após o arroz, trigo e milho. O Brasil é o maior produtor dentre os países da América Latina, porém ainda apresenta baixa produtividade devida às doenças que afetam a cultura. Dentre as doenças bacterianas, a sarna da batata é uma das mais importantes economicamente e sua ocorrência é generalizada no mundo. Diferentes espécies do gênero Streptomyces estão associadas à essa doença e os principais sintomas se caracterizam por lesões irregulares que podem tomar toda a superfície do tubérculo, acarretando diminuição do seu valor comercial ou, até mesmo, impedindo a sua comercialização. Atualmente, a incidência da sarna está aumentando consideravelmente, tornando-se um fator limitante do cultivo de batata no Brasil. O presente trabalho teve por objetivo a identificação de linhagens de Streptomyces sp. associadas à sarna da batata, provenientes de diferentes regiões produtoras do Brasil, por meio de taxonomia polifásica. Cento e noventa linhagens de Streptomyces foram analisadas, sendo 165 nacionais obtidas dos estados da Bahia, Goiás, Minas Gerais, Paraná, São Paulo, Rio Grande do Sul e Santa Catarina; 13 de material vegetal importado do Chile, França e Holanda; e 12 linhagens Tipo de Streptomyces representantes de espécies associadas à sarna. Na caracterização morfológica as linhagens apresentaram heterogeneidade com relação à micromorfologia de hifas e coloração dos esporos. A patogenicidade das linhagens foi avaliada pela presença dos genes nec1, tomA (tomatinase) e txtAB (taxtomina A) e os resultados indicaram que 94 linhagens (52,8%) apresentaram amplificação dos três genes de patogenicidade avaliados, 14 (7,9%) não apresentaram nenhum dos genes e 70 (39,3%) mostraram sinal positivo de amplificação para um ou mais genes. Para algumas linhagens a confirmação da patogenicidade foi efetuada por meio de testes em minitubérculos de batata. Nos testes moleculares, incluindo amplificação com primers específicos para S. scabiei e S. turgidiscabies, PCR-RFLP do gene atpD e análises das seqüências dos genes atpD, gyrB, recA, rpoB e trpB, foi possível a separação das linhagens analisadas em diferentes perfis genéticos. As análises das características morfológicas, patogênicas e moleculares permitiram a identificação de 57 linhagens pertencentes à S. scabiei, 28 à espécie S. ipomoeae, 13 à S. caviscabies/S. setonii, 12 à S. europaeiscabiei e duas à S. sampsonii. As 66 linhagens restantes apresentaram características distintas das espécies Tipo testadas, podendo representar possíveis novas espécies de Streptomyces associadas à sarna no Brasil / Abstract: Potato is the world's fourth most important food crop after rice, wheat and maize. Brazil is the biggest producer among the countries of Latin America, but it still has low productivity due to diseases that affect the crop. Among the bacterial diseases, the potato scab is one of the most economically important, and its occurrence is widespread in the world. Different species of the genus Streptomyces are associated with this disease and the main symptoms are characterized by irregular lesions that can affect all the tuber surface causing decrease of its commercial value or preventing its commercialization. Currently, the incidence of potato scab is increasing considerably, becoming a limiting factor in potato production in Brazil. This study aimed to identify Streptomyces strains associated with potato scab, from different potato growing areas in Brazil, through polyphasic taxonomy. One hundred and ninety strains of Streptomyces were analyzed, including 165 Brazilian strains obtained from potatoes coming from the states of Bahia, Goias, Minas Gerais, Parana, Sao Paulo, Rio Grande do Sul and Santa Catarina; 13 of plant material from Chile, France and Netherlands; and 12 type strains of Streptomyces species associated with potato scab. In the morphological characterization, the strains showed heterogeneity in the hyphal micromorphology and color of spores. The pathogenicity of strains was investigated by presence of the nec1 and tomA genes, and txtAB operon (thaxtomin A). The results indicated that 94 strains (52.8%) showed amplification of the three pathogenicity genes, 14 (7.9%) showed no amplification of the genes and 70 (39.3%) showed positive signal for only one or more genes. The pathogenicity of some strains was confirmed with artificial inoculation onto potato minitubers. In the molecular tests, including PCR amplification with specific primers for S.scabiei and S. turgidiscabies, analysis of PCR-RFLP of atpD gene and sequences analysis of the atpD, gyrB, recA, rpoB and trpB genes, the strains could be separated into different genetic profiles. The morphological, pathogenic and molecular data allowed identifying of 57 strains belonging to S. scabiei, 28 to S. ipomoeae, 13 to S. caviscabies/S. setonii, 12 to S. europaeiscabiei and two to S. sampsonii. The 66 remaining strains showed different genetic profiles in comparison with the type strains of Streptomyces, and may represent new species of Streptomyces associated with potato scab in Brazil / Mestrado / Genetica de Microorganismos / Mestre em Genética e Biologia Molecular

La symbiose mycorhizienne à arbuscules, dont l’apparition est conjointe à celle des plantes terrestres il y a 460 millions d’années, est une association mutualiste à bénéfices réciproques qui s’instaure entre la plupart des plantes terrestres, y compris celles cultivées, et des microorganismes ubiquitaires du sol que sont les champignons mycorhiziens à arbuscules (CMA, phylum des Glomeromycota). Lors cette symbiose, le fort potentiel d’amélioration de la nutrition minérale des plantes, et donc de la production végétale, est un atout dans le contexte mondial actuel d’augmentation de la demande de la production agricole. Afin d’optimiser les services écosystémiques des CMA dans les écosystèmes et en particulier les agroécosystèmes, la maîtrise de cette symbiose en ingénierie écologique nécessite la compréhension des mécanismes complexes qui régissent la dynamique de cette symbiose dans ces écosystèmes. Pour cela, nous avons étudié la diversité des communautés et des populations de CMA dans les agroécosystèmes à différentes échelles spatiales et sous l’influence de différentes pratiques culturales par des techniques d’empreintes moléculaires: séquençage haut-débit et polymorphisme de longueur de fragments de restriction. Les résultats obtenus montrent que la structuration de la diversité des CMA est influencée par le type d’usage de sol (prairie vs. culture), les pratiques culturales (retournement du sol, fertilisation et système de culture) ainsi que par les facteurs abiotiques (e.g. pH du sol). En conclusion, ces différents facteurs sont à prendre en compte dans l’optimisation des services écosystémiques des CMA. / The arbuscular mycorrhizal symbiosis, which appeared at the same time as land plants, 460 million years ago, is a mutualistic beneficial association between most land plants, including those cultivated, and arbuscular mycorrhizal fungi (AMF). AMF, from the Glomeromycota phylum, are widespread soil microorganisms needing a photosynthetic host to complete their life cycle (obligate symbionts). The great potential of plant mineral nutrition improvement and crop production increased during this symbiosis, make AMF an asset in the context of an increase in the demand of world food crop production. The control of that symbiosis by ecology engineering in order to improve ecosystem services, especially in agroecosystems, needs to better understand the mechanisms regulating its dynamic. Therefore, we studied community and population diversity of AMF under influences of different agricultural practices at several spatial scales using genetic fingerprinting methods: high-throughput sequencing and restriction fragment length polymorphism. Results show that AMF diversity is structured by land use type (grassland vs. arable fields), cultural practices (soil disturbance, fertilizations, culturing systems) as well as environmental factors (e.g. soil pH). In conclusion, those different factors have to taken in account in AMF ecosystemic service managing.