Early diagnosis of endometrial cancer (EC) is uncertain and women undergo preventive hysterectomy in cases where a non-invasive treatment can be used instead. To contribute to solving this challenge we investigated if early changes in the nuclear 3D telomere architecture during carcinoma development can be detected prior to the first morphological evidence of precancerous lesions. We utilized Pten heterozygous mice that develop progressive carcinoma in the endometrial tissue similar to EC development in women. We used telomere fluorescence in situ hybridization (FISH), 3D molecular imaging and analysis techniques on interphase nuclei of endometrial glandular epithelial cells to identify alterations in the 3D-telomere profile. We found that telomere dysfunction in Pten heterozygous mice is present already in endometrial simple hyperplasia lesions prior to detectable loss of PTEN protein expression and that the 3D telomere architecture has a specific signature that indicates early telomere dysfunction predictive for endometrial malignant transformation.

Early diagnosis of endometrial cancer (EC) is uncertain and women undergo preventive hysterectomy in cases where a non-invasive treatment can be used instead. To contribute to solving this challenge we investigated if early changes in the nuclear 3D telomere architecture during carcinoma development can be detected prior to the first morphological evidence of precancerous lesions. We utilized Pten heterozygous mice that develop progressive carcinoma in the endometrial tissue similar to EC development in women. We used telomere fluorescence in situ hybridization (FISH), 3D molecular imaging and analysis techniques on interphase nuclei of endometrial glandular epithelial cells to identify alterations in the 3D-telomere profile. We found that telomere dysfunction in Pten heterozygous mice is present already in endometrial simple hyperplasia lesions prior to detectable loss of PTEN protein expression and that the 3D telomere architecture has a specific signature that indicates early telomere dysfunction predictive for endometrial malignant transformation.

Ovarian cancer (OCa) remains the leading cause of death due to a gynecologic malignancy in North American women, and the pathogenesis of this disease is a consequence of the interplay between DNA, RNA and proteins. The genomes of these cancers are characterized by numerical and structural aberrations, resulting in copy number changes of the affected regions. The serine protease, Kallikrein 6 (KLK6), is a promising biomarker and is over-expressed in OCa. However, the mechanisms leading to the observed KLK6 overexpression are poorly understood; and to date, no study examining the chromosomal contributions to the overexpression have been conducted. Utilization of multi-colour Fluorescence in situ Hybridization (FISH)-based technologies to untreated primary serous OCa samples and cancer cell lines, showed that the KLK locus, on 19q13.3/4, is involved in both numerical and structural aberrations; was subject to high-level copy-number heterogeneity (p<0.001); and structural rearrangements of 19q were significantly co-related to grade (p<0.001). Patients with a loss of the KLK locus, or no structural rearrangement on 19q, experienced a trend towards longer disease free survival (DFS and better overall survival (OS), over those with a gain or amplification, or with breakage events on 19q. KLK6-specific immunohistochemistry (IHC) showed weak correlation with KLK6 copy-number, suggesting other mechanisms together with copy-number, drives its over-expression. Among these mechanisms are microRNA (miRNAs), also shown to be affected by the copynumber changes in OCas. Therefore, we investigated the role of miRNAs in OCa and their role in KLK6 regulation. Specifically, we examined the copy-number status and miRNA expression in a representative OCa cell line, OVCAR-3. miRNA expression profiling of OCa cell lines and primary tumours showed their differential expression, including the decrease in expression of the let-7 family members, which are predicted to target KLK6. Indeed, when hsa-let-7a was transiently transfected into OVCAR-3, a reduction of secreted KLK6 protein was detected. Thus, the contribution of numerical and structural aberrations of the OCa genome can directly affect the expression KLK6 through copy-number, but is also aided post-transcriptionally by miRNAs.

Ovarian cancer (OCa) remains the leading cause of death due to a gynecologic malignancy in North American women, and the pathogenesis of this disease is a consequence of the interplay between DNA, RNA and proteins. The genomes of these cancers are characterized by numerical and structural aberrations, resulting in copy number changes of the affected regions. The serine protease, Kallikrein 6 (KLK6), is a promising biomarker and is over-expressed in OCa. However, the mechanisms leading to the observed KLK6 overexpression are poorly understood; and to date, no study examining the chromosomal contributions to the overexpression have been conducted. Utilization of multi-colour Fluorescence in situ Hybridization (FISH)-based technologies to untreated primary serous OCa samples and cancer cell lines, showed that the KLK locus, on 19q13.3/4, is involved in both numerical and structural aberrations; was subject to high-level copy-number heterogeneity (p<0.001); and structural rearrangements of 19q were significantly co-related to grade (p<0.001). Patients with a loss of the KLK locus, or no structural rearrangement on 19q, experienced a trend towards longer disease free survival (DFS and better overall survival (OS), over those with a gain or amplification, or with breakage events on 19q. KLK6-specific immunohistochemistry (IHC) showed weak correlation with KLK6 copy-number, suggesting other mechanisms together with copy-number, drives its over-expression. Among these mechanisms are microRNA (miRNAs), also shown to be affected by the copynumber changes in OCas. Therefore, we investigated the role of miRNAs in OCa and their role in KLK6 regulation. Specifically, we examined the copy-number status and miRNA expression in a representative OCa cell line, OVCAR-3. miRNA expression profiling of OCa cell lines and primary tumours showed their differential expression, including the decrease in expression of the let-7 family members, which are predicted to target KLK6. Indeed, when hsa-let-7a was transiently transfected into OVCAR-3, a reduction of secreted KLK6 protein was detected. Thus, the contribution of numerical and structural aberrations of the OCa genome can directly affect the expression KLK6 through copy-number, but is also aided post-transcriptionally by miRNAs.

Made available in DSpace on 2014-06-11T19:26:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-02-24Bitstream added on 2014-06-13T18:29:26Z : No. of bitstreams: 1 faria_kc_me_sjrp.pdf: 1587104 bytes, checksum: 5b515af867e10b2a892710a2b48a4662 (MD5) / Para verificar a ocorrência de homologias cromossômicas entre espécies de Molossidae e Phyllostomidae (Chiroptera), foram realizadas análises comparativas do bandamento G e, hibridização in situ fluorescente genômica e telomérica nas espécies Carollia perspicillata (Carolliinae), Glossophaga soricina (Glossophaginae), P. hastatus (Phyllostominae), Sturnira lilium, Platyrrhinus lineatus e Artibeus planirostris (Stenodermatinae) de Phyllostomidae e, Molossus ater e Molossus molossus (Molossinae) de Molossidae. As análises do bandamento G evidenciaram que, à exceção de C. perspicillata, todas as demais espécies de Phyllostomidae compartilham homologias cromossômicas com as espécies de Molossidae. As espécies A. planirostris, P. lineatus e S. lilium apresentam 29 dos 32 braços cromossômicos de Molossus. Estas espécies compartilham dois cromossomos inteiros e os braços de oito cromossomos meta ou submetacêntricos destas espécies de Stenodermatinae apresentam homologias com cromossomos acrocêntricos e subtelocêntricos de Molossus. G. soricina também apresenta 29 braços cromossômicos de Molossus, sendo que três cromossomos inteiros são compartilhados e os braços de sete cromossomos de G. soricina apresentam homologias com cromossomos acrocêntricos e subtelocêntricos de Molossus. Todos os braços cromossômicos de P. hastatus apresentaram homologias com os cromossomos de Molossus. P. hastatus e Molossus compartilham cinco cromossomos inteiros e os braços de oito cromossomos de P. hastatus apresentam homologias com os cromossomos acrocêntricos e subtelocêntricos de Molossus. Estes resultados parecem sugerir uma proximidade maior das espécies de Molossidae com P. hastatus (Phyllostominae). Além de rearranjos do tipo fusões e inversões pericêntricas, outros rearranjos cromossômicos não determinados justificam as diferenças entre os cariótipos das espécies de... / To verify the occurrence of chromosome homologies between species of Molossidae and Phyllostomidae (Chiroptera), comparative analysis of the G-banding and, genomic and telomeric fluorescence in situ hibridization were accomplished in the species Carollia perspicillata (Carolliinae), Glossophaga soricina (Glossophaginae), Phyllostomus hastatus (Phyllostominae), Sturnira lilium, Platyrrhinus lineatus and Artibeus planirostris (Stenodermatinae) of Phyllostomidae and, Molossus ater and Molossus molossus (Molossinae) of Molossidae. The analysis of the G-banding evidenced that except C. perspicillata all the other species of Phyllostomidae share chromosome homologies with the species of Molossidae. The species A. planirostris, P. lineatus and S. lilium present 29 of the 32 chromosome arms of Molossus. These species share two whole chromosomes and the arms of eight meta or submetacentric chromosomes of these species of Stenodermatinae present homologies with acrocentric and subtelocentric chromosomes of Molossus. G. soricina also presents 29 chromosome arms of Molossus, in a way that three whole chromosomes are shared and the arms of seven chromosomes of G. soricina present homologies with acrocentric and subtelocentric chromosomes of Molossus. All of the chromosome arms of P. hastatus presented homologies with the chromosomes of Molossus. P. hastatus and Molossus share five whole chromosomes and the arms of eight chromosomes of P. hastatus present homologies with the acrocentrics and subtelocentrics chromosomes of Molossus. These results seem to suggest a larger proximity of the species of Molossidae with P. hastatus (Phyllostominae). Besides rearrangements like fusions and pericentric inversions, other not determined chomosome rearrangements justify the differences between the karyotype of the compared species of Phyllostomidae and Molossidae. The comparative genomic hybridizations with Molossus...(Complete abstract click electronic access below)

Orientador: Eliana Morielle Versute / Banca: Shirley Maria Recco Pimentel / Banca: Guaracy Tadeu Rocha / Resumo: Para verificar a ocorrência de homologias cromossômicas entre espécies de Molossidae e Phyllostomidae (Chiroptera), foram realizadas análises comparativas do bandamento G e, hibridização in situ fluorescente genômica e telomérica nas espécies Carollia perspicillata (Carolliinae), Glossophaga soricina (Glossophaginae), P. hastatus (Phyllostominae), Sturnira lilium, Platyrrhinus lineatus e Artibeus planirostris (Stenodermatinae) de Phyllostomidae e, Molossus ater e Molossus molossus (Molossinae) de Molossidae. As análises do bandamento G evidenciaram que, à exceção de C. perspicillata, todas as demais espécies de Phyllostomidae compartilham homologias cromossômicas com as espécies de Molossidae. As espécies A. planirostris, P. lineatus e S. lilium apresentam 29 dos 32 braços cromossômicos de Molossus. Estas espécies compartilham dois cromossomos inteiros e os braços de oito cromossomos meta ou submetacêntricos destas espécies de Stenodermatinae apresentam homologias com cromossomos acrocêntricos e subtelocêntricos de Molossus. G. soricina também apresenta 29 braços cromossômicos de Molossus, sendo que três cromossomos inteiros são compartilhados e os braços de sete cromossomos de G. soricina apresentam homologias com cromossomos acrocêntricos e subtelocêntricos de Molossus. Todos os braços cromossômicos de P. hastatus apresentaram homologias com os cromossomos de Molossus. P. hastatus e Molossus compartilham cinco cromossomos inteiros e os braços de oito cromossomos de P. hastatus apresentam homologias com os cromossomos acrocêntricos e subtelocêntricos de Molossus. Estes resultados parecem sugerir uma proximidade maior das espécies de Molossidae com P. hastatus (Phyllostominae). Além de rearranjos do tipo fusões e inversões pericêntricas, outros rearranjos cromossômicos não determinados justificam as diferenças entre os cariótipos das espécies de...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: To verify the occurrence of chromosome homologies between species of Molossidae and Phyllostomidae (Chiroptera), comparative analysis of the G-banding and, genomic and telomeric fluorescence in situ hibridization were accomplished in the species Carollia perspicillata (Carolliinae), Glossophaga soricina (Glossophaginae), Phyllostomus hastatus (Phyllostominae), Sturnira lilium, Platyrrhinus lineatus and Artibeus planirostris (Stenodermatinae) of Phyllostomidae and, Molossus ater and Molossus molossus (Molossinae) of Molossidae. The analysis of the G-banding evidenced that except C. perspicillata all the other species of Phyllostomidae share chromosome homologies with the species of Molossidae. The species A. planirostris, P. lineatus and S. lilium present 29 of the 32 chromosome arms of Molossus. These species share two whole chromosomes and the arms of eight meta or submetacentric chromosomes of these species of Stenodermatinae present homologies with acrocentric and subtelocentric chromosomes of Molossus. G. soricina also presents 29 chromosome arms of Molossus, in a way that three whole chromosomes are shared and the arms of seven chromosomes of G. soricina present homologies with acrocentric and subtelocentric chromosomes of Molossus. All of the chromosome arms of P. hastatus presented homologies with the chromosomes of Molossus. P. hastatus and Molossus share five whole chromosomes and the arms of eight chromosomes of P. hastatus present homologies with the acrocentrics and subtelocentrics chromosomes of Molossus. These results seem to suggest a larger proximity of the species of Molossidae with P. hastatus (Phyllostominae). Besides rearrangements like fusions and pericentric inversions, other not determined chomosome rearrangements justify the differences between the karyotype of the compared species of Phyllostomidae and Molossidae. The comparative genomic hybridizations with Molossus...(Complete abstract click electronic access below) / Mestre

Orientadores: Shirlei Maria Recco-Pimentel, Luciana Bolsoni Lourenço Morandini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-16T17:27:31Z (GMT). No. of bitstreams: 1 Vittorazzi_StenioEder_M.pdf: 1698813 bytes, checksum: 820a78de37442254ed35e58e413de026 (MD5) Previous issue date: 2010 / Resumo: O gênero Physalaemus é atualmente constituído de 42 espécies, distribuídas em sete grupos. No grupo de Physalaemus cuvieri, além dessa, estão alocadas outras oito espécies. Estudos citogenéticos disponíveis até momento para algumas espécies do gênero nos mostram um número diplóide de 2n = 22, sendo a morfologia cromossômica similar entre elas. O objetivo desse trabalho foi desenvolver novos marcadores citogenéticos para o estudo do grupo de Physalaemus cuvieri. Foram estudadas três populações de P. cuvieri e duas outras espécies do grupo, P. albonotatus e P. centralis. Foram isoladas três sequências de DNA repetitivo, as quais foram denominadas PcP190EcoRI, PcP883EcoRI e PcP174PstI. A primeira sequência apresentou similaridade com os DNAr 5S disponíveis no GenBank e assim, adicionalmente, foi feito experimento para isolar o DNAr 5S de P. cuvieri. Foram obtidos dois fragmentos com cerca 201 e 690pb, localizados por double- FISH em cromossomos distintos. A sequência PcP190EcoRI mostrou similaridade de aproximadamente 70% com a região de transcrição de ambos os tipos de DNAr 5S, sugerindo a origem dessa sequência a partir do DNAr 5S. A hibridação in situ com sondas das três sequências de DNA repetitivo isoladas, nas três populações de P. cuvieri, em P. albonotatus e em P. centralis, mostrou que todas as regiões cromossômicas marcadas são coincidentes com regiões de banda C detectadas em estudo prévio. No entanto, as populações de P. cuvieri e as espécies estudadas diferem entre si pelo número e localização de marcações com sondas das três sequências. Essas sequências representam bons marcadores cromossômicos, já que permitiram demonstrar tanto variações interpopulacionais em P. cuvieri como também diferenças interespecíficas, corroborando a sugestão prévia de que as diferentes populações de P. cuvieri podem se tratar de um complexo de espécies crípticas. / Abstract: The genus Physalaemus is currently composed of 42 species, divided into seven groups. Within the Physalaemus cuvieri group are eight other species. Cytogenetic studies for some of the species within the genus show a diploid number of 2n = 22 and similar chromosome morphology. The aim of this research was to develop new cytogenetic markers to study the group of Physalaemus cuvieri. We studied three populations of P. cuvieri in addtion to two other species: P. albonotatus and P. centralis. We isolated three repetitive DNA sequences, which were named PcP190EcoRI, PcP883EcoRI and PcP174PstI. The former sequence showed similarities with the 5S rDNA available in GenBank and, therefore, an experiment was done to isolate the 5S rDNA of P. cuvieri. We obtained two fragments of about 201 bp and 690 bp, which were localized by double-FISH to distinct chromosomes. The PcP190EcoRI sequence showed approximately 70% similarity with the transcription regions of both types of 5S rDNA, suggesting the PcP190EcoRI sequence originated from the 5S rDNA. The three repetitive DNA sequences were detected by in situ hybridization to chromosomes from P. albonotatus, P. centralis and the three populations of P. cuvieri. These chromosome regions are coincident with C-bands detected in a previous study. Populations of P. cuvieri and others two species, however, differ by the number and location of the three sequences. These sequences seem to be good chromosomes markers since they were used to show interpopulational variation in P. cuvieri, as well interspecific differences. This supports the previous suggestion that different populations of P. cuvieri may be a complex of cryptic species. / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural

The genus Chenopodium contains many economically important species in the New World, but is relatively understudied and poorly understood, especially in terms of evolutionary relationships. A better understanding of the structure of this genus could significantly help in breeding efforts on its cultivated members, notably the tetraploid C. quinoa and also certain varieties of C. berlandieri, also tetraploid. Of special concern is determining which diploid weed species are the most likely ancestors for C. quinoa, C. berlandieri, and the other tetraploid members of subsection Cellulata. The phylogeny can be understood in part by examining the ribosomal RNA loci and observing how many copies of the 5S and 45S loci each New World species contains. In this work, the 5S and 45S ribosomal RNA loci are characterized by means of fluorescence in situ hybridization in 23 Chenopodium species collected in the New World, with the 5S locus labeled red and the 45S locus labeled green. Based on these results, the pool of most likely candidate ancestor species for C. quinoa and C. berlandieri includes C. fremontii, C. incanum, C. neomexicanum, and C. watsonii.

Abstract : Current prenatal diagnosis depends on invasive procedures and is thus offered only to high-risk pregnancies. Development of non-invasive prenatal diagnosis (NIPD) would change the risk-benefit ratio and make it likely that more women would benefit from prenatal testing. Scientists have documented the presence of rare fetal cells in maternal blood and envisioned targeting them with specific markers and their use in NIPD. Considering their extremely low frequency in maternal blood, fetal cells have been difficult to retrieve and use in clinical practice. Therefore, there is a pressing need for systematic sequential studies to evaluate their feasibility in NIPD. Generally, detection of rare cells within a large cell population carries great potentialities for the prospects of cancer management and NIPD. Manual scanning is very cumbersome and time-consuming Therefore; the first part of our project was, dedicated to the optimization of an effective strategy to evaluate retrieval of rare cells. We have developed a way of distributing a controlled number of target cells among hundreds of thousands of other cells on microscope slides. This strategy allows the precise evaluation of the retrieval of rare events and the comparizon of the efficacy of different techniques and enrichment approaches by knowing the definite number and locations of target cells on the slides. Furthermore, it allows the evaluation of hybridization of missed events. We have also developed a robust custom-made detection algorithm for rare cells using the MetaSystems automated platform and have used this strategy in the validation of manual and automatic scanning of 60 slides with a pre-defined number of rare male cells among a pure population of female cells using XY-FISH. Consequently, we tested the developed classifier for the detection of real fetal cells from maternal blood in both normal and aneuploid pregnancies with Down syndrome. We further evaluated the number of fetal cells with different methods of enrichments in the first and second trimesters. The data collected confirmed the early presence of fetal cells in all of the pregnancies tested and their frequencies were higher in cases of aneuploidies. Fetal cells are in a state of dynamic change throughout the pregnancy. Higher numbers of these cells can be obtained by optimizing the harvest time and methods of enrichment. We found that automatic scanning is more sensitive and reliable than manual detection. Furthermore, it alleviates the burden of scanning large numbers of cells and thus is more suitable for clinical application. We also demonstrated the feasibility of using rare cells in NIPD. Five microdissected amniotic fetal cells from 26 cases of normal and aneuploid pregnancies were quite enough to provide accurate NIPD through using whole genome amplification coupled with QF-PCR. Our findings laid the ground for the use of rare fetal cells in maternal blood for NIPD. // Résumé : Le diagnostic prénatal résulte encore aujourd’hui de procédures invasives, qui présentent des risques pour la grossesse. Le développement du diagnostic prénatal non-invasif (DPNI) changerait le rapport risque : bénéfice, rendant le diagnostic prénatal plus intéressant pour les femmes enceintes. Plusieurs chercheurs ont montré la présence de cellules fœtales dans le sang maternel et des travaux ont été entrepris afin de les cibler et de les utiliser éventuellement en DPNI. Toutefois, la faible concentration des cellules fœtales dans le sang maternel réduit les possibilités d’isolement ainsi que celles de leur utilisation en clinique. Un autre aspect technique du DPNI, le balayage manuel, est très laborieux, surtout en terme de temps technique. Il y a donc un besoin certain pour des études approfondies afin d’évaluer et d’améliorer la faisabilité du DPNI. La détection d’évènements rares dans une grande population cellulaire offre un potentiel pour le diagnostic en oncologie mais aussi en diagnostic prénatal. Dans cette thèse, la première étude était dédiée à l’optimisation d’une stratégie pour détecter les cellules rares. Nous avons développé une méthode d’étalement sur lame d’un nombre précis de cellules cibles parmi des centaines de milliers de cellules. Cette stratégie a permis d’évaluer le taux de détection d’évènements rares et de comparer l’efficacité des techniques d’enrichissement en connaissant le nombre exact et la localisation de cellules cibles sur les lames. De plus, il a été possible d’évaluer les problèmes d’hybridation des évènements manqués. Nous avons, par la suite, développé un algorithme robuste pour la détection de cellules rares en utilisant la plateforme de microscopie automatisée MetaSystems et utilisé cette approche dans la validation des balayages manuel et automatique d’un nombre précis de cellules mâles parmi une large population de cellules femelles marquées avec la technique FISH. Nous avons testé ce classificateur avec des échantillons de sang de femmes enceintes de grossesses normales et aneuploïdes et évalué la fréquence de cellules fœtales isolées par différentes méthodes d’enrichissement au cours des premier et second trimestres de grossesse. Les données accumulées ont confirmé la présence de cellules fœtales chez toutes les grossesses et leur fréquence plus élevée dans les grossesses aneuploïdes. Le nombre de cellules fœtales est dynamique tout au long de la grossesse. De plus, un nombre plus élevé de cellules fœtales peut être obtenu en optimisant le moment du prélèvement et les méthodes d’enrichissement. De plus, le balayage automatique s’est avéré plus sensible et constant que le balayage manuel, ce qui permet de balayer un grand nombre de cellules et devient plus approprié pour une application clinique. Nous avons aussi montré la faisabilité d’utiliser des cellules fœtales dans le cadre du DPNI. Cinq cellules amniotiques microdisséquées, provenant de grossesses normales et aneuploïdes, ont suffi pour poser un diagnostic prénatal par une combinaison de l’amplification du génome complet et de la technique QF-PCR (réaction quantitative en fluorescence d’amplification entraînée par une polymérase) permettant la détection d’anomalies chromosomiques. Nos résultats ouvrent la voie à l’utilisation de cellules fœtales dans le sang maternel pour le DPNI.

Made available in DSpace on 2017-07-10T19:25:13Z (GMT). No. of bitstreams: 1 isamara.pdf: 1125655 bytes, checksum: 8f7b2f7606310b4ddb2713e9e4043ec0 (MD5) Previous issue date: 2012-02-13 / Chemical contamination removal in soil and water depends on microbiological community that is able to degrade these compounds. There is a great evolutionary interest on studying microorganisms that metabolize the xenobiotic ones, since they have relatively been seen as new in the last five decades. Little is known about structure variation of microbiological community of soil due do the absence and presence of s-triazine herbicides.Unlike crop dependent methods that require time to detect bacteria, molecular techniques have been developed to identify individual species in mixed populations under natural enviromments. Fluorescence in situ Hibiridization (FISH) technique overcomes some difficulties that are found out in other molecular techniques, as it does not need DNA isolation and amplification steps and allows the identification of specific genes in intact cells. Thus, this study aimed at comparing the absence/presence of atrazine effect on bacteriological community structure in soil according to the phylogenetic aspect. Target probes were used on subdivisions of alpha, beta and gamma Proteobacteria, gram-positive bacteria with high G+C content, ammonia oxidizing bacteria, nitrite oxidizing bacteria and Planctomycetes. It was also used an AtzB1 specific probe to check the atzB gene presence, which makes part of s-triazine degradation. Bacteriological amount was determined by direct counting on epifluorescence microscopy, while the corresponding values to each probe were expressed in percentages of the total count with DAPI for each sample. According to this study, positive cells were found out for all probes used in both soils, but the abundance of all groups was lower in soil contaminated with atrazine herbicide, thereby demonstrating its negative influence. Planctomycetes was the most affected group with 57% lower abundance in contaminated soil. The nitrite oxidizing bacteria was the second most affected group followed by &#946;-Proteobacteria. It was also detected the gene atzB presence, so, it can be inferred that there are potentially degrading s-triazine bacteria in both soils. / A remoção da contaminação química no solo e água é dependente principalmente da presença de uma comunidade microbiana capaz de degradar tais compostos. A existência de microorganismos capazes de metabolizar xenobióticos é de um considerável interesse evolucionário, uma vez que estes compostos são relativamente novos no planeta nas últimas cinco décadas. Pouco se sabe sobre a variação da estrutura da comunidade microbiana do solo em função da ausência e presença dos herbicidas s-triazínicos. Diferentemente dos métodos dependentes de cultivo, que requerem tempo para a detecção de bactérias, técnicas moleculares vem sendo desenvolvidas para o reconhecimento de espécies individuais em populações mistas em ambientes naturais. A técnica de Hibridização Fluorescente in situ (FISH) supera algumas dificuldades encontradas com outras técnicas moleculares, pois dispensa as etapas de isolamento e amplificação de DNA e permite a identificação de genes específicos em células intactas. Em virtude disso, o presente trabalho teve como objetivo comparar o efeito da ausência/presença de atrazina na estrutura da comunidade bacteriana do solo no aspecto filogenético. Foram utilizadas sondas alvo para as subdivisões de Proteobactéria alfa, beta e gama, bactérias Gram-positivas com alto teor de G + C e Betaproteobactérias oxidantes de amônia, Bactérias oxidantes de Nitrito e Planctomicetos. Também foi utilizada uma sonda específica AtzB1 para verificar a presença do gene atzB que está envolvido na degradação das s-triazínas. A abundância bacteriana foi determinada através de contagem direta em microscopia de epifluorescência, e os valores correspondentes a cada sonda foram expressos em porcentagem da contagem total com DAPI para cada amostra. No presente estudo células positivas para todas as sondas utilizadas foram encontradas em ambos os solos, porém a abundância de todos os grupos foi menor no solo contaminado com o herbicida atrazina, demonstrando dessa forma a influência negativa do mesmo, sendo o grupo mais afetado o dos Planctomicetos com uma abundância 57% menor em solo contaminado. O segundo grupo mais afetado foi o das bactérias oxidantes de nitrito seguido pelo grupo das &#946;-Proteobactérias. Foi também detectado no presente estudo a presença do gene atzB demonstrando que em ambos os solos existem bactérias potencialmente degradadoras de s-triazinas.