Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Bridgette Barry; Committee Member: El-Sayed, Mostafa; Committee Member: Fahrni, Christoph; Committee Member: Kröger, Nils; Committee Member: McCarty, Nael. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Bibliography: leaves 107-138.

Corrigenda pasted onto back end-papers. Bibliography: leaves 163-182. Analyses the proteins involved in Shigella flexneri O-antigen biosynthesis at the molecular level in order to gain a more concise understanding of the biosynthesis machinery and how it functions.

Thesis (MSc (Genetics))—University of Stellenbosch, 2007. / In South Africa, pre-eclampsia is the second highest cause of maternal deaths. The incidence of this disease in the Western Cape alone is 6.8% and places a large burden of health care facilities. The placenta and implantation thereof is thought to play the most significant role in the onset of this disease. Among the many theories for its aetiology, is the acknowledged two - stage theory. This is based on evidence that pre-eclamptic placentas demonstrate altered remodelling and invasion into the uterine endometrium and myometrium. The sub-optimal endometrium invasion leads to less oxygenation of the placental environment causing transient hypoxia. Consequently, the placenta is thought to release unknown factors into the maternal circulation which then culminates in clinical features associated with pre-eclampsia. Neurokinin B is thought to be one of these placental factors and subsequently binds to the NKB receptor in the maternal system. Endothelium-derived nitric oxide synthase has recently been shown to activate this receptor. The aim of this study was to investigate the role of neurokinin B (TAC3) and the neurokinin B receptor (TACR3) genes in the predisposition of pre-eclampsia and their interaction with eNOS in the South African coloured population together with a matched control cohort.

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Yeasts, like most organisms, have to survive in highly variable and hostile environments. Survival therefore requires adaptation to the changing external conditions. On the molecular level, specific adaptation to specific environmental conditions requires the yeast to be able: (i) to sense all relevant environmental parameters; (ii) to relay the perceived signals to the interior of the cell via signal transduction networks; and (iii) to implement a specific molecular response by modifying enzyme activities and by regulating transcription of the appropriate genes. The availability of nutrients is one of the major trophic factors for all unicellular organisms, including yeast. Saccharomyces cerevisiae senses the nutritional composition of the media and implements a specific developmental choice in response to the level of essential nutrients. In conditions in which ample nutrients are available, S. cerevisiae will divide mitotically and populate the growth environment. If the nutrients are exhausted, diploid S. cerevisiae cells can undergo meiosis, which produces four ascospores encased in an ascus. These ascospores are robust and provide the yeast with a means to survive adverse environmental conditions. The ascospores can lie dormant for extended periods of time until the onset of favourable growth conditions, upon which the spores will germinate, mate and give rise to a new yeast population. However, S. cerevisiae has a third developmental option, referred to as pseudohyphal and invasive growth. In growth conditions in which nutrients are limited, but not exhausted, the yeast can undergo a morphological switch, altering its budding pattern and forming chains of elongated cells that can penetrate the growth substrate to forage for nutrients. The focus of this study was on elements of the signal transduction networks regulating invasive growth in S. cerevisiae. Some components of the signal transduction pathways are well characterised, while several transcription factors that are regulated via these pathways remain poorly studied. In this study, the RMEt gene was identified for its ability to enhance starch degradation and invasive growth when present on a multiple copy plasmid. Rme1 p had previously been identified as a repressor of meiosis and, for this reason, the literature review focuses on the regulation of the meiotic process. In particular, the review focuses on the factors governing entry into meiosis in response to nutrient starvation and ploidy. Also, the transcriptional regulation of the master initiator of meiosis, IMEt, and the action of Ime1 p are included in the review. The experimental part of the study entailed a genetic analysis of the role of Rme1 p in invasive growth and starch metabolism. Epistasis analysis was conducted of Rme1 p and elements of the MAP Kinase module, as well as of the transcription factors, Mss11p, Msn1p/Mss10p, Tec1p, Phd1p and F108p. Rme1p is known to bind to the promoter of CLN2, a G1-cyclin, and enhances its expression. Therefore, the cell cyclins CLN1 and CLN2 were included in the study. The study revealed that Rme1 p functions independently or downstream of the MAP Kinase cascade and does not require Cln1 p or Cln2p to induce invasive growth. FL011/MUC1 encodes a cell wall protein that is required for invasive growth. Like the above-mentioned factors, Rme1 p requires FL011 to induce invasive growth. We identified an Rme1 p binding site in the promoter of FL011. Overexpression of Rme1p was able to induce FL01t expression, despite deletions of mss11, msn1, ttos, tee1 and phd1. In the inverse experiment, these factors were able to induce FL011 expression in an rme1 deleted strain. This would indicate that Rme1 p does not function in a hierarchical signalling system with these factors, but could function in a more general role to modify transcription. / AFRIKAANSE OPSOMMING: Die natuur is hoogs veranderlik en alle organismes, insluitende gis, moet by die omgewing kan aanpas om te kan oorleef. Baie eksterne faktore beïnvloed die ontwikkeling van die gissel. Vir die gis om by spesifieke omgewingstoestande aan te pas, moet die gis op 'n molekulêre vlak: (i) al die omgewingsparameters waarneem; (ii) die waargenome omgewingsparameters as seine na die selkern deur middel van seintransduksieweë gelei; en (iii) transkripsie van gene aktiveer of onderdruk en ensiemaktiwiteit reguleer om sodoende die gepaste molekulêre respons te implementeer. Die beskikbaarheid van voedingstowwe in die omgewing is een van die belangrikste omgewingseine wat eensellige organismes moet kan waarneem. Saccharomyces cerevisiae kan spesifieke ontwikkelingsopsies, na gelang van die voedingstowwe wat beskikbaar is, uitoefen. In groeiomstandighede waar daar 'n oorvloed van voedingstowwe is, verdeel S. cerevisiae d.m.v. mitose en vesprei dit deur die omgewing. Sodra die voedingstowwe uitgeput is, word mitose onderdruk. Diploïede S. cerevisiae inisieer meiose, wat aanleiding tot die vorming van vier spore gee. Hierdie spore bevat slegs die helfte van die ouer se chromosome en kan gevolglik met 'n ander spoor paar om weer 'n diploïede gissel te vorm. Die spore is bestand teen strawwe omgewingstoestande en kan vir lang tye oorleef. Wanneer die spoor aan gunstige groeitoestande blootgestel word, ontkiem dit om aan 'n nuwe giskolonie oorsprong te gee. S. cerevisiae het egter 'n derde ontwikkelingsopsie, naamlik pseudohife-differensiëring. Wanneer die beskikbaarheid van voedingstowwe in die omgewing afneem, maar nog nie uitgeput is nie, ondergaan die gis 'n morfologiese verandering. Hierdie verandering word gekenmerk deur selverlenging, nl. botselle wat slegs aan die een punt van die gissel vorm en dogterselle wat aan die moerderselle geheg bly. Dit lei tot die vorming van kettings van selle wat van die giskolonie af weggroei. Voorts kan die selkettings ook die groeisubstraat binnedring. Dit staan as penetrasie-groei bekend en laat die gis toe om na nuwe voedingsbronne te soek. Hierdie studie het op die elemente van seintransduksieweë, wat by penetrasiegroei betrokke is, gefokus. Sekere komponente van die seintransduksieweë is reeds goed gekarakteriseer, terwyl ander komponente nog grootliks onbekend is. In hierdie studie, word 'n rol vir RME1 in die verbetering van styselafbraak en penetrasiegroei geïdentifiseer. Aangesien Rme1 p voorheen as 'n onderdrukker van meiose geïdentifiseer is, is 'n litetaruurstudie oor die inisiasie van meiose saamgestel. Die faktore wat meiose induseer, naamlik 'n gebrek aan voedingstowwe en die sel se ploïedie, word bespreek. Die regulering van die meester inisieerder van meiosie, IME1, asook die proteïene waarmee Ime1p reageer, is ook in die studie ingesluit. Die eksperimentele deel van die studie behels die genetiese analise van Rme1 p tydens penetrasiegroei en styselhidroliese. 'n Epistase-analise tussen Rme1 p en elemente van die MAP-Kinasemodule, asook van die transkripsie faktore Mss11 p, Msn1p/Mss10p, Tec1p, Phd1p en F108p, is onderneem. Rme1p is bekend om aan die promotor van CLN2 te bind en transkripsie te induseer. Daarom is die selsikliene CLN1 en CLN2 in die studie ingesluit. Die studie dui daarop dat Rme1 ponafhanklik van die MAP-Kinasemodule funksioneer en nie Cln1 p en Cln2p benodig om penetrasiegroei te induseer nie. FL011/MUC1 kodeer vir 'n selwandproteïen wat noodsaaklik vir pentrasiegroei is. Soos in die geval van die bogenoemde faktore, benodig Rme1 p FL011 om penetrasiegroei te kan induseer. Ten spyte van mss11-, msn1-, ttos-, tec1- en phd1- delesies, kan ooruitdrukking van Rme1p die transkripsie van FL011 induseer. In die omgekeerde eksperiment kon die bogenoemde faktore FL011-transkripsie ten spyte van 'n rme1 delesie induseer. Die resultate dui daarop dat Rme1 p nie in 'n hiërargiese pad funksioneer nie, maar dat dit waarskynlik 'n meer algemene rol deur transkripsiemodifisering vervul.

Made available in DSpace on 2015-06-17T19:33:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-01-29. Added 1 bitstream(s) on 2015-06-18T12:48:18Z : No. of bitstreams: 1 000831958_20160129.pdf: 141405 bytes, checksum: a56af035cf777e68b39f9624adee2a7e (MD5) Bitstreams deleted on 2016-01-29T12:35:59Z: 000831958_20160129.pdf,. Added 1 bitstream(s) on 2016-01-29T12:36:36Z : No. of bitstreams: 1 000831958.pdf: 462812 bytes, checksum: 2070c5ce1422e2b78e58a79e3c1e4034 (MD5) / Escherichia coli enteropatogênica (EPEC) é uma categoria de E. coli de interesse em saúde pública, pois é responsável por causar diarréia, principalmente em crianças de países em desenvolvimento. Um total de 68 estirpes EPEC isoladas de humanos e animais (búfalos, ovinos e suínos) foram analisadas para marcadores de virulência e submetidos à sorotipagem, subtipagem do gene eae e similaridade clonal por eletroforese em gel de campo pulsado (PFGE). Os resultados da PCR demonstraram que seis isolados de humanos possuíam o gene bfp (EPEC típica), enquanto que 62 estirpes possuíam apenas o gene eae (EPEC atípica). Essas estirpes de EPEC pertenciam a 39 sorotipos (O: H) incluindo sorotipos clássicos de EPEC que estão relacionados a doenças em humanos, como O26:H11, O128:H2 e outros sorotipos relacionados a pessoas com diarreia, como O8:H16 e O76:H7. Seis tipos de intimina foram detectados entre as 68 estirpes de EPEC. São elas a 1, 2, 1, , e . A análise do PFGE, após a digestão Xbal, foi realizada nas 68 estirpes de EPEC. Os isolados se mostraram heterogêneos no PFGE e apresentaram 55 perfis diferentes. Quanto a filogenia, a maioria das estirpes de EPEC foram classificadas dentro do grupo B1. Além disso, algumas estirpes foram classificadas no grupo D, que são constituídos por estirpes de E. coli que podem causar infecções extra-intestinais. A presença de tipos de EPEC potencialmente patogênicas para humanos e EPEC isoladas de animais com características genéticas e fenotípicas em comum indica que a transmissão de agentes zoonoticos pode ocorrer. Portanto, o papel destes animais como reservatórios de EPEC deve ser considerado nas investigações de surtos de diarreia / Escherichia coli (EPEC) is a category of E. coli in interest in public health, as it is responsible for causing diarrhea, especially in children in developing countries. A total of 68 strains of EPEC isolated from humans and animals (buffalo, sheep and pigs) were analyzed for virulence markers, serotyping, subtyping of the eae gene and similarity clonal by electrophoresis in pulsed-field gel electrophoresis (PFGE). The PCR results showed that six human isolates had the bfp gene (typical EPEC), and 62 strains only had the eae gene (atypical EPEC). These strains belonged to 39 EPEC O: H serotypes including classical EPEC that are related to diseases in humans, such as O26: H11, O128: H2 and other serotypes that were related to people with diarrhea, as O8: H16 and O76:H7. Six types of intimin were detected among the 68 strains of EPEC, and 1, 2, 1, , and . The PFGE analysis, after XbaI digestion was performed on 68 strains of EPEC. The isolates were shown in heterogeneous PFGE and had 55 different profiles. Regarding the Phylogeny most strains of EPEC were classified into the group B1. Furthermore, some strains have been classified in group D, which consist of the E. coli strains that cause extra-intestinal infections. The presence of potentially pathogenic for humans types of EPEC and EPEC strains isolated from animals that may indicate disease transmission between animals and humans can occur and have an impact on public health. Furthermore, the role of these animals as EPEC carriers should be considered in outbreak investigations diarrhea. Keywords: EPEC, virulence genes, PFGE, zoonosis

Orientador: Marcos Rogério André / Coorientador: Rosangela Zacarias Machado / Banca: Paulo Eduardo Neves Ferreira Velho / Banca: José Maurício Barbanti Duarte / Resumo: Patógenos transmitidos por vetores artrópodes são mundialmente importantes, podendo causar enfermidades tanto no homen quanto nos animais. Recentemente, diversos estudos têm sido realizados a fim de elucidar o papel dos animais selvagens na epidemiologia desses patógenos. A identificação desses microrganismos, assim como dos seus vetores e hospedeiros, permite mapear áreas de ocorrência desses patógenos, auxiliando os órgãos competentes na elaboração de medidas de controle. Sendo assim, o presente estudo teve como objetivo detectar e caracterizar, por métodos moleculares, micoplasmas hemotróficos e bartonelas em amostras de baço de roedores selvagens e sinantrópicos distribuídos em cinco biomas brasileiros. Para tal, foram analisadas 500 amostras de roedores pertencentes a 51 espécies distribuídas em 13 estados. Dentre as 457 amostras de DNA positivas nos ensaios de PCR baseados nos genes Interphotoreceptor retinoid binding protein [IRBP] ou Glyceraldehyde-3-phosphate dehydrogenase [GAPDH], 100 (21,9%) mostraram-se positivas para Mycoplasma spp. por meio da cPCR baseada no gene 16S rRNA. A análise filogenética de 24 sequências do gene 16S rRNA mostrou a presença de dez diferentes clusters, todos agrupados dentro do grupo Mycoplasma haemofelis. O posicionamento filogenético associado com a baixa porcentagem de identidade entre as sequências amplificadas no presente estudo e aquelas previamente depositadas no Genbank sugere a circulação de novas espécies de hemoplasmas em roedo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Arthropod-borne pathogens are wordwide important, causing diseases in humans and animals. Recently, several studies have been performed in order to elucidate the role of wild animals in the epidemiology of these pathogens. The identification of these microorganisms, as well as their vectors and hosts, allow to map the areas of occurrence of these pathogens, helping competent agencies in the development of control measures. Therefore, the present study aimed to detect and characterize, using molecular methods, hemotrophic mycoplasmas and Bartonella in wild and sinantropic rodent spleen samples distributed in five Brazilian biomes. For this purpose, 500 rodent samples belonging to 51 species distributed in 13 states were analyzed. Among 457 DNA samples positive to PCR assays based on the Interphotoreceptor retinoid binding protein [IRBP] or Glyceraldehyde-3-phosphate dehydrogenase [GAPDH]) genes, 100 (21.9%) were positive to Mycoplasma spp. by cPCR based on 16S rRNA gene. The phylogenetic analysis of 24 sequences of the 16S rRNA gene showed the presence of ten different clusters, which grouped within the Mycoplasma haemofelis group. The phylogenetic position associated with the low percentage of identity between the sequences amplified in the present study and those previously deposited in Genbank suggest the circulation of new hemoplasmas species in rodents in Brazil. Additionally, 117 (25.6%) samples were positive to Bartonella sp. by qPCR. The diversity analysis of the gltA ... (Complete abstract click electronic access below) / Mestre

Orientador: Fernando Antônio de Ávila / Banca: Hélio José Montassier / Banca: José Moacir Marin / Banca: Ariel Eurides Stella / Banca: Oliveiro Caetano de Freitas Neto / Resumo: Escherichia coli enteropatogênica (EPEC) é uma categoria de E. coli de interesse em saúde pública, pois é responsável por causar diarréia, principalmente em crianças de países em desenvolvimento. Um total de 68 estirpes EPEC isoladas de humanos e animais (búfalos, ovinos e suínos) foram analisadas para marcadores de virulência e submetidos à sorotipagem, subtipagem do gene eae e similaridade clonal por eletroforese em gel de campo pulsado (PFGE). Os resultados da PCR demonstraram que seis isolados de humanos possuíam o gene bfp (EPEC típica), enquanto que 62 estirpes possuíam apenas o gene eae (EPEC atípica). Essas estirpes de EPEC pertenciam a 39 sorotipos (O: H) incluindo sorotipos clássicos de EPEC que estão relacionados a doenças em humanos, como O26:H11, O128:H2 e outros sorotipos relacionados a pessoas com diarreia, como O8:H16 e O76:H7. Seis tipos de intimina foram detectados entre as 68 estirpes de EPEC. São elas a 1, 2, 1, , e . A análise do PFGE, após a digestão Xbal, foi realizada nas 68 estirpes de EPEC. Os isolados se mostraram heterogêneos no PFGE e apresentaram 55 perfis diferentes. Quanto a filogenia, a maioria das estirpes de EPEC foram classificadas dentro do grupo B1. Além disso, algumas estirpes foram classificadas no grupo D, que são constituídos por estirpes de E. coli que podem causar infecções extra-intestinais. A presença de tipos de EPEC potencialmente patogênicas para humanos e EPEC isoladas de animais com características genéticas e fenotípicas em comum indica que a transmissão de agentes zoonoticos pode ocorrer. Portanto, o papel destes animais como reservatórios de EPEC deve ser considerado nas investigações de surtos de diarreia / Abstract: Escherichia coli (EPEC) is a category of E. coli in interest in public health, as it is responsible for causing diarrhea, especially in children in developing countries. A total of 68 strains of EPEC isolated from humans and animals (buffalo, sheep and pigs) were analyzed for virulence markers, serotyping, subtyping of the eae gene and similarity clonal by electrophoresis in pulsed-field gel electrophoresis (PFGE). The PCR results showed that six human isolates had the bfp gene (typical EPEC), and 62 strains only had the eae gene (atypical EPEC). These strains belonged to 39 EPEC O: H serotypes including classical EPEC that are related to diseases in humans, such as O26: H11, O128: H2 and other serotypes that were related to people with diarrhea, as O8: H16 and O76:H7. Six types of intimin were detected among the 68 strains of EPEC, and 1, 2, 1, , and . The PFGE analysis, after XbaI digestion was performed on 68 strains of EPEC. The isolates were shown in heterogeneous PFGE and had 55 different profiles. Regarding the Phylogeny most strains of EPEC were classified into the group B1. Furthermore, some strains have been classified in group D, which consist of the E. coli strains that cause extra-intestinal infections. The presence of potentially pathogenic for humans types of EPEC and EPEC strains isolated from animals that may indicate disease transmission between animals and humans can occur and have an impact on public health. Furthermore, the role of these animals as EPEC carriers should be considered in outbreak investigations diarrhea. Keywords: EPEC, virulence genes, PFGE, zoonosis / Doutor

Orientadores: Irani Quagio Grassiotto, Daniela Calcagnotto / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-25T14:34:56Z (GMT). No. of bitstreams: 1 Santana_JulioCesardeOliveira_D.pdf: 22975611 bytes, checksum: d02baacf927c5c48bc5cc9f97db90deb (MD5) Previous issue date: 2014 / Resumo: A superfamília Erythrinoidea é uma das oito famílias que compõem a ordem Characiformes e foi proposta como um grupo monofilético para abrigar as famílias neotropicais Ctenoluciidae, Erythrinidae e Lebiasinidae, e a família africana Hepsetidae. Após a proposição da superfamília, estudos filogenéticos recentes com base em caracteres morfológicos, como osteologia e morfologia de partes moles, e caracteres moleculares tem refutado a ideia de monofiletismo do grupo. Além disso, diferentes autores divergem quanto às relações suprafamiliares de Erythrinoidea. Além dos caracteres tradicionais, o emprego dos caracteres oriundos da análise da ultraestrutura da ontogenia dos espermatozoides e sua forma final tem sido uma importante fonte na complementação dos estudos filogenéticos. O estudo apresentado teve como objetivo realizar uma análise filogenética para testar a monofiletismo de Erythrinoidea e verificar os padrões de relacionamento suprafamiliares em Characiformes, e testar o posicionamento filogenético da família Crenuchidae, supostamente relacionada à superfamília. As análises filogenéticas foram realizadas com base em dados moleculares e dados morfológicos independentemente, e de maneira conjunta (evidência total) através do método de Parcimônia. A ultraestrutura da espermiogênese e dos espermatozoides dos gêneros incluídos em Erythrinoidea, mais a família Crenuchidae e outras possivelmente relacionadas, foram descritos e codificados em uma matriz de dados. Nas três análises realizadas a superfamília Erythrinoidea não é recuperada como monofilética. A família Crenuchidae posiciona-se na base da subordem Characoidei e não está estreitamente relacionada à Erythrinoidea. As análises com dados moleculares e de evidência total apresentaram uma topologia muito semelhante ao nível mais inclusivo e os valores de suporte dos principais clados apresentaram-se maiores na evidência total, mostrando a influência positiva da inserção dos caracteres da morfologia das células espermáticas nas análises filogenéticas / Abstract: The superfamily Erythrinoidea is one of eight superfamilies within the order Characiformes and was proposed to include a monophyletic group composed of the Neotropical fish families Ctenoluciidae, Erythrinidae and Lebiasinidae, and African family Hepsetidae. Current phylogenetic studies based on morphological data, such as osteology and morphology of soft structures, and molecular data have refuted the hypothesis of monophyly of this group. In addition, the suprafamilial relationships in Erythrinoidea have diverged among the authors. In combination with more traditional characters, the analyses of the ultrastructure of sperm ontogeny and its final shape have become an interesting source of characters to complement phylogenetic studies. The goal of this study was to perform a phylogenetic analysis to test the monophyly of the Erythrinoidea and to assess the phylogenetic position of the family Crenuchidae, a group supposed to be closely related to the superfamily. The phylogenetic analyses were performed using molecular and morphological data separately, and in a combined approach (total evidence) through the Parsimony method. The ultrastructure of the spermiogenesis and the sperm shape of Erythrinoidea genera, plus the family Crenuchidae and other species possibly related to the superfamily were described and coded in a matrix data. In all three analyses Erythrinoidea was not recovered as monophyletic. The family Crenuchidae was placed in a basal position within the suborder Characoidei in molecular and total evidence analysis, and was not closely related to the Erythrinoidea. The analyses using only molecular data and total evidence showed a very similar topology for the more inclusive relationship levels. The support values were higher for the total evidence tree when compared to the one resulting of only molecular data possibly pointing to a positive influence of the combination of the spermatic cell data in phylogenetic analyses / Doutorado / Biologia Celular / Doutor em Biologia Celular e Estrutural

Orientador: Renato Goldenberg / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-23T02:40:56Z (GMT). No. of bitstreams: 1 Caddah_MayaraKrasinski_D.pdf: 44109301 bytes, checksum: 6f87fe47d630845de374495c24f66a41 (MD5) Previous issue date: 2013 / Resumo: Miconia é um é um dos maiores gêneros de angiospermas. Tradicionalmente, tem sido considerado complexo e mal circumscrito, assim como outros gêneros aparentados. Estudos filogenéticos recentes, baseados em marcadores moleculares, têm atestado a natureza polifilética de Miconia e suas onze seções. Neste trabalho, é apresentado um estudo filogenético-molecular aprofundado de um dos grupos naturais encontrados em estudos anteriores, o "subclado Miconia discolor", do "clado Miconia IV". Para tanto, foram utilizados sequências de quatro marcadores plastidias (psaI-accD; psnK-L; atpF-H; trnS-G) e dois nucleares (ITS e ETS). Os resultados obtidos permitiram esclarecer o relacionamento interno e externo do grupo. Por meio da otimização de caracteres morfológicos e biogeográficos, são sugeridas hipóteses evolutivas, como a evolução de inflorescências glomeruladas e pseudantos a partir de inflorescências com ramos escorpióides amplos, e a irradiação da diversidade na Floresta Atlântica a partir de poucas colonizações. Os resultados também permitiram a primeira proposição moderna de classificação ingra-genérica para Miconia, através da formalização e circunscrição de novos táxons: Miconia sect. Discolor, e subseções Albicans, Chrysophylla, Discolor e Multispicata, subordinadas à nova seção. Adicionalmente, uma revisão taxonômica é apresentada para a recém proposta subseção Discolor, incluindo descrições, ilustrações, imagens de Microscopia Eletrônica de Varredura, comentários, e uma chave dicotômica de identificação para as espécies. A subseção é composta 32 espécies, das quais três são novas. Trinta e dois nomes heterotípicos foram sinonimizados, e 39 lectotipificações foram propostas. A subseção pode ser reconhecida por apresentar as folhas densamente cobertas por tricomas ramificados na face abaxial (nunca formando um indumento aracnóide), inflorescências geralmente glomeruladas, raramente curtamente scorpióides, lobos do cálice caducos no fruto, e uma distribuição restrita ao sudeste da América do Sul, ocorrendo na Floresta Atlântica e no Cerrado / Abstract: Miconia is one of the biggest genera in angiosperms. It has been traditionally considered very complex and badly circumscribed, and other close genera as well. Phylogenetic studies based on molecular markers have been confirming the polyphily of Miconia and its eleven sections. Here I present a deeper molecular and phylogenetic study of a natural group found out in older studies, the "Miconia discolor subclade", from the "Miconia IV clade". I used sequences of four plastid (psaI-accD; psnK-L; atpF-H; trnS-G) and two nuclear markers (ITS and ETS). The results clarified the inner and outer relationship of that group. Evolutionary hypotheses are suggested by the optimization of morphological and biogeographical charcaters. For example, the evolution of glomerulate inflorescences and pseudanthia from inflorescences of wide, scorpioid branches, and the diversification of the genus in the Atlantic Forest from few colonizations. Additionally, the results allowed the first modern infra-generic rearrangement by the proposition and circumscription of new taxa: Miconia sect. Discolor, with the subsections Albicans, Chrysophylla, Discolor and Multispicata. A revision of the new Miconia subsect. Discolor is presented, with descriptions, illustrations, Scanning Electron Microscopy images, comments, and a taxonomic key for species. The subsection has 32 species and three of them are new. I synonymized 32 heterotypic names proposed 39 lectotipifications. The subsection can be recognized by the abaxial leaf surface usually densely covered by branched trichomes (never forming a cobweb indument), inflorescences usually glomerulate, rarely shortly scorpioid, calyx lobes caducous in fruit, and a distribution restricted to the southeast of South America, in the Atlantic Forest and Cerrado / Doutorado / Biologia Vegetal / Doutora em Biologia Vegetal