Molecular diagnosis and typing of Trypanosoma cruzi populations and lineages in cerebral Chagas disease in a patient with AIDS

Trypanosoma cruzi DNA was amplified from an intracranial biopsy and peripheral blood of an HIV patient with encephalitis; this episode was indicative of AIDS and congenital Chagas disease. The analysis of a microsatellite locus revealed a multiclonal parasite population at the brain lesion with a more complex minicircle signature than that profiled in blood using restriction fragment length polymorphism (RFLP)-PCR and low stringency single primer (LSSP) PCR. Interestingly, different sublineages of T. cruzi II were detected in blood and brain by means of spliced-leader and 24s ribosomal-DNA amplifications. Quantitative-competitive PCR monitored the decrease of parasitic load during treatment and secondary prophylaxis with benznidazole. The synergy between parasiticidal plus antiretroviral treatments probably allowed the patient a longer survival than usually achieved in similar episodes. This is the first case report demonstrating a differential distribution of natural parasite populations and sublineages in Chagas disease reactivation, showing the proliferation of cerebral variants not detectable in peripheral blood.Fil: Burgos, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Bergher, Sandra B.. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Freitas, Jorge M.. Universidade Federal de Minas Gerais; BrasilFil: Bisio, Margarita María Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Altcheh, Jaime Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Teijeiro, Ricardo. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Begher, Sandra B.. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Freilij, Hector León. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Deccarlini, Florencia. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Levalle, Jorge. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Lopez Alcoba, Horacio. Gobierno de la Ciudad de Buenos Aires. Hospital "Ignacio Pirovano"; ArgentinaFil: Burgos, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; ArgentinaFil: Levin, Mariano Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Duffy, Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Macedo, Andrea M.. Universidade Federal de Minas Gerais; BrasilFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentin

Molecular epidemiology of domestic and sylvatic Trypanosoma cruzi infection in rural northwestern Argentina

Genetic diversity of Trypanosoma cruzi populations and parasite transmission dynamics have been well documented throughout the Americas, but few studies have been conducted in the Gran Chaco ecoregion, one of the most highly endemic areas for Chagas disease, caused by T. cruzi. In this study, we assessed the distribution of T. cruzi lineages (identified by PCR strategies) in Triatoma infestans, domestic dogs, cats, humans and sylvatic mammals from two neighbouring rural areas with different histories of transmission and vector control in northern Argentina. Lineage II predominated amongst the 99 isolates characterised and lineage I amongst the six isolates obtained from sylvatic mammals. T. cruzi lineage IIe predominated in domestic habitats; it was found in 87% of 54 isolates from Tr. infestans, in 82% of 33 isolates from dogs, and in the four cats found infected. Domestic and sylvatic cycles overlapped in the study area in the late 1980s, when intense domestic transmission occurred, and still overlap marginally. The introduction of T. cruzi from sylvatic into domestic habitats is likely to occur very rarely in the current epidemiological context. The household distribution of T. cruzi lineages showed that Tr. infestans, dogs and cats from a given house compound shared the same parasite lineage in most cases. Based on molecular evidence, this result lends further support to the importance of dogs and cats as domestic reservoir hosts of T. cruzi. We believe that in Argentina, this is the first time that lineage IIc has been isolated from naturally infected domestic dogs and Tr. infestans.Fil: Cardinal, Marta Victoria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Lauricella, Marta A.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C.G. Malbrán”. Instituto Nacional de Parasitología “Dr. M. Fatala Chabén”; ArgentinaFil: Ceballos, Leonardo A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Lanati, Leonardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Marcet, Paula Lorena. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Levin, Mariano Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Kitron, Uriel D.. Emory University; Estados UnidosFil: Gurtler, Ricardo Esteban. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentin

Caracterização molecular de acessos de jenipapeiro.

O Banco Ativo de Germoplasma de Jenipapo pertencente a Embrapa Tabuleiros Costeiros foi implantado em 2009, no Campo Experimento Jorge Sobral em Nossa Senhora das Dores, visando a conservação do material genético. O objetivo desse trabalho foi realizar a caracterização molecular e avaliar a diversidade genética de 160 indivíduos de 18 acessos de jenipapo por meio de marcadores moleculares ISSR. Os resultados mostraram através da análise de agrupamento ACoP a formação de quatro grupos. Há um grande número de indivíduos agrupados no grupo I da ACoP, indicando pouca divergência entre eles. Os grupos I, II e III, se agruparam em posições diferentes no dendrograma, porém na ACoP estão relacionados. O grupo IV é o mais diferente dos demais grupos. A análise comparativa dos agrupamentos revelou que os marcadores ISSR foram eficientes para a caracterização molecular e existe variabilidade genética entre os acessos

Padrão de diversidade genética de Passiflora spp. em Boyacá, Colômbia

The objective of this work was to characterize the genetic diversity, using ISSR markers, of 70 genotypes of five species of Passiflora spp. in Boyacá, Colombia. For molecular characterization, samples of young leaves were collected from 11 municipalities of the Boyacá department. Genetic similarity was used to cluster the genotypes by the UPGMA method, and genetic structure was evaluated by the Bayesian model. Eight ISSR primers produced 138 loci. The formed cluster consists of two populations, with most individuals of the same species but from different geographic origins. The percentage of polymorphic loci is higher than 80%. The average value of heterozygosity is between 0.29 and 0.36 for population I and II, respectively, and the values of polymorphic information content are low. A moderate genetic differentiation (0.16) and high gene flow (3.35) are observed.O objetivo deste trabalho foi caracterizar a diversidade genética, por meio de marcadores ISSR, de 70 genótipos de cinco espécies de Passiflora spp. em Boyacá, Colômbia. Para a caracterização molecular, foram coletadas folhas jovens em 11 municípios do departamento de Boyacá. A similaridade genética foi utilizada para o agrupamento dos genótipos pelo método UPGMA, e a estrutura genética foi avaliada pelo modelo Bayesiano. Oito iniciadores ISSR produziram 138 locos. O agrupamento formado consiste de duas populações, com a maioria dos indivíduos da mesma espécie mas de diferentes origens geográficas. A percentagem de locos polimórficos é superior a 80%. O valor médio de heterozigosidade fica entre 0,29 e 0,36 para a população I e II, respectivamente, e os valores de conteúdo de informação polimórfica são baixos. Observa-se diferenciação genética moderada (0,16) e alto fluxo gênico (3,35)

Expression of the minor isoform pea ferredoxin in tobacco alters photosynthetic electron partitioning and enhances cyclic electron flow

Ferredoxins (Fds) are ferrosulfoproteins that function as low-potential electron carriers in plants. The Fd family is composed of several isoforms that share high sequence homology but differ in functional characteristics. In leaves, at least two isoforms conduct linear and cyclic photosynthetic electron transport around photosystem I, and mounting evidence suggests the existence of at least partial division of duties between these isoforms. To evaluate the contribution of different kinds of Fds to the control of electron fluxes along the photosynthetic electron transport chain, we overexpressed a minor pea (Pisum sativum) Fd isoform (PsFd1) in tobacco (Nicotiana tabacum) plants. The transplastomic OeFd1 plants exhibited variegated leaves and retarded growth and developmental rates. Photosynthetic studies of these plants indicated a reduction in carbon dioxide assimilation rates, photosystem II photochemistry, and linear electron flow. However, the plants showed an increase in nonphotochemical quenching, better control of excitation pressure at photosystem II, and no evidence of photoinhibition, implying a better dynamic regulation to remove excess energy from the photosynthetic electron transport chain. Finally, analysis of P700 redox status during illumination confirmed that the minor pea Fd isoform promotes enhanced cyclic flow around photosystem I. The two novel features of this work are: (1) that Fd levels achieved in transplastomic plants promote an alternative electron partitioning even under greenhouse light growth conditions, a situation that is exacerbated at higher light intensity measurements; and (2) that an alternative, minor Fd isoform has been overexpressed in plants, giving new evidence of labor division among Fd isoforms.Fil: Blanco, Nicolás Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad de Umea; SueciaFil: Ceccoli, Romina Denis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Dalla Via, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular; ArgentinaFil: Voss, Ingo. Universität Osnabrück; AlemaniaFil: Segretin, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones En Ingeniería Genética y Biología Molecular; ArgentinaFil: Bravo Almonacid, Fernando Felix. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones En Ingeniería Genética y Biología Molecular; ArgentinaFil: Melzer, Michael. Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Physiologie und Zellbiologie; AlemaniaFil: Hajirezaei, Mohammad Reza. Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Physiologie und Zellbiologie; ArgentinaFil: Scheibe, Renate. Universität Osnabrück; AlemaniaFil: Hanke, Guy T.. Universität Osnabrück; Alemani

Inferencia del origen del bovino Criollo Cubano a través del análisis de patri- y matrilinajes

Antes de descubrimiento, no existían bovinos en América. Los primeros, fueron introducidos en la Antillas Mayores (La Española, Puerto Rico, Jamaica y Cuba), y desde allí trasladados al resto de Latinoamérica. Actualmente, existen en Cuba alrededor de 1300 bovinos Criollos, concentrados principalmente en la región oriental. Con el objetivo de analizar el origen materno de esta raza y detectar eventos contemporáneos de flujo génico por vía paterna, se analizó un fragmento de 240 pb del D-loop mitocondrial (mtADN) y 5 microsatélites del cromosoma Y (BTY), en 36 hembras y 21 machos respectivamente. La diversidad genética se estimó mediante el número de haplotipos, el número de sitios polimórficos, el número de diferencias nucleotídicas entre pares de secuencias y el índice de diversidad nucleotídica, mientras que el análisis filogenético se realizó utilizando el método de median joining network. Dicho análisis permitió detectar 15 haplotipos mitocondriales (10 del haplogrupo europeo T3, 3 del africano T1, 1 del cercano oriente T2 y 1 ambiguo T1-T3) y 3 haplotipos en el BTY, ambos del haplogrupo cebuíno Y3. En el mtADN se detectaron 23 sitios polimórficos con una diversidad nucleotídica de 0,014 y 3,36 diferencias medias entre pares de secuencias. En conclusión, la población de bovinos Criollos Cubanos presentó una composición haplotípica mitocondrial comparable a la de otras razas criollas y mediterráneas, hecho que concuerda con su origen histórico. El BTY evidenció altos niveles de introgresion paterna de genes del zebú.Cattle was absent from America before the discovery. Initially, bovine were brought to Greater Antilles (La Española, Puerto Rico, Jamaica and Cuba islands), and in the course of a few years, they were taken from Caribbean islands to the rest of Latin America. Nowadays, Cuban Creole cattle population is about 1300 heads, mainly located in the eastern region of the island. With the aim of analyzing the maternal origin of Cuban Creole cattle and detect possible contemporaneous, male mediated, gene flow, a 240 pb fragment of mitochondrial D-loop (mtDNA) and five microsatellites of Y chromosome (BTY) were studied in 36 dams and 21 sires, respectively. Genetic diversity was evaluated through number of haplotypes, mean number of pairwise differences and nucleotide diversity. The phylogenetic analysis was performed using a median joining. A total of 15 mtDNA haplotypes were detected in the studied population (10 from the European haplogroup T3, 3 from the African T1, 1 from the Nearern East T2, and 1 ambiguous T1-T3). The number of polymorphic sites, the mean nucleotide diversity, and the mean number of pairwise differences were 23, 0.014 and 3.36, respectively. Two patrilinages were detected, both belonging to the Y3 Zebu haplogroup. In conclusion, Cuban Creole cattle population had a mtDNA haplotypic composition similar to the observed in Creole and Mediterranean breeds, what is in concordance with its historical origin. Y chromosome analysis evidenced a male mediated process of zebu introgression.Fil: Liron, Juan Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Acosta, A.. Centro Nacional de Sanidad Agropecuaria. Laboratorio de Genética Molecular; CubaFil: Rogberg Muñoz, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Uffo, O.. Centro Nacional de Sanidad Agropecuaria. Laboratorio de Genética Molecular; CubaFil: Posik, Diego Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Garcia, J.. Ministerio de la Agricultura. Dirección Nacional de Genética; CubaFil: Peral Garcia, Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Giovambattista, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentin

An account on the taxonomy and molecular diversity of a marine rock-pool dweller, Tigriopus fulvus (Copepoda, Harpacticoida)

The copepod genus Tigriopus Norman, 1869 is distributed worldwide in coastal rock pools and it is currently considered to include 14 valid species. Tigriopus fulvus (Fischer 1860), with its subspecies Tigriopus fulvus adriaticus Van Douwe 1913 and Tigriopus fulvusalgiricus Monard 1935, and Tigriopus minutus Bozic 1960 are currently reported to occur in the Mediterranean area, but the actual diversity of the genus is currently unknown. We aimed to assess the actual identity of Mediterranean Tigriopus populations and to elucidate their taxonomy and pattern of genetic diversity. In order to reach these goals, a fragment of a mitochondrial DNA gene (cytochrome c oxidase subunit I, COI) was sequenced to be used as a reference marker. Our data suggest the presence of a single species characterized by a noteworthy geographi-cally based genetic structure in the whole study area. The observed diversity pattern is tentatively ascribed here to a strong monopolization of the rock pools by the first immigrants that reached them. However, such a monopolization is periodically disrupted by local extinction events, which are frequent in the intrinsically unstable rock pool habitats. We propose the name “clockwork monopolization” for this pattern.El género de copépodos Tigriopus Norman, 1869 se distribuye en todo el mundo en charcas de rocas costeras y se considera que actualmente incluye 14 especies válidas. Tigriopus fulvus (Fischer 1860), con sus subespecies Tigriopus fulvus adriaticus Van Douwe 1913 y Tigriopus fulvus algiricus Monard 1935, y Tigriopus minutus Bozic 1960 han sido descritos para el área del Mediterráneo, pero la diversidad real del género es desconocida actualmente. El objetivo de este estudio fue evaluar la identidad real de las poblaciones mediterráneas de Tigriopus y dilucidar su taxonomía y patrón de diversidad genética. Con este fin, se secuenció un fragmento del gen de ADN mitocondrial (citocromo c oxidasa subunidad I, COI) como marcador de referencia. Los resultados sugieren la presencia de una sola especie caracterizada por una estructuración genética con una notable base geográfica en toda el área de estudio. El patrón de diversidad observado aquí se atribuye tentativamente a una fuerte monopolización de las charcas de las costas rocosas por parte de los primeros inmigrantes que las alcanzan. Sin embargo, tal monopolización se interrumpe periódicamente por los eventos de extinción local, los cuales son frecuentes en los hábitats de charcas de rocas que son intrínsecamente inestables. Aquí proponemos para este patrón el nombre de “monopolización periódica” (“clockwork monopolization”)

Presumed TP53 mosaicism: variants detected using a NGS hereditary cancer multigene panel

Aims/Context: NGS multigene panels are routinely used to identify germline pathogenic variants in cancer susceptibility genes. In addition, NGS allows the identification of low-level mosaicism events that may not be detectable by conventional Sanger sequencing. We describe two cases of presumed TP53 mosaic variants detected by NGS on blood-derived DNA, and confirmed by ARMS-PCR and Sanger sequencing. Case 1: female, 87 years old, colon cancer at 83 and metachronous breast cancer at 86, no history of familial cancer. Case 2: female, 75 years old, ovarian cancer at 71, local relapse at 74. Methods: NGS using TruSight® Cancer Sequencing Panel and TruSight® Rapid Capture kit (Illumina) and paired-end sequencing on MiSeq® platform (Illumina). Bioinformatic analysis with MiSeq Reporter, Enrichment, VariantStudio, VEP, Alamut Visual, VarAFT, VarSome and IGV. ARMS-PCR and Sanger sequencing were used to confirm the TP53 variants. Results and Conclusions: Two cases of presumed TP53 mosaic variants were studied. Case 1: the missense alteration TP53: c.764T>G, p.(Ile255Ser) was detected with a variant allele frequency (VAF) of 26% (39/150 reads). This variant is described in ClinVar as a somatic alteration, classified as likely pathogenic. It is not reported in gnomAD and VarSome software classified it as a variant of uncertain significance. Case 2: missense variant TP53: c.524G>A, p.(Arg175His) detected with a VAF of 15% (10/58 reads). This variant is described as pathogenic in HGMD Professional, LOVD and ClinVar, in association with Li-Fraumeni syndrome. These two cases seem to represent TP53 mosaicism, supported by: i) VAF lower than 30%, ii) detection at the sensitivity limit of Sanger sequencing and iii) confirmation by ARMS-PCR. Confirming this hypothesis by studying tumor and other tissue samples and offspring analysis (underway in both cases), is essential for disease diagnosis, assessing recurrence risk and genetic counseling. The hypothesis of acquired aberrant clonal expansion limited to the hematologic compartment, versus a germline variant should be considered in similar cases, and confirmatory methodologies are mandatory.info:eu-repo/semantics/publishedVersio

Conservation of Lactuca watsoniana Trelease, an Azorean priority species : phylogenetics, population genetics and propagation

Tese de Doutoramento, Biologia, 28 de maio de 2018, Universidade dos Açores.Lactuca watsoniana Trel., é uma herbácea perene, endémica do Arquipélago dos Açores. Localmente denominada de “Alfacinha”, pode ser encontrada em quatro das nove ilhas do Arquipélago dos Açores (Faial, Pico, Terceira e São Miguel), estando possivelmente extinta da ilha de São Jorge. O tamanho total estimado das populações é de 500 a 2000 indivíduos, mas observações recentes no campo indicam que poderão ser menos de 500 indivíduos. Considerada como taxon prioritário na Directiva Habitats (Annex B-II) bem como na Convenção de Berna em termos de conservação e está listada como ameaçada (EN B2ab (i, ii, iii); C2a(i)) na Lista Vermelha da IUCN 2017. Atualmente, a Lactuca watsoniana encontra-se restrita a zonas húmidas, ravinas profundas e estreitas, crateras zonas declivosas, prados naturais de Festuca, matos de Erica e florestas de Juniperus entre 600-800 m. Está ameaçada por perda e degradação de habitat, resultante de expansão dos pastos, invasão por espécies exóticas, introdução de herbívoros e distúrbio de áreas sensíveis por turistas e locais. Neste trabalho investigaram-se os seguintes tópicos: i) propagação vegetativa por sementes; ii) genética de populações; e iii) filogenética e filogeografia. Foi estabelecido um protocolo eficaz e exequível para propagação por via seminal, germinando as sementes com 0.1 mg l-1 GA3, ethephon, e um filtro de luz vermelha e um regime de temperatura alterna de 15/10°C, com um fotoperíodo de 12 horas. Este protocolo permitiu a produção de centenas de plântulas viáveis que foram replantadas na população de origem. Dada a necessidade de proceder ao reforço das populações naturais em algumas ilhas, pretendeu-se definir se existiam riscos de contaminação genética resultante da troca de material entre as diferentes ilhas, para isso estudou-se a estrutura e variabilidade genética das populações, usando 8 microssatélites nucleares, desenvolvidos especificamente para a L. watsoniana. Os resultados mostraram uma clara separação entre as várias ilhas dos Açores, estando a maior variação genética dentro das populações (55.0%), mas com níveis relativamente altos de variação entre os clusters (27.3%). Evidenciando um grau de diferenciação entre as populações elevado e fluxo genético com valores inferiores a 1, bem como a existência de isolamento e barreiras geográficas. De modo a clarificar a posição taxonómica da L. watsoniana, nomeadamente em relação a espécies próximas da Europa, Norte da América e de outros Arquipélagos da Macaronésia (Canárias), recorremos a marcadores moleculares nucleares (ITS) e quatro do cloroplasto. Na análise das sequências combinadas de ITS e do cloroplasto (Parsimónia, Máxima verosimilhança e Inferência Baeysiana) o taxon dos Açores, mostrou a existência de um padrão filogeográfico através do arquipélago, com a presença de 5 haplótipos distintos para a L. watsoniana, quatro endémicos em apenas uma ilha (Faial, Pico, Terceira e São Miguel) e um haplótipo com informação genética partilhada do Faial e Pico, bem como uma relação filogenética, bem suportada, com as Lactuca Norte Americanas.ABSTRACT: Lactuca watsoniana Trel., is a perennial herb, endemic to the Azores archipelago. Locally called "Alfacinha", the species is restricted to only four of the nine islands of the archipelago (São Miguel, Terceira, Pico and Faial) and is possibly extinct in São Jorge Island. Estimates of its total population size are 500 to 2,000 individuals, but recent field observations indicate that it can be fewer than 500 individuals. It is therefore considered a priority species for conservation and was listed as endangered on the IUCN Red List 2017. Furthermore, it was included in Annex II of the EC Habitats Directive and is protected under the Berne Convention. Lactuca watsoniana is currently restricted to the steep slopes of craters and ravines in temperate juniper rain forest between 600-800 m of altitude. The species is threatened by habitat loss and degradation resulting from changes in land use, namely expansion of pasture, invasion by exotic species, consumption by introduced herbivores and disturbance of sensitive areas by tourists and locals. In this thesis, we investigated the following topics: i) seed propagation; ii) population genetics; and iii) phylogenetics and phylogeography. We established and efficient and feasible seed propagation protocol by germinating the seeds germinate seeds with 0.1 mg l-1 GA3, ethephon, a red-light filter and a temperature regime of 15/10°C, and 12 hours’ photoperiod. This protocol allowed producing hundreds of viable seedlings that were reintroduced in the source population. Given the need to reinforce natural populations in some of the islands, we aimed to find out if any outbreeding risks existed, resulting from material exchanges between the different islands. For that, we studied the genetic structure and variability of the populations, using eight nuclear microsatellites, developed specifically, for Lactuca watsoniana. Our findings showed a clear separation among the islands, with the largest proportion of genetic variation found within populations (55.0%) but with relatively high levels of genetic variation both among clusters (27.3%). Furthermore, a high variability between the populations, a gene flow value below one, and the presence of geographical isolation and barriers were estimated. In order to clarify the taxonomic position of L. watsoniana, namely the phylogeographic and phylogenetic relationship with the morphologically similar species from Europe, North America and the geographically close taxa from the Canary Islands, we used one nuclear region (ITS) and four chloroplast markers. Parsimony, Maximum likelyhood and Bayesian Inference analyses were conducted and revealed a strongly supported monophyletic Lactuca clade, and a clear separation of Macaronesian endemic Lactuca in sister clades. Lactuca watsoniana, endemic to Azores, showed a phylogeographic pattern across the archipelago, with the presence of five different haplotypes for L. watsoniana: four single island endemics (Faial, Pico, Terceira e São Miguel) and one occurring on both Faial and Pico and a strongly supported phylogenetic relationship with North America Lactuca.Fundo Regional da Ciência pelo financiamento da Bolsa de Doutoramento (M3.1.2/F/032/2011 e FEDER funds through the Operational Programme for Competitiveness Factors - COMPETE