Thesis (M. Sc.)--Université Laval, 2002. / "Fevrier 2002." Includes bibliographical references. Downloaded and printed from Laval University website.

Submitted by Ana Damasceno (ana.damasceno@unipampa.edu.br) on 2017-09-12T18:38:13Z No. of bitstreams: 1 Freitas, Karine Elise Janner de, 2017.pdf: 1520872 bytes, checksum: a4fac980d6a3df8e18e9e49f279baa4b (MD5) / Made available in DSpace on 2017-09-12T18:38:13Z (GMT). No. of bitstreams: 1 Freitas, Karine Elise Janner de, 2017.pdf: 1520872 bytes, checksum: a4fac980d6a3df8e18e9e49f279baa4b (MD5) Previous issue date: 2017-03-31 / A família das Polytrichaceae possui diversos representantes no continente Antártico, e entre elas a espécie Polytrichum strictum Menzies ex Brid. Considerado um organismo bipolar, pois se desenvolve tanto no Ártico como na Antártica, ainda carece de estudos que esclareçam sua classificação taxonômica, já que por diversas vezes foi conduzido como variante de Polytrichum juniperinum Hedw. devido sua morfologia ser similar a espécie e, sua verdadeira origem ainda não estar clara. Em um estudo, sugeriu-se que P. juniperinum poderia ser o ancestral materno de P. strictum, porém a análise apresentou incongruências. Ainda não se tem estudos moleculares dos espécimes oriundos dos polos e, muito menos abordagens a nível genômico do gênero Polytrichum. Com o advento das tecnologias de seqüênciamento de nova geração, os genomas organelares tornan-se uma ferramenta para estudos filogenéticos, já que fornecem dados sobre o conteúdo gênico e arquitetura do genoma, além de inferências filogenéticas complementares sobre a história evolutiva das espécies. Neste trabalho, foi determinada a sequencia parcial dos genomas do cloroplasto (cpDNA) e mitocondrial (mtDNA) de P. strictum e P. juniperinum, com o objetivo de analisar e caracterizar estruturalmente os genomas acessórios dos exemplares do gênero Polytrichum e inferir nas relações filogenéticas entre P. strictum e P. juniperinum. Os genomas acessórios das espécies foram sequenciados em um sequenciador NGS da Ion Torrent. A montagem, anotação, alinhamento, construção da filogenia e análise sintênica foram realizados in silico com softwares específicos. O cpDNA de P. juniperinum apresenta 55.168 pb compreendendo 51 genes, 31 tRNAs, 4 rRNAs e 19 proteínas relacionadas ao fotossistema I e II. O mtDNA de P. juniperinum compreende um total de 88.021 pb com 67 genes incluindo 19 tRNAs, 5 rRNAs, e 12 proteínas relacionadas ao metabolismo oxidativo. O cpDNA de P. strictum apresenta 20.183 pb compreendendo 45 genes, 14 tRNAs, 4 rRNAs, e 18 proteínas do fotossistema I e II. O mtDNA de P. strictum apresenta 58.896 pb contendo um total de 62 genes, 19 tRNAs, 5 rRNAs, e 13 proteínas relacionadas ao metabolismo oxidativo. Nas análises filogenéticas com cpDNA e mtDNA as árvores consenso apresentaram algumas diferenças no padrão de ramificação, porém P. juniperinum e P. strictum foram agrupadas no mesmo clado. Essas informações geradas a partir do cpDNA e mtDNA de P. juniperinum e P. strictum fornecem um aporte para futuros estudos filogenéticos com os espécimes do Ártico. / The Polytrichaceae family has several representants on the Antarctic continent, including Polytrichum strictum Menzies ex Brid. Considered a bipolar organism, because it develops in both the Arctic and Antarctica Continent, it still need studies to clarify its taxonomic classification, since several times it was conducted as a variant of Polytrichum juniperinum Hedw due to its morphology be similar to the species and its true origin still not be clear. In study, it was suggested that P. juniperinum could be the maternal ancestor of P. strictum, but the analysis presented incongruence’s. There are still no molecular studies of the specimens from the poles, let alone genomic approaches of the genus Polytrichum. With advent of new generation sequencing technologies, organellar genomes become as tool for phylogenetic studies, as they provide data on genome content and genome architecture, as well as complementary phylogenetic inferences about the evolutionary history of species. In this work, the sequence of the chloroplast (cpDNA) and mitochondrial (mtDNA) genomes of P. strictum and P. juniperinum was determined with the objective of analyze and structurally characterize the accessory genomes of the genera Polytrichum and infer in the phylogenetic relationships between P. strictum and P. juniperinum.The accessory genomes of the species were sequenced on an Ion Torrent NGS sequencer. Assembly, annotation, alignment, phylogeny construction and syntenic analysis were performed in sílico with specific software. The P. juniperinum cpDNA has 55,168 bp comprising 51 genes, 31 tRNAs, 4 rRNAs and 19 proteins related to photosystem I and II. The P. juniperinum mtDNA comprises a total of 88,021 bp with 67 genes including 19 tRNAs, 5 rRNAs, and 12 proteins related to oxidative metabolism. The P. strictum cpDNA has 20,183 bp comprising 45 genes, 14 tRNAs, 4 rRNAs, and 18 proteins from photosystem I and II. The P. strictum cpDNA has 20,183 bp comprising 45 genes, 14 tRNAs, 4 rRNAs, and 18 proteins from photosystem I and II. The P. strictum mtDNA has 58,896 bp containing a total of 62 genes, 19 tRNAs, 5 rRNAs, and 13 proteins related to oxidative metabolism. In the phylogenetic analyzes with cpDNA and mtDNA the consensus trees presented some differences in the branching pattern, but P. juniperinum and P. strictum were grouped in the same clade. This information generated from cpDNA and mtDNA of P. juniperinum and P. strictum provide a contribution to future phylogenetic studies with the specimens from Arctic.

Made available in DSpace on 2014-08-20T13:32:58Z (GMT). No. of bitstreams: 1 tese_filipe_de_carvalho_victoria.pdf: 30767989 bytes, checksum: d4b2b8995ad70a6cbd4d6e6ff672fa95 (MD5) Previous issue date: 2011-05-27 / Iron is an essential element for plant development, involved in metabolic processes, such respiration and photosynthesis. However, data regarding the genotype by environment interaction are lacking. Comparative analysis with lower plant groups and crop plants can increase the understanding about these processes. The use of bryophytes as model plants rise as a promising strategy since they present simpler patterns of development. The present work aimed to identify the occurrence patterns of molecular markers in model plant species, as well as to infer about the phylogenetical relationships of gene families related with iron homoestasis in plants, allowing the development of tranfer strategies of genomic data across model and orphan species. Using bioinformatics tools, a survey analysis was performed to detect repetitive elements in EST banks of eleven plant species. To validate the SSR markers found, 100 primer pairs were developed on the microsatelite sequences obtained for Physcomitrella patens Brid. and tested against genomic DNA of Polytrichum juniperinum Hedw. Phylogenetic and divergence time analysis was performed for the gene families Iron Regulated Transporter (IRT), Ferric Redectase Oxidase (FRO), Nicotinamide synthase (NAS), Yellow Stripe-Like (YSL) and Natural Resistance-Associated Macrophage Protein (NRAMP), related to the iron homoestasis, with help of the Bayesian inference and using the rice, Arabidopsis and P. patens genes for the Blast search in distinct land plants species. Also, primers for transposable elements recognizably related to Ysl genes were developed and applied jointly with the SSR primers by the IRAP/REMAP technic searching to find microsatellite markers associated to copies of this gene family. A total of 13,133 SSR markers were discovered in non- redundant EST databases made for all eleven species chosen for this study. The dimer motifs are more frequent in lower plant species, such as green algae and mosses, and the trimer motifs are more frequent for the majority of higher plant groups, such as monocots and dicots. Thirty percent of EST-SSE were successfully transferred with a relative polimorphism information across Physcomitrella patens Brid. and P. juniperinum, being promising for mapping and comparative genome analyses in plants. A total of 243 iron uptake gene sequences for 30 plant species were found using rice and Arabidopsis thaliana (L.) Heynh. homologues as queries. The evolutionary fingerprinting analyses suggested a positive selective pressure on iron uptake genes for most of the plant homologues analyzed, enabling an optimization and maintenance of gene function. The divergence time analysis indicates IRT as the most ancient gene family and FRO as the most recent. NRAMP and YSL genes appear as a close branch in the evolution of iron uptake gene families. No recent duplication in grasses were found based in the bayesian inference, and paralogue copies were only observed for dicot species. The Nramp cis-acting homology search indicated an ancestral duplication hypothesis for this gene family in grasses. Using IRAP/REMAP techniques, it was observed that YSL homologues in Physcomitrella are surrounded by copia-like retrotransposons as occurs in the maize ZmYSL1 copy. Also Polytrchum juniperinum Hedw. in vitro cultures were estabilished using spores as explants. Protonemal and gametophyte development were obtained using a growth regulator free culture medium. / O ferro é um elemento essencial para o crescimento e desenvolvimento das plantas, envolvido em processos metabólicos essenciais, como fotossíntese e respiração. Porém, são poucos os dados relacionando a interação entre diferentes genótipos e ambientes. Análises comparativas entre plantas inferiores e plantas cultivadas podem possibilitar o melhor entendimento destes processos. O uso de briófitas como modelo para estudos de processos biológicos em plantas surge como uma estratégia promissora devido ao padrão relativamente simples de desenvolvimento destas plantas. O presente trabalho objetivou identificar padrões de ocorrência de marcadores moleculares em plantas modelo, bem como inferir acerca da filogenia das famílias gênicas envolvidas na homoestase do ferro em plantas, possibilitando a criação de estratégias de transferência de informação genômica entre espécies modelo e espécies órfãs. Utilizando ferramentas de bioinformática foram realizadas análises exploratórias para detectar as ocorrências de elementos repetitivos em bancos de ESTs de onze espécies de plantas. Para a validação destes marcadores moleculares foram desenvolvidos 100 conjuntos de iniciadores a partir das sequências contendo microssatélites obtidas para Physcomitrella patens Brid. e testadas contra o DNA genômico de Polytrichum juniperinum Hedw. Foram realizadas análises filogenéticas e de divergência das famílias gênicas Iron Regulated Transporter (IRT), Ferric Redectase Oxidase (FRO), Nicotinamide synthase (NAS), Yellow Stripe-Like (YSL) e Natural Resistance-Associated Macrophage Protein (NRAMP), envolvidas na homoestase de ferro por meio de inferência bayesiana, utilizando genes de arroz, Arabidopsis e Physcomitrella patens Brid. na busca de homólogos em diferentes espécies de plantas terrestres, com o auxílio da ferramenta Blast (NCBI). Também foram desenvolvidos iniciadores para elementos transponíveis reconhecidamente associados a genes Ysl de milho e utilizados conjuntamente com os iniciadores EST-SSR por meio da técnica IRAP/REMAP buscando encontrar marcadores microssatélites associados a cópias desta familia gênica. Como resultados foram identificados 13.133 marcadores microssatélites em bancos de dados não redundantes de regiões expressas (EST) de onze espécies de plantas. Os motivos dinucleotídeos foram mais frequentes em espécies basais, enquanto os motivos trinucleotídeos foram mais frequentes em espécies derivadas. Em 30% dos conjuntos de iniciadores EST SSR testados contra o DNA de P. juniperinum, foi obtido bandas polimórficas promissoras para estudos de mapeamento comparativo e de diversidade genética. Foram encontrados 243 homólogos de genes relacionados as famílias gênicas envolvidas com a homoestase de ferro em trinta espécies de plantas. A análise de fingerprinting realizada sugere que a maioria destes genes estão submetidos a seleção positiva, indicando acúmulo de mutações adaptativas, essencial para a manutenção e otimização da resposta gênica. A análise de tempo de divergência indica que os genes IRT são mais basais e os genes FRO os mais recentes entre as familias gênicas estudadas. As famílias NRAMP e YSL são evolutivamente próximas. A análise bayesiana das sequências e de regiões promotoras dos genes NRAMP não indica duplicações recentes em gramíneas, sendo as duplicações provenientes de divergência ancestral a origem do grupo. Parálogos foram identificados somente em dicotiledôneas. Por meio da transferência de marcadores IRAP/REMAP é observado que genes YSL de P. patens estão cercados por retroelementos do tipo cópia, a exemplo do que ocorre com o gene ZmYSL1 em milho. Também foi estabelecido o cultivo, em condições axênicas, de Polytrichum juniperinum Hedw. utilizando esporos como explantes, onde foi observado que protonemas são obtidos utilizando meio de cultura livre de fitorreguladores, regenerando gametófitos em cultivo in vitro.

No description available.

Trembling aspen (Populus tremuloides (Michx.)) has become established along a mining road in the lower northern Quebec region (49°39' to 49°45'N and 79°01' to 79°02' W) in areas that have not supported aspen in the past. The primary means of regeneration of aspen is through vegetative root suckers, but it is doubtful that it could progress through this region at such a fast rate solely by asexual reproduction. Aspen are known to produce large amounts of seeds that could account for aspen's rapid progression, but sexual reproduction of aspen is rare; very little is known about Populus tremuloides seed germination and seed survival in natural conditions. The aim of this study was to determine seedbed conditions that facilitate the emergence and survival of Populus tremuloides seedlings, and to identify the key factors involved in these processes. Observations of established saplings and a sowing experiment were conducted on both post harvest and post fire sites. Our data on established saplings showed that there were seed-origin trembling aspen located in both post-harvest and burned areas indicating that Populus tremuloides can and has established from seed in areas where aspen was previously absent. Both our sowing experiment and our greenhouse experiment showed that the emergence of seedlings was relatively low, but that Polytrichum strictum moss and exposed mineral soil depressions were the best seedbeds for seed germination. Extreme temperatures and availability of moisture appeared to be controlling factors on seed germination, but ultimately the physical and biological characteristics of each substrate influenced the substrate's response to these factors in a different way. We conclude that sexual reproduction of trembling aspen may and has occurred in this region, and is promoted by the presence of exposed mineral soil and Polytrichum strictum moss. / Keywords: Bryophytes, Populus tremuloides, Polytrichum, Sphagnum, seedling, seedbed, germination, seed.

Abstract Previous reports on the effects of enhanced UV-B radiation on bryophytes have been equivocal. This study shows that mosses not only respond to enhanced UV-B, but they are affected by changes in ambient radiation. The studies were conducted with two model species common in northern environments; red-stemmed feather moss (Pleurozium schreberi) and juniper haircap moss (Polytrichum juniperinum). Both species showed high concentrations of methanol-extractable UV-absorbing compounds (UACs) with high spring-time and early-summer UV, whereas in P. juniperinum, the concentration was affected by early-summer drought. The UACs of P. juniperinum increased again towards autumn suggesting a role in winter hardening. The (spring-time) cell wall-bound UV screen was important to both species. The fundamental adaptation of P. juniperinum to open and exposed environments was reflected in relatively higher concentrations of total UACs compared to P. schreberi. The enhanced UV-B experiments in situ were conducted over two years in Oulu and six years at the FUVIRC site in Sodankylä. Some of the effects of UV-B were seen within the first years of the experiments, or even within hours, while others were observed after several years. Five or six years of enhanced UV-B treatment increased the methanol-extractable UACs of P. schreberi and decreased the green shoot growth of P. juniperinum. The immediate light environment was proposed to have an impact on the varying UAC concentrations. Some mitigating effects of UV-A were observed as well. Off-site measured, reconstructed and modelled UV radiation data was used for comparisons of light environment in situ, or when performing a reconstructive research with historical samples. The environmental sample banks can provide a useful tool to study past environmental conditions, and even reconstruct past radiation levels. It was shown in this study that UACs in P. schreberi and P. juniperinum have fundamental roles as UV-B screens in the cell walls, but there is also a variable response with the soluble fraction that reacts and adapts to the changes in UV radiation. The responses to increasing UV-B radiation vary in magnitude and in time. As P. schreberi and P. juniperinum possess circumboreal and cosmopolitan distributions, the effects of UV-B on these species and consequently on ecosystems has a broad application.