La fertilisation chez les plantes dépend de la livraison des cellules spermatiques contenues dans le pollen à l’ovule. Au contact du stigmate, le grain de pollen s’hydrate et forme une protubérance, le tube pollinique, chargé de livrer les noyaux spermatiques à l’ovule. Le tube pollinique est une cellule à croissance rapide, anisotrope et non autotrophe; ainsi tout au long de sa croissance à travers l’apoplaste du tissu pistillaire, le tube pollinique puise ses sources de carbohydrates et de minéraux du pistil. Ces éléments servent à la synthèse des constituants de la paroi qui seront acheminés par des vésicules de sécrétion jusqu’à l’apex du tube. Ce dernier doit aussi résister à des pressions mécaniques pour maintenir sa forme cylindrique et doit répondre à différents signaux directionnels pour pouvoir atteindre l’ovule. Mon projet de doctorat était de comprendre le rôle du cytosquelette dans la croissance anisotrope du tube pollinique et d’identifier les éléments responsables de sa croissance et de son guidage. Le cytosquelette du tube pollinique est composé des microfilaments d’actine et des microtubules. Pour assurer une bonne croissance des tubes polliniques in vitro, les carbohydrates et les éléments de croissance doivent être ajoutés au milieu à des concentrations bien spécifiques. J’ai donc optimisé les conditions de croissance du pollen d’Arabidopsis thaliana et de Camellia japonica qui ont été utilisés avec le pollen de Lilium longiflorum comme modèles pour mes expériences. J’ai développé une méthode rapide et efficace de fixation et de marquage du tube pollinique basée sur la technologie des microondes. J’ai aussi utilisé des outils pharmacologiques, mécaniques et moléculaires couplés à différentes techniques de microscopie pour comprendre le rôle du cytosquelette d’actine lors de la croissance et le tropisme du tube pollinique. J’ai trouvé que le cytosquelette d’actine et plus précisément l’anneau d’actine localisé dans la partie sub-apicale du tube est fortement impliqué dans la croissance et le maintien de l’architecture du tube à travers le contrôle de la livraison des vésicules de sécrétion. J’ai construit une chambre galvanotropique qui peut être montée sur un microscope inversé et qui sert à envoyer des signaux tropistiques bien précis à des tubes polliniques en croissance. J’ai trouvé que les filaments d’actine sont impliqués dans la capacité du tube pollinique à changer de direction. Ce comportement tropistique dépend de la concentration du calcium dans le milieu de croissance et du flux de calcium à travers des canaux calciques. Le gradient de calcium établi dans le tube pollinique affecte l’activité de certaines protéines qui se lient à l’actine et dont le rôle est la réorganisation des filaments d’actine. Parmi ces protéines, il y a celles de dépolymérisation de l’actine (ADF) dont deux spécifiquement exprimées dans le gamétophyte mâle d’Arabidopsis (ADF7 et ADF10). Par marquage avec des proteins fluorescents, j’ai trouvé que l’ADF7 et l’ADF10 ont des expressions différentielles pendant la microsporogenèse et la germination et croissance du tube pollinique et qu’elles partagent entre elles des rôles importants durant ces différents stades. / Fertilization in plants depends on the delivery of the sperm cells in the pollen grain through the pollen tube to the ovule. The pollen tube is a highly anisotropic, fast growing cellular protuberance. Because the pollen tube is non autotrophic, it requires a steady supply of carbohydrates and minerals supplied by the pistil to sustain its growth. These elements serve for the synthesis of cell wall material, delivered to the site of cell wall assembly in secretory vesicles that are transported along the actin cytoskeleton and deposited at the growing apex of the tube. The tube has to resist external deformation forces in order to maintain its cylindrical shape and to respond to various directional signals in order to reach its target. My objectives were to identify the role of the cytoskeleton in the anisotropic growth of the pollen tube and to determine how the tube responds to directional cues. The cytoskeleton in the pollen tube consists of microfilaments and microtubules, both forming long filamentous elements. For in vitro growing pollen tubes, carbohydrates and growth minerals have to be added to the growth medium in specific amounts order to sustain pollen tube growth. I optimized the growth conditions of Arabidopsis thaliana and Camellia japonica pollen tubes which, in addition to pollen from Lilium longiflorum, were used as model species for my experiments. I developed a microwave based, fast and efficient fixation and labelling protocol for pollen tubes. I used pharmacological, mechanical, molecular and microscopical tools to study the role of the cytoskeleton in pollen tube growth and tropism. I found that the actin cytoskeleton, and more specifically the subapical actin fringe, plays an important role in the regulation of pollen tube growth and architecture through the controlled delivery of secretory vesicles to the growing apex. I constructed a galvanotropic chamber that can be mounted on an inverted microscope to induce controlled tropic triggers. I found that the actin cytoskeleton is also involved in the ability of the pollen tube to change its direction. This tropic behaviour was shown to be dependent on the concentration of calcium ions in the growth medium and calcium influx through calcium channels. The cytosolic calcium gradient in the pollen tube regulates the activity of various actin binding proteins that are responsible for remodelling the actin cytoskeleton. Among these proteins are two Arabidopsis gametophyte-specific actin depolymerizing factors (ADFs) that I tagged with two intrinsically fluorescent proteins. I found that ADF7 and ADF10 are differentially expressed during microsporogenesis and pollen tube germination and growth and that they likely divide important functions between them.

Made available in DSpace on 2015-03-26T13:54:53Z (GMT). No. of bitstreams: 1 texto completo.pdf: 278166 bytes, checksum: ac8bc005df1ef0e6da3abf17c619b10c (MD5) Previous issue date: 2009-07-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / An experiment was conducted in the poultry sector of aviculture of the animal Science department of the Universidade Federal de Viçosa - UFV, aiming to establish the methionine plus cystine to lysine to Japanese quail in phase position. 480 female quails were used, with initial age of 65 days, distributed in a completely randomized blocks desing with six treatments, ten replicates and eight birds per experimental unit. Treatments consisted of a basal diet deficient in methionine plus cystine (0.65%), with 19.3% crude protein and 2800 kcal metabolizable energy/kg, supplemented with six levels of DL-Methionine 98% (0,116; 0,167; 0,218; 0,269; 0,320 e 0,371%), corresponding to the relationship methionine plus cystine to lysine of 0.65, 0.70, 0.75, 0.80, 0, 85 and 0.90, and the lysine set at 1.00%. The variables studied were: feed intake (g / bird / day), egg production per bird day (%), egg production per hen housed (%), production of commercial eggs (%), egg weight (g), egg mass (g / bird / day), feed conversion by egg mass (kg feed / kg egg), feed per dozen eggs (kg feed / dz of eggs), change in body weight (g), viability of the poultry (%), weight of egg components (yolk (g), albumen (g) and shell (g)), percentage of components of eggs (%) height and diameter of eggs (mm) and specific gravity (g/cm³). There was increasing linear effect for feed intake, diameter of eggs, weight of pods and percentage of egg yolk, while for percentage of bark was observed linear decreasing effect. For the parameter weight of the eggs the best adjustment of data was obtained using the Linear Response Plateau model (LRP). It was verified quadratic effect for egg mass, feed conversion by egg mass, egg production per bird days, egg productionper hen housed, weight of the yolk, the albumen weight and height of eggs. It was concluded that the relationship methionine plus cystine to lysine of 0.84 and the feed to a daily intake of 221.0 mg of this amino acid, corresponding to the. / Foi conduzido um experimento no Setor de Avicultura do Departamento de Zootecnia da Universidade Federal de Viçosa UFV, com o objetivo de estabelecer a relação de metionina mais cistina digestível com lisina digestível para codornas japonesas na fase de postura. Foram utilizadas 480 codornas fêmeas, com idade inicial de 65 dias, distribuídas em delineamento em blocos casualisados com seis tratamentos, dez repetições e oito aves porunidade experimental. Os tratamentos consistiam de uma ração basal deficiente em metionina mais cistina (0,65%), com 19,6% de proteína bruta e 2800 kcal de energia metabolizável/kg, suplementada com seis níveis de DL-Metionina 98% (0,116; 0,167; 0,218; 0,269; 0,320 e 0,371%), correspondendo à relação metionina mais cistina digestível com lisina digestível de 0,65; 0,70; 0,75; 0,80; 0,85 e 0,90, sendo a lisina digestível fixada em 1,00%. Os parâmetros estudados foram: consumo de ração (g/ave/dia), produção de ovos por ave dia (%), produção de ovos por ave alojada (%), produção de ovos comercializáveis (%), peso do ovo (g), massa de ovos (g/ave/dia), conversão alimentar por massa de ovos (kg de ração/kg de ovos), conversão alimentar por dúzia de ovos (kg de ração/dz de ovos), viabilidade das aves (%), variação do peso corporal (g), peso dos componentes dos ovos (gema (g), albúmen (g) e casca (g)), porcentagem dos componentes dos ovos (%), diâmetro dos ovos (mm) e altura e gravidade específica (g/cm3). Observou-se efeito linear crescente para consumo de ração, diâmetro dos ovos, peso da casca e porcentagem de gema.Para porcentagem de casca foi observado efeito linear decrescente. Para o peso dos ovos o melhor ajuste dos dados foi obtido com a utilização do modelo Linear Response Plateau (LRP). Foi verificado efeito quadrático para a massa de ovos, conversão alimentar por massa de ovos, produção de ovos por ave dia, produção de ovos por ave alojada, peso da gema, peso do albúmen e altura dos ovos. Concluiuse que a relação metionina mais cistina com lisina que proporcionou os melhores resultados de desempenho e satisfatória qualidade de ovo foi de 0,84.

Höga kvävenedfall och förändringar inom jord- och skogsbruk har lett till igenväxning av svenska sandmarker. Sand- och grustäkter kan fungera som tillflyktsort för kärlväxtarter som är beroende av de torra och näringsfattiga markförhållanden som finns i sandmarker. Vapnö grustäkt i Hallands län undersöktes 2010 och visade sig ha en hög biologisk mångfald med bland annat 145 kärlväxtarter, varav fyra rödlistade. Syftet med den här studien var att se hur artsammansättningen av kärlväxter ser ut idag, sju år senare. Området inventerades vid tio tillfällen från april till augusti och samtliga kärlväxtarter noterades. Resultatet blev en lista på 224 arter varav 63 var återfynd från 2010 och 161 var nya arter för området. Det fanns fem rödlistade arter: Knippnejlika (Dianthus armeria) (EN), hårginst (Genista pilosa) (NT), backtimjan (Thymus serpyllum) (NT), skogsalm (Ulmus glabra) (CR) och naverlönn (Acer campestre) (CR). Det totala antalet arter och rödlistade arter har ökat sen 2010, vilket tyder på en positiv utveckling av områdets biologiska mångfald. Den höga artmångfalden beror troligen på det öppna, varierande landskapet och de rödlistade arterna växer där tack vare den alltmer ovanliga sandmarken. Områdets mångfald av kärlväxter hotas av igenväxning samt konkurrens från de invasiva arterna blomsterlupin (Lupinus polyphyllus) och parkslide (Fallopia japonica). Detta kan motverkas av störningar i form av slåtter, uppgrävning, naturvårdsbränning eller bete. / Nitrogen deposition and changes in agriculture and forestry have led to a decrease of sandy habitats in Sweden due to regrowth of vegetation. Sand- and gravelpits can act as refuges for vascular plants that require the dry and nutrient-poor conditions of sandy soils. Vapnö gravelpit in Halland county in Sweden was surveyed in 2010 and proved to hold a high biodiversity including 145 species of vascular plants, of which four were red-listed. Now, seven years later, the purpose of this study was to see how the composition of vascular plants has changed since then. The area was studied on ten occasions from April to August, and all species of vascular plants were noted. The study resulted in a list of 224 species, of which 63 were remaining since 2010 and 161 were new species for the area. There were five red-listed species: Dianthus armeria (EN), Genista pilosa (NT), Thymus serpyllum (NT), Ulmus glabra (CR) and Acer campestre (CR). The total number of species and red-listed species have increased, suggesting a positive development of the biodiversity of the area. The high species diversity is probably due to the open, varied landscape and the presence of the red-listed species due to the increasingly rare sandy habitat. The diversity of vascular plants in the area is threatened by regrowth of vegetation, as well as the invasive species Lupinus polyphyllus and Fallopia japonica. These threats can be counteracted by disturbance in the form of mowing or digging up plants, prescribed burning or grazing.

Ce travail s’intègre dans le cadre du programme européen COMET (7ième PCRD EURATOM) et vise à évaluer les réponses épigénétiques (particulièrement la méthylation de l’ADN), lors d’expositions chroniques à de faibles niveaux de substances radioactives.Lors d’une première expérience, les poissons zèbres (Danio rerio) ont été exposés au laboratoire à des concentrations environnementales d’uranium appauvri : 2 et 20 µg L-1. Cette expérimentation a révélé un impact sur la méthylation de l’ADN génomique, majoritairement chez les mâles exposés, croissant avec la durée et le niveau d’exposition. Lors d’une seconde expérience, nous avons observé un impact sur les profils de méthylation de la descendance issue de parents exposés, ainsi qu’une perturbation du statut transcriptomique et des dommages histologiques dans le muscle squelettique des larves issues de parents exposés.Les outils développés ont pu être appliqués à la problématique d’étude des effets biologiques induits par les radionucléides émis lors de l’accident de la centrale nucléaire de Fukushima Daiichi. Les analyses réalisées sur la grenouille arboricole Japonaise (Hyla japonica) ont révélé une corrélation positive entre la dose totale de radioactivité absorbée par ces grenouilles, l’hyperméthylation de l’ADN génomique et l’augmentation des dommages à l’ADN mitochondrial.L’ensemble de ces travaux a permis de mettre en évidence la sensibilité des réponses épigénétiques chez différents organismes soumis à de faibles doses de radionucléides, qui pourraient ainsi permettre de mieux caractériser les mécanismes d’adaptation et les potentiels effets transgénérationnels induits par les radionucléides. / This work integrates within the general framework of the European program COMET (7th Framework Programme EURATOM) and aims to assess the epigenetic responses (particularly DNA methylation), during chronic exposure to low levels of radioactive materials. During a first experiment, zebrafish (Danio rerio) were exposed in laboratory controlled conditions to environmentally relevant concentrations of depleted uranium: 2 and 20 µg L-1. This experiment allowed an impact on the genomic DNA methylation to be demonstrated, mainly in exposed males, which increased with the duration and level of exposure. In a second experiment, we observed an impact on DNA methylation patterns in the progeny of exposed parents, as well as a perturbation of transcriptomic, and histological damage in larvae skeletal muscle from exposed parents.The methods developed were applied to the second context focusing on the study of biological effects induced by radionuclides emitted following the Fukushima Daiichi nuclear power plant accident. The analyses performed on the Japanese tree frog (Hyla japonica) revealed a positive correlation between the total dose of radiation absorbed by these frogs, hypermethylation of genomic DNA as well as increasing damage to mitochondrial DNA.This work highlighted the sensitivity of epigenetic responses in different biological models exposed to low levels of radionuclides, and could be used to further characterize adaptation mechanisms and potential transgenerational effects induced by radionuclides.

No description available.

The Enemy Release Hypothesis proposes that introduced species often achieve larger individual sizes and greater population abundance in their introduced range because they have escaped their natural enemies - predators and parasites - that regulate populations in their native range. The main objective of this study is to test the Enemy Release Hypothesis (ERH) by investigating the identity, prevalence and intensity of parasites in two marine species introduced to New Zealand - the recently introduced but spatially restricted Asian portunid crab, Charybdis japonica, and the longer-established Asian nesting mussel, Musculista senhousia. Host choice of a native generalist parasite presented with the non-native and native mussels, and prey selection by a native predator presented with these bivalves will be examined. This is the first study of its kind in New Zealand. The parasite fauna of the only established New Zealand population of C. japonica (Waitemata Harbour, Auckland), was compared to that from (a) a population of C. japonica from its native region (Japan) and (b) to multiple populations of the native New Zealand crab Ovalipes catharus, a native New Zealand portunid. Results showed the introduced crab harboured only one species of endoparasite (a nematode), and two types of melanised lesions. Neither the parasite nor the lesions were present in the native crab populations. The native crab was host to only one parasite species, which occurred at very low prevalence, and was present in only one of the six populations examined from throughout New Zealand. Carapace width in the introduced crab was no larger than that reported in literature from its native are, but was larger than carapace widths of the Japanese sample. M. senhousia was examined from five sites within New Zealand. Parasites in M. senhousia were compared with a sympatric native bivalve, Austrovenus stutchburyi, two native mytilids, (Perna canaliculus and Xenostrobus pulex) and with samples of M. senhousia from Italy and the USA where it is introduced, and Japan where it is native. Two native generalist parasites, the pea crab Pinnotheres novaezelandiae, and a copepod, were found within M. senhousia in New Zealand, but only at low prevalence. A greater array of organisms was associated with the native bivalves. No parasites were recovered from any of the overseas samples of M. senhousia, including the Japanese samples. This may be caused by the preservation medium used, but could be a true reflection of the parasite fauna in these populations. The site where the two native parasites were exploiting M. senhousia was the only site sampled where two native mussels, P. canaliculus and X. pulex, also occurred. Consequently, effects of these two generalist parasites on the three mussel species were examined. In P. canaliculus, presence of native pea crabs was associated with lower tissue dry weight and greater shell depth. Shell width and depth were both greater in the presence of copepods. However, the prevalence of pea crabs and copepods was much lower in M. senhousia compared to the two native mussels, indicating some release from the effects of these parasites for the non-native species. Experimental choice tests showed that the pea crab, P. novaezelandiae, does not actively select M. senhousia as a host, preferring the larger native mussel, P. canaliculus. Rates of infection of M. senhousia are, therefore, likely to remain low in natural habitats where there are large numbers of native hosts. In addition, a generalist predator, the crab O. catharus, showed no preference when foraging on the three mussel species under experimental conditions. Thus, some predation pressure may be exerted on M. senhousia by this native crab in the natural environment. Investigation of multiple populations of both native and non-native species has shown large variation in parasite prevalence and intensity among populations of each species. After examining C. japonica and the comparable native O. catharus, evidence to support the ERH was found to be weak. As the native crab was relatively free of parasites, it seems unlikely that parasite infection is important within native populations and therefore, the success of C. japonica is unlikely to be caused by comparatively greater freedom from parasites (a central tenet of the ERH). There was also no evidence for host-switching by native parasites into the introduced C. japonica population. In contrast, native parasites were present at very low prevalence in the non-native mussel M. senhousia. Length of time since introduction can be an important factor in host switching between native and introduced hosts, but unless prevalence of these parasites is high, the introduced species still escapes from enemies that could control a population. Therefore every non-native species needs to be examined using multiple populations to investigate variation in parasite fauna, prevalence and intensity, as the same species, if introduced numerous times, could potentially show contrasting results for the ERH unless multiple populations are examined.

農林水産研究情報センターで作成したPDFファイルを使用している。

農林水産研究情報センターで作成したPDFファイルを使用している。

Invasive species are the second-leading cause of the decline of native species, making it a critical global environmental issue (Pimentel 2005). The goal of this study was to identify which non-native invasive plant species are common in eastern Travis County and which environmental factors associate with their establishment and spread in this area. Five parks and preserves were sampled, as they are intended for the conservation of native species and are more accessible for educational use. Six of the 15 species searched for, Bothriochloa ischaemum, Lactuca serriola, Ligustrum lucidum, Lonicera japonica, Melia azedarach, and Sorghum halepense, were each found in at least one of the five sites. The presences and absences of these species were compared to a suite of ecosystem properties, including habitat, disturbance, the average soil depth, and the horizontal and vertical distances to the nearest pond, lake, stream, or river. None of these six species appears to need observable recent disturbance. All of these six species, both woody and herbaceous, can tolerate shallow soils. The woody invasive species Ligustrum lucidum and Melia azedarach seem to prefer more mesic habitats. The invasive grass species Bothriochloa ischaemum and Sorghum halepense seem to prefer habitats that are more open. Several invasions of potential conservation concern were identified. / text

Resumo: O nitrogênio é o nutriente que proporciona melhores respostas no crescimento das gramas, bem como a formação do tapete em menor tempo, com boa qualidade. A espessura do corte do tapete de grama também pode afetar a produtividade. Tapetes muito finos podem romper no manuseio, sendo descartados, ou apresentam menor pegamento e tapetes muito espessos prejudicam a rebrota na área de produção. Dessa forma realizaram-se os experimentos com os objetivos de determinar a dose de N que permita a produção de tapetes de grama bermuda com qualidade e em menor tempo, bem como avaliar os benefícios da aplicação de ajifer, "coproduto" do processo de fabricação do Glutamato Monossódico como fonte de N na grama esmeralda, avaliando a espessura de corte na qualidade do tapete formado. Os dois experimentos foram instalados e conduzidos em propriedade comercial de produção de grama, localizada na cidade de Capela do Alto, SP. As espécies utilizadas foram: a grama Zoysia japonica Steud. - esmeralda e a grama Cynodon dactylon (Pers) L. variedade Celebration - bermuda. O delineamento experimental utilizado para a grama esmeralda foi em parcelas subdivididas com 4 repetições, em esquema fatorial 7x3 em blocos casualizados. As parcelas principais foram compostas por cinco doses de Ajifer que corresponderam a 0, 100, 200, 300 e 400 kg de N ha-1, com complementação de P e K, mais duas testemunhas relativas, sendo uma composta por 300 kg ha-1 de N-ajifer e outra por 300 kg ha-1 de N-uréia + P e K, e as subparcelas por três espessuras de corte de tapete (0,9; 1,6 e 2,2 cm). O delineamento experimental utilizado para a grama bermuda foi em blocos ao acaso, com cinco doses de N: 0, 150, 300, 450 e 600 kg de N ha-1, e quatro repetições. Doses acima de 300 kg ha-1 de N-ajifer não proporcionaram maiores respostas na formação de tapetes de grama esmeralda avaliados pela taxa de cobertura do solo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Nitrogen is the nutrient that gives greater responses in turfgrass growth, as well as turfgrass sod formation in less time, with good quality. The thickness of the turfgrass sod cut may also affect the yield. Very thin sods can break with handling, being disposed, or presents less regrowth and very thick sods affect the regrowth in the production area. Thus the objectives of the experiments were to determine N rate that allows the production of Bermuda grass sod with quality and in less time, as well as assess the benefits of implementing Ajifer, coproduct of the manufacturing process of monosodium glutamate, as a source of N in zoysiagrass, evaluating the cut thickness of the sod formed related to quality. The two experiments were conducted in a property of turfgrass commercial production, in the city of Capela do Alto / SP. The species used were: Zoysia japonica Steud. - zoysiagrass and Cynodon dactylon (Pers) L. - Bermuda grass. The experimental design for zoysiagrass was split plot in a 7X3 factorial scheme. The plots were composed of five Ajifer doses corresponding to 0, 100, 200, 300 and 400 kg N ha- 1, complemented with P and K, plus two more controls, one composed of 300 kg ha-1 of N-ajifer and another by 300 kg ha-1 of urea-N + P and K. The subplots consisted of three slice thicknesses of sod (0.9, 1.6 and 2.2 cm). The experimental design for the Bermuda grass was randomized blocks with five treatments: 0, 150, 300, 450 and 600 kg N ha-1, and four replications. Doses above 300 kg ha-1 of N-ajifer did not provided responses in the formation of zoysiagrass sod measured by the soil cover rate. The use of Ajifer as nitrogen source provided responses similar to urea for the zoysiagrass sod formation. The lack of phosphorus and potassium provided lower... (Complete abstract click electronic access below) / Orientador: Dirceu Maximino Fernandes / Coorientador: Roberto Lyra Villas Bôas / Banca: Leonardo Theodoro Büll / Banca: Hélio Grassi Filho / Banca: Leandro José Grava de Godoy / Banca: Marco Antonio Tecchio / Doutor