Cell-to-cell communication is the driving force behind successful reproduction in flowering plants. Extensive extracellular communication events occur between the male and female gametophytes during pollen tube reception to facilitate successful fertilization. These signaling events culminate into a product of great importance for both animals and plants: the seed. In this study, the pathogen defense regulator PATTERN-TRIGGERED IMMUNITY COMPROMISED RECEPTOR-LIKE CYTOPLASMIC KINASE 1 (PCRK1) was identified to function in pollen tube reception from both the male and female gametophytes in the flowering plant <i>Arabidopsis thaliana</i> using a forward genetic screen. A knockout of <i>pcrk1</i> suppresses the pollen tube overgrowth phenotype leading to infertility in <i>nortia</i> mutants. In addition, <i>pcrk1</i> pollen affected the pollen tube overgrowth phenotypes of pollen tube reception mutants <i>feronia</i> and <i>turan</i>. Shared molecular components of pollen tube reception and pathogen invasion have been reported. This study reveals another link between pathogen defense and pollen tube reception. By studying the links between fertility and disease in plants, we may be able to uncover potential trade-offs with fertility when breeding for pathogen resistance.<br>

<p>Developing embryos rely on morphogenetic signals to inform cells about where they are in space and respond to their positions through the appropriate expression of fate-determining genes. Computational and theoretical analyses are powerful tools that have proven to enhance and inform experimental work in developmental biology. In the study of positional information, mechanistic ordinary and partial differential equations are able to test and suggest hypotheses for morphogen network evolution. Information theoretic interpretations of these profiles have also been proven to be valuable towards making predictions.</p> <p>These approaches are reviewed and used here together to investigate the morphogenetic signals instructing pattern formation during the earliest phase of development in the cochlea. When the transcription factors SOX2 and pSMAD1/5/9 (two crucial carriers of positional information)<br> are quantified here for the first time, new observations, questions, and hypotheses emerge that have been out of reach otherwise. Perhaps most intriguingly is the identification of a linear pSMAD1/5/9 profile over a supermajority of the radial axis. </p> <p>This linear profile is shown to ‘set the stage’ by creating a 1:1 map between position and signal concentration. Feasible mechanisms responsible for maintaining this profile are simulated to propose the existence of a yet-unidentified BMP sink on the medial edge and suggests a role for Follistatin interaction with BMP, which there are currently doubts around. This likewise sets thestage for new experimental and simulation work to home in on the network dynamics implemented by the cochlea to turn a diffusive morphogen system into a linear signal. While BMP sets the stage of the radial axis, adding SOX2 more precisely assigns cells their places for this opening act with its steep profile that reduces positional error. The transition into subsequent phases where cell fates are assigned relies dependently on the precision encoded in this first phase in order to create the cellular pattern required to enable the sense of hearing. </p>

<p dir="ltr">Uncovering the mechanisms of senescence in maize will give us a deeper understanding needed to drive future yield increases. Previous work on senescence response to sink disruption has identified a set of genes and biochemical mechanisms. Still, little is understood about the impact of this phenotype on yield and other commercially relevant traits. Uncovering the genetic basis of senescence in maize and testing the effect of these alleles on yield will provide a mechanistic framework for considering this trait to drive future yield increases.</p><p dir="ltr">Ear removal experiments demonstrated that senescence timing is insensitive to the presence or absence of an ear outside a critical window from 10 to 45 days after pollination. Nitrogen fertilization did not impact the SSRS response measured in the upper canopy. In further characterizing the SSRS phenotype, we have provided a spatial and temporal map of the B73 senescence response to sink disruption from the top of the plant to the ear leaf and discovered that this phenomenon is dose dependent and proportional to the size of the sink across two genotypes and years. This relationship was successfully used to predict kernel numbers and grain weight from spectral leaf properties as early as 4 weeks after pollination using remote sensing under agronomic conditions.</p><p dir="ltr">A population of 343 exPVP inbred lines was evaluated for source-sink regulated senescence and hybrid testcrosses were made for a subset of 200 inbred lines to testers for measurement of yield and ear photometry phenotypes. Source-sink regulated senescence of inbred parents was correlated with the yield of intra-family hybrids but was not generally correlated with the yield of hybrids made from crosses between two heterotic groups. The presence of multiple significant SNP association at the Bonferroni-corrected threshold at loci that are associated both with kernel traits and SSRS suggests shared genetic regulation of two traits that is likely driving the observed trait correlations of SSRS with kernel size and yield.</p><p dir="ltr">The maize nested association mapping (NAM) parents reveal a previously unknown breadth of SSRS phenotypes in the global diversity of maize germplasm. Mapping genes for SSRS in the NAM populations supports previously reported loci with large, dominant effects as well as evidence for previously unreported modifiers that are capable of suppressing the dominant alleles and producing a quantitative distribution in SSRS phenotypes. There are distinct alleles within sub-populations worth further study such as sweetcorn populations with non-senescence responses to sink disruption. A multi-factor analysis for QTL mapping, GWAS, and mutant variant sequencing identified highly significant loci on chromosomes 1 from 30.4Mbp to 35.8Mbp, chromosome 2 from 183.2Mbp to 190.8Mbp, chromosome 4 from 38.2Mbp to 134.8Mbp (crosses a centromere), chromosome 5 from 140.8Mbp to 233.9Mbp, chromosome 8 from 112.5Mbp to 123.8Mbp, and chromosome 8 from 155.7Mbp to 163.9Mbp. Candidate genes co-located with Bonferroni SNP in these regions may contribute to SSRS phenotypes through regulation of autophagy, accumulation of flavonoids, and sequestration of sugar in cell walls as an alternative sink. It is possible that co-regulation of these genes could cause all of them to be involved in the stress response of B73 to sugar accumulation. To find the causal variants for these traits, fine mapping and comparisons of near-isogenic lines will be required to narrow the list of candidate genes. Uncovering the alleles responsible for SSRS in global maize diversity could provide the building blocks for a physiological approach to increasing yields through optimizing the senescence responses to elevated sugar levels during grain-fill.</p>

<p dir="ltr">Organizational newcomers strive to adjust when they start new jobs, yet little is known about how remote and hybrid work structures influence this process. Previous research has adopted variable-centered approaches to explore the frequency with which newcomers engage in dozens of proactive behaviors in traditional, face-to-face work environments. The current study builds upon this work to capture the socialization process in modern work environments. Adopting a person-centered approach, this study 1.) identifies profiles of newcomers’ perceptions of their work environments, 2.) identifies profiles of newcomer proactive behaviors, 3.) examines the effect of virtuality on these two sets of profiles, and 4.) explores which behavior profiles are associated with the most favorable changes in adjustment.</p>

Les gènes des doigts WIP-zinc provenaient de l'établissement de l'évolution rapide du clade Viridiplantae de bryophytes et ptéridophytes. Depuis les bryophytes ancestrales des premières plantes terrestres deux clades principaux ont evolveld, basé sur notre analyse cladistique de la partie C-terminale des WIP. Le thème commun et le caractère démontré par les protéines à doigts de zinc AtWIP sont mis en évidence par leurs découvertes dans des rôles régulateurs de croissance et de développement orgue. Cependant, la protéine moléculaire interagissant partenaires et les mécanismes par lesquels les fonctions de WIP sont orchestrés restent encore inconnues. Ici, nous montrons les interactions entre protéines moléculaires et des modes de localisation sub-cellulaire de CmWIP1 et ses interacteurs pour élucider son rôle de régulateur dans le sexe détermination Cucumis melo fleurs. Sur la base des interactions levures deux écran hybride de protéine-protéine de la banque d'ADNc de melon généré, nous déclarons que la protéine interagit physiquement CmWIP1 très fortement avec CmbZIP et CmLHP1. Aussi interaction n'a été observée avec le complexe CKII en C. melo qui se compose de CmCKIIα, CmCKIIβ1 et CmCKIIβ2 sous-unités. Approches de génétique inverse ont été utilisées pour tenter de valider fonctionnellement les interacteurs clés in planta. Le passage d'homme à fleurs femelles en traits gynoïques résultats de répression épigénétique de l'expression d'un facteur de doigt de zinc de type de transcription, CmWIP1 situé au niveau des loci g dans Cucumis melo. Lorsqu'elle est exprimée, CmWIP1 est responsable de l'avortement carpien entraînant simples fleurs mâles sexués d'une origine bisexuel initial. La surexpression de CmWIP1 (sous promoteur 35SCaMV) chez Arabidopsis thaliana a donné lieu à des plantes présentant un retard de croissance global du-et-dessus des parties sous-sol plantes, feuilles dentelées vrais, des anomalies de croissance floraux et sillique ainsi que médiocre rendement des semences. 35S: CmWIP1 lignées d'insertion développés ont été surveillés en permanence et phénotypées sur T1 à T4 générations pour la stabilité de la dentelure phénotype feuilles. Fait intéressant, deux autres lignes sur-expression portant AtWIP1 et AtWIP2 causés dentelures des feuilles semblables à celles de CmWIP1 surexpression tout sous promoteurs 35SCaMV. Deux lignées stables homozygote pour 35S: CmWIP1 insertion ont été sélectionnés à la génération T4 et muté à 0,3% EMS. Un millier de vracs lignées familiales m2 (5 plants par vrac) ont été examinés pour les personnes réversion avec des feuilles non dentelée et taux de croissance restaurés. Écrans stade végétatif révélé deux révertants putatifs et 7% albinos. Les écrans suivants pour révertants ont été réalisées à des stades de reproduction et également pour les essais de la longueur des racines primaires ont été réalisées afin de valider révertants putatifs. Révertants putatifs familles ont encore été validés en tant que candidats pour la cartographie suppresseur par séquençage Sanger de la 35S :: CmWIP1 insertion par le dépistage de la séquence des mutations qui pourraient être la mutation causale. / The WIP-zinc finger genes originated from the early evolutionary establishment of the Viridiplantae clade from bryophytes and pteridophytes. From the ancestral bryophytes the first terrestrial plants two main clades have evolveld, based on our cladistic analysis of the C-terminal part of the WIPs. From the in silico analysis, CmWIP1 encodes are largely bi-partite protein in nature with the N-terminal acquired for protein-protein interactions whilst the C-terminal part is possibly mainly for DNA binding and some unknown processes involved in chromatin modulation/regulation (the presence of POST-SET domains). The common theme and character demonstrated by the AtWIP-Zinc finger proteins are highlighted by their discoveries in regulatory roles of organ growth and development. However, the molecular protein interacting partners and mechanisms by which the WIP functions are orchestrated still remain unknown. Here we show molecular protein interactions and sub-cellular localization patterns of CmWIP1 and its interactors to elucidate its regulatory role in the sex determination Cucumis melo flowers. Based on the protein-protein interactions yeast two hybrid screen of the melon cDNA library generated, we report that CmWIP1 protein physically interacts very strongly with CmbZIP and CmLHP1. Also interactions were observed with the CKII complex in C. melo which is made up of CmCKIIα, CmCKIIβ1 and CmCKIIβ2 subunits. CmWIP1 also interacts with CmTHF1 and CmPTR. Reverse genetic approaches were utilized in attempts to functionally validate the key interactors in planta. The transition from male to female flowers in gynoecious lines results from epigenetic repression of the expression of a zinc finger type transcription factor, CmWIP1 located at the g loci in Cucumis melo. When expressed, CmWIP1 is responsible for carpel abortion resulting in single sexed male flowers from an initial bisexual origin. Over-expression of CmWIP1 (under 35SCaMV promoter) in Arabidopsis thaliana resulted in plants with overall growth retardation of above- and under-ground plant parts, serrated true leaves, floral and sillique growth abnormalities as well as poor seed yield. 35S:CmWIP1 insertion lines developed were continuously monitored and phenotyped over T1 to T4 generations for stability of the leaf serration phenotype. Interestingly, two other over-expression lines carrying AtWIP1 and AtWIP2 caused leaf serrations similar to that of CmWIP1 overexpression all under 35SCaMV promoters. Two stable lines homozygote for 35S:CmWIP1 insertion were selected at the T4 generation and mutagenized with 0.3 % EMS. A thousand bulks of M2 family lines (5 plants per bulk) were screened for revertant individuals with unserrated leaves and restored growth rates. Vegetative stage screens revealed both putative revertants and 7 % albinos. Subsequent screens for revertants were carried out at the reproductive stages and also for primary root length assays were carried out to validate putative revertants. Putative revertants families were further validated as candidates for suppressor mapping via Sanger sequencing of the 35S::CmWIP1 insert by screening of the sequence for mutations which could be the causative mutation.

Nous avons étudié les mécanismes d'impact de l'algue envahissante Caulerpa taxifolia (Vahl) C. Agardh sur les poissons en Méditerranée, en particulier à l'aide d'une étude approfondie sur une espèce « modèle » : Symphodus ocellatus (Forsskål). Un suivi des peuplements de poissons ainsi que des expérimentations in situ ont été réalisés au niveau du département des Alpes-Maritimes, sur des milieux colonisés par l'algue et des milieux témoins. Caulerpa taxifolia qui forme des prairies de frondes très denses et hautes, de la fin de l'été jusqu'au début de l'hiver, représente une gêne physique pour l'accès à la nourriture benthique et aux microhabitats. Le suivi de deux récifs artificiels crées in situ a montré que l'envasement et l'obstruction de cavités par C. taxifolia diminuent la capacité d'accueil d'un milieu rocheux pour la faune ichtyologique. La raréfaction d'abris convenables mène à une augmentation de la mortalité des petits individus par prédation. L'étude de contenus digestifs ainsi que des acides gras corporels chez S. ocellatus montre un changement de régime alimentaire sur les milieux envahis (augmentation de la consommation de plancton au détriment des proies benthiques). En aquarium, nous avons montré que l'accessibilité aux proies benthiques diminue avec la densification de l'algue. Nous avons observé in situ que C. taxifolia pose également le problème de l'accès et de la détection des proies benthiques pour les rougets de roche Mullus surmuletus. Sur les milieux colonisés, le bilan énergétique global se traduit par des déficits de 21% dans le contenu lipidique corporel chez les jeunes S. ocellatus et de 59% dans les lipides de stockage du foie ainsi que par un déficit pondéral au niveau du foie et des ovaires chez les femelles reproductrices. Cependant, la qualité des œufs n'est pas affectée. Par ailleurs, in situ, les toxines de C. taxifolia n'ont pas d'influence sur le succès de développement embryonnaire de S. ocellatus.

Le cholestérol, élément nutritif indispensable mais toxique en excès, est naturellement converti en oxystérols. Les LXRs (Liver X Receptor) α et β sont les récepteurs nucléaires des oxystérols ayant un rôle hypocholestérolémiant et contrôlant plusieurs fonctions physiologiques. Notre but a été d'étudier leur rôle dans la reproduction chez la femelle. Dans l'ovaire, l'induction de l'ovulation chez des souris lxrα;β-/- provoque une hyperstimulation ovarienne (OHSS), caractérisée par une augmentation de la masse, des troubles vasculaires et de la sensibilité hormonale. Les LXRs contrôlent de plus l'oestradiolémie. Au niveau utérin, nous montrons un rôle spécifique de LXRβ. Les souris lxrβ-/- présentent une séquestration anormale d'esters de cholestérol dans les myocytes associée à un défaut de contractilité utérine. Cette étude montre l'importance des LXRs dans la reproduction chez la femelle et permettra de comprendre le lien entre déséquilibre alimentaire et troubles de la fertilité.

Made available in DSpace on 2014-12-17T15:49:13Z (GMT). No. of bitstreams: 1 PamelaLR_DISSERT.pdf: 3477786 bytes, checksum: e908a438292b6fd69e56fc50da98d37c (MD5) Previous issue date: 2013-03-11 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Vriesea minarum is a rupiculous bromeliad species, with naturally fragmented populations, restricted to the Iron Quadrangle, Minas Gerais, Brazil. It is a threatened species, which is suffering from habitat loss due to the growth of cities and mining activities. The knowledge of genetic variability in plant populations is one of the main branches of conservation genetics, linking genetic data to conservation strategies while the knowledge about plant reproductive biology can aid in understanding key aspects of their life story, as well as in the comprehension of their distribution and survival strategies. Thus, the study of diversity, richness, and genetic structure, as well as the reproductive biology of populations of V. minarum can contribute to the development of conservation actions. Chapter 1 presents the transferability of 14 microsatellite loci for V. minarum. Among the results of this chapter, we highlight the successful transferability of 10 microsatellite loci described for other species of Bromeliaceae, all of which are polymorphic. In Chapter 2, we present the genetic analyses of 12 populations of V. minarum that are distributed throughout the Iron Quadrangle. We used the 10 microsatellite loci tested in Chapter 1. The results show a low population structuring (Fst = 0.088), but with different values of genetic richness (mean = 2.566) and gene diversity (mean = 0.635) for all populations; and a high inbreeding coefficient (Gis = 0.376). These may be the result of pollinators action and/or efficient seed dispersal, thus allowing a high connectivity among populations of naturally fragmented outcrops. The reproductive biology and floral morphology of a population of V. minarum, located in the Parque Estadual da Serra do Rola-Mo?a, are studied in Chapter 3. This reserve is the only public environmental protection area where the species occurs. As a result of field experiments and observations, we found that the species has its flowering period from January to March, with flowers that last for two days and that it has a mixed pollination syndrome. It is primarily alogamous, but also has the capacity to be self-ferilized. It is expected that data obtained in chapters 1, 2 and 3 serve as basis for other studies with species from the ferruginous rocky fields, since until now, to our knowledge, there are no other survey of endemic species from the Iron Quadrangle, seeking to merge the genetic knowledge, with the data of the reproductive biology, with the ultimate aim of biodiversity conservation. Considering the great habitat loss for the species by mining, it becomes crucial to analyze the creation of new protected areas for its conservation / Vriesea minarum ? uma esp?cie de brom?lias rup?cola, com popula??es naturalmente fragmentadas, restrita a regi?o do Quadril?tero Ferr?fero, em Minas Gerais, Brasil. ? uma esp?cie amea?ada, que est? sofrendo com a perda de habitat devido ao crescimento das cidades e ?s atividades de minera??o. O conhecimento da variabilidade gen?tica em popula??es de plantas ? um dos principais ramos de gen?tica da conserva??o, associando dados gen?ticos para as estrat?gias de conserva??o, enquanto que o conhecimento sobre a biologia reprodutiva pode ajudar na compreens?o de aspectos fundamentais da hist?ria de vida, distribui??o e estrat?gias de sobreviv?ncia das plantas. Assim, o estudo da diversidade, riqueza, estrutura gen?tica e biologia reprodutiva das popula??es de V. minarum podem contribuir para o desenvolvimento de a??es de conserva??o. O cap?tulo 1 apresenta a transferabilidade de 14 loci de microssat?lites para V. minarum. Entre os resultados desse cap?tulo, destaca-se o sucesso da transferabilidade de 10 loci de microssat?lites descritos para outras esp?cies de Bromeliaceae, sendo todos eles polim?rficos. No cap?tulo 2, ? apresentada a gen?tica de 12 popula??es de V. minarum que se distribuem por todo o Quadril?tero Ferr?fero. Os resultados obtidos mostram pouca estrutura??o entre as popula??es (Fst = 0,088), mas com diferentes valores de riqueza (m?dia = 2.566) e diversidade gen?tica (m?dia = 0.635) para todas as popula??es; o coeficiente de endogamia foi alto (Gis = 0.376). Estes dados podem ser resultado da a??o de polinizadores e/ou dispers?o de sementes eficientes, j? que as popula??es s?o naturalmente fragmentadas. No cap?tulo 3, ? estudada a biologia reprodutiva e morfologia floral de uma popula??o de V. minarum, situada no Parque Estadual da Serra do Rola-Mo?a, Minas Gerais. Como resultado, foi poss?vel identificar que a esp?cie possui flora??o de janeiro a mar?o; com flores que duram dois dias; s?ndrome mista de poliniza??o; sendo primariamente al?gama, mas tamb?m tem capacidade para ser auto fecundada. Espera-se que dados obtidos nos cap?tulos 1, 2 e 3 sirvam como base para outros estudos com esp?cies de campos rupestres ferruginosos, j? que at? o presente momento, n?o ? de nosso conhecimento a exist?ncia de registros de outras pesquisas feitas com esp?cies end?micas do Quadril?tero Ferr?fero, que busquem conciliar o entendimento da gen?tica, com os dados da biologia reprodutiva, tendo como alvo a conserva??o da biodiversidade neste h?bitat altamente amea?ado pela minera??o. Torna-se crucial uma an?lise cuidadosa para a cria??o de novas ?reas de prote??o, para conserva??o das popula??es da esp?cie

<p>Plant height is an important agronomic trait and a major target for crop improvement. Owing to the ease of detection and measurement of plant stature, as well as its high heritability, several height-related mutants have been reported in maize. The genes underlying a few of those mutants have also been identified, with a majority of them related to the biosynthesis or signaling of two key phytohormones - gibberellins (GAs) and brassinosteroids (BRs). However, most other maize dwarfing mutants, and especially those that result from gain-of-function mutations, remain uncharacterized. The present study was undertaken to characterize a novel dominant dwarfing mutant, named <i>D13</i>. This mutant appeared in the M1 population of the inbred B73 that was generated by mutagenesis with ethyl methanesulfonate (EMS). Like most other maize dwarfing mutants, the reduction in <i>D13</i> height was largely due to the compression of the internodes. However, unlike the GA or BR mutants, <i>D13</i> had no defects in the female or male inflorescences. Further, in contrast to the GA and BR mutants, the mesocotyl elongation during etiolation was not impacted in <i>D13</i>. <i>D13</i> seedlings developed red coloration in two to three lowermost leaves. In addition, <i>D13</i> also showed enhanced tillering when the phenotype was very severe. The size of the shoot apical meristem of <i>D13</i> was reduced slightly, and significant aberrations in the structure of vascular bundles in the mutant were observed. All anatomical and phenotypic features of <i>D13</i> were highly exaggerated in homozygous state, indicating the partially dominant nature of the <i>D13</i> mutation. Interestingly, the heterozygous mutants showed remarkable variation in their phenotype, which was maintained across generations. Moreover, the <i>D13</i> phenotype was found to be sensitive to the genetic background, being completely suppressed in Mo17, Oh7B, enhanced in CML322, P39 and changed to different degrees in others. To identify the genetic defect responsible for the <i>D13</i> mutant phenotype, a map-based cloning approach was used, which identified a single base-pair change from G to A (G2976A) in the coding region of a glutamate receptor gene (Zm00001d015007). The G2976A missense mutation resulted in the replacement of alanine with threonine at the location 670. The replaced alanine is highly conserved in glutamate receptors across all domains of life from cyanobacteria to plants to mammals, suggesting a causal relationship between the G2976A substitution and the <i>D13</i> phenotype. To validate this relationship, a targeted EMS-based mutagenesis approach was used to knock-out (inactivate) the <i>D13</i> mutant allele. A suppressor mutant was found in which the <i>D13</i> mutant phenotype reverted to the normal tall phenotype. The sequence of the revertant allele, designated <i>D13</i>*, revealed that the original <i>D13</i> mutant allele underwent a second G to A mutation (G1520A) to change glycine into aspartic acid at position 473. This intragenic second-site mutation in the <i>D13</i> allele suppressed the function of the <i>D13</i> allele, thereby preventing it from interfering with the function of the wild type allele. To further unveil the genes and underlying mechanisms that enable the <i>D13</i> mutant to confer a dwarf phenotype, transcriptomic and metabolomic analyses of <i>D13</i> mutants were conducted and compared to the wild type sibs. While the omics analysis confirmed that stress responses were upregulated and genes related to shoot system development were downregulated in the mutant, the data did not allow us to pinpoint the underlying mechanisms that connect the <i>D13</i> mutation with its dwarfing phenotype. Furthermore, it remains unclear whether these stress and shoot system-related changes result in the manifestation of <i>D13</i> phenotype, or the dwarf phenotype due to <i>D13</i> mutation activates the stress-related mechanisms. This is the first study that signifies the importance of a glutamate receptor gene in controlling plant height.</p>

Surveys and vegetation analyses were used to determine the known distribution and the characteristics of the habitat utilised by Anolis sagrei in Taiwan. Sampled lizards were used for morphological comparisons, and to investigate the reproductive biology of this species in Taiwan. The results of this study indicate that the distribution of A. sagrei in Taiwan is extensive (≥237 ha) in Chiayi City and County (southwestern study site) and scattered (≥8 ha) in Hualien City and County (eastern study site). These lizards were mostly found in open sunny degraded man-made habitats. Although some variations were noted in the comparisons between the A. sagrei collected from the two study sites, it was concluded that the two populations likely have the same founder population. The reproductive biology study indicated that photoperiod and the associated temperatures determine the reproductive cycles in A. sagrei. It also demonstrated that reproduction in this species is energetically demanding. / Nature Conservation / MSc.(Nature Conservation)