Ecology and Evolution of Common Milkweed

All organisms must interact with and adapt to their surrounding environment. There are myriad ways in which species accomplish this; ultimately resulting in the vast diversity of life on earth today. Changes in the environment can have profound impacts on an organisms\u27 ability to compete and utilize their surroundings. Plants are particularly impacted by local environmental differences because of the fact that they are immobile. This environmental variation exists at both large and small spatial scales. For example, on larger scales, forces such as fire and grazers can remove dominant plant competitors. on smaller scales, variation in resource availability (e.g. light, nutrients, water) may benefit more phenotypically plastic species. to better understand how changes in the environment, on both large and small spatial scales, I established a two part study using milkweed (Asclepias spp.) as a model system. in the first chapter, I ask how fire, large grazers, and nutrients have affected milkweed abundance over relatively long time and large spatial scales. Here I found that most milkweed species increase in abundance with burning alone but expressed species-specific responses to other treatment combinations. This indicates that milkweed species have likely experienced unique fluctuations in abundance as fire and large herbivores moved across the landscape. The second aspect of this research focuses in on a single year and relatively small spatial scales. Here, using common milkweed (A. syriaca), I ask how environmental variation shapes spatial structuring of phenotypes within fine-scale physical distance and how genotypes impact phenotypes. I found that environment, not genotype, had a relatively larger role on fine-scale phenotypic variation. Combined, these results have implications for understanding the role of large and small scale environmental variations in plant phenotypes and plant abundance

Cilengitide down-modulates invasiveness and vasculogenic mimicry of neuropilin-1 expressing melanoma cells through the inhibition of αvβ5 integrin.

During melanoma progression, tumour cells show increased adhesiveness to the vascular wall, invade the extracellular matrix (ECM) and frequently form functional channels similar to vascular vessels (vasculogenic mimicry). These properties are mainly mediated by the interaction of integrins with ECM components. Since we had previously identified neuropilin 1 (NRP-1), a coreceptor of vascular endothelial growth factor A (VEGF-A), as an important determinant of melanoma aggressiveness, aims of this study were to identify the specific integrins involved in the highly invasive phenotype of NRP-1 expressing cells and to investigate their role as targets to counteract melanoma progression. Melanoma aggressiveness was evaluated in vitro as cell ability to migrate through an ECM layer and to form tubule-like structures using transfected cells. Integrins relevant to these processes were identified using specific blocking antibodies. The αvβ5 integrin was found to be responsible for about 80% of the capability of NRP-1 expressing cells to adhere on vitronectin. In these cells αvβ5 expression level was twice higher than in low-invasive control cells and contributed to the ability of melanoma cells to form tubule-like structures on matrigel. Cilengitide, a potent inhibitor of αν integrins activation, reduced ECM invasion, vasculogenic mimicry and secretion of VEGF-A and metalloproteinase 9 by melanoma cells. In conclusion, we demonstrated that ανβ5 integrin is involved in the highly aggressive phenotype of melanoma cells expressing NRP-1. Moreover, we identified a novel mechanism that contributes to the antimelanoma activity of the αv integrin inhibitor cilengitide based on the inhibition of vasculogenic mimicry

EGFR-Mediated Carcinoma Cell Metastasis Mediated by Integrin αvβ5 Depends on Activation of c-Src and Cleavage of MUC1

Receptor tyrosine kinases and integrins play an essential role in tumor cell invasion and metastasis. We previously showed that EGF and other growth factors induce human carcinoma cell invasion and metastasis mediated by integrin αvβ5 that is prevented by Src blockade [1]. MUC1, a transmembrane glycoprotein, is expressed in most epithelial tumors as a heterodimer consisting of an extracellular and a transmembrane subunit. The MUC1 cytoplasmic domain of the transmembrane subunit (MUC1.CD) translocates to the nucleus where it promotes the transcription of a metastatic gene signature associated with epithelial to mesenchymal transition. Here, we demonstrate a requirement for MUC1 in carcinoma cell metastasis dependent on EGFR and Src without affecting primary tumor growth. EGF stimulates Src-dependent MUC1 cleavage and nuclear localization leading to the expression of genes linked to metastasis. Moreover, expression of MUC1.CD results in its nuclear localization and is sufficient for transcription of the metastatic gene signature and tumor cell metastasis. These results demonstrate that EGFR and Src activity contribute to carcinoma cell invasion and metastasis mediated by integrin αvβ5 in part by promoting proteolytic cleavage of MUC1 and highlight the ability of MUC1.CD to promote metastasis in a context-dependent manner. Our findings may have implications for the use and future design of targeted therapies in cancers known to express EGFR, Src, or MUC1

Nutrient_Data

Data from greenhouse nutrient experiment

Effects of organic farming practices in a bocage context on the wheat microbiota and its associated functions

La chute de diversité des agrosystèmes est liée à l’intensification des pratiques agricoles et à la destruction d'éléments paysagers semi naturels au cours de la révolution verte. Peu d'études ont analysé leurs conséquences sur le microbiote des plantes, pourtant responsable de nombreuses fonctions pour son hôte. Ainsi, nous avons tenté de comprendre les effets de ces deux facteurs, sur le microbiote racinaire du blé, à deux échelles spatiales. Un dispositif unique d'échantillonnage aux échelles spatiales emboîtées (locale et paysagère) a été utilisé. Dans un premier axe, nous avons montré que l’agriculture biologique et les bords de champs, plus que les haies, ont des effets positifs sur la diversité du microbiote du blé. Toutefois, les effets des facteurs locaux et paysagers sont contrastés entre les champignons et bactéries indiquant des mécanismes d’assemblage se jouant à différentes échelles spatiales. Nous avons également déterminé que l’utilisation d’intrants synthétiques (phytosanitaire et fertilisant) et les paramètres physico-chimiques du sol affectent plus particulièrement la richesse des champignons et l’équitabilité des bactéries. Les modifications de microbiote induites par ces paramètres se sont répercutées sur la production de grains du blé et sur sa résistance à l’attaque de pathogènes. Dans un deuxième axe, nous avons montré la possible utilisation des adventices comme plantes auxiliaires via leur fonction de transfert et d’enrichissement de microorganismes endosphérique à une plante cible, le blé. Nos travaux suggèrent que les pratiques agricoles biologiques et la présence d'éléments semi naturels ont un effet positif sur le maintien de la diversité du microbiote endosphérique du blé à des échelles locale et paysagère mais également que la flore adventice peut représenter un réservoir riche de microorganismes recrutable par le blé. Les facteurs paysagers peuvent donc affecter le microbiote des plantes et ont besoin d’être mieux pris en compte afin promouvoir la fertilité des agrosystèmes.The diversity loss of agrosystems is mainly caused by agricultural intensification and semi-natural landscape elements destruction during the green revolution. Few studies have investigated the consequences of diversity loss on plant microbiota, despite the numerous functions it provides for its host. Thus, we attempted to understand the effects of these two factors on the wheat root microbiota at both local and landscape spatial scales using a unique sampling design with these nested spatial scales. In a first axis, we showed that organic farming and field margins, more than hedgerows, have positive effects on the diversity of wheat microbiota. However, the effects of local and landscape factors are contrasted between fungi and bacteria, indicating assembly mechanisms playing at different spatial scales. We also determined that the use of synthetic inputs (crop protection and fertilizer) and soil physicochemical parameters affected particularly fungal richness and bacterial evenness. The microbiota modifications induced by these parameters had repercussions for the wheat grain production and for its pathogen resistance. In a second axis, we showed the possible use of weeds as auxiliary plants via their transfer and enrichment function of endospheric microorganisms to wheat as a focus plan. Our work suggests that organic farming practices and the presence of semi-natural elements have a positive effect to uphold of endopheric microbiota diversity in wheat, at local and landscape scales but also that weeds can represent a rich reservoir of microorganisms that can be recruited by wheat. Landscape factors can therefore affect plant microbiota and need to be further considered to promote agrosystem fertility

Quel est l'apport de la création d'un réseau gérontologique dans un territoire rural ? (Étude du réseau "Part-âge" dans le canton d'Antrain)

RENNES1-BU Santé (352382103) / SudocSudocFranceF

Profils et projets d'installation des internes de médecine générale bretons (sont-ils en corrélation avec les besoins de la région Bretagne en terme d'offre de soins de proximité ?)

La médecine générale connaît une crise démographique au point de ne plus pouvoir assurer un accès aux soins primaires équitable. Nous avons étudié les profils et projets d'installations des internes bretons pour voir s'ils étaient en corrélation avec les besoins de la région Bretagne en terme d'offre de soins de proximité. Une enquête descriptive a été réalisée en 2012 via un questionnaire adressé aux internes. Le taux de réponse est de 46%. 95% ont choisi délibérément la médecine générale. Après l'internat, 50% remplaceraient en libéral pendant 1 à 3 ans. 45% s'installeraient en semi-rural et 79% resteraient en Bretagne. Ils connaissent peu les modes d'exercices coordonnés et les aides à l'installation. 30% du panel travaillerait volontiers dans les zones rurales ou prioritaires. L'étude du profil des internes projetant d'exercer en milieu rural et réceptifs aux aides à l'installation pourrait servir à l'identification de médecins intéressés par un exercice dans les zones sous-dotées.General practice is undergoing a demographic crisis which results in a lack of secure and equitable access to primary care. We studied the profiles and plans of Brittany interns in order to know if they fit the need of Brittany in term of Community care delivery. We designed a descriptive survey in 2012 with a questionnaire sent to all interns. The response rate was 46%. 95% intentionally chose general practice. After their internship, 50% would chose to be locum for one to three years. 45% would chose semi-rural areas and 79% would stay in Brittany. They knew little about the ways of coordinated exercises and financial incentives. 30% would willingly work in rural and priority areas. This survey intends to target the profile of interns interested in working in rural areas as well as the ones who respond positively to financial incentives to cover underserved areas.RENNES1-BU Santé (352382103) / SudocSudocFranceF