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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Apport de l'analyse chromosomique sur différents microréseaux d'ADN dans l'identification de nouvelles mutations et la caractérisation de gènes candidats impliqués dans la déficience intellectuelle / Contribution of chromosome analysis on different DNA Micro-Arrays in the identification of novel mutations and characterization of candidate genes involved in intellectual disability

Huynh, Minh Tuan 15 November 2013 (has links)
Anomalies de structure du génome et Déficience Intellectuelle : Recherche des gènes candidats de Déficience intellectuelle en utilisant l'analyse chromosomique sur microréseau d'ADN pangénomique 180K et l'analyse chromosomique sur microréseau d'ADN de haute résolution 1M ciblée des gènes candidats de Déficience intellectuelle. L'analyse chromosomique sur microréseau d'ADN (ACM) de haute résolution est une innovation technologique puissante afin de détecter les aberrations chromosomiques concernant les variations du nombre de copies. En utilisant l'ACM 180K, l'ACM 1M et la PCR quantitative, nous avons identifié les 5 variations du nombre de copies (CNV) intragéniques pathogènes de novo impliquant les gènes : RUNX1T1, KIAA1468, FABP7, ZEB2 (syndrome de Mowat-Wilson) et ANKRD11 (syndrome de KBG). Les 5 patients ayant une DI et une dysmorphie faciale. L'ACM 180K a révélé une délétion d'une taille de 92 kb emportant le gène KIAA1468 candidat pour le syndrome de West chez un enfant de 3 ans présentant une DI sévère et une encéphalopathie épileptique infantile précoce. Le criblage des mutations du gène KIAA1468 a été réalisé chez 35 patients atteints de syndrome de West. Un variant intronique c.2761-7 T>C et un variant faux-sens hérité de la mère c.3547 G>A avec signification clinque inconnue ont été identifiés. En utilisant des approches par l'ACM 1M de haute résolution chez 45 patients atteints de DI idiopathique modérée à sévère, un seul CNV causal a été identifié, une délétion intragénique d'une taille de 28.37 kb du gène ZEB2. Notre étude confirme une fréquence très faible des délétions/duplications intragéniques avec la détection d'une seule aberration chromosomique (1/45). En conclusion, si la fréquence des mutations ponctuelles est élevée, nous avons également souligné l'application de la technique de séquençage à haut débit avec un rendement diagnostique jusqu'à 45%-55% des cas de DI sévère idiopathique chez lesquels aucun CNV n'a été détecté sur ACM / Chromosomal structural abnormalities and Intellectual Disability : In search of intellectual disability candidate genes by using pangenomic comparative genomic hybridization 180 K and high resolution comparative genomic hybridization 1M targeting intellectual disability candidate gene.High resolution microarray-based comparative genomic hybridization (a-CGH) has been a powerful technical innovation in order to detect submicroscopic chromosomal aberrations related to copy number variations. By using a-CGH 180K, 1M high resolution a-CGH and quantitative PCR, we have identified 5 pathogenic intragenic copy number variations (CNVs) de novo : RUNX1T1, KIAA1468, FABP7, ZEB2 (Mowat-Wilson syndrome) and ANKRD11 (KBG syndrome). All five patients had intellectual disability (ID) and facial dysmorphism. Interestingly, a-CGH 180K has revealed a 92 kb deletion of a candidate gene KIAA1468 for West syndrome in a 3 year-old boy with severe ID and early infantile epileptic encephalopathy. Mutational screening for candidate gene KIAA1468 was performed in 35 patients with West syndrome. An intronic variant c.2761-7 T>C and a non synonymous maternally inherited variant c.3547 G>A with unknown clinical significance were identified. By using 1M high-resolution a-CGH approach in 45 patients presenting moderate to severe idiopathic ID, only one causal CNV was identified, a 28.37 kb intragenic ZEB2 deletion. Our study has confirmed the low frequency of intragenic deletion/duplication with the detection of only one chromosomal aberration (1/45). In conclusion, providing that the high frequency of intragenic point mutation, we also stressed the application of next-generation sequencing technology with 45-55% diagnostic yield in patients with idiopathic severe ID in case of no apparent CNV(s) on high-resolution a-CGH
2

Nitrogen Use Efficiency of Polymer-Coated Urea

Ransom, Curtis J. 19 March 2014 (has links) (PDF)
Plants require N to complete their life cycle. Without adequate concentration of N, crops will not produce their potential yields. For turfgrass systems, N fertilizer application allows for the maintenance of functional, aesthetic, and recreational properties. However, fertilizer mismanagement is common and leads to N pollution in the environment. Controlled-release and slow-release fertilizers can enhance nitrogen (N)-use efficiency, reduce N pollution, minimize the need for repeated fertilizer applications, and reduce turfgrass shoot growth and associated costs. In order to evaluate the effectiveness of these fertilizers in the Intermountain West, research is needed. The timing of N release was evaluated for seven urea fertilizers: uncoated, sulfur coated (SCU), polymer-sulfur coated (PSCU), and four polymer-coated (PCU) with release timings of 45, 75, 120, and 180 d estimated release. These products were placed on bare soil, a Kentucky bluegrass (Poa pratensis L.) thatch layer, and incorporated into soil. These three placement treatments were replicated to allow for enough samples to be placed in two locations. The first was outside in a field to represent field conditions with diurnal fluctuating temperatures and the second was placed in a storage facility to replicate laboratory conditions with static diurnal temperatures. The PCU prills incorporated into soil under field conditions generally released N over the estimated release period. However, when applied to bare soil or thatch, N from PCU had 80% or greater N release by 35 d after application regardless of expected release time. Fertilizers under laboratory conditions had minimal N release despite having similar average daily temperatures, suggesting that fluctuating temperatures impact N release. The PSCU and SCU treatments were no different from uncoated urea, showing no slow release properties for this particular product. Spring-applied N fertilizer trials were conducted over two years to determine the optimal N rate for Kentucky bluegrass. Similar PCU120 products were applied at 50, 75, and 100% of the recommended full rate, while also being compared to an unfertilized control and urea applied either all at once or split monthly. Spring-applied PCU showed minimal initial N response while urea applied all at once resulted in an initial spike of N uptake. Once PCU began to release N, there was minimal difference for all rates compared to urea split monthly for biomass growth, verdure, and shoot tissue N. Although at the 50% rate, there were a few sampling dates with slower growth and lower verdure. The decrease in verdure at this low rate was slight, and it is recommended that PCU could be applied effectively at a reduced rate between 50 and 75%. Although for better results, additional quick release N is required to compensate for early season lag in N release.
3

Environmental Implications of Polymer Coated Urea

LeMonte, Joshua James 19 April 2011 (has links) (PDF)
Nitrogen is an essential plant nutrient in the biosphere. Although N is necessary and beneficial for life, it is also a common pollutant in the atmosphere and hydrosphere as it may be lost to the atmosphere as ammonia (NH3) or nitrous oxide (N2O) gases or to groundwater as nitrate (NO3-) following fertilization. Polymer coated urea (PCU) is one type of N fertilizer which uses temperature-controlled diffusion to control N release to better match plant demand and mitigate environmental losses of N. The objectives of this project were to simultaneously compare the effects of PCU on gaseous (as N2O and NH3) and aqueous (as NO3-) N losses to the environment as compared to uncoated urea in grass systems over the entire PCU N-release period and to investigate the viability of photoacoustic infrared spectroscopy as a method to ascertain N2O and NH3 losses following fertilization. Two field studies were conducted on established turfgrass sites with a mixture of Kentucky bluegrass (KBG; Poa pratensis L.) and perennial ryegrass (PRG; Lolium perenne L.) in sand (Site 1) and loam (Site 2) soils. Each study compared an untreated control to 200 kg N ha-1 applied as either uncoated urea or PCU (Duration 45 CR®). In these studies PCU reduced NH3 emissions by 41-49% and N2O emissions by 16-54%, while improving growth and verdure. Leachate NO3- observations were inconclusive at each site. Glasshouse studies were conducted to compare N2O and NH3 emissions from PCU and uncoated urea to an untreated control utilizing a non-static, non-flow-through chamber in conjunction with photoacoustic infrared spectroscopy (PAIRS) for gas collection and analysis. Three short-term studies (17-21 d) were done with sand, sandy loam, and loam soils and a full-term (45 d) study with the loam soil. Each study was done in maize (Zea mays L.). Volatilization of ammonia was reduced by 72% and 22% in the sandy loam and loam soils, respectively, in 2008-2009 and by 14% in the loam in 2010. Evolution of N2O was reduced by 42% and 63% in the sandy loam and loam soils in 2008-2009 and by 99% in the loam in 2010. Overall, PCU decreased gaseous losses of N following fertilization while providing a steady supply of N to the plant. The utilization of PAIRS is a viable analysis method which gives higher temporal resolution analysis than is typically reported. These considerable decreases in environmental losses of N are major steps toward conserving natural resources and mitigating the negative environmental impacts associated with N fertilization in grass systems.

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