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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.
11

Genetic Analysis of Development and Behavior in Hypoxia and Cellular Characterization of Anoxia Induced Meiotic Prophase Arrest in Caenorhabditis Elegans

Little, Brent Ashley 08 1900 (has links)
It was hypothesized that chronic hypoxia will affect various biological processes including developmental trajectory and behavior. To test this hypothesis, embryos were raised to adulthood in severe hypoxic environments (0.5% O2 or 1% O2, 22°C) and analyzed for survival rate, developmental progression, and altered behaviors. Wildtype hermaphrodites survive chronic hypoxia yet developmental trajectory is slowed. The hermaphrodites raised in chronic hypoxia had different phenotypes in comparison to the normoxic controls. First, hermaphrodites exposed to chronic hypoxia produced a significantly lower number of embryos and had a slight increase in male progeny. This suggests that chronic hypoxia exposure during development affects the germline. Second, animals raised in chronic hypoxia from embryos to young adults have a slight increase in lifespan when re-exposed to a normoxic environment, indicating that chronic hypoxia does not negatively decrease lifespan. Finally, hermaphrodites that were raised in hypoxia will lay the majority of their eggs on the area of the agar plate where the bacterial lawn is not present. This is in contrast to animals in normoxia, which lay the majority of their eggs on the bacterial lawn. One hypothesis for this hypoxia-induced egg-laying behavior is that the animal can sense microenvironments in hypoxia. To examine if various pathways are involved with chronic-hypoxia responses RNAi and assayed genetic mutants were used. Specifically, genetic mutations affecting oxygen sensing (egl-9), aerotaxis (npr-1), TFG-ß signaling (dbl-1, daf-7) and predicted oxygen-binding proteins (globin-like genes) were phenotypically analyzed. Results indicate that mutations in several of these genes (npr-1, dbl-1) resulted in a decrease in hypoxia survival rate. A mutation in egl-9 also had a detrimental affect on the viability of an animal raised in chronic hypoxia. However, a similar phenotype was not observed in the vhl-1 mutation indicating that the phenotype may not be due to a mere increase in HIF-1 levels, per se. A mutation in the globin-like gene (glb-13(tm2825)) suppressed the hypoxia-induced egg-laying phenotype. That is, the glb-13(tm2825) animal raised in chronic hypoxia laid eggs on the bacterial lawn at a significantly higher rate in comparison to wildtype controls, thus suggesting that globin-like molecules may be involved with the sensing of microenvironments. Together, this research lays the foundation for understanding the implications of chronic hypoxia in developing organisms.
12

The role of zic genes in zebrafish development

Joynes, Rachel Anne January 2011 (has links)
No description available.
13

Ips typographus (Coleoptera: Scolytinae) as an invader: Analysis and modelling in Belgium

Piel, Frédéric 18 December 2006 (has links)
Nos recherches abordent, par une approche multidisciplinaire, l’écologie spatiale et la dynamique d’invasion du ravageur de l’épicéa Ips typographus (Coleoptera : Scolytinae) en Belgique. Bien que cette espèce ne puisse pas être considérée au sens strict comme invasive en Belgique où elle est implantée depuis le milieu du 19ème siècle, de très vraisemblables introductions de souches exotiques en provenance de Russie et des Pays baltes, en font un modèle exceptionnel pour l’étude de ces processus. Une analyse en milieu urbain, suivant des transects centre-périphérie, a d’une part suggéré l’introduction probable de ces souches exotiques et d’autre part permis d’étudier ce ravageur forestier dans un milieu qui lui est a priori défavorable. Il en résulte que, malgré un effet de la structure urbaine sur l’abondance du scolyte, sa présence a été observée partout, y compris dans les zones densément bâties du centre de Bruxelles. Cela suggère, en terme de dispersion, que cette espèce est capable d’atteindre des arbres isolés, et en terme d’infestation, que tout épicéa constitue un hôte potentiel tant en milieu forestier qu’en milieu ouvert ou urbain. Une étape préliminaire dans l’estimation des risques liés aux invasions biologiques est d’effectuer une analyse de filière, afin d’analyser les différentes voies d’introduction et les risques liés aux pays d’origine des marchandises importées. Sur base de l’analyse de l’ensemble des sources de données statistiques disponibles, nous avons déterminé l’ampleur du commerce de grumes d’épicéa entre l’est de l’Europe et la Belgique, les modes de transport utilisés, les origines et destinations des grumes, ainsi que la variabilité de la localisation et du nombre des différents points d’entrée de ces marchandises sur le territoire belge d’une année à l’autre, depuis le début des importations en 1996. Notre analyse illustre les difficultés inhérentes à ce genre d’étude, particulièrement au niveau de la disponibilité des données à une échelle appropriée. Par une approche de modélisation, nous avons envisagé différents scénarios de dispersion de souches introduites d’Ips typographus afin d’estimer l’expansion de celles-ci en Belgique. Notre modèle a permis de mettre en évidence l’importance de la bonne connaissance de certains paramètres biologiques caractétistiques de l’espèce étudiée (phénologie, capacité de dispersion, taux de croissance). Par ailleurs, les volumes d’importation et la localisation des points d’entrée des marchandises semblent jouer un rôle secondaire. Enfin, nous avons utilisé des marqueurs génétiques afin d’essayer de prouver l’introduction de souches russes et baltes du scolyte de l’épicéa en Belgique. Des échantillons ont été collectés dans neuf pays européens ainsi que sur l’ensemble du territoire wallon. La structure génétique observée n’a pas permis de mettre en évidence une différenciation entre les populations de l’est et de l’ouest de l’Europe. La présence d’haplotypes communs à l’est et à l’ouest rejoint l’hypothèse d’une homogénéisation des populations en relation avec le large pouvoir de dispersion du typographe. Cependant, un grand nombre de mutations a été observé entre 2 haplotypes. Des introductions d’origines lointaines telles que la Sibérie ne sont donc pas improbables. Les résultats détaillés de chacune de ces études sont développés dans les différents articles constituant cette thèse. La discussion générale met ceux-ci en relation et aborde les perspectives découlant de nos recherches.
14

CHALLENGES IN ESTIMATING SIZE AND CONSERVATION OF BLACK BEAR IN WEST-CENTRAL FLORIDA

Brown, Joshua Hager 01 January 2004 (has links)
The Greater Chassahowitkza Ecosystem black bear (Ursus americanus floridanus) population of west-central Florida is likely to be the smallest documented population of the species. It has experienced almost no recruitment since 1997 and exhibits behavior that appears to be a response to human activities. The local diet is dominated by the fruit of saw palmetto and sabal palm, species that exhibit patchy distributions and irregular mast production. These food supplies are often separated by busy highways that have killed 6 bears since 1997, 21% of known individuals. Motion-activated camera surveys suggest that the bear population is declining in this rapidly urbanizing part of Florida; results of the 2002 survey estimated 28 " 18 bears in the GCE, while 2003 estimates recorded 12 " 7 individuals (Lincoln-Petersen). Additionally, blood and hair samples suggest the genetics of this population are extremely depauperate. I recommend a different fire regime in palm-dominated habitats, restoring landscape connectivity to nearby bear populations, and supplementation of the population. Because the threats to this population are manifold and its immediate future is in doubt, a combination of conservation and management tools will be required to prevent extinction of this isolated black bear population.
15

Simulation of Mathematical Models in Genetic Analysis

Patel, Dinesh Govindlal 01 January 1964 (has links)
In recent years a new field of statistics has become of importance in many branches of experimental science. This is the Monte Carlo Method, so called because it is based on simulation of stochastic processes. By stochastic process, it is meant some possible physical process in the real world that has some random or stochastic element in its structure. This is the subject which may appropriately be called the dynamic part of statistics or the statistics of "change," in contrast with the static statistical problems which have so far been the more systematically studied. Many obvious examples of such processes are to be found in various branches of science and technology, for example, the phenomenon of Brownian Motion, the growth of a bacterial colony, the fluctuating numbers of electrons and protons in a cosmic ray shower or the random segregation and assortment of genes (chemical entities responsible for governing physical traits for the plant and animal systems) under linkage condition. Their occurrences are predominant in the fields of medicine, genetics, physics, oceanography, economics, engineering and industry, to name only a few scientific disciplines. The scientists making measurements in his laboratory, the meteriologist attempting to forecast weather, the control systems engineer designing a servomechanism (such as an aircraft or a thermostatic control), the electrical engineer designing a communication system (such as the radio link between entertainer and audience or the apparatus and cables that transmit messages from one point to another), economist studying price fluctuations in business cycles and the neurosurgion studying brain wave records, all are encountering problems to which the theory of stochastic processes may be relevant. Let us consider a few of these processes in a little more detail. In statistical physics many parts of the theory of stochastic processes were developed in correlation with the study of fluctuations and noise in physical systems (Einstein, 1905; Smoluchowski, 1906; and Schottky, 1918). Consequently, the theory of stochastic processes can be regarded as the mathematical foundation of statistical physics. The stochastic models for population growth consider the size and composition of a population which is constantly fluctuating. These are mostly considered by Bailey (1957), Bartlett (1960), and Bharucha-Reid (1960). In communication theory a wide variety of problems involving communication and/or control such as the problem of automatic tracking of moving objects, the reception of radio signals in the presence of natural and artificial disturbances, the reproduction of sound and images, the design of guidance systems, the design of control systems for industrial processes may be regarded as special cases of the following general problem; that is, let T denote a set of points in a time axis such that at each point t in T an observation has been made of a random variable X(t). Given the observations [x(t), t fT] and a quantity Z related to the observation, one desires to from in an optimum manner, estimates of, and tests of hypothesis about Z and various functions h(Z).
16

Genetické zhodnocení siků (\kur{Cervus nippon} spp.) z ochranářského hlediska

MATĚJKOVÁ, Adéla January 2018 (has links)
This thesis is focused on genetic evaluetion of Cervus nippon komplex and particulary on Cervus nippon pseudaxi and cervus nippon taiouanus kept i European ex situ instituion
17

Reverse genetic analysis of gene Pp1s148_40v6 in Physcomitrella patens : an AtMAX2 orthologue?

De Villiers, Ruan Morne 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The plant metabolite, strigolactone, has recently gained the status of phytohormone as the result of several studies that implicated its role in plant architecture. These studies would characteristically rely on the use of mutants, such as the rms lines that were generated in peas, that shared several characteristics. This method allowed for the identification of several genetic component of the shared pathway. It is now known that the biosynthesis of strigolactone is dependent on the sequential action of an isomerase (D27) and two carotenoid cleavage deoxygenases (CCD7 and CCD8). Furthermore, it is known that strigolactone perception is localised to the plant nucleus, where it interacts with an α/β-fold hydrolase (D14) which would concomitantly binds to target proteins. The F box protein (MAX2) is able to recognize this proteïen complex. Through a MAX2 dependent mechanism the target protein becomes tagged for proteolysis. However, this model, though intricate, has only really been shown in higher plants. The model bryophyte, Physcomitrella patens, serves as a useful tool in genetic studies due to its predisposition for homologous recombination. More recently it has also gained interest in studies pertaining to strigolactones, which has led to the generation of a Ppccd8Δ mutant. Compared to the wild type, the Ppccd8Δ line produces more protonemal tissue. Furthermore, exogenous strigolactones have also been shown to inhibit colony expansion. Here we shown that there is only a single candidate gene, PpMAX2, present in the P. patens genome that could serve as a homologue for the Arabidopsis thaliana MAX2. Furthermore, we show that a recombinant GFP:PpMAX2 localises to the nucleus of P. patens cells. A Ppmax2:: mutant was generated which, unexpectedly, did not show the phenotype of Ppccd8Δ. Ppmax2:: has an apparent inability to produce protonema and appears to rather dedicate its growth to the production of gametophores. A double mutant, Ppccd8Δ max2Δ was generated which also displayed the characteristic phenotype of Ppmax2::. It seems therefore that the activity of PpMAX2 is able to override that of PpCCD8. By employing a GUS reporter system, we showed that the promoter, PPpMAX2, is predominantly active within gametophore tissues. Taken together, these results suggest that the activity of PpMAX2 facilitates the transition of gametophore tissue to protonema tissue. Although exogenous strigolactones did not appear to affect the growth of the Ppmax2:: line as it did the PpWT or Ppccd8Δ lines, those responses that have been ascribed to strigolactones to date have mostly been observed in protonemal tissue. We therefore suspect that any strigolactone response that might have been elicited in Ppmax2:: would have been masked by its phenotype of predominantly protonemal tissue. We are therefore hesitant to make any sweeping statements in regards to the role PpMAX2 might have in strigolactone perception in P. patens. However, though we suspect that PpMAX2 might not be a true functional homologue for the characterised MAX2 homologues from higher plants, we suspect that it may well be the ancestral predecessor of MAX2. / AFRIKAANSE OPSOMMING: Strigolaktoon is ‘n metaboliet wat deur plante vervaardig word en is redelik onlangs as ’n fitohormoon geklassifiseer. Die klassifikasie as fitohormoon is die gevolg van verskeie studies wat strigolaktoon se rol in die plantstruktuur beklemtoon het. In hierdie studie is daar gebruik gemaak van mutante, soos onderandere die rms lyne, wat gegenereer is in ertjies, wat verskeie kenmerke deel. Sodoende is verskeie komponente van ’n gedeelde molekulêre padweg geïdentifiseer. Daar word tans verstaan dat die sintese van strigolaktoon afhanklik is van die stapsgewyse aksies van ’n isomerase (D27) en twee karotenoïedklewingsdeoksigenases (CCD7 en CCD8). Verder is dit bekend dat strigolaktoon waargeneem word in die plant nukleus deur te assosieer met ’n α/β-vou-hidrolase (D14) wat vervolgens met teikenproteïene bind. Die kompleks word deur ’n F-boks proteïen (MAX2) herken wat daartoe lei dat die teikenproteïen gemerk word vir proteolise; altans, dit is tans die model wat vir hoër plante aanvaar word. Die model briofiet, Physcomitrella patens, word dikwels aangewend in genetiese studies weens dit ’n hoër vatbaarheid vir homoloë rekombinasie het. Om P. patens te benut in navorsing wat die rol van strigolaktoon ondersoek is ook voordelig, aangesien daar reeds ’n Ppccd8Δ mutant beskikbaar is. In vergelyking met die wilde tipe, produseer Ppccd8Δ meer protonemale weefsel en blyk dit dat strigolaktoon die vermoë het om kolonie verspreiding te bekamp. Hier wys ons dat daar ’n enkele kandidaat geen, PpMAX2, in die genoom van die P. patens teenwoordig is wat as ’n homoloog vir die Arabidopsis thaliana MAX2 kan dien. Verder wys ons dat ’n rekombinante GFP:PpMAX2 proteïen wel na die selkern van P. patens selle lokaliseer. ’n Ppmax2:: mutant is gegenereer wat, onverwags, nie die fenotipe van Ppccd8Δ vertoon het nie. Ppmax2:: het ’n onvermoë om protonema te produseer en wy groei eerder aan die produksie van gametofiete. ’n Dubbele mutant, Ppccd8Δ max2Δ, is gegenereer wat ook die fenotipe van Ppmax2:: vertoon het; dus kom ons tot die gevolgtrekking dat die aktiwiteit van PpMAX2 dié van PpCCD8 oorheers. Deur gebruik te maak van ’n GUS verklikkersisteem kon ons aflei dat die aktiwiteit van die PPpMAX2 promotor hoofsaaklik tot die uitdrukking van PpMAX2 in gametofiet weefsel lei. Dit is moontlik dat die aktiwiteit PpMAX2 dus die oorgang van gametofoor weefsel na protonema weefsel te weg bring. Alhoewel strigolaktoon nie die groei van die Ppmax2:: lyn beïnvloed soos vir die PpWT of Ppccd8Δ lyne nie, vermoed ons dat die reaksie slegs in die protonemale weefsel waargeneem sal word. Daar kan tans nie met absolute sekerheid gesê word of PpMAX2 enigsins verbonde met strigolaktoon persepsie in mos is nie, tog vermoed ons dat PpMAX2 ’n primitiewe voorloper vir die gekarakteriseerde MAX2 homoloë van die hoër plante is.
18

Scalable, modular, integrated genetic analysis systems

Bidulock, Allison Christel Elizabeth Unknown Date
No description available.
19

An Application of Armitage Trend Test to Genome-wide Association Studies

Scott, Nigel A 17 July 2009 (has links)
Genome-wide Association (GWA) studies have become a widely used method for analyzing genetic data. It is useful in detecting associations that may exist between particular alleles and diseases of interest. This thesis investigates the dataset provided from problem 1 of the Genetic Analysis Workshop 16 (GAW 16). The dataset consists of GWA data from the North American Rheumatoid Arthritis Consortium (NARAC). The thesis attempts to determine a set of single nucleotide polymorphisms (SNP) that are associated significantly with rheumatoid arthritis. Moreover, this thesis also attempts to address the question of whether the one-sided alternative hypothesis that the minor allele is positively associated with the disease or the two-sided alternative hypothesis that the genotypes at a locus are associated with the disease is appropriate, or put another way, the question of whether examining both alternative hypotheses yield more information.
20

Development of a high-frequency in vivo transposon mutagenesis system for cyanobacteria and establishment of the forward genetic analysis of the Chl d-dominated cyanobacterium, Acaryochloris marina by use of the system / シアノバクテリアにおける高頻度なin vivoのトランスポゾンタギング系の開発およびその系を利用したChl dを利用するシアノバクテリア、Acaryochloris marinaにおける順遺伝学的解析の確立

Watabe, Kazuyuki 23 March 2015 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第19069号 / 人博第722号 / 新制||人||173(附属図書館) / 26||人博||722(吉田南総合図書館) / 32020 / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)准教授 土屋 徹, 教授 宮下 英明, 教授 川本 卓男 / 学位規則第4条第1項該当

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