Thesis (M.A.)--York University, 2007. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 74-77). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR29562

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Patrick M. Gaffney, College of Earth, Ocean, & Environment. Includes bibliographical references.

2 PDF files included one for title page and one for main document Title from title page PDF (University of Missouri--St. Louis, viewed February 8, 2010). Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 91-106).

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Rousseau, Ronald; Committee Member: Meredith, Carson; Committee Member: Prausnitz, Mark; Committee Member: Teja, Amyn; Committee Member: Wilkinson, Angus. Part of the SMARTech Electronic Thesis and Dissertation Collection.

The thesis presents research on the life-history polymorphism in the mite Sancassania berlesei. Males of this species are andropolymorphic: there are two distinct male phenotypes. One, the fighter, develops a third thickened leg pair, with which it kills off other fighters and males which do not exhibit a third thickened leg pair, the non-fighters. A review of the life-history of S. berlesei is given, focussing on its general biology, diet, dispersal and mating behaviour. This is followed by a review of the andropolymorphism, and the current understanding of the mechanisms underlying it. The major conclusions from the experimental work presented in this thesis are that fighters primarily develop at low population densities; though the proportion of males becoming fighters at any given density may change over time. This change is likely to be due to condition-dependence. Data is presented to illuminate these matters and a model is developed linking fighter development to the costs of being a fighter (in terms of survival) and the benefits of being a fighter (in terms of fecundity). The sex ratio in S. berlesei is 1:1, and there is no evidence of density or frequency-dependent deviations from this. A delay in food supply at maturation delays the time of maximum fecundity of females for about seven days and lowers their overall egg output. Density-dependent effects reduce the overall daily fecundity of females in higher densities. Female survival is affected by density, food present and rearing conditions. Nearly all eggs laid by S. berlesei hatch regardless of the conditions. Eggs laid in very poor conditions hatched even earlier than the average time of between day three and four. At density two, animals do synchronise their frequency, when isolated together from egg stage. Poor conditions reverse female density-dependence from convex to concave with the lowest life expectancy at intermediate densities. The trade-off between survival and fecundity is the likely cause. Amalgamating the results from the previous experiments, the influence of stochastic population dynamics on male strategy was then modelled. The results indicate that the fighter morph development rule is sensitive to the probability of low population densities arising. When low densities occur, there is a selective advantage to being a fighter. With increasing probability of lower densities, becoming a fighter is more feasible. The ESS rule changes, while in a stable high density environment a density-dependent fighter rule is never selected for. This indicates an influence of stochastic population dynamics on life-history evolution. Modelling demographic stochasticity in the fighter rule shows some buffering effect of this form of stochasticity. The fighter morph determination rule is less sensitive to environmental stochasticity with a high frequency of low densities. Using an agent based model with diploid genetics, I show that under high densities a fighter male is less successful at passing on his genes than a non-fighter. At a density of one male, the fighter gains no advantage to developing the fighter phenotype (as he is not competing with other males). In this case, the advantage may arise through future increases in density (such as through immigration or maturation of offspring). The density-dependent fighter development rule is then switched within the model from density-dependent to frequency-dependent, and the model indicates, that even under the frequency-dependent rule a possible ratio of fighters to non-fighters could exist. The system does not reach this state due to condition-dependence in reality. Following on from the findings discussed above, that morph determination has a condition-dependent component, I develop an argument that relates the observed forms of morph determination (density-dependent and frequency-dependent) in three closely related species of mites via an underlying condition-dependence. It is shown that condition-dependence is likely the linking factor between frequency and density-dependence. This is shown to be possibly a rule for all species displaying polymorphism which includes physical alterations of their bodies.

No description available.

Στην παρούσα εργασία επιχειρήθηκε η ταυτοποίηση της κρυσταλλικής φάσης της δραστικής ουσίας ρισπεριδόνη στα εμπορικά δισκία αυτής. Να σημειωθεί ότι για τη ρισπεριδόνη είναι γνωστά τρία πολύμορφα. Οι τεχνικές που χρησιμοποιήθηκαν για την υλοποίηση αυτού του σκοπού, ήταν η περίθλαση ακτίνων Χ (XRPD), η φασματοσκοπία υπερύθρου (IR) και η φασματοσκοπία Raman. Η ανάλυση με τις τρεις αυτές τεχνικές κατέδειξε ότι ενώ οι φασματοσκοπίες Raman και IR είχαν χαμηλότερα όρια ανίχνευσης, ως προς τη ρισπεριδόνη, ωστόσο δεν κατάφεραν να αναγνωρίσουν το χρησιμοποιούμενο πολύμορφο. Αυτό κατέστει εφικτό με χρήση της περίθλασης ακτίνων Χ, με τη βοήθεια της οποίας πιστοποιήθηκε ότι η ρισπεριδόνη δεν υπόκεινται σε κανενός είδους κρυσταλλική μετατροπή τόσο κατά τη διαδικασία παραγωγής του δισκίου όσο και κατά την πάροδο ενός χρονικού διαστήματος δύο ετών. / The scope of the current study was the identification of the crystal phase of an active pharmaceutical ingredient, called risperidone, in the commercial tablets. In this point it should be noticed that there are three known polymorphs for risperidone. The techniques used for the materialization of this target were X-ray Powder Diffraction (XRPD), Raman spectroscopy and Infra-red spectroscopy (IR). The analysis with these three techniques showed that although Raman and IR had lower detection limits nevertheless they did not have the ability to identify the existent polymorph. This was attained by using XRPD, by means of which it was certified that risperidone does not undergo any crystalline transformation neither during the manufacturing procedure nor during a period of two years.

T helper type--2 (Th2) immunity orchestrates responses against extracellular pathogens under normal conditions and mediates pathogenic responses against innocuous substances when dysregulated, leading to allergic disease. Among the cytokines expressed by Th2 cells, interleukin (IL)--13 has emerged as a critical effector molecule in Th2 responses and common IL13 variants are associated with allergy--related phenotypes in populations of distinct ethnic background. IL13 expression in human T cells is paralleled by extensive IL13 locus remodeling, which results in the appearance of multiple DNase I hypersensitive (HS) sites. Among these, HS4 in the distal IL13 promoter is constitutively present in both naive and polarized Th2 cells, and spans a single nucleotide polymorphism, IL13--1512AC (rs1881457), which is common and strongly associated with total serum IgE levels. This dissertation combines in vitro and ex vivo approaches to characterize the role of HS4 in the regulation of IL13 gene expression and to provide novel insights into the mechanisms that underlie the association between IL13--1512AC and allergic disease.The results showed that HS4 acts as a novel cis--acting element that up--regulates IL13 transcription in activated Th2 cells. The enhancing activity of HS4 mapped within the 3' end of this element and was dependent on binding/recruitment of the transcription factors NF90 and NF45. Moreover, the IL13--1512C risk allele significantly enhanced HS4--dependent IL13 expression by creating a binding site for the transcription factor Oct--1. The increased expression of the --1512C allele was dependent on endogenous levels of Oct--1. Collectively, these results illustrate how a functional variant in an important regulatory element may modulate susceptibility to a common complex disease.

The mechanisms behind speciation have been subject of debate for centuries. The presence of resource polymorphism has been discovered to play a significant part in this process, and has been proven to induce phenotypic and genetic divergence. Although resource polymorphism has been intensely studied during the last few decades, there is a gap of information as to why this can be observed in some systems but not in others. Recent studies of European whitefish (Coregonus lavaretus) in Scandinavian lakes have shown that predation, in this case by Northern pike (Esox lucius), could be the factor that induces resource polymorphism. European whitefish is known to diverge into several ecomorphs in Scandinavian lakes, but only in the presence of pike. Divergence is assumed to be caused by the size selectivity of pike, and the following niche separation and eventually reproductive isolation. In this study, pike prey selectivity was studied in the field through sample fishing using hooks baited with whitefish of different sizes. The hypothesis was that pike prefers smaller prey over larger and mainly hunts in the littoral zone. This should causes smaller whitefish ecomorphs to be prone to predation in the littoral and thus utilize refuge spawning grounds with low predation pressure. However, no pike were caught on whitefish spawning grounds, and fishing at two additional pike rich sites displayed a preference towards medium-sized whitefish (p < 0.05). This indicates a size selectivity, although further and improved studies would be required to answer the question of the pike’s role in resource polymorphism.