11 resultados para Chlamydia-like organism
em Brock University, Canada
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The study centers on the power of Right-Wing Authoritarianism (RWA) and Social Dominance Orientation (SDO) as predictors of prejudice against stereotypical and nonstereotypical homosexuals under the threat of death and the threat of uncertainty. Right-wing authoritarianism (RWA) is an individual difference variable that measures the tendency for individuals to unquestionably follow those perceived to be authorities. Social Dominance Orientation (SDO) is an individual difference variable that measures the degree to which an individual prefers inequality among social groups. The RWA and SDO Scales are considered to be two of the strongest predictors of prejudice, such as prejudice against homosexuals. The study focuses on the unique predictive power of these two variables in predicting prejudice against homosexuals. The study also examines the role of situational threat in prejudice, specifically the threat of death (mortality salience) and the threat of uncertainty (uncertainty salience). Competing predictions from theories involving the threat of death (Terror Management Theory) and the threat of uncertainty (Uncertainty Management Theory) are also tested. The preference for expected information in the form of stereotypes concerning male homosexuals (that is, a stereotypical or non-stereotypical homosexual) were tested. The difference between the predictive power ofRWA and SDO was examined by measuring how these variables predict liking of a stereotypical or non-stereotypical homosexual under the threat of death, the threat of uncertainty, or a control condition. Along with completing a measure for RWA and a measure for SDO, participants were asked to think of their own death, of their being uncertain or about watching television then were asked to read about a week in the life of either a stereotypical or non-stereotypical male homosexual. Participants were then asked to evaluate the individual and his essay. Based on the participants' evaluations, results from 180 heterosexual university students show that RWA and SDO are strong predictors for disliking of a stereotypical homosexual under the threat of uncertainty and disliking of a non-stereotypical homosexual under the threat of death. Furthermore, however, results show that RWA is a particularly strong predictor of disliking of a stereotypical homosexual under the threat of uncertainty, whereas SDO is an exceptionally strong predictor of disliking of the non-stereotypical homosexual under the threat of death. This further adds to the notion that RWA and SDO are indeed unique predictors of prejudice. Implications are also explored, including the fact that the study simuhaneously examined the role of individual difference variables and situational threat variables, as well as exploratory analysis on Dominating Authoritarians.
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Early in his landmark ecocritical book The Comedy of Survival, Joseph Meeker develops an intriguing hypothesis about human behaviour. He remarks the species Homo sapiens tend to behave like an invasive or pioneering organism, entering a bio-geographical region and aggressively outcompeting all other species for space and resources. Moreover, he suggests, human cultural traditions, at least in the West, have reinforced such behaviour, continually insisting that the impulses he describes are both necessary and right. While Meeker's work goes on to assess a number of literary works in both the tragic and comic modes, his work never fully explores this hypothesis in the context of human pioneers; that is, there is no ~xploration o( how these themes manifest themselves within our culture and what role they might play in the culture of specific pioneering groups. This project is an attempt at just such an analysis, examining the validity of Meeker's hypothesis through a case study of settler literature in Upper Canada/Ontario between the . years 1800-1867. It explores Meeker's work within three main areas: first, Chapter Two situates his book historically within the field of ecocriticism, showing what came before and the explosion of ecocritical inquiry that followed its release. This chapter also delves into the rift between the natural sciences and humanities, arguing that a move towards deeper interdisciplinarity is r:tecessary for the future. Chapter Three examines the biological and ecological ground on which Meeker rests his hypothesis through exploring evolutionary biology as well as invasive and pioneer species behaviour. Lastly, Chapter Four examines how these ecological principles are manifested in the writings of early Canadian settlers, suggesting that Meeker's hypothesis indeed finds itself on stable footing.
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The anther smut fungus U stilago violacea has been developed as an important model organIsm for genetic, morphological and physiological studies. Valuable information on the nuclear genetics on U stilago violacea has been obtained in the last 20-25 years. However, in this organism almost nothing is known about mitochondria which make up an important aspect of the fungal genetic system. One fundamental aspect, mitochondrial inheritance, was addressed by this investigation. Mitochondrial DNA (mtDNA) of U. violacea was purified and restriction fragments cloned. MtDNA restriction fragment length polymorphisms (RFLPs) were identified among different isolates and were used as genetic markers for studying mitochondrial inheritance in crosses between polymorphic isolates. Matings of the yeast-like haploid cells of opposite mating types resulted in dikaryons containing mitochondria from both parents. The dikaryons were induced to form hyphae and then allowed to revert to haploid growth, resulting 1ll a colony that is bisectored for the two nuclear types. Both nuclear-type progeny of each cross were examined for parental mitochondrial type: Either mitochondrial type was observed 1ll the progeny. Thus, mitochondrial inheritance is biparental in this organism. The recovery of both mitochondrial types in the progeny was non-random. In progeny with the nuclear genotype of the al mating type parent mitochondria from both parents were inherited equally well. However, 1ll progeny with the a2 mating type, mitochondria were inherited almost exclusively (94%) from the a2 parent.
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Transcribed on front paste-down: W.G. Phelps Oct. 29 1890.
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Neuropeptides are the largest group of signalling chemicals that can convey the information from the brain to the cells of all tissues. DPKQDFMRFamide, a member of one of the largest families of neuropeptides, FMRFamide-like peptides, has modulatory effects on nerve-evoked contractions of Drosophila body wall muscles (Hewes et aI.,1998) which are at least in part mediated by the ability of the peptide to enhance neurotransmitter release from the presynaptic terminal (Hewes et aI., 1998, Dunn & Mercier., 2005). However, DPKQDFMRFamide is also able to act directly on Drosophila body wall muscles by inducing contractions which require the influx of extracellular Ca 2+ (Clark et aI., 2008). The present study was aimed at identifying which proteins, including the membrane-bound receptor and second messenger molecules, are involved in mechanisms mediating this myotropic effect of the peptide. DPKQDFMRFamide induced contractions were reduced by 70% and 90%, respectively, in larvae in which FMRFamide G-protein coupled receptor gene (CG2114) was silenced either ubiquitously or specifically in muscle tissue, when compared to the response of the control larvae in which the expression of the same gene was not manipulated. Using an enzyme immunoassay (EIA) method, it was determined that at concentrations of 1 ~M- 0.01 ~M, the peptide failed to increase cAMP and cGMP levels in Drosophila body wall muscles. In addition, the physiological effect of DPKQDFMRFamide at a threshold dose was not potentiated by 3-lsobutyl-1-methylxanthine, a phosphodiesterase inhibitor, nor was the response to 1 ~M peptide blocked or reduced by inhibitors of cAMP-dependent or cGMP-dependent protein kinases. The response to DPKQDFMRFamide was not affected in the mutants of the phosholipase C-~ (PLC~) gene (norpA larvae) or IP3 receptor mutants, which suggested that the PLC-IP3 pathway is not involved in mediat ing the peptide's effects. Alatransgenic flies lacking activity of calcium/calmodul in-dependent protein kinase (CamKII showed an increase in muscle tonus following the application of 1 JlM DPKQDFMRFamide similar to the control larvae. Heat shock treatment potentiated the response to DPKQDFMRFamide in both ala1 and control flies by approximately 150 and 100 % from a non heat-shocked larvae, respectively. Furthermore, a CaMKII inhibitor, KN-93, did not affect the ability of peptide to increase muscle tonus. Thus, al though DPKQDFMRFamide acts through a G-protein coupled FMRFamide receptor, it does not appear to act via cAMP, cGMP, IP3, PLC or CaMKl1. The mechanism through which the FMRFamide receptor acts remains to be determined.
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Printed for Russell, Cutler and Co.
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The plant family Apocynaceae accumulates thousands of monoterpene indole alkaloids (MIAs) which originate, biosynthetically, from the common secoiridoid intermediate, strictosidine, that is formed from the condensation of tryptophan and secologanin molecules. MIAs demonstrate remarkable structural diversity and have pharmaceutically valuable biological activities. For example; a subunit of the potent anti-neoplastic molecules vincristine and vinblastine is the aspidosperma alkaloid, vindoline. Vindoline accumulates to trace levels under natural conditions. Research programs have determined that there is significant developmental and light regulation involved in the biosynthesis of this MIA. Furthermore, the biosynthetic pathway leading to vindoline is split among at least five independent cell types. Little is known of how intermediates are shuttled between these cell types. The late stage events in vindoline biosynthesis involve six enzymatic steps from tabersonine. The fourth biochemical step, in this pathway, is an indole N-methylation performed by a recently identified N-methyltransfearse (NMT). For almost twenty years the gene encoding this NMT had eluded discovery; however, in 2010 Liscombe et al. reported the identification of a γ-tocopherol C-methyltransferase homologue capable of indole N-methylating 2,3-dihydrotabersonine and Virus Induced Gene Silencing (VIGS) suppression of the messenger has since proven its involvement in vindoline biosynthesis. Recent large scale sequencing initiatives, performed on non-model medicinal plant transcriptomes, has permitted identification of candidate genes, presumably involved, in MIA biosynthesis never seen before in plant specialized metabolism research. Probing the transcriptome assemblies of Catharanthus roseus (L.)G.Don, Vinca minor L., Rauwolfia serpentine (L.)Benth ex Kurz, Tabernaemontana elegans, and Amsonia hubrichtii, with the nucleotide sequence of the N-methyltransferase involved in vindoline biosynthesis, revealed eight new homologous methyltransferases. This thesis describes the identification, molecular cloning, recombinant expression and biochemical characterization of two picrinine NMTs, one from V. minor and one from R. serpentina, a perivine NMT from C. roseus, and an ajmaline NMT from R. serpentina. While these TLMTs were expressed and functional in planta, they were active at relatively low levels and their N-methylated alkaloid products were not apparent our from alkaloid isolates of the plants. It appears that, for the most part, these TLMTs, participate in apparently silent biochemical pathways, awaiting the appropriate developmental and environmental cues for activity.
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Some cross-sectional and prospective studies have demonstrated a positive correlation between habitual tea consumption and bone mineral density in post-menopausal women. Rooibos tea contains no caffeine and is a rich source of flavonoids such as rutin, orientin, hyperoside and luteolin. These flavonoids have similar structures to estradiol, and therefore may act as estrogen mimics to promote favourable outcomes in bone. The overall objective of this research was to identify flavonoids that could enhance mineral content in human osteoblast Saos2 cells. Mineral was quantified by alizarin red staining and characterized by quantifying alkaline phosphatase (ALP) activity, cell mitochondria activity and toxicity, in addition to changes in regulatory markers of osteoblastic activity. Rutin (≥50μM), hyperoside (≥5.0μM), orientin (0.1μM-1.0μM, 15μM-100μM) and luteolin (5.0μM) enhanced mineral content. This was in part due to elevated ALP and mitochondrial activity, and lower toxicity, pro-inflammatory cytokines, and Wnt inhibitors.
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Personal technologies and social media use have changed the socialization experience of our 21st century learners. As learners have a new, embodied, virtual identity that is an omnipresent force within their social interactions, this study sought to examine how virtual identity influences student relationships both within and outside of a school context. This study also explored how personal technologies and social media use have influenced learners’ perceptions of their own 21st century learning. Using a qualitative inquiry, purposeful sampling was employed to recruit 6 participants between the ages of 15 to 19 to examine their social networking site use and education experience. Data were collected from single, one-on-one semi-structured interviews in which participants discussed their experiences using social media. Data were also collected from the teens’ personal Instagram accounts, and a personal reflexive researcher’s journal was kept for triangulation of data. Open and axial coding strategies alongside constant comparative methods were used to analyze data. Participants shared how they and their peers use social media, the pressures and expectations from other users, social media’s influence on peer relationships, and how social media influences their choices in the physical realm. All 6 participants explained that their teachers do not talk to them about their social media use, and even offered critiques of the school system itself and its inability to prepare students for the new realities of a digital world. This study concludes that while social media is very influential on students’ socialization, educators should be more concerned about the lack of guidance and support that students receive in school in terms of appropriate social media use and the navigation of virtual identity.
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The capacity for all living cells to sense and interact with their environment is a necessity for life. In highly evolved, eukaryotic species, like humans, signalling mechanisms are necessary to regulate the function and survival of all cells in the organism. Synchronizing systemic signalling systems at the cellular, organ and whole-organism level is a formidable task, and for most species requires a large number of signalling molecules and their receptors. One of the major types of signalling molecules used throughout the animal kingdom are modulatory substances (e.x. hormones and peptides). Modulators can act as chemical transmitters, facilitating communication at chemical synapses. There are hundreds of circulating modulators within the mammalian system, but the reason for so many remains a mystery. Recent work with the fruit fly, Drosophila melanogaster demonstrated the capacity for peptides to modulate synaptic transmission in a neuron-specific manner, suggesting that peptides are not simply redundant, but rather may have highly specific roles. Thus, the diversity of peptides may reflect cell-specific functions. The main objective of my doctoral thesis was to examine the extent to which neuromodulator substances and their receptors modulate synaptic transmission at a cell-specific level using D. melanogaster. Using three different modulatory substances, i) octopamine - a biogenic amine released from motor neuron terminals, ii) DPKQDFMRFa - a neuropeptide secreted into circulation, and iii) Proctolin - a pentapeptide released both from motor neuron terminals and into circulation, I was able to investigate not only the capacity of these various substances to work in a cell-selective manner, but also examine the different mechanisms of action and how modulatory substances work in concert to execute systemic functionality . The results support the idea that modulatory substances act in a circuit-selective manner in the central nervous system and in the periphery in order to coordinate and synchronize physiologically and behaviourally relevant outputs. The findings contribute as to why the nervous system encodes so many modulatory substances.