No description available.

No description available.

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.

Emotion regulation plays an important role in emotional well-being, as well as in the protection against and recovery from mood and anxiety disorders. Previous studies of the functional neuroanatomy of emotion regulation have reported greater activity in prefrontal control-related regions during active regulation. These activations are accompanied by decreases in activity in emotion-responsive regions such as the amygdala and insula. These findings are widely interpreted as consistent with models of cognitive control that implicate top-down, negative influences from prefrontal cortex upon emotion-related processing in other regions. However, no studies to date have used measures of effective connectivity to investigate the likely influence of prefrontal control regions upon emotion-responsive regions in the context of effortful emotion regulation. In the present study, participants alternated between responding naturally to negative emotional stimuli and reinterpreting the negative stimuli with the goal of reducing their experienced negative affect. Functional magnetic resonance imaging (fMRI) was used to measure whole-brain blood-oxygen level dependent signal throughout the task. fMRI data were analyzed using partial least squares (PLS) and structural equations modeling (SEM) to test for differences in effective connectivity between natural and regulated emotional responding. Results indicate that three paths significantly distinguish between regulation and non-regulation negative conditions. The path from inferior frontal gyrus (IFG) to anterior cingulate cortex (ACC) was significantly less positive during regulation than natural responding. In addition, the reciprocal paths between ACC and insula were more negative during regulation than natural responding. Taken as a whole, these changes in effective connectivity are consistent with assumptions of top-down modulation during effortful emotion regulation. In addition, these changes suggest a pivotal role for the influence of IFG upon ACC and the ACC-insula loop in emotion regulation. The processes represented by these changes and implications for future research are discussed.

In eukaryotes, the regulation of mRNA translation and decay provides a mechanism which can be finely tuned to control gene expression. This ability to control the life cycle of an mRNA begins with the control of mRNA export from the nucleus and extends to the processes which regulate the degradation of the message. In my work, summarized below, I describe how some of the proteins involved in cytoplasmic decay regulate many aspects of the control of mRNA and also describe a novel regulatory mechanism involving the relocation of cytoplasmic mRNA back into the nucleus of the cell.Firstly, I have identified that the protein Pat1, which has been shown to be critical for translational repression and activation of decapping, consists of essentially 3 major domains. By means of a deletional functional analysis, I show that two of these domains are the primary functional domains responsible for all of the currently ascribed function of Pat1. One domain promotes translational repression and P-body assembly, while the second domain promotes mRNA decapping after assembly of the mRNA into a P-body mRNP. Along with the first evidence that Pat1 binds to RNA, we also determine numerous domain-specific interactions with mRNA decapping factors.In eukaryotic cells mRNAs are produced in the nucleus followed by what is thought to be unidirectional export to the cytoplasm. In the cytosol, mRNAs either associate with ribosomes for translation or can be found in cytoplasmic RNP granules, termed P-bodies, when they are translationally repressed. I have now demonstrated that yeast mRNAs can be re-imported into the nucleus. Import of mRNAs into the nucleus is in competition with translation and increased in strains lacking specific components of cytoplasmic processing bodies, which also exhibit nuclear-cytoplasmic shuttling. This indicates that one function of cytoplasmic granules is to limit the import of cytoplasmic mRNAs back into the nucleus. These results demonstrate a novel pathway for mRNA import into the nucleus and suggest distinct pathways of mRNA export of nascent mRNAs and imported mRNAs.

Experiential avoidance (EA) is an emotion-regulation strategy used to control or avoid unpleasant internal experiences. Experimental studies, however, have shown that EA is associated with an ironic increase in unpleasant experiences. While single manipulation laboratory experiments can demonstrate the immediate ironic detrimental effects of EA, a different methodology is needed to establish how such ironic processes unfold over time in the natural environment. The current study uses a longitudinal design and daily-diary methodology to examine daily associations between EA and negative affect (NA) over a three-week period among college-students who initially reported high levels of psychological distress. A daily measure of state EA based on several avoidant behaviors (thought suppression, emotion suppression, distraction, reflective pondering, and lack of experiential acceptance) was developed for this study. Before and after making daily web-based reports of EA and NA for 21 consecutive days, participants completed a standardized checklist of psychological symptoms, with pre-post change scores on this measure serving as an index of symptomatic improvement. Multilevel modeling analyses showed that, as predicted, symptomatic improvement was associated with decreasing trajectories of EA and NA during the 21-day study period. More symptomatic improvement was associated with weakening (decoupling) of same-day EA-NA links over time. Contrary to predictions, same-day and one-day lagged associations between NA and EA were not associated with symptomatic change. Additional multilevel analyses showed that symptomatic worsening was associated with more daily EA, over and above what was accounted for by daily NA. Likewise, traditional between-person regression analyses showed that overall mean levels of daily EA (aggregated across days) predicted symptomatic worsening, even after statistically accounting for mean levels of daily NA. The results of this study provide partial support for the hypothesis that EA and NA are related to each other in an ironic positive feedback loop that unfolds over time and that symptomatic improvement may involve a process by which EA and NA both decrease and decouple from each other over time. These findings emphasize the importance of using methodologies that track the relationship between EA and its consequences over time using within-person analyses, rather than solely relying on between-person designs.

Azotobacter vinelandii is a free-living diazotroph. This bacterium fixes atmospheric nitrogen in different environments using three genetically distinct nitrogenases. A. vinelandii is also capable of utilizing nitrate and nitrite from the environment. Nitrate is reduced sequentially into nitrite and ammonia. The assimilatory nitrate reductase and nitrite reductase are encoded by the nasAB operon. Previous genetic studies identified a number of factors that influence nasAB expression. However, the molecular mechanisms controlling the expression of nasAB are unclear.The current study was initiated to characterize the region preceding the nasAB operon which was previously implicated in its regulation and to further study the molecular mechanisms of nasAB regulation. The results confirm that nasAB is subject to multiple layers of regulation. The operon is under the control of an NtrC-dependent promoter; nitrate/nitrite induction occurs at the post-transcriptional level via antitermination within the nasAB leader region; and nitrate/nitrite induction is mediated by NasS/NasT, a sensor-antiterminator two-component regulatory system.Together, these data suggest a model for the regulation of the assimilatory nitrate reductase operon in A. vinelandii.

Plant non specific lipid transfer proteins (nsLTPs) enhance in vitro transfer of phospholipids between membranes. Our analysis exploited the large amount of Arabidopsis transcriptome data in public databases to learn more about the function of nsLTPs. The analysis revealed that some nsLTPs are expressed only in roots, some are seed specific, and others are specific for tissues above ground whereas certain nsLTPs show a more general expression pattern. Only few nsLTPs showed a strong up or downregulation after that the Arabidopsis plant had suffered from biotic or abiotic stresses. However, salt, high osmosis and UV-B radiation caused upregulation of some nsLTP genes. Further, when the coexpression pattern of the A.thaliana nsLTPs were investigated, we found that there were several modules of nsLTP genes that showed strong coexpression indicating an involvement in related biological processes. Our finding reveals that the nsLTPs gene was significantly correlated with lipase and peroxidase activity. Hence we concluded that the nsLTPs may play a role in seed germination, signalling and ligning biosynthesis.

The World Health Organization, Surgeon General of the United States, and Public Health Agency of Canada have all stated that childhood obesity is one of the most serious health challenges of the 21st century. Thus a purported obesity epidemic among children has generated intense interest in its associated health risks. Increasingly, the medical literature and media blame mothers for failing to provide proper care for their children's health by ignoring the growing weight of their children. While previous literature explores how parenting magazines can be considered public educators about children's health, there is limited literature addressing what parenting magazines specifically say about mothers and childhood obesity. Through a qualitative content analysis of the Canadian parenting magazine Today’s Parent, this paper argues that Today’s Parent stigmatizes mothers by blaming them for the weight issues of children, and suggests future research is needed to investigate to what extent this influences parenting practices.

Lifespan theories of emotion suggest that the ability to regulate emotion improves with age. The supporting evidence, however, is indirect: older adults pay less attention to negative events, remember less negative information, and report fewer experiences of negative emotion. Few studies directly measure emotion regulation by explicitly instructing older adults to modulate their feelings while exposed to emotion-evoking stimuli. The purpose of this thesis was to directly compare younger and older adults in their ability to modulate feelings to investigate whether aging results in decline, stability, or improvement in emotion regulation and also to examine potential mechanisms underlying regulation skills. The study employed a startle modulation paradigm to measure both emotional reactivity and regulation. Two experimental tasks (Stroop colour-word interference, reversal learning) were also administered to explore the relationship between emotion regulation and two theoretically-relevant processes: (a) cognitive control and (b) modification of learned emotional associations. There were three main findings: (1) emotional reactivity was preserved in older adults. Both age groups showed emotion-modulated startle (negative > neutral) during the pre-regulation viewing period; (2) age-related decline in emotion regulation was evident on an objective measure of emotion regulation (startle eyeblink reflex) but not on a subjective measure (self-ratings). Specifically, for older adults, startle eyeblink was not enhanced or attenuated following increase and decrease instructions, respectively. In contrast, both groups showed similar modulation of valence and arousal ratings by regulation instruction (increase > look > decrease); (3) for older adults, reversal learning performance correlated positively with the degree of reappraisal-related startle attenuation in the decrease condition, suggesting a possible mechanism for impaired down-regulation. These findings suggest that even when emotional reactivity is similar, older adults are less effective at modulating their physiological responses.