Body size in the field cricket Gryllus integer (Orthoptera : Gryllidae) :heritability and male mating success

The influence of male body weight on the aggressive and mating behaviour of male Gryllus integer was studied under laboratory conditions. The relationship between adult age and weight was first determined; female weight increased and male weight decreased with age. Virgin males that had been isolated since the adult molt were paired for similar age and a difference in weight of greater than 200 mg. Paired males and a virgin female were observed in a glass arena for 24 minutes or until a mating occurred. Larger males mated significantly more often than smaller males. Larger males attacked more often, were more successful in aggressive encounters and had more contact with the female. Males that did not mate had lower rates of courtship and mounts than males that mated. Females in trials that did not result in a mating were signifcantly heavier than females in trials that resulted in a mating. Larger males that mated were significantly closer in weight to the weight of the female than larger males in trials that did not result in a mating. Larger males in trials that did not result in a mating had higher rates of aggressive stridulation than larger males that mated. Male weight is therefore important in mating success; fitness traits should theoretically show low genetic variability. However, significant heritability values were found for live weight, dry weight, head width, pronotum width and length, hind femur length and forewing length when estimated from the regression of offspring on mid-parent values, offspring and female and male values separately and full-sib correlations. The heritability of hind femur width was significant when estimated from the regression of offspring on male parent and from full-sib correlations. Heritability estimates of forewing length were significantly higher when estimated from the regression of offspring on female parent than when estimated from the regression of offspring on male parent. High phenotypic, genetic and environmental correlations were found between all pairs of traits. Data on male mating success and the heritability of fitness traits were discussed in terms of the maintenance of genetic variability.

Sexual selections in the northern fall field cricket, Gryllus pennsylvanicus: a manipulation of the adult sex ratio

The operational sex ratio has long been considered an important constraint on the structure of mating systems. The effects of an experimentally manipulated sex ratio on mating behavior and selection were investigated in a polygynous species, Gryllus pennsylvanicus, where the potential exists for spatial/temporal fluctuations in sex ratio of field populations. Four different sex ratios (males: females, 5:0, 5:2, 5:5, 5:10) were investigated. Observations were conducted in late summer over two field seasons, from 2400 h , to 1000 h EST. Several male characters thought to be associated with male reproduc.tive success were studied: calling duration, searching distance, weight, fighting behavior, courtship frequency, and mating success. Variance in male mating success was used as the indicator for the opportunity for sexual selection. Total selection was estimated as the univariate regression coefficient between relative fitness and the character of interest, while direct selection was estimated as standardized partial regression coefficients generated from a multiple regression of relative fitness on each character. The opportunity for sexual selection was highest at 5:2 and lowest at 5:10. The frequency of fighting behavior was highest at 5:2 and 5:5. Fighting ability (% wins) was determined to be an important correlate of male body weight. Direct selection for increased male body weight was detected at 5:2, while total selection for body weight was seen at 5:5. Selection on male body weight was not detected at 5: 10. Calling duration decreased as sex ratio became more female-biased. Total and direct selection were detected for increased calling at 5:2, only total selection for calling was seen at 5:5, whereas direct selection against calling was detected at 5: 10. Searching distance also decreased as sex ratio became more female-biased, however no form of selection was detected for searching at any of the sex ratios. Data are discussed in terms of sexual selection on male reproductive tactics, the mating system and maintenance of genetic variation in male reproductive behavior.

Investigating the association between motor proficiency and body satisfaction in grade 5 children

The inverse relationships between motor proficiency and overweight, and between overweight and body satisfaction have been well documented. However, the association between motor proficiency and body satisfaction has been largely neglected in the literature. Knowledge of the influence that low motor proficiency may have on body satisfaction is essential if the full burden that those children with poor motor abilities face is to be fully recognized, as low body satisfaction has been linked to an increased risk for low self-esteem, depression, and disordered eating. The cohort investigated in this report included 1907 (971 males, 936 female) Grade 5 students from the Physical Health Activity Study Team (PHAST) project in the Niagara Region of Southern Ontario. Children were grouped as overweight or healthy weight (using BMI cut offs for age and gender), and as low motor proficiency or normal motor proficiency (cut-off set at lowest 10% Bruininks Oseretsky Test of Motor Proficiency-short form (BOTMPsf). It was apparent from analyses of variance (ANOVAs) by gender that boys demonstrated significantly higher motor proficiency scores. As a result separate multiple logistic regressions by gender were used to determine the relationship between body satisfaction, BMI, and motor proficiency. There was a significant relationship between BMI and body satisfaction for both genders (p<0.01) and for males a significant relationship between motor proficiency and body satisfaction (p<0.03). Overweight females were less likely to be satisfied with their bodies with an odds ratio (OR) of 0.33 (CI: 0.23-0.47). The same trend was found in overweight males (OR: 0.42, CI: 0.29-0.59). Males with low motor proficiency were significantly less satisfied with their bodies (OR: 0.53, CI: 0.29-0.97). Males with poor motor proficiency were at greater risk for low body satisfaction regardless of their overweight status. Overweight is known to be prevalent among children with low motor proficiency and, these results indicate that low body satisfaction is also a significant concern. These findings confirm that attention needs to be paid to perceptions of body satisfaction among children with low motor proficiency. This is particularly true for boys, as their bodies may fail them in two common societal expectations, shape and skill and for whom their risk of low body satisfaction is heightened by their poor motor proficiency.

Social comparison and body image in non or infrequent exercisers and exercisers

Body image refers to an individual's internal representation ofhis/her outer self (Cash, 1994; Thompson, Heinberg, Altabe, & Tantleff-Dunn, 1999). It is a multidimensional construct which includes an individual's attitudes towards hislher own physical characteristics (Bane & McAuley, 1998; Cash, 1994; Cash, 2004; Davison & McCabe, 2005; Muth & Cash, 1997; Sabiston, Crocker, & Munroe-Chandler, 2005). Social comparison is the process of thinking about the self in relation to others in order to determine if one's opinions and abilities are adequate and to assess one's social status (Festinger, 1954; Wood, 1996). Research investigating the role of social comparisons on body image has provided some information on the types and nature of the comparisons that are made. The act of making social comparisons may have a negative impact on body image (van den Berg et ai., 2007). Although exercise may improve body image, the impact of social comparisons in exercise settings may be less positive, and there may be differences in the social comparison tendencies between non or infrequent exercisers and exercisers. The present study examined the nature of social comparisons that female collegeaged non or infrequent exercisers and exercisers made with respect to their bodies, and the relationship of these social comparisons to body image attitudes. Specifically, the frequency and direction of comparisons on specific tal-gets and body dimensions were examined in both non or infrequent exercisers and exercisers. Finally, the relationship between body-image attitudes and the frequency and direction with which body-related social comparisons were made for non or infrequent exercisers and exercisers were examined. One hundred and fifty-two participants completed the study (n = 70 non or ill infrequent exercisers; n = 82 exercisers). Participants completed measures of social physique anxiety (SPA), body dissatisfaction, body esteem, body image cognitions, leisure time physical activity, and social comparisons. Results suggested that both groups (non or infrequent exercisers and exercisers) generally made social comparisons and most frequently made comparisons with same-sex friends, and least frequently with same-sex parents. Also, both groups made more appearance-related comparisons than non-appearance-related comparisons. Further, both groups made more negative comparisons with almost all targets. However, non or infrequent exercisers generally made more negative comparisons on all body dimensions, while exercisers made negative comparisons only on weight and body shape dimensions. MANOV As were conducted to examine if any differences on social comparisons between the two groups existed. Results of the MANOVAs indicated that frequency of comparisons with targets, the frequency of comparisons on body dimensions, and direction of comparisons with targets did not differ based on exercise status. However, the direction of comparison of specific body dimensions revealed a significant (F (7, 144) = 3.26,p < .05; 1]2 = .132) difference based on exercise status. Follow-up ANOVAs showed significant differences on five variables: physical attractiveness (F (1, 150) = 6.33,p < .05; 1]2 = .041); fitness (F(l, 150) = 11.89,p < .05; 1]2 = .073); co-ordination (F(I, 150) = 5.61,p < .05; 1]2 = .036); strength (F(I, dO) = 12.83,p < .05; 1]2 = .079); muscle mass or tone (F(l, 150) = 17.34,p < .05; 1]2 = 1.04), with exercisers making more positive comparisons than non or infrequent exercisers. The results from the regression analyses for non or infrequent exercisers showed appearance orientation was a significant predictor of the frequency of social comparisons N (B = .429, SEB = .154, /3 = .312,p < .01). Also, trait body image measures accounted for significant variance in the direction of social comparisons (F(9, 57) = 13.43,p < .001, R2adj = .68). Specifically, SPA (B = -.583, SEB = .186, /3 = -.446,p < .01) and body esteem-weight concerns (B = .522, SEB = .207, /3 = .432,p < .01) were significant predictors of the direction of comparisons. For exercisers, regressions revealed that specific trait measures of body image significantly predicted the frequency of comparisons (F(9, 71) = 8.67,p < .001, R2adj = .463). Specifically, SPA (B = .508, SEB = .147, /3 = .497,p < .01) and appearance orientation (B = .457, SEB = .134, /3 = .335,p < .01) were significant predictors of the frequency of social comparisons. Lastly, for exercisers, the results for the regression of body image measures on the direction of social comparisons were also significant (F(9, 70) = 14.65,p < .001, R2adj = .609) with body dissatisfaction (B = .368, SEB = .143, /3 = .362,p < .05), appearan.ce orientation (B = .256, SEB = .123, /3 = .175,p < .05), and fitness orientation (B = .423, SEB = .194, /3 = .266,p < .05) significant predictors of the direction of social comparison. The results indicated that young women made frequent social comparisons regardless of exercise status. However, exercisers m,a de more positive comparisons on all the body dimensions than non or infrequent exercisers. Also, certain trait body image measures may be good predictors of one's body comp~son tendencies. However, the measures which predict comparison tendencies may be different for non or infrequent exercisers and exercisers. Future research should examine the effects of social comparisons in different populations (i.e., males, the obese, older adults, etc.). Implications for practice and research were discussed.

The effects of postural threat on cognitive strategies used to maintain upright stance

It is well established that postural threat modifies postural control, although little is known regarding the underlying mechanism(s) responsible. It is possible that changes in postural control under conditions of elevated postural threat result from alterations in cognitive strategies. The purpose of this study was to determine the influence of elevated postural threat on cognitive strategies and to determine the relationship between postural control, psychological, and cognitive measures. It was hypothesized that elevated postural threat would cause a shift to more conscious control of posture. It was also expected that a relationship between fear of falling and postural control would exist that could be explained by changes in conscious control of posture. Forty-eight healthy young adults stood on a force plate at two different surface heights: ground level (LOW) and 3.2m above ground level (HIGH). Center of pressure (COP) summary measures calculated to quantify postural control were the mean position (AP-COP MP), root mean square (AP-COP RMS) and mean power frequency (AP-COP MPF) in the anteriorposterior direction. Trunk sway measures calculated in the pitch direction were trunk angle and trunk velocity. Psychological measures including perceived balance confidence, perceived fear of falling, perceived anxiety, and perceived stability were self reported. As a physiological indicator of anxiety, electrodermal activity was collected. The cognitive strategies assessed were movement reinvestment and attention focus. A modified state-sp-ecific version of the Movement Specific Reinvestment Scale was used to measure conscious motor processing (CMP) and movement self-consciousness (MSC). An attention focus questionnaire was developed to assess the amount of attention directed to internal and external sources. An effect of postural threat on cognitive strategies was observed as participants reported more conscious control and a greater concern or worry about their posture at the HIGH postural threat condition as well as an increased internal and external focus of attention. In addition changes in postural control, psychological, and physiological measures were found. The participants leaned away from the edge of the platform, the frequency of their postural adjustments increased, and the velocity of their trunk movements increased. Participants felt less confident, more fearful, more anxious, and less stable with an accompanying increase in physiological anxiety. Significant correlations between perceived anxiety, AP-COP MP, and cognitive measures revealed a possible relationship that could be mediated by cognitive measures. It was found that with greater conscious motor processing, more movement self-consciousness, and a greater amount of attention focused externally there was a larger shift of the mean position away from the edge of the platform. This thesis provides evidence that postural threat can influence cognitive strategies causing a shift to more conscious control of movement which is associated with leaning away from the edge of the platform. Shifting the position of the body away from the direction of the postural threat may reflect a cognitive strategy to ensure safety in this situation due to the inability to employ a stepping strategy when standing on an elevated platform.

The convergence of psychopathy, self-rated vulnerability, and other-rated vulnerability

Previous research has found that victims of crime tend to exhibit asynchronous movement (e.g. Grayson & Stein, 1981), and the fact that victims display different body language suggests that they may be sending inadvertent signals to their own vulnerability (e.g. Murzynski & Degelman, 1996). Body language has also be en linked with s e l f identification as a victim (Wheeler et aI., 2009), and self-identification has be en found to act as a proxy for more severe victimization (Baumer, 2002) and greater fear of crime (Greenberg & Beach, 2004). The first prediction in the present study, then, was that self-perceived vulnerability would be correlated with body language, while number of previous victimizations mayor may not show the same relationship. Findings from the present study indicate that self-perceived vulnerability exhibits a positive correlation with the body language cues that approaches significance r (10) = .45,p =.07, one-tailed. Different types of victimization, however, were not significantly correlated with these cues. A second goal of the study was to examine the relationship between psychopathic traits and accuracy in judgments of vulnerability. Seventy male participants rated the vulnerability of 12 female targets filmed walking down a hallway who had provided selfratings of vulnerability. Individuals scoring higher on Factor 2 and total psychopathy were significantly less discrepant from target self-rat~ngs of vulnerability, r (64) = - .39,p < .001; r (64) = - .29,p >.01, respectively. The final purpose of this study was to determine which body language cues were mos t salient to raters when making judgments of vulnerability. Participants rated the apparent vulnerability of a target in 7 video clips portraying each body language cue in isolation and a natural walk. Results of repeated measures analyses indicate that the videos rated as most vulnerable to victimization were those displaying low energy and l a ck of synchrony, followed by wide stride, short stride, and stiffknees, while the video displaying ne ck stiffness did not receive significantly different ratings from the mode l ' s natural walk. Replication with a larger sample size is necessary to increase confidence in findings and implications.

Intracellular antioxidant and DNA repair enzymes as correlates of stress resistance and longevity in vertebrates

In animals, both stress resistance and longevity appear to be influenced by the insulin/insulin-like growth factor-l signaling (lIS) pathway, the basic organization of which is highly conserved from invertebrates to vertebrates. Reduced lIS or genetic disruption of the lIS pathway leads to the activation of forkhead box transcription factors, which is thought to upregulate the expression of genes involved in enhancing stress resistance, including perhaps key antioxidant enzymes as well as DNA repair enzymes. Enhanced antioxidant and DNA repair capacities may underlie the enhanced cellular stress resistance observed in long-lived animals, however little data is available that directly supports this idea. I used three. experimental approaches to test the association of intracellular antioxidant and DNA base excision repair (BER) capacities with stress resistance and longevity: (1) a comparison of multiple vertebrate endotherm species of varying body masses and longevities; (2) a comparison of long-lived Snell dwarf mice and their normallittermates; and (3) a comparison of hypometabolic animals undergoing hibernation or estivation with their active counterparts. The activities of the five major intracellular antioxidant enzymes as well as the two rate-limiting enzymes in the BER pathway, apurininc/apyrimidinic (AP) endonuclease and polymerase ~, were measured. These measurements were performed in one or more of the following: (1) cultured dermal fibroblasts; (2) brain tissue; (3) heart tissue; (4) liver tissue. My results indicate that antioxidant enzymes are not universally upregulated in association with enhanced stress resistance and longevity. I also did not find that BER enzyme activity was positively correlated with longevity, in an inter-species context, though there was evidence for enhanced BER in long-lived Snell dwarf mice. Thus, while there were instances in which enhanced antioxidant and BER enzyme activities were associated with increased stress resistance and/or longevity, this was not universally the case, indicating that other mechanisms must be involved. These results suggest the need to re-examine existing 'oxidative stress' hypotheses of longevity and probe further into the molecular physiology of longevity to discover its mechanistic basis.

Exploring Body-Related Experiences among Individuals with Spinal Cord Injury

Using modified constructivist grounded theory, the purpose of the present study was to explore body-related experiences, specifically body image, in people with spinal cord injury. A total of nine participants (five women, four men) who had a broad range of body image experiences (from very negative to very positive) were interviewed. Most participants explained experiencing a fluctuating body image that varied from day-to-day. Negative body image experiences were represented by appearance, weight concerns, and function with all body image experiences encompassed by self-presentational concerns and tactics (an unanticipated finding). Positive body image was represented by acceptance, appreciation and gratitude of the body. Interestingly, negative body image experiences were not found to be represented by the opposite of positive body image experiences as they were each distinct. These findings have direct implications for medical professionals in hospital and rehabilitation settings to understand the importance of body image after spinal cord injury.

Living in the Skin That I Am: An Organizational Autoethnography of an Adult Educator's Plight to Survive the Stigma of Invisible and Episodic Disability in an Academy of Administritiva

Through the reflective lens of an adult educator with invisible and episodic disabilities, this paper has been written as an organizational autoethnography. Through a process of autoethnographical sensemaking, it is intended to illuminate important gaps in organizational theory. Feminist/relational care ethics, critical reflection, and transformative learning serve as the educational theories that comprise its framework. In telling my story, embodied writing and performance narrative are used to convey the felt existence of a body exposed through words—where my “abled” and “disabled” professional teaching and learning identities may be studied against the backdrop of organizational policies and procedures. Words used to describe unfamiliar experiences and situations shape meaning for which new meaning may emerge. At the conclusion of this paper, an alternative frame of reference—a view from the margins—may be offered to articulate authenticity in the expectancy of workplace equity for adult educators with disabilities. Taken collectively on a larger level, it is hoped that this research may provide a source of inspiration for systemic organizational change in adult learning environments.

The ambivalent identity of Wong Kar-wai's cinema

Ayant réalisé neuf longs-métrages entre 1988 et 2007, aussi que plusieurs campagnes publicitaires, vidéo-clips, courts-métrages et projets collectifs, Wong Kar-wai est un des réalisateurs contemporains les plus importants actuellement. Issu de l'industrie cinématographique fortement commerciale de Hong Kong, Wong est parvenu à attirer l'attention du circuit international des festivals de cinéma avec son style visuel unique et son récit fragmenté. Considéré par plusieurs critiques comme le poète de la recherche d’identité de Hong Kong après 1997, Wong Kar-wai défie toutes les tentatives de catégorisation. L’étude qui se poursuivit ici a donc pour objet essentiel de fournir une analyse attentive et complète de son oeuvre, tout en se concentrant sur les traits stylistiques qui donnent à ses films une unité. Ces caractéristiques correspondent à une certaine façon de raconter des histoires, de composer des personnages et des récits, de manipuler le temps et d'utiliser des ressources techniques de sorte que ses films offrent une identité cohérente. L'objectif est d'analyser les différents composants de ses images pour découvrir comment ses films communiquent les uns avec les autres afin de créer une identité unique. Pour atteindre cet objectif, je pose comme hypothèse de travail que le cinéma de Wong est marqué par une structure dualiste qui permet à ses films de présenter des qualités contradictoires simultanément. La plupart de mes arguments se concentrent sur le travail du philosophe français Gilles Deleuze, qui a proposé une théorie du cinéma divisé entre l’image-mouvement et l’image-temps. Je considère que sa théorie fournit un cadre valide sur lequel les films de Wong peuvent être projetés. Tandis que ma recherche se concentre sur l’interprétation textuelle des films, je profiterais également d’une analyse comparative.

Well-Being Freedom and The Possibility of Public-Provision Unit in Global Context

The purpose of this paper is, first, to investigate the interconnections of substantive freedoms, which are indispensable for every individual to “lead the kind of lives they have reason to value” (Sen, 1999b, p.10,18), and which have legitimate and ethical reasons to be publicly secured, second, to investigate a conception of public-provision unit that embodies “the right to well-being freedom”, and a conception of decision-making unit that corresponds to it, based on the perspective of Sen’s capability theory and its extension, comparing with that of Rawls’ Theory of Justice and A Law of People. If we intend to construct such a public-provision unit, which conducts redistribution as a whole, and which receives every individual who cannot belong to any fixed local group, what kind of a body should we assume as a public-provision unit? And further, what kind of a body should we assume as a decision-making unit, which is responsible for deciding or revising the basic conceptions of public provision unit?

Design thinking and the precautionary principle : development of a theoretical model complementing preventive judgment for design for sustainability enriched through a study of architectural competitions adopting LEED

Cette thèse contribue à une théorie générale de la conception du projet. S’inscrivant dans une demande marquée par les enjeux du développement durable, l’objectif principal de cette recherche est la contribution d’un modèle théorique de la conception permettant de mieux situer l’utilisation des outils et des normes d’évaluation de la durabilité d’un projet. Les principes fondamentaux de ces instruments normatifs sont analysés selon quatre dimensions : ontologique, méthodologique, épistémologique et téléologique. Les indicateurs de certains effets contre-productifs reliés, en particulier, à la mise en compte de ces normes confirment la nécessité d’une théorie du jugement qualitatif. Notre hypothèse principale prend appui sur le cadre conceptuel offert par la notion de « principe de précaution » dont les premières formulations remontent du début des années 1970, et qui avaient précisément pour objectif de remédier aux défaillances des outils et méthodes d’évaluation scientifique traditionnelles. La thèse est divisée en cinq parties. Commençant par une revue historique des modèles classiques des théories de la conception (design thinking) elle se concentre sur l’évolution des modalités de prise en compte de la durabilité. Dans cette perspective, on constate que les théories de la « conception verte » (green design) datant du début des années 1960 ou encore, les théories de la « conception écologique » (ecological design) datant des années 1970 et 1980, ont finalement convergé avec les récentes théories de la «conception durable» (sustainable design) à partir du début des années 1990. Les différentes approches du « principe de précaution » sont ensuite examinées sous l’angle de la question de la durabilité du projet. Les standards d’évaluation des risques sont comparés aux approches utilisant le principe de précaution, révélant certaines limites lors de la conception d’un projet. Un premier modèle théorique de la conception intégrant les principales dimensions du principe de précaution est ainsi esquissé. Ce modèle propose une vision globale permettant de juger un projet intégrant des principes de développement durable et se présente comme une alternative aux approches traditionnelles d’évaluation des risques, à la fois déterministes et instrumentales. L’hypothèse du principe de précaution est dès lors proposée et examinée dans le contexte spécifique du projet architectural. Cette exploration débute par une présentation de la notion classique de «prudence» telle qu’elle fut historiquement utilisée pour guider le jugement architectural. Qu’en est-il par conséquent des défis présentés par le jugement des projets d’architecture dans la montée en puissance des méthodes d’évaluation standardisées (ex. Leadership Energy and Environmental Design; LEED) ? La thèse propose une réinterprétation de la théorie de la conception telle que proposée par Donald A. Schön comme une façon de prendre en compte les outils d’évaluation tels que LEED. Cet exercice révèle cependant un obstacle épistémologique qui devra être pris en compte dans une reformulation du modèle. En accord avec l’épistémologie constructiviste, un nouveau modèle théorique est alors confronté à l’étude et l’illustration de trois concours d'architecture canadienne contemporains ayant adopté la méthode d'évaluation de la durabilité normalisée par LEED. Une série préliminaire de «tensions» est identifiée dans le processus de la conception et du jugement des projets. Ces tensions sont ensuite catégorisées dans leurs homologues conceptuels, construits à l’intersection du principe de précaution et des théories de la conception. Ces tensions se divisent en quatre catégories : (1) conceptualisation - analogique/logique; (2) incertitude - épistémologique/méthodologique; (3) comparabilité - interprétation/analytique, et (4) proposition - universalité/ pertinence contextuelle. Ces tensions conceptuelles sont considérées comme autant de vecteurs entrant en corrélation avec le modèle théorique qu’elles contribuent à enrichir sans pour autant constituer des validations au sens positiviste du terme. Ces confrontations au réel permettent de mieux définir l’obstacle épistémologique identifié précédemment. Cette thèse met donc en évidence les impacts généralement sous-estimés, des normalisations environnementales sur le processus de conception et de jugement des projets. Elle prend pour exemple, de façon non restrictive, l’examen de concours d'architecture canadiens pour bâtiments publics. La conclusion souligne la nécessité d'une nouvelle forme de « prudence réflexive » ainsi qu’une utilisation plus critique des outils actuels d’évaluation de la durabilité. Elle appelle une instrumentalisation fondée sur l'intégration globale, plutôt que sur l'opposition des approches environnementales.

Role of the homeodomain transcription factor Hoxa13 in embryonic development and formation of extra-embryonic structures

La famille des gènes Hox code pour des facteurs de transcription connus pour leur contribution essentielle à l’élaboration de l’architecture du corps et ce, au sein de tout le règne animal. Au cours de l’évolution chez les vertébrés, les gènes Hox ont été redéfinis pour générer toute une variété de nouveaux tissus/organes. Souvent, cette diversification s’est effectuée via des changements quant au contrôle transcriptionnel des gènes Hox. Chez les mammifères, la fonction de Hoxa13 n’est pas restreinte qu’à l’embryon même, mais s’avère également essentielle pour le développement de la vascularisation fœtale au sein du labyrinthe placentaire, suggérant ainsi que sa fonction au sein de cette structure aurait accompagné l’émergence des espèces placentaires. Au chapitre 2, nous mettons en lumière le recrutement de deux autres gènes Hoxa, soient Hoxa10 et Hoxa11, au compartiment extra-embryonnaire. Nous démontrons que l’expression de Hoxa10, Hoxa11 et Hoxa13 est requise au sein de l’allantoïde, précurseur du cordon ombilical et du système vasculaire fœtal au sein du labyrinthe placentaire. De façon intéressante, nous avons découvert que l’expression des gènes Hoxa10-13 dans l’allantoïde n’est pas restreinte qu’aux mammifères placentaires, mais est également présente chez un vertébré non-placentaire, indiquant que le recrutement des ces gènes dans l’allantoïde précède fort probablement l’émergence des espèces placentaires. Nous avons généré des réarrangements génétiques et utilisé des essais transgéniques pour étudier les mécanismes régulant l’expression des gènes Hoxa dans l’allantoïde. Nous avons identifié un fragment intergénique de 50 kb capable d’induire l’expression d’un gène rapporteur dans l’allantoïde. Cependant, nous avons trouvé que le mécanisme de régulation contrôlant l’expression du gène Hoxa au sein du compartiment extra-embryonnaire est fort complexe et repose sur plus qu’un seul élément cis-régulateur. Au chapitre 3, nous avons utilisé la cartographie génétique du destin cellulaire pour évaluer la contribution globale des cellules exprimant Hoxa13 aux différentes structures embryonnaires. Plus particulièrement, nous avons examiné plus en détail l’analyse de la cartographie du destin cellulaire de Hoxa13 dans les pattes antérieures en développement. Nous avons pu déterminer que, dans le squelette du membre, tous les éléments squelettiques de l’autopode (main), à l’exception de quelques cellules dans les éléments carpiens les plus proximaux, proviennent des cellules exprimant Hoxa13. En contraste, nous avons découvert que, au sein du compartiment musculaire, les cellules exprimant Hoxa13 et leurs descendantes (Hoxa13lin+) s’étendent à des domaines plus proximaux du membre, où ils contribuent à générer la plupart des masses musculaires de l’avant-bras et, en partie, du triceps. De façon intéressante, nous avons découvert que les cellules exprimant Hoxa13 et leurs descendantes ne sont pas distribuées uniformément parmi les différents muscles. Au sein d’une même masse musculaire, les fibres avec une contribution Hoxa13lin+ différente peuvent être identifiées et les fibres avec une contribution semblable sont souvent regroupées ensemble. Ce résultat évoque la possibilité que Hoxa13 soit impliqué dans la mise en place de caractéristiques spécifiques des groupes musculaires, ou la mise en place de connections nerf-muscle. Prises dans leur ensemble, les données ici présentées permettent de mieux comprendre le rôle de Hoxa13 au sein des compartiments embryonnaires et extra-embryonnaires. Par ailleurs, nos résultats seront d’une importance primordiale pour soutenir les futures études visant à expliquer les mécanismes transcriptionnels soutenant la régulation des gènes Hoxa dans les tissus extra-embryonnaires.

The Dystopic Body in Margaret Atwood's The Handmaid's Tale

Cette thèse analyse le corps dystopique dans La Servante Ecarlate. Elle vise à examiner les façons dont le pouvoir masculiniste subjugue les servantes à travers l'objectivation et l'effacement de leur corps, puis à analyser le corps féminin comme un élément perturbateur, un site où se produit une constante subversion du pouvoir tout au long du roman. L'introduction offre une brève discussion sur la raison derrière le choix de La Servante Ecarlate comme une étude de cas, qui est dans le but de développer le concept du corps dystopique à partir d'un point de vue féministe. Elle délimite aussi mon argument sur le corps dystopique et le pouvoir. Le premier chapitre intitulé ‟Perspectives Critiques” présente une revue critique de la littérature, introduit ma contribution à l'étude du roman, et expose mes arguments sur l'utopie féministe, la dystopie, le corps dystopique et la circulation du pouvoir. Dans le deuxième chapitre intitulé ‟Le Corps Dystopique” je démontre que la dystopie dans une certaine mesure est déjà profondément enracinée dans le présent. Cette section se concentre sur les différents aspects de la dystopie principalement la reproduction, la sexualité, la surveillance et le code vestimentaire tout en étudiant leur impact sur le corps de la servante. Ces aspects sont abordés en détail dans des sous-chapitres séparés. Le dernier chapitre intitulé ‟La Subversion du Pouvoir” examine dans un premier lieu le mode d'échange de pouvoir entre le commandant et son épouse Serena Joy. Il étudie les façons dont chacun des personnages se positionne par rapport au pouvoir afin d’exploiter le corps d’Offred. Puis, il examine l'ironie qui se cache derrière le jeu de pouvoir constant dans le roman, dévoilant ainsi la perpétuation de la dystopie corporelle étant donné que le corps de la femme ne cesse d'être l'objet de la lutte. Ce travail étudie l'expérience corporelle de la femme dans un régime totalitaire et les façons dont le corps féminin devient dystopique. Il présente le corps féminin comme la proie des hommes et des femmes, et la dystopie comme étroitement dépendante et générée par la conception de ce corps dans la société de Gilead. Mots clés: Dystopie, Corps, Pouvoir, Féminisme, Ironie, Margaret Atwood

Effect of levodopa on cortico-striatal and cortico-cerebellar circuits in Parkinson's disease

La maladie de Parkinson (MP) est la deuxième maladie neurodégénérative la plus commune. Les symptômes principalement observés chez les patients atteints de la MP sont la rigidité, les tremblements, la bradykinésie et une instabilité posturale. Leur sévérité est souvent asymétrique. La cause principale de ces symptômes moteurs est la dégénérescence du circuit dopaminergique nigro-striatal qui mène à un débalancement d’activité du circuit cortico-striatal. Ce débalancement de circuits est le point essentiel de cette thèse. Dans les protocoles de recherche décrits ici, des patients atteints de la MP (avant et après une dose de levodopa) et des participants contrôles sains ont effectué des mouvements auto-initiés ou en réponse à des stimulis externes pendant que l’on mesurait leur activité cérébrale en imagerie par résonance magnétique fonctionnelle (IRMf). Dans cette thèse, nous abordons et mettons en évidence quatre (4) points principaux. En première partie (chapitre 2), nous présentons un recensement de la littérature sur les cicruits cortico-striataux et cortico-cérébelleux dans la MP. En utilisant des méthodes de neuroimagerie, des changements d’activité cérébrale et cérébelleuse ont été observés chez les patients atteints de la MP comparés aux participants sains. Même si les augmentations d’activité du cervelet ont souvent été attribuées à des mécanismes compensatoires, nos résultats suggèrent qu’elles sont plus probablement liées aux changements pathophysiologiques de la MP et à la perturbation du circuit cortico-cérébelleux. En général, nous suggérons (1) que le circuit cortico-cérébelleux est perturbé chez les patients atteints de la MP, et que les changements d’activité du cervelet sont liés à la pathophysiologie de la MP plutôt qu’à des mécanismes compensatoires. En deuxième partie (chapitre 3), nous discutons des effets de la levodopa sur les hausses et baisses d’activité observés chez les patients atteints de la MP, ainsi que sur l’activité du putamen pendant les mouvements d’origine interne et externe. De nombreuses études en neuroimagerie ont montré une baisse d’activité (hypo-activité) préfrontale liée à la déplétion de dopamine. En revanche, l’utilisation de tâches cognitives a montré des augmentations d’activité (hyper-activité) corticale chez les patients atteints de la MP comparés aux participants sains. Nous avons suggéré précédemment que ces hypo- et hyper-activités des régions préfrontales dépendent de l’implication du striatum. Dans cette thèse nous suggérons de plus (2) que la levodopa ne rétablit pas ces hyper-activations, mais plutôt qu’elles sont liées à la perturbation du circuit méso-cortical, et aussi possiblement associées à l’administration de médication dopaminergique à long terme. Nous montrons aussi (3) que la levodopa a un effet non-spécifique à la tâche sur l’activité du circuit cortico-striatal moteur, et qu’elle n’a pas d’effet sur l’activité du circuit cortico-striatal cognitif. Nous montrons enfin (chapitre 4) que la levodopa a un effet asymétrique sur les mouvements de la main droite et gauche. À peu près 50% des patients atteints de la MP démontrent une asymétrie des symptômes moteurs, et ceci persiste à travers la durée de la maladie. Nos résultats suggèrent (4) que la levodopa pourrait avoir un plus grand effet sur les patrons d’activations des mouvements de la main la plus affectée.