Le paradoxe du backpacking chez les jeunes Québécois : entre individualisation et connexion

L’ouverture au monde est de rigueur chez les jeunes d’aujourd’hui au Québec comme ailleurs. Membres d’office de la génération Y, les jeunes sont d’emblée familiers avec les « nouvelles technologies ». En effet, les moyens numériques et les réseaux sociaux n’ont plus de secrets pour eux et leur permettent de nouer contact à l’échelle de la planète. Il devient dès lors tentant de partir à l’aventure, sac au dos, afin de se conformer à l’ouverture au monde vue comme une qualité. Le présent mémoire de maîtrise envisage le backpacking, c’est-à-dire la façon de voyager qui a actuellement la cote chez les jeunes, en particulier les étudiants, en mettant un sac sur son dos et en partant à l’aventure afin de pouvoir enrichir les qualités qu’ils reconnaissent à leur propre personne. En effet, quitter son épicentre social, souvent seul, en « voyageant léger » dans des contrées étrangères contribue à la capacité d’agir de son propre chef et d’être soi-même, en acquérant des qualités susceptibles de mettre en exergue leur individualité. La tendance se conçoit en théorie à la lumière des thèses sur l’individualisation présentes en sociologie et qui, ici, seront considérées avec nuances. L’analyse mise en œuvre s’appuie sur des entrevues semi-directives recueillies de la bouche de backpackers jugés représentatifs de cette inclination à mettre sa routine quotidienne entre parenthèses afin de vouloir agir par soi-même. Or, l’étude produite dans les pages du mémoire révèle que, à leur niveau, ils voyagent librement, mais en ayant en main téléphone intelligent ou portable grâce auquel ils restent constamment connectés avec leur épicentre social, leurs parents et amis, qui ce faisant exerce un pouvoir d’inflexion sur leur périple et sur leurs agissements à l’étranger. Comment expliquer ce paradoxe? Voyager sac au dos dans l’intention d’agir par soi-même, mais être continuellement sujet au regard des autres, lesquels peuvent gouverner à certains égards la marge de manœuvre propice à l’individualisation qui a valeur de qualité. Voilà ce que cherche à expliquer ce mémoire.Being open to the world is trending with today’s youth in Quebec and elsewhere. Members of the Generation Y, young people are already familiar with "new technologies". Indeed, the digital ways and the social media networks have no secret for them, and allow them to keep in touch on a worldwide scale. It then becomes tempting to leave on an adventure, a bag on their back, to conform to the view of being open to the world as a quality. The present Master’s thesis considers the notion of backpacking, namely a trending way of travelling by young people, in particular students, by putting a bag on their back and leaving on a journey to enrich their qualities as individuals. Indeed, leaving their social epicenter, often alone, while traveling "light" in foreign parts of the world contributes to their capacity to act on their own initiative and acquiring qualities susceptible to highlight their individuality. This trend is theoretically designed in the light of theses about individualization present in sociology and which, here, will be considered with nuances. The current analysis leans on semi-directive interviews from backpackers considered representative of this inclination to put their daily routine on hold in order to act by themselves. The study produced in the pages of this report reveals that, at their level, they travel freely, while keeping a smart phone or a portable device which they constantly remain connected to their social epicenter, their parents and friends. In doing so, the devices exercise a power of inflection on their trip and on their actions abroad. How do we explain this paradox? Backpacking with the intention to act on their own, but constantly be subjected to others opinions, which in turn can in some respects govern the control facilitating individualization at its quality value. That is what the Master’s thesis tries to explain

Reversible low-light induced photoswitching of crowned spiropyran-DO3A complexed with gadolinium(III) ions.

Photoswitchable spiropyran has been conjugated to the crowned ring system DO3A, which improves its solubility in dipolar and polar media and stabilizes the merocyanine isomer. Adding the lanthanide ion gadolinium(III) to the macrocyclic ring system leads to a photoresponsive magnetic resonance imaging contrast agent that displays an increased spin-lattice relaxation time (T₁) upon visible light stimulation. In this work, the photoresponse of this photochromic molecule to weak light illumination using blue and green light emitting diodes was investigated, simulating the emission spectra from bioluminescent enzymes. Photon emission rate of the light emitting diodes was changed, from 1.75 × 10¹⁶ photons·s⁻¹ to 2.37 × 10¹² photons·s⁻¹. We observed a consistent visible light-induced isomerization of the merocyanine to the spiropyran form with photon fluxes as low as 2.37 × 10¹² photons·s⁻¹ resulting in a relaxivity change of the compound. This demonstrates the potential for use of the described imaging probes in low light level applications such as sensing bioluminescence enzyme activity. The isomerization behavior of gadolinium(III)-ion complexed and non-complexed spiropyran-DO3A was analyzed in water and ethanol solution in response to low light illumination and compared to the emitted photon emission rate from over-expressed Gaussia princeps luciferase

Using a Robust and Sensitive GFP-Based cGMP Sensor for Real-Time Imaging in Intact Caenorhabditis elegans.

cGMP plays a role in sensory signaling and plasticity by regulating ion channels, phosphodiesterases, and kinases. Studies that primarily used genetic and biochemical tools suggest that cGMP is spatiotemporally regulated in multiple sensory modalities. FRET- and GFP-based cGMP sensors were developed to visualize cGMP in primary cell culture and Caenorhabditis elegans to corroborate these findings. While a FRET-based sensor has been used in an intact animal to visualize cGMP, the requirement of a multiple emission system limits its ability to be used on its own as well as with other fluorophores. Here, we demonstrate that a C. elegans codon-optimized version of the cpEGFP-based cGMP sensor FlincG3 can be used to visualize rapidly changing cGMP levels in living, behaving C. elegans We coexpressed FlincG3 with the blue-light-activated guanylyl cyclases BeCyclOp and bPGC in body wall muscles, and found that the rate of change in FlincG3 fluorescence correlated with the rate of cGMP production by each cyclase. Furthermore, we show that FlincG3 responds to cultivation temperature, NaCl concentration changes, and sodium dodecyl sulfate in the sensory neurons AFD, ASEL/R, and PHB, respectively. Intriguingly, FlincG3 fluorescence in ASEL and ASER decreased in response to a NaCl concentration upstep and downstep, respectively, which is opposite in sign to the coexpressed calcium sensor jRGECO1a and previously published calcium recordings. These results illustrate that FlincG3 can be used to report rapidly changing cGMP levels in an intact animal, and that the reporter can potentially reveal unexpected spatiotemporal landscapes of cGMP in response to stimuli

Changes in cGMP Levels Affect the Localization of EGL-4 in AWC in Caenorhabditis elegans

The Protein Kinase G, EGL-4, is required within the C. elegans AWC sensory neurons to promote olfactory adaptation. After prolonged stimulation of these neurons, EGL-4 translocates from the cytosol to the nuclei of the AWC. This nuclear translocation event is both necessary and sufficient for adaptation of the AWC neuron to odor. A cGMP binding motif within EGL-4 and the Gα protein ODR-3 are both required for this translocation event, while loss of the guanylyl cyclase ODR-1 was shown to result in constitutively nuclear localization of EGL-4. However, the molecular changes that are integrated over time to produce a stably adapted response in the AWC are unknown. Here we show that odor-induced fluctuations in cGMP levels in the adult cilia may be responsible in part for sending EGL-4 into the AWC nucleus to produce long-term adaptation. We found that reductions in cGMP that result from mutations in the genes encoding the cilia-localized guanylyl cyclases ODR-1 and DAF-11 result in constitutively nuclear EGL-4 even in naive animals. Conversely, increases in cGMP levels that result from mutations in cGMP phosphodiesterases block EGL-4 nuclear entry even after prolonged odor exposure. Expression of a single phosphodiesterase in adult, naive animals was sufficient to modestly increase the number of animals with nuclear EGL-4. Further, coincident acute treatment of animals with odor and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) decreased the number of animals with nuclear EGL-4. These data suggest that reducing cGMP levels in AWC is necessary and even partially sufficient for nuclear translocation of EGL-4 and adaptation as a result of prolonged odor exposure. Our genetic analysis and chemical treatment of C. elegans further indicate that cilia morphology, as defined by fluorescent microscopic observation of the sensory endings, may allow for odor-induced fluctuations in cGMP levels and this fluctuation may be responsible for sending EGL-4 into the AWC nucleus

Regulators of AWC-Mediated Olfactory Plasticity in Caenorhabditis elegans

While most sensory neurons will adapt to prolonged stimulation by down-regulating their responsiveness to the signal, it is not clear which events initiate long-lasting sensory adaptation. Likewise, we are just beginning to understand how the physiology of the adapted cell is altered. Caenorhabditis elegans is inherently attracted to specific odors that are sensed by the paired AWC olfactory sensory neurons. The attraction diminishes if the animal experiences these odors for a prolonged period of time in the absence of food. The AWC neuron responds acutely to odor-exposure by closing calcium channels. While odortaxis requires a Gα subunit protein, cGMP-gated channels, and guanylyl cyclases, adaptation to prolonged odor exposure requires nuclear entry of the cGMP-dependent protein kinase, EGL-4. We asked which candidate members of the olfactory signal transduction pathway promote nuclear entry of EGL-4 and which molecules might induce long-term adaptation downstream of EGL-4 nuclear entry. We found that initiation of long-term adaptation, as assessed by nuclear entry of EGL-4, is dependent on G-protein mediated signaling but is independent of fluxes in calcium levels. We show that long-term adaptation requires polyunsaturated fatty acids (PUFAs) that may act on the transient receptor potential (TRP) channel type V OSM-9 downstream of EGL-4 nuclear entry. We also present evidence that high diacylglycerol (DAG) levels block long-term adaptation without affecting EGL-4 nuclear entry. Our analysis provides a model for the process of long-term adaptation that occurs within the AWC neuron of C. elegans: G-protein signaling initiates long-lasting olfactory adaptation by promoting the nuclear entry of EGL-4, and once EGL-4 has entered the nucleus, processes such as PUFA activation of the TRP channel OSM-9 may dampen the output of the AWC neuron

Calcineurin and Protein kinase G regulate C. elegans behavioral quiescence during locomotion in liquid

<p>Abstract</p> <p>Background</p> <p>Most rhythmic motor behaviors in nature are episodic i.e. they alternate between different behavioral states, including quiescence. Electrophysiological studies in invertebrate behavioral switching, maintenance and quiescence have elucidated several neuronal mechanisms that generate a temporal pattern in behavior. However, the genetic bases of these processes are less well studied. We have previously uncovered a novel episodic behavior exhibited by <it>C. elegans </it>in liquid media where they alternate between distinct phases of rhythmic swimming and quiescence. Here, we have investigated the effect of several genes and their site of action on the behavioral quiescence exhibited in liquid by the nematode <it>C. elegans</it>.</p> <p>Results</p> <p>We have previously reported that high cholinergic signaling promotes quiescence and command interneurons are critical for timing the quiescence bout durations. We have found that in addition to command interneurons, sensory neurons are also critical for quiescence. We show that the protein phosphatase calcineurin homolog <it>tax-6 </it>promotes swimming whereas the protein kinase G homolog <it>egl-4 </it>promotes quiescence. <it>tax-6 </it>expression in the sensory neurons is sufficient to account for its effect. <it>egl-4 </it>also acts in multiple sensory neurons to mediate its effect on quiescence. In addition our data is consistent with regulation of quiescence by <it>egl-4 </it>acting functionally downstream of release of acetylcholine (ACh) by motor neurons.</p> <p>Conclusions</p> <p>Our study provides genetic evidence for mechanisms underlying the maintenance of a behavioral state operating at multiple neuronal levels through the activities of a kinase and a phosphatase. These results in a genetically tractable organism establish a framework for further dissection of the mechanism of quiescence during episodic behaviors.</p

A cGMP-dependent protein kinase is implicated in wild-type motility in C. elegans

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65790/1/j.1471-4159.2001.00131.x.pd

Ammonium-Acetate Is Sensed by Gustatory and Olfactory Neurons in Caenorhabditis elegans

Background: Caenorhabditis elegans chemosensation has been successfully studied using behavioral assays that treat detection of volatile and water soluble chemicals as separate senses, analogous to smell and taste. However, considerable ambiguity has been associated with the attractive properties of the compound ammonium-acetate (NH 4Ac). NH 4Ac has been used in behavioral assays both as a chemosensory neutral compound and as an attractant. Methodology/Main Findings: Here we show that over a range of concentrations NH4Ac can be detected both as a water soluble attractant and as an odorant, and that ammonia and acetic acid individually act as olfactory attractants. We use genetic analysis to show that NaCl and NH4Ac sensation are mediated by separate pathways and that ammonium sensation depends on the cyclic nucleotide gated ion channel TAX-2/TAX-4, but acetate sensation does not. Furthermore we show that sodium-acetate (NaAc) and ammonium-chloride (NH4Cl) are not detected as Na + and Cl 2 specific stimuli, respectively. Conclusions/Significance: These findings clarify the behavioral response of C. elegans to NH4Ac. The results should have an impact on the design and interpretation of chemosensory experiments studying detection and adaptation to soluble compounds in the nematode Caenorhabditis elegans

Caenorhabditis elegans behavioral genetics: where are the knobs?

Thousands of behavioral mutants of Caenorhabditis elegans have been studied. I suggest a set of criteria by which some genes important in the evolution of behavior might be recognized, and identify neuropeptide signaling pathways as candidates

Novel and Conserved Protein Macoilin Is Required for Diverse Neuronal Functions in Caenorhabditis elegans

Neural signals are processed in nervous systems of animals responding to variable environmental stimuli. This study shows that a novel and highly conserved protein, macoilin (MACO-1), plays an essential role in diverse neural functions in Caenorhabditis elegans. maco-1 mutants showed abnormal behaviors, including defective locomotion, thermotaxis, and chemotaxis. Expression of human macoilin in the C. elegans nervous system weakly rescued the abnormal thermotactic phenotype of the maco-1 mutants, suggesting that macoilin is functionally conserved across species. Abnormal thermotaxis may have been caused by impaired locomotion of maco-1 mutants. However, calcium imaging of AFD thermosensory neurons and AIY postsynaptic interneurons of maco-1 mutants suggest that macoilin is required for appropriate responses of AFD and AIY neurons to thermal stimuli. Studies on localization of MACO-1 showed that C. elegans and human macoilins are localized mainly to the rough endoplasmic reticulum. Our results suggest that macoilin is required for various neural events, such as the regulation of neuronal activity