Kinase C substrates and synaptic plasticity in Aplysia

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Experiment on inter- and intra-specific phenotypic plasticity of three phytoplankton species in response to ocean acidification

Phenotypic plasticity describes the phenotypic adjustment of the same genotype to different environmental conditions and is best described by a reaction norm. We focus on the effect of ocean acidification (OA) on inter - and intraspecific reaction norms of three globally important phytoplankton species (Emiliania huxleyi, Gephyrocapsa oceanica, Chaetoceros affinis). Despite significant differences in growth rates between the species, they all showed a high potential for phenotypic buffering (no significant difference in growth rates between ambient and high CO2 condition). Only three coccolithophore genotypes showed a reduced growth in high CO2. Largely diverging responses to high CO2 of single coc-colithophore genotypes compared to the respective mean species responses, however, raise the question if an extrapolation to the population level is possible from single genotype experiments. We therefore compared the mean response of all tested genotypes to a total species response comprising the same genotypes, which was not significantly different in the coccolithophores. Assessing species reac-tion norm to different environmental conditions on short time scale in a genotype-mix could thus reduce sampling effort while increasing predictive power.

MIMU sensors for joint kinematic estimation: anatomical landmarking and frame correction

The ability to capture human motion allows researchers to evaluate an individual’s gait. Gait can be measured in different ways, from camera-based systems to Magnetic and Inertial Measurement Units (MIMU). The former uses cameras to track positional information of photo-reflective markers, while the latter uses accelerometers, gyroscopes, and magnetometers to measure segment orientation. Both systems can be used to measure joint kinematics, but the results vary because of their differences in anatomical calibrations. The objective of this thesis was to study potential solutions for reducing joint angle discrepancies between MIMU and camera-based systems. The first study worked to correct the anatomical frame differences between MIMU and camera-based systems via the joint angles of both systems. This study looked at full lower body correction versus correcting a single joint. Single joint correction showed slightly better alignment of both systems, but does not take into account that body segments are generally affected by more than one joint. The second study explores the possibility of anatomical landmarking using a single camera and a pointer apparatus. Results showed anatomical landmark position could be determined using a single camera, as the anatomical landmarks found from this study and a camera-based system showed similar results. This thesis worked on providing a novel way for obtaining anatomical landmarks with a single point-and-shoot camera, as well aligning anatomical frames between MIMUs and camera-based systems using joint angles.

Impaired GABA Plasticity at ovBNST Synapses Predicts Compulsive Drinking in Schedule-Induced Polydipsia

Schedule-Induced Polydipsia (SIP) is an animal model of adjunctive drinking induced when a hungry rat receives food on a fixed interval of time. This model has been implemented as a model of compulsive behaviour and may represent a powerful tool to understand the neural mechanisms of compulsion. The bed nucleus of the stria terminalis (BNST) is thought to translate challenges to energy homeostasis into consummatory behaviours, and is therefore likely to contribute to drinking behaviours displayed by food restricted rats in the SIP paradigm. Furthermore, the BNST seems implicated in various compulsive behaviors, including compulsive water drinking in rats. Therefore, the goal of this project was to determine whether compulsive drinking in the SIP paradigm was associated with alterations in transmission at oval BNST (ovBNST) synapses. Rats undergoing the SIP procedure had restricted food access (1-hours/day) for a total of 29 days. After 7 days of food restriction and for the next 21 consecutive days, the rats had daily 2-hour access to operant conditioning chambers where they were presented with a 45-mg food pellet every minute. Water consumed during these 2-hour sessions was measured and the rats that drank 15 ml or more water for a minimum of 3 consecutive days were considered High Drinkers (HD; n=17) or otherwise, Low Drinkers (LD; n=13). Brain slices whole-cell patch clamp recordings conducted 18-hours after the last SIP training showed that chronic food restriction changed low frequency stimulation (LFS) - induced long-term potentiation of ovBNST inhibitory synaptic transmission (iLTP) into LFS - induced long-term depression (iLTD) in a majority of neurons, regardless of drinking behaviours. However, ad libitum access to food between the last day of SIP training and brain slice recordings (18-hour refeed) rescued LFS-induced iLTP in LD but not in HD, suggesting that impaired bi-directional plasticity of ovBNST synapses may contribute to compulsive drinking in the SIP paradigm.

Ecophysiology of Adonis distorta, a high-mountain species endemic of the Central Apennines

Morphological, anatomical and physiological plant and leaf traits of A. distorta, an endemic species of the Central Apennines on the Majella Massif, growing at 2,675 m a.s.l, were analyzed. The length of the phenological cycle starts immediately after the snowmelt at the end of May, lasting 128 ± 10 days. The low A. distorta height  (Hmax= 64 ± 4 mm) and total leaf area (TLA= 38 ± 9 cm2) associated to a high leaf mass area (LMA =11.8±0.6 mg cm−2) and a relatively high leaf tissue density (LTD = 124.6±14.3 mg cm−3) seem to be adaptive traits to the stress factors of the environment where it grows. From a physiological point of view, the high A. distorta photosynthetic rates (PN =19.6 ± 2.3 µmol m−2 s−1) and total chlorophyll content (Chla+b = 0.88 ± 0.13 mg g−1) in July are justified by the favorable temperature. PN decreases by 87% in September at the beginning of plant senescence. Photosynthesis and leaf respiration (RD) variations allow A. distorta to maintain a positive carbon balance during the growing season becoming indicative of the efficiency of plant carbon use. The results could be an important tool for conservation programmes of the A. distorta wild populations.

Plasticity varies with boldness in a weakly-electric fish

The expression of animal personality is indicated by patterns of consistency in  individual behaviour. Often, the differences exhibited between individuals are consistent across situations. However, between some situations, this can be biased by variable levels of individual plasticity. The interaction between individual plasticity and animal personality can be illustrated by examining situation-sensitive personality traits such as boldness (i.e. risk-taking and exploration tendency). For the weakly electric fish Gnathonemus petersii, light condition is a major factor influencing behaviour. Adapted to navigate in low-light conditions, this species chooses to be more active in dark environments where risk from visual predators is lower. However, G. petersii also exhibit individual differences in their degree of behavioural change from light to dark. The present study, therefore, aims to  examine if an increase of motivation to explore in the safety of the dark, not only affects mean levels of boldness, but also the variation between individuals, as a result of differences  in individual plasticity.  Results: Boldness was consistent between a novel-object and a novel-environment situation in bright light. However, no consistency in boldness was noted between a bright (risky) and a  dark (safe) novel environment. Furthermore, there was a negative association between boldness and the degree of change across novel environments, with shier individuals  exhibiting greater behavioural plasticity.  Conclusions: This study highlights that individual plasticity can vary with personality. In  addition, the effect of light suggests that variation in boldness is situation specific. Finally,  there appears to be a trade-off between personality and individual plasticity with shy but  plastic individuals minimizing costs when perceiving risk and bold but stable individuals  consistently maximizing rewards, which can be maladaptive.

High plasticity of loggerhead nesting site fidelity: from using repeatedly the same small beach during different seasons to deposit consecutive nests in different islands distant more than 100 km

[EN] Sea turtles exhibit a strong natal homing associated with a high nesting site philopatry. Mark-recapture and genetic studies confirm these patterns suggesting differences among and within species. In the present study, we have analysed the degree of nest site fidelity of a loggerhead population nesting on the islands of Cape Verde and have evaluated the existence of intrapopulational variability in this trait. The loggerhead is the only sea turtle species that nests in Cape Verde, and 15,000–25,000 nests per season have been estimated for the whole archipelago.

Modelling the niche for a marine vertebrate: A case study incorporating behavioural plasticity, proximate threats and climate change

[EN] The integration of satellite telemetry, remotely sensed environmental data, and habitat/environmental modelling has provided for a growing understanding of spatial and temporal ecology of species of conservation concern. The Republic of Cape Verde comprises the only substantial rookery for the loggerhead turtle Caretta caretta in the eastern Atlantic. A size related dichotomy in adult foraging patterns has previously been revealed for adult sea turtles from this population with a proportion of adults foraging neritically, whilst the majority forage oceanically. Here we describe observed habitat use and employ ecological niche modelling to identify suitable foraging habitats for animals utilising these two distinct behavioural strategies. We also investigate how these predicted habitat niches may alter under the influence of climate change induced oceanic temperature rises.

Tractographie de la matière blanche orientée par a priori anatomiques et microstructurels = White matter tractography guided by anatomical and microstructural priors

Résumé : L'imagerie par résonance magnétique pondérée en diffusion est une modalité unique sensible aux mouvements microscopiques des molécules d'eau dans les tissus biologiques. Il est possible d'utiliser les caractéristiques de ce mouvement pour inférer la structure macroscopique des faisceaux de la matière blanche du cerveau. La technique, appelée tractographie, est devenue l'outil de choix pour étudier cette structure de façon non invasive. Par exemple, la tractographie est utilisée en planification neurochirurgicale et pour le suivi du développement de maladies neurodégénératives. Dans cette thèse, nous exposons certains des biais introduits lors de reconstructions par tractographie, et des méthodes sont proposées pour les réduire. D'abord, nous utilisons des connaissances anatomiques a priori pour orienter la reconstruction. Ainsi, nous montrons que l'information anatomique sur la nature des tissus permet d'estimer des faisceaux anatomiquement plausibles et de réduire les biais dans l'estimation de structures complexes de la matière blanche. Ensuite, nous utilisons des connaissances microstructurelles a priori dans la reconstruction, afin de permettre à la tractographie de suivre le mouvement des molécules d'eau non seulement le long des faisceaux, mais aussi dans des milieux microstructurels spécifiques. La tractographie peut ainsi distinguer différents faisceaux, réduire les erreurs de reconstruction et permettre l'étude de la microstructure le long de la matière blanche. Somme toute, nous montrons que l'utilisation de connaissances anatomiques et microstructurelles a priori, en tractographie, augmente l'exactitude des reconstructions de la matière blanche du cerveau.

Die Plastizität des Nervensystems. Konsequenzen für die Pädagogik

Die Rolle von Umwelteinflüssen auf den Erwerb von Sinnesleistungen und Sprachkompetenz wird anhand von Deprivationsexperimenten aufgezeigt. Die so erläuterte Plastizität des Nervensystems beschränkt sich für Teilfunktionen auf kritische Phasen der Kindheit. Nach diesen ist das Gehirn für diese Funktion nicht mehr lernfähig. Neuroanatomische Studien stützen die Feststellung, daß Potentialitäten des Gehirns genetisch vorgegeben, aber teilweise in ihrer selektiven Ausprägung umweltabhängig sind. Daraus werden Schlußfolgerungen für die pädagogische Verantwortung in kritischen Phasen der Erziehung gezogen. Werden diese Phasen nicht genutzt, so sind sie unwiederbringlich vertan. (DIPF/Orig.)

Anatomy in the Library: Anatomical Models on Course Reserves

In Fall 2015, the Engineering and Physical Science Library (EPSL) began lending anatomical models as part of its course reserves program. EPSL received a partial skeleton and two muscle model figures from instructors of BSCI105. These models circulate for 4 hours at a time and are generally used by small, collaborative groups of students in the library. This poster will look at the challenges and rewards for adding these items to EPSL’s course reserves.

Scanning Laser Optical Tomography Resolves Structural Plasticity during Regeneration in an Insect Brain

Background: Optical Projection Tomography (OPT) is a microscopic technique that generates three dimensional images from whole mount samples the size of which exceeds the maximum focal depth of confocal laser scanning microscopes. As an advancement of conventional emission-OPT, Scanning Laser Optical Tomography (SLOTy) allows simultaneous detection of fluorescence and absorbance with high sensitivity. In the present study, we employ SLOTy in a paradigm of brain plasticity in an insect model system. Methodology: We visualize and quantify volumetric changes in sensory information procession centers in the adult locust, Locusta migratoria. Olfactory receptor neurons, which project from the antenna into the brain, are axotomized by crushing the antennal nerve or ablating the entire antenna. We follow the resulting degeneration and regeneration in the olfactory centers (antennal lobes and mushroom bodies) by measuring their size in reconstructed SLOTy images with respect to the untreated control side. Within three weeks post treatment antennal lobes with ablated antennae lose as much as 60% of their initial volume. In contrast, antennal lobes with crushed antennal nerves initially shrink as well, but regain size back to normal within three weeks. The combined application of transmission-and fluorescence projections of Neurobiotin labeled axotomized fibers confirms that recovery of normal size is restored by regenerated afferents. Remarkably, SLOTy images reveal that degeneration of olfactory receptor axons has a trans-synaptic effect on second order brain centers and leads to size reduction of the mushroom body calyx. Conclusions: This study demonstrates that SLOTy is a suitable method for rapid screening of volumetric plasticity in insect brains and suggests its application also to vertebrate preparations.

Moringa oleifera plasticity to face climatic changes

Extreme abiotic factors, such drought combined with heat waves and/or high UVB radiation are predicted to become more frequent in the future. The impact on plant production of these challenges on multipurpose Moringa oleifera L. remains unclear. A susceptibility of this species may lead to increase poverty in endangered regions. M. oleifera is a woody species native from sub-Himalaya regions under high climate stress pressure. The interest on this species is emerging due to its several medicinal properties and its nutritional value. Agropharmaceutical industry is interest in this species too. To understand the impact of increased climate factors, young (2 months old) plants of this species were exposed to water deficit (WD) and UVB (alone or combined). WD and WD+UVB imposition consists of unwater for 4 days. After 1 day withholding water, UVB and WD+UVB were irradiated with 26.3 kJ m-2 distributed per 3 days. Immediately after treatment exposition (1 day) and after 10 days, plant water status, growth, carbon metabolism and oxidative stress were measured. Overall no significant differences were observed in WD, regarding the parameters analysed, except on gas exchanges, MDA and phenols. The plants exposed to UVB showed, in general, more severe effects, as higher pigment content, MDA and membrane permeability, while no changes were observed in the total antioxidant activity. Plants exposed to UVB+WD, despite changes observed, the impact was lower than the one observed in UVB exposed plants, meaning that a protective/adaptive mechanism was developed in the plants under combined stressors. On the other hand, in all treatments the net CO2 assimilation rate decreased. Results suggest that M. oleifera has some tolerance to WD and UVB, and that develops mechanism of adaptation to these two types of stress that often arise in combination under a climate change scenario.

Plasticity in Insect Olfaction: To Smell or Not to Smell?

International audience

The spatial rhetoric of Gustav Zeiller's popular anatomical museum

This article focuses on the public experience of science by studying the exhibition practice of a small popular anatomy museum. The owner, Gustav Zeiller, a little-known German model maker and entrepreneur, opened his private collection in Dresden in 1888 with the aim of providing experts and laymen alike with a scientific education on bodily matters and health care. The spatial configuration of his museum environment turned the wax models into didactic instruments. Relying on the possible connexion between material culture studies and history of the emotions, this article highlights how Zeiller choreographed the encounter between the museum objects and its visitors. I argue that the spatial set up of his museum objects entailed rhetorical choices that did not simply address the social utility of his museum. Moreover, it fulfilled the aim of modifying the emotional disposition of his intended spectatorship. I hope to show that studying the emotional responses toward artefacts can offer a fruitful approach to examine the public experience of medicine.