Development of a miniaturized microscope for depth-scanning imaging at subcellular resolution in freely behaving animals

Le fonctionnement du cerveau humain est fascinant. En seulement quelques millisecondes, des milliards de neurones synchronisés perçoivent, traitent et redirigent les informations permettant le contrôle de notre corps, de nos sentiments et de nos pensées. Malheureusement, notre compréhension du cerveau reste limitée et de multiples questions physiologiques demeurent. Comment sont exactement reliés le fonctionnement neuronal et le comportement humain ? L’imagerie de l’activité neuronale au moyen de systèmes miniatures est l’une des voies les plus prometteuses permettant d’étudier le cerveau des animaux se déplaçant librement. Cependant, le développement de ces outils n’est pas évident et de multiples compromis techniques doivent être faits pour arriver à des systèmes suffisamment petits et légers. Les outils actuels ont donc souvent des limitations concernant leurs caractéristiques physiques et optiques. L’un des problèmes majeur est le manque d’une lentille miniature électriquement réglable et à faible consommation d’énergie permettant l’imagerie avec un balayage en profondeur. Dans cette thèse, nous proposons un nouveau type de dispositif d’imagerie miniature qui présente de multiples avantages mécaniques, électriques et optiques par rapport aux systèmes existants. Le faible poids, la petite dimension, la capacité de moduler électriquement la distance focale à l’aide d’une lentille à cristaux liquides (CL) et la capacité d’imager des structures fines sont au cœur des innovations proposées. Dans un premier temps, nous présenterons nos travaux (théoriques et expérimentaux) de conception, assemblage et optimisation de la lentille à CL accordable (TLCL, pour tunable liquid crystal lens). Deuxièmement, nous présenterons la preuve de concept macroscopique du couplage optique entre la TLCL et la lentille à gradient d’indice (GRIN, pour gradient index) en forme d’une tige. Utilisant le même système, nous démontrerons la capacité de balayage en profondeur dans le cerveau des animaux anesthésiés. Troisièmement, nous montrerons un dispositif d’imagerie (2D) miniature avec de nouvelles caractéristiques mécaniques et optiques permettant d’imager de fines structures neuronales dans des tranches de tissus cérébraux fixes. Enfin, nous présenterons le dispositif miniaturisé, avec une TLCL intégrée. Grâce à notre système, nous obtenons ≈ 100 µm d’ajustement électrique de la profondeur d’imagerie qui permet d’enregistrer l’activité de fines structures neuronales lors des différents comportements (toilettage, marche, etc.) de la souris.The functioning of the human brain is fascinating. In only a few milliseconds, billions of finely tuned and synchronized neurons perceive, process and exit the information that drives our body, our feelings and our thoughts. Unfortunately, our understating of the brain is limited and multiple physiological questions remain. How exactly are related neural functioning and human behavior ? The imaging of the neuronal activity by means of miniaturized systems is one of the most promising avenues allowing to study the brain of the freely moving subjects. However, the development of these tools is not obvious and multiple technical trade-offs must be made to build a system that is sufficiently small and light. Therefore, the available tools have different limitations regarding their physical and optical characteristics. One of the major problems is the lack of an electrically adjustable and energy-efficient miniature lens allowing to scan in depth. In this thesis, we propose a new type of miniature imaging device that has multiple mechanical, electrical and optical advantages over existing systems. The low weight, the small size, the ability to electrically modulate the focal distance using a liquid crystal (LC) lens and the ability to image fine structures are among the proposed innovations. First, we present our work (theoretical and experimental) of design, assembling and optimization of the tunable LC lens (TLCL). Second, we present the macroscopic proof-of-concept optical coupling between the TLCL and the gradient index lens (GRIN) in the form of a rod. Using the same system, we demonstrate the depth scanning ability in the brain of anaesthetized animals. Third, we show a miniature (2D) imaging device with new mechanical and optical features allowing to image fine neural structures in fixed brain tissue slices. Finally, we present a state-of-the-art miniaturized device with an integrated TLCL. Using our system, we obtain a ≈ 100 µm electrical depth adjustment that allows to record the activity of fine neuronal structures during the various behaviours (grooming, walking, etc.) of the mouse

Experimental study of the thermal stability of materials in high temperature oxygen-containing media

An experimental study is made of the interaction of several materials with a high temperature medium containing oxygen. The temperature of the surface was measured as a function of time. It is found that the higher the velocity of mass removal from the surface, the more effective is the material from the viewpoint of heat resistance

Оптимальное восстановление функций по неточно заданному преобразованию Радона на классах, задаваемых степенью оператора Лапласа

We consider the problem of optimal recovery of function in Schwartz space from inaccurate data (in the mean square metric) on it’s Radon transform. We present explicit expressions for the error of optimal recovery and a set of optimal methods. As a consequence we prove one inequality for functions in Schwartz space.В работе рассматривается задача оптимального восстановления функции из пространства Шварца по неточно заданному (в средне квадратичной метрике) преобразованию Радона. Получены явные выражения для погрешности оптимального восстановления и семейства оптимальных методов. В качестве следствия приведено одно неравенство для функций из пространства Шварца

BDNF Val66Met polymorphism is associated with self-reported empathy

Empathy is an important driver of human social behaviors and presents genetic roots that have been studied in neuroimaging using the intermediate phenotype approach. Notably, the Val66Met polymorphism of the Brain-derived neurotrophic factor (BDNF) gene has been identified as a potential target in neuroimaging studies based on its influence on emotion perception and social cognition, but its impact on self-reported empathy has never been documented. Using a neurogenetic approach, we investigated the association between the BDNF Val66Met polymorphism and self-reported empathy (Davis’ Interpersonal Reactivity Index; IRI) in a sample of 110 young adults. Our results indicate that the BDNF genotype is significantly associated with the linear combination of the four facets of the IRI, one of the most widely used self-reported empathy questionnaire. Crucially, the effect of BDNF Val66Met goes beyond the variance explained by two polymorphisms of the oxytocin transporter gene previously associated with empathy and its neural underpinnings (OXTR rs53576 and rs2254298). These results represent the first evidence suggesting a link between the BDNF gene and self-reported empathy and warrant further studies of this polymorphism due to its potential clinical significance

Exploring the directionality of <i>Escherichia coli </i>formate hydrogenlyase:a membrane-bound enzyme capable of fixing carbon dioxide to organic acid

During mixed‐acid fermentation Escherichia coli produces formate, which is initially excreted out the cell. Accumulation of formate, and dropping extracellular pH, leads to biosynthesis of the formate hydrogenlyase (FHL) complex. FHL consists of membrane and soluble domains anchored within the inner membrane. The soluble domain comprises a [NiFe] hydrogenase and a formate dehydrogenase that link formate oxidation directly to proton reduction with the release of CO (2) and H(2). Thus, the function of FHL is to oxidize excess formate at low pH. FHL subunits share identity with subunits of the respiratory Complex I. In particular, the FHL membrane domain contains subunits (HycC and HycD) that are homologs of NuoL/M/N and NuoH, respectively, which have been implicated in proton translocation. In this work, strain engineering and new assays demonstrate unequivocally the nonphysiological reverse activity of FHL in vivo and in vitro. Harnessing FHL to reduce CO (2) to formate is biotechnologically important. Moreover, assays for both possible FHL reactions provide opportunities to explore the bioenergetics using biochemical and genetic approaches. Comprehensive mutagenesis of hycC did not identify any single amino acid residues essential for FHL operation. However, the HycD E199, E201, and E203 residues were found to be critically important for FHL function

Modelling the emergent dynamics and major metabolites of the human colonic microbiota

Funded by Scottish Government's Rural and Environment Science and Analytical Services Division (RESAS) Acknowledgements We would like to thank Thanasis Vogogias, David Nutter and Alec Mann for their assistance in developing the software for this model. We also acknowledge the Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS) for their financial support. Furthermore,many thanks go to the two anonymous reviewers whose hard work has greatly improved this paper.Peer reviewedPublisher PD

Evidence for Escherichia coli DcuD carrier dependent FOF1-ATPase activity during fermentation of glycerol

During fermentation Escherichia coli excrete succinate mainly via Dcu family carriers. Current work reveals the total and N,N’-dicyclohexylcarbodiimide (DCCD) inhibited ATPase activity at pH 7.5 and 5.5 in E. coli wild type and dcu mutants upon glycerol fermentation. The overall ATPase activity was highest at pH 7.5 in dcuABCD mutant. In wild type cells 50% of the activity came from the FOF1-ATPase but in dcuD mutant it reached ~80%. K+ (100 mM) stimulate total but not DCCD inhibited ATPase activity 40% and 20% in wild type and dcuD mutant, respectively. 90% of overall ATPase activity was inhibited by DCCD at pH 5.5 only in dcuABC mutant. At pH 7.5 the H+ fluxes in E. coli wild type, dcuD and dcuABCD mutants was similar but in dcuABC triple mutant the H+ flux decreased 1.4 fold reaching 1.15 mM/min when glycerol was supplemented. In succinate assays the H+ flux was higher in the strains where DcuD is absent. No significant differences were determined in wild type and mutants specific growth rate except dcuD strain. Taken together it is suggested that during glycerol fermentation DcuD has impact on H+ fluxes, FOF1-ATPase activity and depends on potassium ions

Formate-Dependent Microbial Conversion of CO2 and the Dominant Pathways of Methanogenesis in Production Water of High-temperature Oil Reservoirs Amended with Bicarbonate

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Transformation of students’ perceptions of disability as a result of inclusive education: a posse ad esse

Introduction. The relevance of the research is determined by the necessity to fill knowledge gaps related to understanding the socio-cultural transformations taking place in the student environment due to the extensive development of inclusive technologies in universities. Aim. The present research aimed to identify transformations in the public consciousness of students associated with the period of application of the inclusive approach and to determine the factors that determine them. Methodology and research methods. The study relies on the theoretical and methodological concept of constructing a metasystem “personality – group – society” in the context of an individual assimilating social experience. In determining the empirical basis of the study, the principle of unity and differentiation was applied to identify potential causal relationships between the socio-demographic characteristics of respondents and the development of predominant sentiments regarding the resolution of integration issues in society for individuals with disabilities. A comparison of the semantic dominants of the attitudes towards disabled students, who studied in 2008 (at the initial stage of awareness of the need for an inclusive approach) and in 2023 (at a mature stage characterised by many years of experience in ensuring a barrier-free educational environment in universities), allowed the authors to identify a number of fundamental socio-cultural characteristics of modern students for further qualitative research. Results. The research outcomes revealed that there have been no qualitative changes in the public consciousness of modern students regarding people with disabilities, despite the extensive development of inclusion in universities. Additionally, there are still persistent manifestations of stigmatisation of students with health problems. The negative impact of overestimating the effect of administrative factors on the inclusive process, on the one hand, and ignoring the need to support the development of social values in the student’s personality, on the other, was revealed. Scientific novelty. The research contributes to the development of scientific reflection methods in line with the phenomenological approach and clarifies the subject area of studying inclusive processes in universities. Practical significance. The presented materials and conclusions may be of scientific and practical interest to both researchers and organisers of inclusive processes in universities.Введение. Актуальность исследования обусловлена необходимостью восполнения пробелов в знаниях, связанных с осмыслением социокультурных трансформаций, происходящих в университетской среде вследствие экстенсивного развития инклюзивных технологий в вузах. Цель исследования – выявление связанных с периодом применения инклюзивного подхода трансформаций в общественном сознании студентов и определение обуславливающих их факторов. Методология, методы и методики. Исследование опирается на теоретико-методологическое представление о построении метасистемы «личность – группа – общество» в контексте усвоения личностью социального опыта. При определении эмпирической базы исследования был применен принцип единства и дифференциации с целью выявления возможных причинно-следственных связей между социально-демографическими характеристиками респондентов и формированием доминирующих настроений по отношению к решению проблем интеграции в обществе людей с инвалидностью. Сопоставление смысловых доминант отношения к инвалидам студентов, обучавшихся в 2008 году (на начальной стадии осознания необходимости применения инклюзивного подхода) и в 2023 году (на зрелой стадии, характеризующейся многолетним опытом обеспечения безбарьерности образовательной среды в вузах), позволило выявить ряд принципиальных для дальнейших качественных исследований социокультурных характеристик современного студенчества. Результаты позволили сделать вывод об отсутствии качественных изменений в общественном сознании современных студентов в отношении инвалидов, несмотря на экстенсивное развитие инклюзии в вузах, и о сохраняющихся проявлениях стигматизации обучающихся с проблемами здоровья. Выявлено негативное влияние переоценки эффекта воздействия административного фактора на инклюзивный процесс, с одной стороны, и игнорирование необходимости поддержки процессов развития общественных ценностей личности студента, с другой. Научная новизна. Исследование вносит вклад в развитие методов научной рефлексии в русле феноменологического подхода и уточняет предметную область изучения инклюзивных процессов в вузах. Практическая значимость. Материалы и выводы настоящей работы могут представлять научно-практический интерес как для исследователей, так и для организаторов инклюзивных процессов в вузах

Neutralization of Botulinum Neurotoxin by a Human Monoclonal Antibody Specific for the Catalytic Light Chain

Background: Botulinum neurotoxins (BoNT) are a family of category A select bioterror agents and the most potent biological toxins known. Cloned antibody therapeutics hold considerable promise as BoNT therapeutics, but the therapeutic utility of antibodies that bind the BoNT light chain domain (LC), a metalloprotease that functions in the cytosol of cholinergic neurons, has not been thoroughly explored. Methods and Findings: We used an optimized hybridoma method to clone a fully human antibody specific for the LC of serotype A BoNT (BoNT/A). The 4LCA antibody demonstrated potent in vivo neutralization when administered alone and collaborated with an antibody specific for the HC. In Neuro-2a neuroblastoma cells, the 4LCA antibody prevented the cleavage of the BoNT/A proteolytic target, SNAP-25. Unlike an antibody specific for the HC, the 4LCA antibody did not block entry of BoNT/A into cultured cells. Instead, it was taken up into synaptic vesicles along with BoNT/A. The 4LCA antibody also directly inhibited BoNT/A catalytic activity in vitro. Conclusions: An antibody specific for the BoNT/A LC can potently inhibit BoNT/A in vivo and in vitro, using mechanisms not previously associated with BoNT-neutralizing antibodies. Antibodies specific for BoNT LC may be valuable components o