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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
431

THE EFFECTS OF ALTERNATE-LINE SHADING ON VISUAL SEARCH IN GRID-BASED GRAPHIC DESIGNS

Lee, Michael P 01 January 2014 (has links)
Objective: The goal of this research was to determine whether alternate-line shading (zebra-striping) of grid-based displays affects the strategy (i.e., “visual flow”) and efficiency of serial search. Background: Grids, matrices, and tables are commonly used to organize information. A number of design techniques and psychological principles are relevant to how viewers’ eyes can be guided through such visual works. One common technique for grids, “zebra-striping,” is intended to guide eyes through the design, or “create visual flow” by alternating shaded and unshaded rows or columns. Method: 13 participants completed a visual serial search task. The target was embedded in a grid that had 1) no shading, 2) shading of alternating rows, or 3) shading of alternating columns. Response times and error rates were analyzed to determine search strategy and efficiency. Results: Our analysis found evidence supporting a weak effect of shading on search strategy. The direction of shading had an impact on which parts of the grid were responded to most rapidly. However, a left-to-right reading bias and middle-to-outside edge effect were also found. Overall performance was reliably better when the grid had no shading. Exploratory analyses suggest individual differences may be a factor. Conclusion: Shading seems to create visual flow that is relatively weak compared to search strategies related to the edge effect or left-to-right reading biases. In general, however, the presence of any type of shading reduced search performance. Application: Designers creating a grid-based display should not automatically assume that shading will change viewers search strategies. Furthermore, although strategic shading may be useful for tasks other than that studied here, our current data indicate that shading can actually be detrimental to visual search for complex (i.e., conjunctive) targets.
432

Development and functional regeneration of the zebrafish lateral line system

Sousa, Filipe Pinto Teixeira 17 February 2012 (has links)
Per a aquesta tesi, utilitzo la línia lateral del peix zebra com a sistema model per adreçar dues qüestions fonamentals: En una primera línia d’investigació exploro la relació entre la funció d’un òrgan i la seva arquitectura. La regeneració de cèl.lules ciliades a la línia lateral del peix zebra ocorre mitjançant la divisió dels seus progenitors en determinades posicions dins les zones ventral i dorsal del neuromast. Durant la regeneració de les cèl.lules ciliades, es forma una línia de simetria vertical, que bisecciona l’epiteli del neuromast en dues meitats de polaritats planars oposades. La qüestió de com es controla l’anisotropia de la regeneració de les cèl.lules ciliades i com integrar aquest procés en l’establiment de la simetria bilateral d’aquest organ, roman encara per esclarir. En aquest estudi mostro que la simetria bilateral del neuromast es sosté degut a l’activitat compartimentalitzada de Notch qui, permetent l’estabilització dels progenitors de cèl.lules ciliades en compartiments polars específics, organitza l’anisotropia de la regeneració. En una segona línia d’investigació, descric el rol del complex de remodelació de cromatina ATPasa brg1 durant la formació d’organs mecanosensorials al peix zebra. Així mostro que els mutants de brg1 desenvolupen un sistema de linia lateral truncat, donat que brg1 es necessari per a la regulació de múltiples events cel.lulars al primordi de la línia lateral. / In this thesis I use the zebrafish lateral line as a model system to address two fundamental questions. In a first line of investigation I explore the relation between an organ function and its architecture. The regeneration of hair cells in the zebrafish lateral line occurs trough the division of hair-cell progenitors at specific locations in the dorsal and ventral aspects of the neuromasts. As hair cells regenerate a vertical midline that bisects the neuromast epithelium into perfect mirror-symmetric plane-polarized halves is formed. Each half contains hair cells of identical planar orientation but opposite to that of the confronting half. How hair cell regeneration anisotropy is controlled and how this process is integrated in the establishment of this organ bilateral symmetry is poorly understood. Here I show that the neuromast bilateral symmetry is sustained by compartmentalized Notch activity, which governs regeneration anisotropy by permitting the stabilization of hair cell progenitors in specific polar compartments. In a second line of research I report the role of the chromatin remodeling complex ATPase brg1 during mechanosensory organ formation in the zebrafish. I show that brg1 mutants develop a truncated lateral line system as brg1 is needed in the regulation of multiple cellular events in the lateral line primordium.
433

Prospecção química de esponjas marinhas e bioensaios relacionados às atividades anticâncer in vitro e de defesa em modelo zebrafish

Silva, Renata Biegelmeyer da January 2013 (has links)
A descoberta de fármacos a partir de produtos isolados de organismos marinhos tem apresentado um grande crescimento nos últimos anos, principalmente devido aos avanços tecnológicos analíticos, síntese química e biotecnologia. Dentre estes, as esponjas representam uma das principais fontes de metabólitos protótipos para diversas atividades, destacando-se os efeitos antitumorais. Neste contexto, este trabalho teve como objetivo a investigação química e biológica de três esponjas coletadas na costa sul-brasileira: Haliclona tubifera, Polymastia janeirensis e Scopalina ruetzleri. Considerando a correlação entre câncer, distúrbios da coagulação e desbalanço de espécies reativas de oxigênio (EROs), foram realizados ensaios visando a aquisição destas atividades e a identificação de substâncias bioativas. Para a esponja H. tubifera foram observados interessantes efeitos antitumorais em células de glioma e neuroblastoma humano (IC50 < 20 μg/ml), além das atividades antioxidante e anticoagulante para a fração acetato de etila. O composto majoritário desta fração foi isolado como um derivado N-Boc e sua configuração foi estabelecida utilizando um novo protocolo de dicroísmo circular e semissíntese de derivados. Assim, este esfingosídeo de cadeia longa isolado (2R,3R,6R,7Z)-2-amino-7-octadecene-1,3,6-triol, foi denominado halisphingosine A. Um novo composto minoritário, halisphingosine B foi obtido usando técnicas de isolamento em escala nanomolar. Sua configuração absoluta foi estabelecida por comparação com o composto A. Da mesma forma, para a esponja S. ruetzleri, a fração acetato de etila demonstrou os resultados mais promissores. Um potencial efeito anticâncer e de inibição dos radicais peroxila foi observado. Além disso, um efeito modulador da peroxidação lipídica foi evidenciado em ensaio ex vivo de dienos conjugados. Através da análise por RMN de 1H, verificou-se que a fração era majoritariamente constituída por ácidos graxos, os quais foram derivatizados para caracterização por Cromatografia Gasosa (GC/FID). Foram identificados 32 ácidos graxos principalmente poli-insaturados (53%). Ácidos graxos minoritários não usuais para o ambiente marinho também foram caracterizados. A esponja P. janeirensis apresentou os efeitos citotóxicos mais promissores em células de glioma e neuroblastoma humano, com um IC50 < 1,0 μg/ml para o extrato aquoso (pH 6,8), sendo este efeito pH-dependente, uma vez que o extrato (pH 5,8) não alterou a viabilidade celular. Para P. janeirensis, foi também investigado seu potencial de defesa química em modelo de Zebrafish. Foi observado que o extrato aquoso desencadeia um efeito de fuga, alterando significativamente o comportamento espaço-temporal de peixes Danio rerio. Analisando em conjunto, os dados do presente trabalho representam uma nova contribuição para o estudo químico e biológico de espécies de esponjas marinhas da costa sul-brasileira e apontam as potencialidades destas esponjas na busca de moléculas protótipos para fármacos, especialmente relacionados à terapia do câncer. / Drug discovery from marine natural products has increased in the past few years, mainly due to technological advances in spectroscopy, chemical synthesis and biotechnology. Among all marine animals, sponges represent one of the major sources of prototype metabolites for several biological activities, highlighting the antitumor effects. In this context, this study carried out chemical and biological investigation of three sponges collected on the South Brazilian coastline: Haliclona tubifera, Polymastia janeirensis and Scopalina ruetzleri. Considering the correlation between cancer, clotting disorders and imbalance of reactive oxygen species (ROS), experiments were conducted for acquisition of these activities and identification of bioactive compounds. H. tubifera showed an interesting cytotoxic effect in human neuroblastoma and glioma cell lines (IC50 <20 μg/ml), antioxidant and anticoagulant effect for ethyl acetate (EtOAc) fraction. The major compound of EtOAc fraction was isolated as an N-Boc derivative and its configuration was established using a new circular dichroism protocol with the production of semi-synthetic derivatives. This long chain sphingoid base (2R,3R,6R,Z)-2-aminooctadec-7-ene-1,3,6-triol was named as halisphingosine A. A new minor compound, halisphingosine B was obtained using nanomol scale techniques and their absolute configuration was established by comparison with compound A. Likewise, for the sponge S. ruetzleri, the EtOAc fraction showed the most promising results. A potential anticancer effect, inhibition of peroxyl radicals and modulation effect of lipid peroxidation was observed. Fingerprint 1H NMR analysis showed that this fraction is mainly constituted of fatty acids. Through Fatty Acid Methyl Ester (FAMEs) analysis by GC/FID, it was possible to identify 32 fatty acids, of which around 50% were Polyunsaturated Fatty Acids (PUFAs). In addition, some minor unusual fatty acids for the marine biosphere were identified. It was observed for P. janeirensis the most promising cytotoxic effects on human glioma and neuroblastoma cells, with an IC50 <1.0 μg/ml to aqueous extract (pH 6.8), being this effect pH-dependent, since the extract (pH 5.8) did not affect the cell viability. Moreover, P. janeirensis was investigated along their potential chemical defense in Zebrafish model. Aqueous extract trigged an escape effect, significantly altering the spatio-temporal swimming activity of animals. Taken together, the data presented from this study represent a new contribution to chemical and biological research of marine sponge species from South Brazilian coastline, and point the potentialities of sponges to search chemical prototypes for drugs, especially related to cancer therapy.
434

Aspects of endocrine disruptors remediation using in vitro and in vivo ecotoxicological assays / Aspectos da remediação de disruptores endócrinos utilizando ensaios ecotoxicológicos in vitro e in vivo

Silva, Juliana Polloni [UNESP] 07 March 2017 (has links)
Submitted by JULIANA POLLONI SILVA null (ju_polloni@yahoo.com.br) on 2017-05-05T15:55:40Z No. of bitstreams: 1 Tese_UNESPSorocaba_JulianaPolloniSilva_2017.pdf: 5158035 bytes, checksum: 4293a506e5ebdca8245dde20cdbecec4 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-05-05T16:08:14Z (GMT) No. of bitstreams: 1 silva_jp_dr_soro.pdf: 5158035 bytes, checksum: 4293a506e5ebdca8245dde20cdbecec4 (MD5) / Made available in DSpace on 2017-05-05T16:08:14Z (GMT). No. of bitstreams: 1 silva_jp_dr_soro.pdf: 5158035 bytes, checksum: 4293a506e5ebdca8245dde20cdbecec4 (MD5) Previous issue date: 2017-03-07 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Produtos químicos capazes de causar desregulação endócrina em vertebrados e invertebrados têm sido detectados a baixas concentrações em ambientes aquáticos do mundo. Desta maneira, tornou-se de interesse mundial a busca por metodologias de remoção mesmos nos ambientes aquáticos. Por isso pesquisa teve como objetivo investigar três materiais (carvão ativado em pós – PAC, zeólitas naturais em pó – ZP e substâncias húmicas aquáticas – AHS) na remediação química e ecotoxicológica de 17ß-estradiol (E2) e 17α-etinilestradiol (EE2) em água mediante ensaios químicos e biológicos in vitro e in vivo. Uma concentração ambientalmente relevante de hormônios (30 ng.L-1) foi utilizada durante os ensaios em laboratório. Os resultados obtidos por meio de uma extensa relação de parâmetros morfológicos, reprodutivos e histológicos adotados permitiram concluir o significativo impacto dos HSFs sobre o desenvolvimento e manutenção de peixes expostos. Comprovou-se a superior eficiência do PAC em relação aos demais substratos na remoção de interferentes endócrinos (IEs) em água. Não obstante, suas propriedades não garantiram o mesmo desempenho com relação a amostras ambientais e, tampouco possibilitou a recuperação das injurias biológicas monitoradas após período de depuração investigado. Um estudo adicional também permitiu a elaboração de um protocolo histoquímico capaz de identificar a produção de vitelogenina (VTG) incitada pela exposição ao esteróide sintético EE2. / Chemicals with potential to cause endocrine disruption in vertebrates and invertebrates have been detected at low concentrations in the world's aquatic environments. Therefore, the search for removal methodologies in aquatic environments became a worldwide interest. The aim of this research was to investigate three materials (powered activated carbon - PAC, powered natural zeolites - ZP and aquatic humic substances - AHS) in chemical and ecotoxicological remediation of 17ß-estradiol (E2) and 17α-ethinylestradiol (EE2) in water through chemical and biological tests in vitro and in vivo. An environmentally relevant concentration of hormones (30 ng.L-1) was used during laboratory tests. The results obtained through an extensive list of morphological, reproductive and histological parameters showed the significant impact of HSFs on the development and maintenance of exposed fish. The superior efficiency of PAC was verified in relation to the other substrates in the endocrine disrupting chemicals (EDCs) removal in water. Nevertheless, their properties did not guarantee the same performance to the environmental samples, neither allow biological injuries monitored to be recovered after the period of depuration investigated. An additional study also allowed the development of a histochemical protocol capable of identifying the production of vitellogenin (VTG) prompted by exposure to the synthetic steroid EE2. / FAPESP: 2012/24495-6 / FAPESP: 2014/22733-2
435

Prospecção química de esponjas marinhas e bioensaios relacionados às atividades anticâncer in vitro e de defesa em modelo zebrafish

Silva, Renata Biegelmeyer da January 2013 (has links)
A descoberta de fármacos a partir de produtos isolados de organismos marinhos tem apresentado um grande crescimento nos últimos anos, principalmente devido aos avanços tecnológicos analíticos, síntese química e biotecnologia. Dentre estes, as esponjas representam uma das principais fontes de metabólitos protótipos para diversas atividades, destacando-se os efeitos antitumorais. Neste contexto, este trabalho teve como objetivo a investigação química e biológica de três esponjas coletadas na costa sul-brasileira: Haliclona tubifera, Polymastia janeirensis e Scopalina ruetzleri. Considerando a correlação entre câncer, distúrbios da coagulação e desbalanço de espécies reativas de oxigênio (EROs), foram realizados ensaios visando a aquisição destas atividades e a identificação de substâncias bioativas. Para a esponja H. tubifera foram observados interessantes efeitos antitumorais em células de glioma e neuroblastoma humano (IC50 < 20 μg/ml), além das atividades antioxidante e anticoagulante para a fração acetato de etila. O composto majoritário desta fração foi isolado como um derivado N-Boc e sua configuração foi estabelecida utilizando um novo protocolo de dicroísmo circular e semissíntese de derivados. Assim, este esfingosídeo de cadeia longa isolado (2R,3R,6R,7Z)-2-amino-7-octadecene-1,3,6-triol, foi denominado halisphingosine A. Um novo composto minoritário, halisphingosine B foi obtido usando técnicas de isolamento em escala nanomolar. Sua configuração absoluta foi estabelecida por comparação com o composto A. Da mesma forma, para a esponja S. ruetzleri, a fração acetato de etila demonstrou os resultados mais promissores. Um potencial efeito anticâncer e de inibição dos radicais peroxila foi observado. Além disso, um efeito modulador da peroxidação lipídica foi evidenciado em ensaio ex vivo de dienos conjugados. Através da análise por RMN de 1H, verificou-se que a fração era majoritariamente constituída por ácidos graxos, os quais foram derivatizados para caracterização por Cromatografia Gasosa (GC/FID). Foram identificados 32 ácidos graxos principalmente poli-insaturados (53%). Ácidos graxos minoritários não usuais para o ambiente marinho também foram caracterizados. A esponja P. janeirensis apresentou os efeitos citotóxicos mais promissores em células de glioma e neuroblastoma humano, com um IC50 < 1,0 μg/ml para o extrato aquoso (pH 6,8), sendo este efeito pH-dependente, uma vez que o extrato (pH 5,8) não alterou a viabilidade celular. Para P. janeirensis, foi também investigado seu potencial de defesa química em modelo de Zebrafish. Foi observado que o extrato aquoso desencadeia um efeito de fuga, alterando significativamente o comportamento espaço-temporal de peixes Danio rerio. Analisando em conjunto, os dados do presente trabalho representam uma nova contribuição para o estudo químico e biológico de espécies de esponjas marinhas da costa sul-brasileira e apontam as potencialidades destas esponjas na busca de moléculas protótipos para fármacos, especialmente relacionados à terapia do câncer. / Drug discovery from marine natural products has increased in the past few years, mainly due to technological advances in spectroscopy, chemical synthesis and biotechnology. Among all marine animals, sponges represent one of the major sources of prototype metabolites for several biological activities, highlighting the antitumor effects. In this context, this study carried out chemical and biological investigation of three sponges collected on the South Brazilian coastline: Haliclona tubifera, Polymastia janeirensis and Scopalina ruetzleri. Considering the correlation between cancer, clotting disorders and imbalance of reactive oxygen species (ROS), experiments were conducted for acquisition of these activities and identification of bioactive compounds. H. tubifera showed an interesting cytotoxic effect in human neuroblastoma and glioma cell lines (IC50 <20 μg/ml), antioxidant and anticoagulant effect for ethyl acetate (EtOAc) fraction. The major compound of EtOAc fraction was isolated as an N-Boc derivative and its configuration was established using a new circular dichroism protocol with the production of semi-synthetic derivatives. This long chain sphingoid base (2R,3R,6R,Z)-2-aminooctadec-7-ene-1,3,6-triol was named as halisphingosine A. A new minor compound, halisphingosine B was obtained using nanomol scale techniques and their absolute configuration was established by comparison with compound A. Likewise, for the sponge S. ruetzleri, the EtOAc fraction showed the most promising results. A potential anticancer effect, inhibition of peroxyl radicals and modulation effect of lipid peroxidation was observed. Fingerprint 1H NMR analysis showed that this fraction is mainly constituted of fatty acids. Through Fatty Acid Methyl Ester (FAMEs) analysis by GC/FID, it was possible to identify 32 fatty acids, of which around 50% were Polyunsaturated Fatty Acids (PUFAs). In addition, some minor unusual fatty acids for the marine biosphere were identified. It was observed for P. janeirensis the most promising cytotoxic effects on human glioma and neuroblastoma cells, with an IC50 <1.0 μg/ml to aqueous extract (pH 6.8), being this effect pH-dependent, since the extract (pH 5.8) did not affect the cell viability. Moreover, P. janeirensis was investigated along their potential chemical defense in Zebrafish model. Aqueous extract trigged an escape effect, significantly altering the spatio-temporal swimming activity of animals. Taken together, the data presented from this study represent a new contribution to chemical and biological research of marine sponge species from South Brazilian coastline, and point the potentialities of sponges to search chemical prototypes for drugs, especially related to cancer therapy.
436

Evaluation and characterisation of two zebrafish models of schizophrenia

Daggett, Jenny January 2016 (has links)
Cognitive deficits are the single strongest predictor of the functional outcome in patients with schizophrenia. Current treatments are largely ineffective in improving cognitive impairments and promising pre-clinical research has mostly failed to translate clinically. Despite the advances provided by rodent models, the neurobiological basis of cognitive deficits in schizophrenia is poorly understood. Therefore, this thesis proposes a zebrafish model for studying cognitive impairments of schizophrenia. Although more evolutionarily distant to humans compared to the rat, the zebrafish has emerged as a popular vertebrate model of human disorders due to its genetic tractability, complex nervous system and elaborate behavioural repertoire. We investigated the effects of genetic alterations and neurodevelopmental disruption on behaviour and learning in zebrafish. Using both disc1 mutant lines and sub-chronic phencyclidine (PCP) on larvae from 6-10 dpf, we were able to assess behavioural changes as a function of developmental age. In particular, this thesis aimed to develop appropriate behavioural assays to assess zebrafish learning and executive function relevant to disorders seen in human patients with schizophrenia. It was possible to demonstrate robust learning across several domains, namely, reversal, classical avoidance and non-associative learning, alongside locomotor and anxiety-related behaviours. There were varied deficits associated with each of the two – genetic (disc1 gene mutation) and environmental (sub-chronic PCP) – manipulations, consistent with observations in rat research. Together, the research in this thesis demonstrates that a zebrafish model exhibits behaviour resembling that of mammalian models of schizophrenia and provides a foundation for the utility of zebrafish in examining cognitive impairments associated with schizophrenia.
437

Estudo dos efeitos dos elementos traços presentes nas partículas provenientes da queima do diesel no sistema reprodutivo de Danio rerio (zebrafisch): análise morfológica e histológica / Effects of trace elements present in diesel exhaust particulates in the reproductive system of Danio rerio (zebrafish): Morphological and histological analysis

Fabiana Moura Novaes Mendez 11 December 2012 (has links)
A qualidade do ar nas áreas urbanas tende a apresentar concentrações indesejáveis de contaminantes provenientes da queima de biomassa, não havendo um sistema abrangente de monitoramento. Achados in vivo mostram que o diesel pode conter compostos que modulam a atividade do estrógeno. Estudos in vitro apoiam essa ideia, como o estudo realizado com cloreto de metileno extraído do diesel que comprova atuar como ativadores de ligação para os receptores de estrógeno. Esse trabalho tem por objetivo avaliar o efeito da exposição à metais presentes nas partículas de exaustao de diesel (PED) na morfologia do ovaário através da histologia, e análise do padrão de expressão dos receptores de estrógeno (ERs) no ovário de zebrafish (Danio rerio) usando a metodologia de PCR em tempo real. Fêmeas adultas de zebrafish foram expostas à concentrações ambientais de combinado de metais (Ni = 0,181 mg/L ; Fe = 0,07455 mg/L ; Pb= 0,05 mg/ L; Cd = 0,029 mg/ L; Cr = 0,161 mg/L ; Cu = 0,017 mg / L) por 3 dias. Em relação a contagem de ovócitos atrésicos a média observada nos animais expostos foi de 1,5 ± 0,4 e nos controles foi de 1,34 ± 0,3. Contudo, não houve diferença significativa entre os grupos (p > 0,05). Na expressão dos três genes receptores de estrógeno (esr1, esr2a, esr2b) as médias foram: 0,68; 1,32; 0,54; respectivamente. No entanto, não houve alteração significativa na expressão desses genes em relação aos controles. Os elementos traços presentes nas PED em concentração ambiental e em exposição aguda na fase adulta não alteram a expressão dos ERs o também não afetam o número de folículos atrésicos nos ovários / The air quality in urban areas tends to have undesirable concentrations of contaminants from biomass combustion, without a monitoring system. In vivo findings show that diesel may contain compounds that modulate the activity of estrogen. In vitro studies support this idea, as the study with methylene chloride extract from diesel proves that this substance act as activators binding to the estrogen receptors (ERs). This study aims to evaluate the effect of exposure to metals present in diesel exhaust particles (PED) in ovary morphology through histology, and analysis of expression pattern of ERs in ovary of zebrafish (Danio rerio) using real time PCR metodology. Adult females were exposed to ambient concentrations of combined metals (Ni = 0.181 mg / L, Fe = 0.07455 mg / L Pb = 0,05 mg / L; Cd = 0.029 mg / L; = 0.161 mg Cr / L, Cu = 0.017 mg / L) for 3 days. The mean of atretic oocytes counting observed in animals exposed was 1.5 ± 0.4 and the controls was 1.34 ± 0.3. However, no significant difference between groups was observed (p> 0.05). The expression of the three genes estrogen receptor (esr1, esr2a, esr2b) mean were: 0.68, 1.32, 0.54, respectively. However, no significant change in the expression of these genes in relation to controls was observed. In conclusion, the trace elements present in the PED concentration in environmental and acute exposure in adulthood not alter the expression of ERs and does not affect the number of atretic follicles in the ovary
438

Être impulsif rend moins altruiste : une expérience avec les diamants mandarins

Chia, Camille 03 1900 (has links)
L’altruisme réciproque, le mécanisme le plus vraisemblable expliquant l’existence de la coopération entre individus non-apparentés, peut être modélisé par le Dilemme du Prisonnier. Ce jeu prédit que la coopération devrait évoluer lorsque les joueurs prévoient d’interagir ensemble à maintes reprises et adoptent des stratégies conditionnelles telles que «Tit-For-Tat» ou Pavlov. Bien que la coopération soit à la source de toutes sociétés humaines, celle-ci est rarement observée chez les animaux. Une explication plausible serait que ces derniers sont plus impulsifs que les humains. Plusieurs études ayant évalué les effets de l’impulsivité sur la coopération ont en effet trouvé un impact négatif du phénomène de « discounting » sur la réciprocité. Néanmoins, l’impulsivité n’est pas un concept unitaire et le rôle de l’impulsivité motrice, une autre facette de l’impulsivité, reste inexploré, alors qu’elle pourrait également restreindre la coopération en altérant la capacité des individus à ajuster de manière flexible leur comportement face aux décisions prises par leur partenaire. En effet, l’impulsivité motrice se définit comme étant l’incapacité à inhiber un comportement qui n’est plus approprié suite à un changement de situation et est donc contreproductif (Broos et al., 2012; MacLean et al., 2014). Pour résoudre cette hypothèse, nous avons mené une expérience avec des diamants mandarins (Taenyopigia guttata) que nous avons appariés en fonction de leur niveau d’impulsivité motrice, puis nous les avons fait jouer dans un Dilemme du Prisonnier Alterné. Tel qu’attendu, nous avons trouvé que la coopération mutuelle survenait plus fréquemment entre les partenaires autocontrôlés que les paires d’individus impulsifs, ce qui serait dû à une différence entre les stratégies employées par les deux types d’individus. Plus précisément, les individus autocontrôlés utilisaient une stratégie « Generous TFT », tel que prédit par la théorie, alors que les oiseaux impulsifs choisissaient de coopérer avec une probabilité fixe, laquelle était indépendante de la décision précédemment prise par le partenaire. Si l’incapacité des individus impulsifs à utiliser des stratégies réactionnelles est due à une capacité de la mémoire de travail réduite, nos résultats pourraient alors contribuer à expliquer les différences interspécifiques qui existent au niveau des comportements coopératifs. / Reciprocal altruism, the most probable mechanism for cooperation among unrelated individuals, can be modelled as a Prisoner’s Dilemma. This game predicts that cooperation should evolve whenever the players, who expect to interact repeatedly, adopt conditional strategies. Yet, experimental data suggest that reciprocity would be rare in animal societies, maybe because animals, compared to humans, are very impulsive. Several studies examining the effect of impulsiveness on cooperation have indeed found a negative impact of temporal discounting. On the other hand, the role of impulsive action, another facet of impulsiveness, remains unexplored, though it could also impede cooperation by affecting the capacity of individuals to flexibly adjust their behaviour to their partner’s decision. To address this hypothesis, we conducted an experiment with zebra finches (Taenyopigia guttata) that were paired assortatively with respect to their level of impulsive action and then played an Alternating Prisoner’s Dilemma. As anticipated, we found that mutual cooperation occurred more frequently between self-controlled partners than between impulsive ones, a difference that was caused by differences in the strategy used by both types of individuals. Specifically, self-controlled individuals used a Generous TFT strategy, as predicted by theory, whereas impulsive birds chose to cooperate with a fixed probability, which was independent of their partner’s previous decision. If the inability of impulsive individuals to use reactive strategies are due to their reduced working memory capacity, our findings might contribute to explaining interspecific differences in cooperative behaviour.
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Delivery of CRISPR/Cas9 RNAs into Blood Cells of Zebrafish: Potential for Genome Editing in Somatic Cells

Schneider, Sara Jane 08 1900 (has links)
Factor VIII is a clotting factor found on the intrinsic side of the coagulation cascade. A mutation in the factor VIII gene causes the disease Hemophilia A, for which there is no cure. The most common treatment is administration of recombinant factor VIII. However, this can cause an immune response that renders the treatment ineffective in certain hemophilia patients. For this reason a new treatment, or cure, needs to be developed. Gene editing is one solution to correcting the factor VIII mutation. CRISPR/Cas9 mediated gene editing introduces a double stranded break in the genomic DNA. Where this break occurs repair mechanisms cause insertions and deletions, or if a template oligonucleotide can be provided point mutations could be introduced or corrected. However, to accomplish this goal for editing factor VIII mutations, a way to deliver the components of CRISPR/Cas9 into somatic cells is needed. In this study, I confirmed that the CRISPR/Cas9 system was able to create a mutation in the factor VIII gene in zebrafish. I also showed that the components of CRISPR/Cas9 could be piggybacked by vivo morpholino into a variety of blood cells. This study also confirmed that the vivo morpholino did not interfere with the gRNA binding to the DNA, or Cas9 protein inducing the double stranded break.
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Spatial Correlation and Facilitation Between <i>Dreissena</i> and <i>Hexagenia</i>: Possible Food-Web Disruption?

DeVanna, Kristen M. January 2011 (has links)
No description available.

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