• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 18
  • 9
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 40
  • 40
  • 9
  • 7
  • 7
  • 5
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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.
31

Zum Einfluss von Gunkgo biloba-Extrakt (EGb761) und seiner Komponenten auf die Expression von Transthyretin im Maushirn: eine immunhistochemische Studie

May, Tobias 27 February 2014 (has links)
Mit über 35 Millionen Betroffenen weltweit ist die Alzheimersche Erkrankung (AD) die häufigste Demenzerkrankung in westlichen Industrieländern. Durch stetig steigende Prävalenz, gekoppelt mit der zunehmenden Lebenserwartung, erfährt die AD eine immer schwerwiegendere ökonomische und soziale Bedeutung, zumal es bis heute keine wirksame Therapie gibt. Entsprechend ist für mögliche Therapieansätze dieser Erkrankung ein genaues Verständnis der neuropathologischen Mechanismen unerlässlich. So werden neben Therapien, die die cholinerge Hypofunktion und damit auch die zwei weiteren Hauptmerkmale (Amyloid-Plaques und neurofibrilläre Tangles) der AD positiv beeinflussen, auch viele weitere Therapieansätze geprüft. So weiß man, dass einige Substanzen die Expression verschiedener Proteine im Gehirn beeinflussen können, die eine mögliche Rolle bei der Pathogenese der AD spielen. Vor allem untersucht die vorliegende Arbeit, ob eine chronische Behandlung mit dem Ginkgo biloba-Extrakt EGb761 eine veränderte Expression der Proteine Transthyretin (TTR), Prolaktin, Gesamt-Tau und Wachstumshormon (GH) in Hirnen von Mäusen bewirkt. Diese Marker zeigten sich in Mikroarray-Vorversuchen in Hirnmaterial von mit Ginkgo biloba behandelten Mäusen auf Ebene der Genexpression verändert. Veränderungen werden in verschiedenen Fütterungsgruppen dargestellt und diskutiert. Hierzu wird das Methodenspektrum der Immunhistochemie sowie der computergestützten Bildanalyse mittels Densitometrie genutzt. EGb761 sowie im Besonderen dessen Flavonoid-Fraktion bewirkten – im Vergleich zur Kontrollgruppe – eine signifikant erhöhte Immunreaktivität des Proteins Transthyretin in der hippokampalen Formation, während die Terpenoid-Fraktion keine Wirkung auslöste. Die übrigen Marker erschienen unbeeinflusst. Die Ergebnisse werden sowohl im Zusammenhang mit der aktuellen Literatur zu AD als auch mit verschiedenen, vermeintlich neuroprotektiven Proteinen diskutiert.
32

Anti-salmonella adhesion activity of Saccharomyces boulardii ; Effects of of Ginkgo biloba on activities of Cytochromes P-450 /

Mohutsky, Michael A. January 2002 (has links)
Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 207-232).
33

Desenvolvimento de néctares mistos de frutas tropicais adicionados de Ginkgo biloba e Panax ginseng / Development of tropical fruit mixed nectars with addition of Ginkgo biloba e Panax ginseng

Sousa, Paulo Henrique Machado de 06 November 2006 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2016-11-11T16:46:37Z No. of bitstreams: 1 texto completo.pdf: 682521 bytes, checksum: 869569e287896b20f5fe279b28aee120 (MD5) / Made available in DSpace on 2016-11-11T16:46:37Z (GMT). No. of bitstreams: 1 texto completo.pdf: 682521 bytes, checksum: 869569e287896b20f5fe279b28aee120 (MD5) Previous issue date: 2006-11-06 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Com o apelo da mudança para hábitos saudáveis, observa-se o aumento do consumo de fruta fresca em todo o mundo, que se estende aos sucos processados. Bebidas com novos sabores e aromas estão sendo elaboradas, sendo as bebidas mistas de frutas mais uma opção para os consumidores e uma tendência do mercado internacional. A adição de componentes funcionais também vem sendo feita, e os extratos de Ginkgo biloba e Panax ginseng vêm como uma nova opção, por apresentarem inúmeros benefícios à saúde, agregando valor aos produtos de frutas. Diante do exposto, o presente trabalho objetivou a elaboração de néctares mistos à base de caju, manga e acerola, adicionados de extratos de Ginkgo biloba e Panax ginseng e a mistura dos dois extratos, além de estudar a estabilidade dos produtos por um período de seis meses. Foram formulados néctares mistos de frutas tropicais, a partir de 35% de polpa e sólidos solúveis totais padronizados a 11 °Brix. Os teores de polpas variaram segundo um delineamento de misturas: caju (12,25%-21,00%); acerola (1,75%-10,50%); e manga (12,25%-21,00%). A formulação com 12,25% de caju, 21,00% de manga e 1,75% de acerola foi a mais aceita pelos provadores, e apresentou 49,9 mg de vitamina C/100mL de néctar. As respostas sensoriais também foram avaliadas através de análise de agrupamento e os grupos obtidos foram submetidos à análise de componentes principais, revelando a existência de três grupos distintos entre os provadores, indicando claramente a segmentação dos consumidores que preferiam formulações diferenciadas. A adição de extratos de Ginkgo biloba, Panax ginseng e a mistura de ambos em concentrações 15, 20, 25 e 30mg/100mL de néctar foi testada nos néctares, observando-se diminuição das notas de aceitação com o aumento da concentração dos extratos. Foram selecionados os néctares com adição de 15 mg de extrato de Ginkgo biloba/100 mL, 20 mg de extrato de Panax ginseng / 100 mL e a mistura com 10 mg de extrato de Ginkgo biloba e 10 mg de extrato de Panax ginseng/100 mL para avaliação da estabilidade durante 180 dias de armazenamento em condições similares às de comercialização. O tratamento térmico de 90 oC / 60s, conjuntamente com a adição de benzoato de sódio e metabissulfito foram suficientes para garantir a estabilidade microbiológica dos néctares formulados à temperatura ambiente. Os valores de pH, sólidos solúveis, acidez, e açúcares redutores apresentaram pouca variação ao longo dos 180 dias de armazenamento a temperatura ambiente. Os teores de vitamina C foram os que apresentaram maiores variações em todos os néctares mistos de frutas no decorrer de armazenamento. O tempo de armazenamento não afetou a qualidade sensorial dos produtos; sendo que a adição de extrato de Ginkgo biloba ao néctar misto de frutas alterou a aceitação pelos consumidores, sendo a aceitação destes produtos menores. Os resultados sensoriais foram avaliados através da metodologia de Mapa de Preferência Interno, que permitiu identificar a segmentação dos consumidores no aroma, sabor e impressão global, podendo ser feita uma identificação e caracterização de preferências e grupos consumidores. Os néctares sem adição de extrato (controle) e com adição de Panax ginseng foram os mais aceitos pelos consumidores em todos os atributos testados. / With the appealing of changes to healthy habits, it is observed that the consumption of fresh fruit has increased all over the world, and processed juices are an extension of that. Beverages presenting new flavors and aromas are being elaborated; being the mixed fruit drinks one more option to consumers and a trend to international market. The addition of functional components can also be noticed, and extracts of Ginkgo biloba e Panax ginseng are new options, once they present large benefits to human s health and aggregate value to fruit products. According to what was quoted, the actual work had as objective to develop mixed nectars based on cashew apple, mango and acerola, added to extracts of Ginkgo biloba e Panax ginseng and the mix of both extracts, as well as to study the stability of the developed products for six months. They were developed mixed nectars of tropical fruit formulated with at least 35% of pulp and total soluble solids, with 11°Brix. The values of pulp varied according to design of the mixtures: cashew apple (12.25%-21.00%); acerola (1.75%-10.50%); and mango (12.25%-21.00%). The formulation containing 12.25% of cashew apple, 21.00% of mango and 1.75% of acerola was best accepted among the panelists, and it showed 49.9mg of vitamin C/100mL of nectar. The sensorial responses were also evaluated trough cluster analyses and the obtained groups were submitted to main components analyses, showing the existence of three distinct groups among the panelists, indicating clearly consumer s segmentation that preferred different formulations. The addition of Ginkgo biloba and Panax ginseng extracts and the mixture of both in concentrations of 15, 20, 25 and 30mg/100ml nectar were tested at nectars; it was observed that values decreased as the concentration of the extract was being enhanced. They was selected the nectars with addition of 15mg of Ginkgo biloba extract/100 mL, 20 mg of Panax ginseng extract/100 mL and the mixture containing 10 mg of de Ginkgo biloba extract and 10 mg of Panax ginseng extract/100 mL for stability evaluation for the period of 180 days of storage in similar conditions of commercialization. The thermal treatment of 90 o C / 60s, combined to the addition of sodium benzoate and sodium metabisulfite were sufficient to guarantee microbiological stability of the formulated nectars at room temperature. The values of pH, soluble solids, acidity and reducing sugar showed little variation during 180 days of storage at room temperature. The contents of vitamin C were the ones that presented the highest variations in all mixed fruit nectars during the storage. The storage period did not affect the sensorial quality of the products, besides that, the addition of Ginkgo biloba extract to the mixed fruit nectar altered the consumers acceptance, being these products acceptance the lowest ones. The sensorial results were evaluated trough internal preference mapping methodology, which allowed an identification of the consumers segmentation of aroma, flavor and global impression, being possible an identification of characterization of preferences and consumers groups. The nectars without the addition of extract (control) and addition of Panax ginseng were preferred by consumers in all tested attributes.
34

Efeito da associação de Ginkgo biloba e exercício físico no tratamento da osteoporose induzida por glicocorticoides em ratas

SANTOS, Hilda Michelly Paiva dos 06 June 2013 (has links)
Submitted by (lucia.rodrigues@ufrpe.br) on 2016-06-06T15:31:47Z No. of bitstreams: 1 Hilda Michelly Paiva dos Santos.pdf: 3040421 bytes, checksum: 104adb4e836e15777aa8ef5d542a03fa (MD5) / Made available in DSpace on 2016-06-06T15:31:47Z (GMT). No. of bitstreams: 1 Hilda Michelly Paiva dos Santos.pdf: 3040421 bytes, checksum: 104adb4e836e15777aa8ef5d542a03fa (MD5) Previous issue date: 2013-06-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Osteoporosis is a systemic disorder characterized by decreased bone mineral density (BMD), with deterioration of bone microarchitecture, leading to increased skeletal fragility and fracture risk. Treatment of osteoporosis involves the use of bisphosphonates, calcitonin, PTH replacement, therapy and exercise. However, several in vitro studies have shown that Ginkgo biloba extract (EGb 761) and its components showed estrogenic agonist action, and contributes to cellular defense mechanism against cellular proliferation, initiation and progression of cancer. Thus, the present study evaluated the effect of the extract of G. biloba in dosages of 14, 28 and 56mg/Kg/day and its association with the protocol of swimming exercise on glucocorticoid-induced osteoporosis in adult rats by histopathology, immunohistochemistry (detection of calcium by the Von Kossa stain), biochemistry (serum calcium, alkaline phosphatase and molar concentration of hydroxyproline) and quantitative computed tomography. The induction of osteoporosis was effected by administration of dexamethasone at dose of 7mg/kg for 5 weeks. As a positive control we used the sodium alendronato at dose of 0.2 mg/kg/day. The evaluations were performed at 1 °, 25 ° and 50 ° days of treatment. The results showed that lower doses of the extract with or without a swimming protocol showed similar results to those observed in control animals and the ones treated with sodium aledronato, but the highest dosage of the extract without the associating of the swimming protocol caused hypercalcemia at 25th day, and on the 50th day when associated with swimming protocol. It is concluded that the extract of G. biloba isolated or associated with a swimming protocol at doses of 14 and 28mg/Kg reverts induced osteoporosis in rats. However, more studies are necessary in order to better comprehend the effect of dose/time of this extract with or without a physical activity in the pathology of osteoporosis and its possible consequences on the physiology of other systems. / A osteoporose é um distúrbio ósseo sistêmico caracterizado pela diminuição da densidade mineral óssea (DMO), com deteriorização da microarquitetura óssea, levando a um aumento da fragilidade esquelética e do risco de fraturas. O tratamento da osteoporose envolve a utilização de bifosfatos, calcitonina, terapia de reposição de hormônio da paratireoíde e exercícios físicos. Entretanto, vários estudos in vitro têm revelado que o extrato de Ginkgo biloba (EGb 761) e componentes (quercetina e kaempferol) apresentaram ação agonista estrogênico, além de contribuir para o mecanismo de defesa celular contra hiperproliferação celular, iniciação e progressão de neoplasias. Assim, a presente pesquisa avaliou o efeito do extrato de G. biloba nas dosagens de 14, 28 e 56mg/Kg/dia e da sua associação com o protocolo de exercício de natação sobre a osteoporose induzida por glicocorticoides em ratas adultas, através da análise histopatológica, histoquímica (detecção de cálcio pelo Von Kossa), bioquímica (níveis séricos de cálcio e fosfatase alcalina e concentração molar de hidroxiprolina) e pela tomografia computadorizada quantitativa. A indução da osteoporose foi efetuada mediante administração da dexametasona na dosagem de 7mg/Kg por 5 semanas. Como controle positivo utilizou-se o alendronato de sódio na dosagem de 0,2mg/Kg/dia. As avaliações foram realizadas no 1°, 25° e 50° dias de tratamento. Os resultados mostraram que as menores dosagens do extrato associada ou não a um protocolo de natação apresentaram resultados similares aos observados nos animais do grupo controle e nos tratados com aledronato de sódio, porém a maior dosagem do extrado sem associação do protocolo de natação ocasionou hipercalcemia no 25° dia, e no 50° dia quando associado ao protocolo de natação. Assim conclui-se que o extrato de G. biloba isolado ou associado a um protocolo de natação nas dosagens de 14 e 28mg/Kg reverte o quadro da osteoporose induzida em ratas. Entretanto, são necessários maiores estudos com a finalidade de melhor compreder o efeito dose/tempo desse extrato associado ou não a uma atividade física na patologia da osteoporose e suas possíveis consequências na fisiologia de outros sistemas.
35

Avaliação dos aspectos toxicológicos dos fitoterápicos: um estudo comparativo / Evaluation of toxicological aspects of the herbal medicines:a comparative study

Turolla, Monica Silva dos Reis 13 April 2004 (has links)
Esta Dissertação apresenta informações gerais sobre os medicamentos fitoterápicos e os aspectos toxicológicos de uma amostra de dez plantas medicinais comercializadas como medicamentos fitoterápicos no Brasil, pesquisados junto aos principais bancos de dados e fontes públicas de informação. A análise dos medicamentos fitoterápicos cobre as dimensões histórica, econômica e farmacêutica. No tocante aos aspectos toxicológicos, foram avaliados os dados de toxicidade pré-clínica de dez plantas selecionadas, e realizado um levantamento das informações publicadas para Hypericum perforatum e Piper methysticum, relacionadas ao termo toxicidade, segundo três importantes bancos de dados. Adicionalmente, este trabalho aborda as propostas para realização de ensaios de toxicidade pré-clínica para os fitoterápicos segundo a OMS e legislação brasileira, e as normas para avaliação de substâncias químicas segundo a OECD. / This thesis presents general information on herbal medicines and on the toxicological aspects of a sample of ten medicinal plants traded as herbal medicines in Brazil. The survey was carried out in the main databases and public sources of information. The analysis on the herbal medicines encompasses the historical, economic and pharmaceutical dimensions. In what concerns toxicological aspects, data on pre-clinical toxicity were evaluated for Hypericum perforatum and Piper methysticum, these keywords being related to toxicity in three important databases. In addition, this study discusses the proposals for pre-clinical toxicity trials on herbal medicines according to WHO and the Brazilian legislation, and the standards for evaluation of chemical substances according to OECD.
36

Avaliação dos aspectos toxicológicos dos fitoterápicos: um estudo comparativo / Evaluation of toxicological aspects of the herbal medicines:a comparative study

Monica Silva dos Reis Turolla 13 April 2004 (has links)
Esta Dissertação apresenta informações gerais sobre os medicamentos fitoterápicos e os aspectos toxicológicos de uma amostra de dez plantas medicinais comercializadas como medicamentos fitoterápicos no Brasil, pesquisados junto aos principais bancos de dados e fontes públicas de informação. A análise dos medicamentos fitoterápicos cobre as dimensões histórica, econômica e farmacêutica. No tocante aos aspectos toxicológicos, foram avaliados os dados de toxicidade pré-clínica de dez plantas selecionadas, e realizado um levantamento das informações publicadas para Hypericum perforatum e Piper methysticum, relacionadas ao termo toxicidade, segundo três importantes bancos de dados. Adicionalmente, este trabalho aborda as propostas para realização de ensaios de toxicidade pré-clínica para os fitoterápicos segundo a OMS e legislação brasileira, e as normas para avaliação de substâncias químicas segundo a OECD. / This thesis presents general information on herbal medicines and on the toxicological aspects of a sample of ten medicinal plants traded as herbal medicines in Brazil. The survey was carried out in the main databases and public sources of information. The analysis on the herbal medicines encompasses the historical, economic and pharmaceutical dimensions. In what concerns toxicological aspects, data on pre-clinical toxicity were evaluated for Hypericum perforatum and Piper methysticum, these keywords being related to toxicity in three important databases. In addition, this study discusses the proposals for pre-clinical toxicity trials on herbal medicines according to WHO and the Brazilian legislation, and the standards for evaluation of chemical substances according to OECD.
37

"Estudo da ação do nível elevado de pressão sonora e do extrato seco de Ginkgo biloba EGb761 na citoarquitetura da cóclea de cobaias adultas" / Morphological study on the effects of high sound pressure and Ginkgo biloba EGb 761 dry extract to the cochlea cell architecture of adult guinea pigs

Silva, Nadejda Maria Avila Varginha de Moraes e 06 April 2005 (has links)
A preocupação com a exposição do Homem ao ruído excessivo data dos primórdios da civilização. Com a modernidade, os níveis de ruído têm sido crescentes não só nas atividades laborais, como também nas sociais e recreativas, levando a perda auditiva induzida por níveis de pressão sonora elevada (PAINPS) a ser considerada a segunda maior causa de surdez. Esses fatos nos levaram a realizar estudo experimental buscando avaliar o efeito do nível de pressão sonora elevada e do extrato seco de Ginkgo biloba EGb 761 na cóclea de cobaias albinas, fêmeas e adultas, pela avaliação de eventuais alterações da sua citoarquitetura, por meio de microscopia de luz e pela observação das alterações do epitélio sensorial com microscopia eletrônica de varredura / Human exposition to excessive sound levels has been a cause for preoccupation since the early stages of our civilization. In the Modern Era, sound levels have increased not only at work but also during social and leisure activities, leading the hearing loss induced by high levels of sound pressure to be considered the second most important cause of deafness. Bearing that in mind an experimental work was designed in an attempt to search for the effects of high sound pressure and Ginkgo biloba EGb 761 dry extract to the cochlea of albino adult female guinea pigs with the evaluation of cell architecture alterations by means of light microscopy and also by the evaluation of alterations to the sensory epithelium with the scanning electron microscopy (SEM) array
38

"Estudo da ação do nível elevado de pressão sonora e do extrato seco de Ginkgo biloba EGb761 na citoarquitetura da cóclea de cobaias adultas" / Morphological study on the effects of high sound pressure and Ginkgo biloba EGb 761 dry extract to the cochlea cell architecture of adult guinea pigs

Nadejda Maria Avila Varginha de Moraes e Silva 06 April 2005 (has links)
A preocupação com a exposição do Homem ao ruído excessivo data dos primórdios da civilização. Com a modernidade, os níveis de ruído têm sido crescentes não só nas atividades laborais, como também nas sociais e recreativas, levando a perda auditiva induzida por níveis de pressão sonora elevada (PAINPS) a ser considerada a segunda maior causa de surdez. Esses fatos nos levaram a realizar estudo experimental buscando avaliar o efeito do nível de pressão sonora elevada e do extrato seco de Ginkgo biloba EGb 761 na cóclea de cobaias albinas, fêmeas e adultas, pela avaliação de eventuais alterações da sua citoarquitetura, por meio de microscopia de luz e pela observação das alterações do epitélio sensorial com microscopia eletrônica de varredura / Human exposition to excessive sound levels has been a cause for preoccupation since the early stages of our civilization. In the Modern Era, sound levels have increased not only at work but also during social and leisure activities, leading the hearing loss induced by high levels of sound pressure to be considered the second most important cause of deafness. Bearing that in mind an experimental work was designed in an attempt to search for the effects of high sound pressure and Ginkgo biloba EGb 761 dry extract to the cochlea of albino adult female guinea pigs with the evaluation of cell architecture alterations by means of light microscopy and also by the evaluation of alterations to the sensory epithelium with the scanning electron microscopy (SEM) array
39

Origin & Evolution of the C3HDZ-ACL5-SACL Regulatory Module in Land Plants

Solé Gil, Anna 07 September 2023 (has links)
[ES] El correcto desarrollo de tejidos vasculares depende del ajuste preciso entre la proliferación de células vasculares y la diferenciación celular. En Arabidopsis thaliana, la proliferación de células vasculares en el cambium es potenciada por la citoquinina, la síntesi de la cual está promovida por la actividad dependiente de auxina de un heterodímero de factores de transcripción (TF) formado por LONESOME HIGHWAY (LHW) y por TARGET OF MONOPTEROS 5 (TMO5). Como mecanismo de seguridad, las auxinas también activan un módulo inhibidor que implica la inducción precisa de la Termospermina (Tspm) sintasa ACAULIS5 (ACL5) en células vasculares proliferantes por acción conjunta de las auxinas y del TF Class III HD-ZIP (C3HDZ) AtHB8. Entonces, la Tspm permite la traducción de las proteínas SACL de forma celular autónoma, que perjudican la actividad de LHW. Sin embargo, la observación de que estos elementos están presentes en los genomas de todas las plantas terrestres - y no sólo de las plantas vasculares - plantea dos preguntas desde una perspectiva evolutiva: (i) ¿cuál es la función de estos genes en las plantas terrestres no vasculares? y (ii) ¿cuándo se creó el módulo regulador concreto? En esta Tesis, mediante la combinación de análisis filogenéticos, celulares y moleculares con la hepática Marchantia polymorpha, proponemos que la auxina y C3HDZ son reguladores ancestrales de la expresión de ACL5, y que esta conexión se mantiene en las traqueófitas y las briófitas existentes. Por el contrario, la traducción dependiente de Tspm de SACL parece ser específica de las traqueófitas, basado en la aparición de un uORF conservado en la secuencia 5' líder de los tránscritos de SACL y en evidencia experimental basada en ensayos transitorios para la traducción de SACL. De acuerdo con estas observaciones, las funciones de MpACL5 y MpSACL son diferentes en M. polymorpha. MpACL5 se expresa en "notches" apicales y modula la bifurcación de los meristemos. Por otro lado, la expresión de MpSACL está mayoritariamente excluida de los "notches" apicales y su actividad afecta negativamente la producción de gemas y rizoides mediante la interacción con MpRSL1. Finalmente, la hibridación de ARN in situ de ortólogos de C3HDZ, ACL5 y SACL en la gimnosperma Ginkgo biloba, el helecho Ceratopteris richardii y la licófita Selaginella kraussiana indican que la expresión de los tres genes se solapa en los tejidos vasculares. Nuestros resultados sugieren que la función de C3HDZ, ACL5 y SACL ha seguido trayectorias evolutivas divergentes en briófitas y traqueófitas, para controlar, finalmente, diferentes funciones específicas dentro de cada linaje. Sólo en las traqueófitas se formó el módulo regulador y se asoció con la restricción de la proliferación de células vasculares. / [CA] El correcte desenvolupament dels teixits vasculars depèn del precís ajust entre la proliferació de cèl·lules vasculars i la diferenciació cel·lular. En Arabidopsis thaliana, la proliferació de cèl·lules vasculars al càmbium és potenciada per la citoquinina, la síntesi de la qual està promoguda per l'activitat dependent d'auxina d'un heterodímer de factors de transcripció (TF) format per LONESOME HIGHWAY (LHW) i TARGET OF MONOPTEROS 5 (TMO5). Com a mecanisme de seguretat, l'auxina també activa un mòdul inhibidor que implica la inducció precisa de la Termospermina (Tspm) sintasa ACAULIS5 (ACL5) en cèl·lules vasculars proliferants per l'acció conjunta de l'auxina i del TF Class III HD-ZIP (C3HDZ) AtHB8. Llavors, la Tspm permet la traducció de les proteïnes SACL de forma autònoma cel·lular, que perjudiquen l'activitat de LHW. Tanmateix, l'observació de que aquests elements estan presents en els genomes de totes les plantes terrestres - i no només de les plantes vasculars - planteja dues preguntes des d'una perspectiva evolutiva: (i) quina és la funció d'aquests gens en les plantes terrestres no vasculars? i (ii) quan es va crear el mòdul regulador complet? En aquesta Tesi, mitjançant la combinació d'anàlisis filogenètics, cel·lulars i moleculars amb la hepàtica Marchantia polymorpha, proposem que l'auxina i C3HDZ són reguladors ancestrals de l'expressió d'ACL5, i que aquesta connexió es mantén en els traqueòfits i briòfits existents. Per contra, la traducció depenent de Tspm de SACL sembla ser específica dels traqueòfits, basat en l'aparició d'un uORF conservat a la seqüència 5' líder dels trànscrits de SACL i en evidència experimental basada en assajos transitoris per a la traducció de SACL. D'acord amb aquestes observacions, les funcions de MpACL5 i MpSACL són diferents a M. polymorpha. MpACL5 s'expressa en "notch" apicals i modula la bifurcació dels meristems. D'altra banda, l'expressió de MpSACL està majoritàriament exclosa dels "notch" apicals i la seva activitat afecta negativament la producció de gemmes i rizoids mitjançant la interacció amb MpRSL1. Finalment, la hibridació d'ARN in situ d'ortòlegs de C3HDZ, ACL5 i SACL a la gimnosperma Ginkgo biloba, la falguera Ceratopteris richardii i el licòfit Selaginella kraussiana indica que l'expressió dels tres gens es solapa als teixits vasculars. Els nostres resultats suggereixen que la funció de C3HDZ, ACL5 i SACL va seguir trajectòries evolutives divergents en briòfits i traqueòfits, per controlar, finalment, diferents funcions específiques dins de cada llinatge. Només en els traqueòfits es va formar el mòdul regulador i es va associar amb la restricció de la proliferació de cèl·lules vasculars. / [EN] The correct development of vascular tissues depends on the precise adjustment between vascular cell proliferation and cell differentiation. In Arabidopsis thaliana, vascular cell proliferation in the cambium is enhanced by cytokinin, whose synthesis is promoted by the auxin-dependent activity of a transcription factor (TF) heterodimer formed by LONESOME HIGHWAY (LHW) and TARGET OF MONOPTEROS 5 (TMO5). As a safety mechanism, auxin also deploys a negative feedforward regulatory module which involves the precise induction of the Thermospermine (Tspm) synthase ACAULIS5 (ACL5) in proliferating vascular cells by the joint action of auxin and the class-III HD-ZIP (C3HDZ) AtHB8 TF. Tspm then allows the cell-autonomous translation of the SACL proteins, which impair the activity of LHW. However, the observation that these elements are present in the genomes of all land plants -and not only vascular plants- poses two questions from an evolutionary perspective: (i) what is the function of these genes in non-vascular land plants? and (ii) when was the full regulatory module assembled? In this Thesis, through the combination of phylogenetic, cellular, and molecular genetic analyses with the liverwort Marchantia polymorpha, we propose that auxin and C3HDZ are ancestral regulators of ACL5 expression, and that this connection is maintained in extant tracheophytes and bryophytes. On the contrary, thermospermine-dependent translation of SACL seems to be specific of tracheophytes, based on the appearance of a conserved uORF in the 5' leader sequence of SACL transcripts and on experimental evidence using transient assays for SACL translation. In agreement with these observations, the functions of MpACL5 and MpSACL are different in M. polymorpha. MpACL5 is expressed in apical notches and modulates meristem bifurcation. On the other hand, MpSACL expression is mostly excluded from apical notches and its activity negatively affects gemmae and rhizoid production through the interaction with MpRSL1. Finally, in situ RNA hibridization of C3HDZ, ACL5 and SACL orthologs in the gymnosperm Ginkgo biloba, the fern Ceratopteris richardi and the lycophyte Selaginella kraussiana indicates that the expression of the three genes overlaps in vascular tissues. Our results suggest that the function of C3HDZ, ACL5 and SACL followed divergent evolutionary trajectories in bryophytes and tracheophytes, to ultimately control different lineage-specific functions. Only in tracheophytes was the regulatory module assembled and associated with the restriction of vascular cell proliferation. / Solé Gil, A. (2023). Origin & Evolution of the C3HDZ-ACL5-SACL Regulatory Module in Land Plants [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196681
40

A case for memory enhancement : ethical, social, legal, and policy implications for enhancing the memory

Muriithi, Paul Mutuanyingi January 2014 (has links)
The desire to enhance and make ourselves better is not a new one and it has continued to intrigue throughout the ages. Individuals have continued to seek ways to improve and enhance their well-being for example through nutrition, physical exercise, education and so on. Crucial to this improvement of their well-being is improving their ability to remember. Hence, people interested in improving their well-being, are often interested in memory as well. The rationale being that memory is crucial to our well-being. The desire to improve one’s memory then is almost certainly as old as the desire to improve one’s well-being. Traditionally, people have used different means in an attempt to enhance their memories: for example in learning through storytelling, studying, and apprenticeship. In remembering through practices like mnemonics, repetition, singing, and drumming. In retaining, storing and consolidating memories through nutrition and stimulants like coffee to help keep awake; and by external aids like notepads and computers. In forgetting through rituals and rites. Recent scientific advances in biotechnology, nanotechnology, molecular biology, neuroscience, and information technologies, present a wide variety of technologies to enhance many different aspects of human functioning. Thus, some commentators have identified human enhancement as central and one of the most fascinating subject in bioethics in the last two decades. Within, this period, most of the commentators have addressed the Ethical, Social, Legal and Policy (ESLP) issues in human enhancements as a whole as opposed to specific enhancements. However, this is problematic and recently various commentators have found this to be deficient and called for a contextualized case-by-case analysis to human enhancements for example genetic enhancement, moral enhancement, and in my case memory enhancement (ME). The rationale being that the reasons for accepting/rejecting a particular enhancement vary depending on the enhancement itself. Given this enormous variation, moral and legal generalizations about all enhancement processes and technologies are unwise and they should instead be evaluated individually. Taking this as a point of departure, this research will focus specifically on making a case for ME and in doing so assessing the ESLP implications arising from ME. My analysis will draw on the already existing literature for and against enhancement, especially in part two of this thesis; but it will be novel in providing a much more in-depth analysis of ME. From this perspective, I will contribute to the ME debate through two reviews that address the question how we enhance the memory, and through four original papers discussed in part three of this thesis, where I examine and evaluate critically specific ESLP issues that arise with the use of ME. In the conclusion, I will amalgamate all my contribution to the ME debate and suggest the future direction for the ME debate.

Page generated in 0.4546 seconds