Hoje há um grande interesse em componentes da dieta, como os polifenóis do chá verde, os quais podem exercer efeitos de proteção contra várias doenças neurológicas, incluindo Alzheimer, isquemia e acidente vascular cerebral. O objetivo deste estudo foi investigar o efeito da (-) epicatequina 3-galato (ECG), um dos principais antioxidantes do chá verde, em células da linhagem C6. Avaliamos morfologia e integridade celular, captação de glutamato e secreção de S100B e o efeito sobre a genotoxicidade induzida por H2O2, na presença de 0,1; 1 e 10 μM de ECG. Após 6 h de incubação, houve alteração morfológica somente com 10 μM de ECG. Entretanto, após 24 h, todas as concentrações de ECG induziram formação de processos ao redor do corpo celular. Houve perda da integridade celular (~ 6%) somente após 24 h, apenas na presença de 10 μM de ECG. Houve diminuição (~36%) na captação de glutamato após 1 h com 1 e 10 μM de ECG. Após 6 h, houve aumento na captação de glutamato (~70%) a partir de 0,1 μM. Também se observou aumento significativo na secreção de S100B com 1 μM de ECG (~ 36%) e com 10 μM (69%) após 1 h, enquanto após 6 h, todas concentrações induziram um aumento na secreção de S100B (~60%). Curiosamente, na presença de 10 μM de ECG houve efeito genotóxico, dependente do tempo de exposição. Já com doses mais baixas (0,1 e 1 μM), a ECG foi capaz de prevenir completamente a genotoxicidade induzida pelo H2O2. Em suma, demonstramos que a ECG pode modular captação de glutamato e secreção de S100B. Além disso, pode exercer efeitos genoprotetores ou genotóxicos em células C6, dependendo da concentração e do tempo de incubação. Estes resultados sugerem que a ECG pode contribuir para o papel neuroprotetor das células gliais e contrapor-se a patologias neurológicas associadas ao estresse oxidativo. / There is a current interest in dietary compounds, such as green tea polyphenols, that can favor protection against a variety of brain disorders, including Alzheimer’s disease, ischemia and stroke. The objective of the present study was to investigate the effects of (-)-epicatechin-3-gallate (ECG), one of three major green tea antioxidants, on C6 lineage cells. We evaluated cell morphology and integrity; specific astrocyte activities; glutamate uptake; S100B secretion and the effect on genotoxicity induced by H2O2 in the presence of 0.1, 1 and 10 μM ECG. During 6 h of incubation, cell morphology was altered only at 10 μM ECG; After 24 h, cells become stellate (process-bearing cells), in the presence of all concentrations of ECG. Loss of cell integrity (~ 6%) was observed after 24 h with 10 μM ECG. ECG (1–10 μM) induced a decrease (~ 36%) in glutamate uptake after 1 h, however, after 6 h, occurred a sustained increase in glutamate uptake (~ 70%) from 0.1 μM. A significant increase in S100B secretion was observed at 1 μM ECG (36%) and 10 μM ECG (69%) after 1 h, in contrast to 6 h, when all doses induced a significant increase (~ 60%). Interestingly, ECG 10 μM showed genotoxic effects depending on time of incubation. In contrast, smaller doses of ECG (0.1 and 1 μM) were able to almost completelly prevent genotoxicity induced by H2O2. In summary, this study demonstrates that ECG can induce a significant improvement in glutamate uptake and S100B secretion. Also, ECG can exert genoprotective or genotoxic effects in C6 cells depending on concentration and time of incubation. These results suggest that ECG could contribute to the neuroprotective role of astroglial cells to counteract brain pathologies associated with oxidative stress.

Submitted by Eduarda Figueiredo (eduarda.ffigueiredo@ufpe.br) on 2015-03-13T13:08:25Z No. of bitstreams: 2 DISSERTAÇÃO.SEMINÁRIO.II.pdf: 1553286 bytes, checksum: e92761ec43759c185de388e17e889c2d (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-13T13:08:25Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO.SEMINÁRIO.II.pdf: 1553286 bytes, checksum: e92761ec43759c185de388e17e889c2d (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2012-02-17 / CAPES / O uso de insumos vegetais vem aumentando no Brasil e em outras partes do mundo, o que é comprovado pelo aumento do consumo de chás. Nesse contexto, Camellia sinensis, popularmente conhecida como chá verde, vem se destacando em várias pesquisas por sua composição rica em compostos fenólicos, os quais constituem potentes antioxidantes. Existem riscos para a saúde pública devido ao aumento do consumo de chás contaminados por manipulação e armazenamento inadequado, portanto este trabalho tem por objetivo avaliar o efeito da radiação gama sobre a quantidade de fenólicos totais, atividade antioxidante e carga fúngica do extrato aquoso de chá verde visando o tratamento sanitário deste alimento. Foram analisadas alíquotas de amostra a granel adquirida na CEASA/PE, antes e após a irradiação gama (doses de 0; 5; 7,5 e 10 kGy). O teor de fenólicos totais dos extratos aquosos foi determinado utilizando o reagente Folin-Ciocalteu tendo a catequina como padrão de referência e a absorbância determinada a 725nm. Os resultados foram expressos em mg de fenólicos totais em equivalente de catequina por g de amostra. Os mesmos extratos acima obtidos foram utilizados para avaliar sua capacidade de sequestrar o radical livre DPPH, e os resultados expressos como percentual de sequestro de radical livre. As análises microbiológicas foram realizadas a partir das amostras irradiadas e controle. O processamento por radiação em diferentes doses (5; 7,5 e 10 kGy) não provocou perdas de compostos fenólicos totais nem reduziu a capacidade antioxidante dos extratos aquosos do chá verde em relação à amostra controle. Observou-se ainda, que a radiação pode ter provocado um efeito catalisador, reduzindo o tempo necessário para se atingir a atividade máxima de sequestro de DPPH. Paralelamente, a radiação gama foi eficaz na redução da carga fúngica do chá verde, diminuindo o número de unidades formadoras de colônia por grama (UFC/g), conforme o aumento da dose de radiação. Confirmando o efeito da radiação gama como um tratamento alimentar eficaz, apesar não ter sido eficiente na eliminação de fungos aflatoxigênicos.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O objetivo desse estudo in vitro foi avaliar o efeito do flavonÃide epigalocatequina-3-galato (EGCG) na resistÃncia de uniÃo à dentina nos perÃodos imediato e apÃs 6 meses de armazenamento. Trinta terceiros molares humanos recÃm-extraÃdos tiveram o esmalte oclusal removidos, obtendo-se uma superfÃcie plana de dentina. Os dentes foram divididos em 5 grupos (n=6) de acordo com a soluÃÃo de re-hidrataÃÃo da dentina. As superfÃcies expostas de dentina foram condicionadas com Ãcido fosfÃrico a 35% por 15s, lavadas por 30s, e secas com jatos de ar. Os dentes dos grupos G1, G2, G3, G4 e G5 foram re-hidratados, respectivamente, com Ãgua destilada, EGCG a 0,02%, 0,1%, 0,5% e clorexidina a 2%. Cada soluÃÃo de re-hidrataÃÃo foi mantida em contato coma superfÃcie dentinÃria por 60s. O sistema adesivo - Adper Single Bond 2 (3M ESPE) foi aplicado de acordo com a instruÃÃes do fabricante. Cinco incrementos de 1 mm de espessura de resina composta foram aplicados e fotoativados individualmente por 20 segundos. Os dentes foram armazenados em Ãgua destilada a 37ÂC por 24h. Em seguida, foram confeccionados cortes seriados perpendiculares entre si, atravÃs da interface de uniÃo, para obter espÃcimes em forma de palito com a Ãrea de secÃÃo transversal de aproximadamente 1 mm2. Metade dos espÃcimes foi testada imediatamente enquanto a outra metade foi armazenada em soluÃÃo de azida de sÃdio a 0,3 mMol/l a 37ÂC por seis meses. Cada espÃcime foi tracionado a velocidade de 0,5mm/minuto em uma mÃquina universal de ensaios. Os valores de resistÃncia de uniÃo foram estatisticamente avaliados por ANOVA a dois critÃrios e Student-Newman-Keuls, com nÃvel de significÃncia de 95%. A mÃdia (desvio padrÃo) dos valores de resistÃncia de uniÃo (em MPa) foram os seguintes: No perÃodo imediato - G1= 34,17 (7,75); G2= 31,39 (7,82); G3= 34,74 (9,14); G4= 27,11 (7,78); G5= 34,68 (7,30). No perÃodo de 6 meses - G1= 27,67 (6,98); G2= 31,75 (10,58); G3= 35,99 (10,91); G4= 31,18 (9,29); G5= 31,62 (5,78). O EGCG a 0,02 % e a 0,1% nÃo afetou a resistÃncia de uniÃo, no perÃodo imediato (p>0,05). ApÃs 6 meses de armazenamento, o EGCG em diferentes concentraÃÃes manteve a resistÃncia de uniÃo. EGCG pode ser usado como uma alternativa para melhorar a durabilidade das restauraÃÃes adesivas, pois preserva a resistÃncia de uniÃo das interfaces.

Orientador: Jose B. Lopes de Faria / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-12T08:15:20Z (GMT). No. of bitstreams: 1 Ribaldo_PerolaDelBianco_M.pdf: 920213 bytes, checksum: e99a6b84c11f7c94edce6679b6c82c1d (MD5) Previous issue date: 2008 / Resumo: Introdução e Objetivos: Ha. muito se sabe que a hiperglicemia e a hipertensão arterial são fenômenos promotores de estresse oxidativo no tecido renal. O estresse oxidativo, por sua vez, contribui fortemente com a doença renal do diabetes, especialmente pela geração de oxidantes via NAD(P)H oxidase. Em contrapartida, inúmeros pesquisadores tem sugerido que o chá verde (Camellia sinensis) possa reduzir o estresse oxidativo. Desta forma, como objetivos deste estudo, testamos se a administração de chá verde a ratos espontaneamente hipertensos (SHR) diabéticos ameniza o dano renal, verificando ainda se os efeitos se fazem por redução do estresse oxidativo. Métodos: Ratos SHR com 12 semanas de idade foram tornados diabéticos por injeção de estreptozotocina (50 MG/kg) e os grupos controle receberam somente o veiculo (tampão citrato de sódio pH 4.5). Animais diabéticos (SD) (glicemia > 270 MG/dl) e controle (SC) foram randomicamente divididos para receber chá verde (CV) ou água (A) como fonte única de líquidos, totalizando 8 a 10 animais por grupo, sendo eles SCA (SHR controle recebendo água), SCC (SHR controle recebendo chá verde), SDA (SHR diabético recebendo água) e SDC (SHR diabético recebendo chá verde). Peso, glicemia, pressão arterial sistólica (PAS) e albuminuria foram determinados a cada 4 das 12 semanas de acompanhamento. Resultados: Durante as 12 semanas de estudo, as glicemias foram significativamente maiores (p<0.001) nos animais SDA do que nos controles SCA e SCC , não sendo alteradas pela administração de CV. As PAS não foram afetadas pelo diabetes ou pelo tratamento com CV. A albuminuria dos animais não diabéticos SCA e SCC foram semelhantes, aumentando significativamente (p=0.048) nos SDA e reduzindo no tratamento com o CV (SDC) de forma significativa (p=0.048). A atividade da NAD(P)H oxidase, determinada por quimiluminescência foi significativamente maior (p=) no grupo SDA comparado ao SCA. O tratamento com CV reduziu de forma significativa (p=0.01) na ausência e presença do diabetes. A expressão da subunidade NOX-4 da NAD(P)H oxidase, determinada por Western Blot, aumentou de forma significativa (p=0.04) no grupo SDA em relação aos grupos não diabéticos SCA e SCC. Porem, em ratos diabéticos tratados com CV (SDC) esta expressão reduziu significativamente (p=0.04) chegando aos níveis do controle. A nitro tirosina, um marcador de modificação de proteína induzida pelo estresse oxidativo/nitros ativo avaliada por Western Blot, foi significativamente (p=0.04) maior no SDA do que no SCA e SCC, sendo no entanto significativamente reduzida (p=0.04) no grupo SDC . A expressão renal de colágeno IV determinada por Western Blot foi significativamente aumentada (p=0.008) nos ratos SDA comparados aos SCA e SCC. NA presença do diabetes, a administração de CV reduziu de forma significativa (p=0.013) esta variável. Conclusão: Em ratos hipertensos e diabéticos, o chá verde restabeleceu o equilíbrio redox, reduzindo marcadores de nefropatia sem alterar glicemia e pressão arterial. Desta forma, o consumo de chá verde pode ser benéfico a pacientes diabéticos e hipertensos. / Abstract:It has been suggested that green tea (GT) has beneficial properties in the treatment or prevention of human disease. The major biological mechanisms of action of GT are being attributed to its antioxidant properties. Several lines of evidence suggest that oxidative stress contributes to the pathogenesis of diabetic nephropathy. The effect of GT on diabetic nephropathy is unclear. We tested the hypothesis that GT prevents diabetes and hypertension-related renal oxidative stress and attenuates renal injury. Spontaneously hypertensive rats (SHR) with streptozotocin-induced diabetes and control SHR were treated daily with tap water or fresh GT extract. After 12 weeks, the systolic blood pressure was unchanged by diabetes or GT. However, there was a decrease in body weight and a significant (p<0.0001) increase in blood glucose level in diabetic SHR. These parameters were unaffected by GT therapy. GT prevented the increase in 8-hydroxy-2'- deoxyguanosine, an indicator of renal oxidative stress-induced DNA, and nitrotyrosine, an indicator of oxidative stress-induced protein modification, that were significantly (p<0.01) elevated in diabetic SHR. Likewise, GT attenuated(p=0.048) ADPH oxidase-dependent superoxide generation and the expression of renal ortex NOX-4, a subunit of NADPH oxidase, that were elevated (p=0.013) in diabetic HR. Treatment with GT significantly (p=0.048) reduced the indices of renal injury, lbuminuria and renal expression of collagen IV in diabetic SHR. GT reestablished he redox state and reduced the indicators of nephropathy without altering blood lucose and blood pressure levels in diabetic SHR. These findingssuggest that the onsumption of GT may ameliorate nephropathy in diabetic hypertensive patients. / Mestrado / Ciencias Basicas / Mestre em Clinica Medica

Most of the fields planted with clonal tea in Malawi are deficient in micronutrients. This was evident in leaf analysis data collected in 2007 from 170 mature clonal tea fields of some of the tea estates in Malawi, which showed very high incidences of B, Zn and Cu deficiencies. Current fertiliser recommendations have emphasised much on macronutrients, such as N, Pand K, but little attention has been paid to micronutrient elements despite continuous removal through harvesting. A study was therefore conducted to assess the effect of foliar applications of Cu, Zn and B containing fertilisers on yield and quality of mature clonal tea plants. Field experiments were laid out in randomised blocks in two fields planted with cultivars PC 105 and 108 at Mianga and Glenorchy estates in the Mulanje district in Malawi and were replicated four times at each site. The treatments were T1 (control, no spray), T2 [ 0.1% boric acid (190.8g B/ha)], T3 [1% copper sulphate solution (4.35kg Cu/ha)], T4 [1.25kg/ha zinc oxide (1kg Zn /ha)], T5 [0.1% boric acid, 1% copper sulphate solution, 1.25kg/ha zinc oxide], T6 [1% of Commercial micronutrient mix ( N 1.7%, P 2.3%, K 1.6%, Mg 0.25%, Fe 1288 mg/kg, Mn 1005 mg/kg, Zn 2182 mg/kg, Cu 732 mg /kg, B 8202 mg/kg, Mo 3681 mg/kg, kelp extract 75 mg/kg, amino acids 50 g/kg, phytofulvate 50 g/kg)], and T7 [2.48kg/ha zinc sulphate (1kg Zn /ha)]. Micronutrient foliar sprays affected yield significantly at Glenorchy tea estate, but had no significant effect on yield at Mianga estate. Copper sulphate solution applied at 1% concentration decreased yield, but the other foliar applications did not impact yield relative to the control at Glenorchy. Tea quality by taster’s scores was not affected at Mianga estate, whilst at Glenorchy quality was affected, with the commercial micronutrient mix giving the lowest total score. Individual parameters that contributed to the differences in total scores at Glenorchy estate included brightness, briskness, colour of liquor, colour of infusion and colour with milk. Thearubigin (TR) concentration was the only biochemical quality parameter that was affected by the micronutrient foliar sprays. The level of TR was increased in all treatments that received the foliar sprays and the control treatment gave the lowest amount of TRs at both sites. An increase in the Thearubigin/Theaflavin (TR/TF) ratio, obtained in all treatments that received the foliar sprays, provides evidence that more catechins were being converted to TRs than TFs during fermentation. Foliar levels of B, Zn and Cu were raised significantly by the application of the respective foliar sprays, except for the commercial micronutrient mix which did not significantly increase B and Zn levels at both sites, but raised Cu levels to the recommended level only at Mianga, but not at Glenorchy estate. Concentration of Cu was extremely high in tea leaves treated with copper sulphate either alone or in combination with boric acid and zinc oxide. Levels of other nutrient elements, namely N, P, K, S, Zn, Cu, Mg, Mn, Mo, Ca, Fe, B, Al and Na in the soils where different foliar sprays were applied were similar at both sites. Likewise, foliar levels of N, P, K, S, Zn, Cu, Mg, Mn, Mo, Ca, Fe, B, Al and Na were not different in all plots at Mianga, but at Glenorchy differences in foliar levels of Al and S were noted. High concentrations of Al and S in the leaves were observed in plots that received copper sulphate applied alone. High foliar concentrations of Al and Cu in leaves treated with copper sulphate could be the reason for the low yields obtained in the plots treated only with copper sulphate at Glenorchy estate. Foliar application of Cu, Zn and B in forms of 0.1% boric acid (190.8g B/ha)], 1% copper sulphate solution (4.35kg Cu/ha)], [1.25kg/ha zinc oxide (1kg Zn /ha)], 1% of a Commercial micronutrient mix (N 1.7%, P 2.3%, K 1.6%, Mg 0.25%, Fe 1288 mg/kg, Mn 1005 mg/kg, Zn 2182 mg/kg, Cu 732 mg /kg, B 8202 mg/kg, Mo 3681 mg/kg, kelp extract 75 mg/kg, amino acids 50 g/kg, phytofulvate 50 g/kg), and 2.48kg/ha zincsulphate (1kg Zn /ha) to mature clonal tea did not significantly increase yields and tea tasters scores, therefore their application to clonal tea with the aim of improving yield and quality may not be necessary. Results from this study indicated that clonal tea, specifically cultivars (PC 108 and PC 105), could not give positive results in terms of yield and quality of tea due to foliar application of Cu, Zn and B within the first season of application. However, if application is aimed at raising concentrations of Cu, Zn, and B, then boric acid, zinc sulphate, zinc oxide and the commercial micronutrient mix may be used without negatively affecting yield and quality of tea significantly. Copper sulphate however, at the application concentration and frequency used, should not be done because of the observed yield decline in copper sulphate treated plots. More prolonged research is required to determine if long term applications can correct perceived deficiencies and increase yield. / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Plant Production and Soil Science / unrestricted

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第12777号 / 論農博第2787号 / 新制||農||1018(附属図書館) / 学位論文||H25||N4790(農学部図書室) / 30760 / (主査)教授 矢﨑 一史, 教授 間藤 徹, 教授 奥本 裕 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

In today's interconnected digital landscape, the protection of sensitive information is of great importance. As a result, the field of cryptography plays a vital role in ensuring individuals' anonymity and data integrity. In this context, this thesis presents a comprehensive analysis of symmetric encryption algorithms, specifically focusing on the Advanced Encryption Standard (AES) and Camellia. By investigating the performance aspects of these algorithms, including encryption time, decryption time, and ciphertext size, the goal is to provide valuable insights for selecting suitable cryptographic solutions. The findings indicate that while there is a difference in performance between the algorithms, the disparity is not substantial in practical terms. Both AES and Camellia, as well as their larger key-size alternatives, demonstrated comparable performance, with AES128 showing marginally faster encryption time. The study's implementation also involves encrypting a data set with sensitive information on students. It encrypts the school classes with separate keys and assigns roles to users, enabling access control based on user roles. The implemented solution successfully addressed the problem of role-based access control and encryption of unique identifiers, as verified through the verification and validation method. The implications of this study extend to industries and society, where cryptography plays a vital role in protecting individuals' anonymity and data integrity. The results presented in this paper can serve as a valuable reference for selecting suitable cryptographic algorithms for various systems and applications, particularly for anonymization of usernames or short, unique identifiers. However, it is important to note that the experiment primarily focused on small data sets, and further investigations may yield different results for larger data sets.

Thesis (M.Sc. (Medical Sciences)) -- University of Limpopo, 2021 / Infertility, defined as the inability to conceive following one year of unprotected sexual intercourse, respectively affects 25% of couples globally. Oxidative stress (OS) has been greatly related to the idiopathic cause of infertility and Camellia sinensis contains antioxidants that may enhance reproductive functions. This study focussed on the effects of Camellia sinensis (green and black tea) on human sperm functions in both normal and abnormal samples. Semen samples (n= 59) collected from donors were liquefied, analysed, and classified as normal (n=40) and abnormal (n= 19) using the WHO criteria. Samples were washed and exposed to aqueous leaf extracts of green and black tea (0, 0.4, 4, 40, 405 μg/ml) for 1 hour. Human Tubular Fluid (HTF) served as the control. The respective sperm parameters were analysed (sperm motility, vitality, DNA fragmentation, mitochondrial membrane potential (MMP), capacitation and acrosome reaction (CTC) and reactive oxygen species (ROS). Green and black tea significantly increased vitality, and intact MMP, while it significantly reduced, CTC, and intracellular ROS as well as DNA fragmented spermatozoa in both normal and abnormal samples compared to the control (p<0.05). A significant increase in sperm CTC, ROS, with a decrease in sperm vitality, and intact MMP was observed in the abnormal compared to the normal samples (p<0.05). No significant change in motility was observed between normal and abnormal samples compared to their respective controls, in both green and black tea (p>0.05). Camellia sinensis improved human sperm function in vitro and may be attributed to its antioxidant activity. / National Research Foundation (NRF)

L'élongation cellulaire de cellules cultivant bout comme hyphae fongueux, inculquez hairs, des tubes de pollen et des neurones, est limité au bout de la cellule, qui permet à ces cellules d'envahir l'encerclement substrate et atteindre une cible. Les cellules cultivant bout d'équipement sont entourées par le mur polysaccharide rigide qui régule la croissance et l'élongation de ces cellules, un mécanisme qui est radicalement différent des cellules non-walled. La compréhension du règlement du mur de cellule les propriétés mécaniques dans le contrôle de la croissance et du fonctionnement cellulaire du tube de pollen, une cellule rapidement grandissante d'équipement, est le but de ce projet. Le tube de pollen porte des spermatozoïdes du grain de pollen à l'ovule pour la fertilisation et sur sa voie du stigmate vers l'ovaire le tube de pollen envahit physiquement le stylar le tissu émettant de la fleur. Pour atteindre sa cible il doit aussi changer sa direction de croissance les temps multiples. Pour évaluer la conduite de tubes de pollen grandissants, un dans le système expérimental vitro basé sur la technologie de laboratoire-sur-fragment (LOC) et MEMS (les systèmes micro-électromécaniques) ont été conçus. En utilisant ces artifices nous avons mesuré une variété de propriétés physiques caractérisant le tube de pollen de Camélia, comme la croissance la croissance accélérée, envahissante et dilatant la force. Dans une des organisations expérimentales les tubes ont été exposés aux ouvertures en forme de fente faites de l'élastique PDMS (polydimethylsiloxane) la matière nous permettant de mesurer la force qu'un tube de pollen exerce pour dilater la croissance substrate. Cette capacité d'invasion est essentielle pour les tubes de pollen de leur permettre d'entrer dans les espaces intercellulaires étroits dans les tissus pistillar. Dans d'autres essais nous avons utilisé l'organisation microfluidic pour évaluer si les tubes de pollen peuvent s'allonger dans l'air et s'ils ont une mémoire directionnelle. Une des applications auxquelles le laboratoire s'intéresse est l'enquête de processus intracellulaires comme le mouvement d'organelles fluorescemment étiqueté ou les macromolécules pendant que les tubes de pollen grandissent dans les artifices LOC. Pour prouver que les artifices sont compatibles avec la microscopie optique à haute résolution et la microscopie de fluorescence, j'ai utilisé le colorant de styryl FM1-43 pour étiqueter le système endomembrane de tubes de pollen de cognassier du Japon de Camélia. L'observation du cône de vésicule, une agrégation d'endocytic et les vésicules exocytic dans le cytoplasme apical du bout de tube de pollen, n'a pas posé de problèmes des tubes de pollen trouvés dans le LOC. Pourtant, le colorant particulier en question a adhéré au sidewalls du LOC microfluidic le réseau, en faisant l'observation de tubes de pollen près du difficile sidewalls à cause du signal extrêmement fluorescent du mur. Cette propriété du colorant pourrait être utile de refléter la géométrie de réseau en faisant marcher dans le mode de fluorescence. / Cellular elongation of tip-growing cells such as fungal hyphae, root hairs, pollen tubes and neurons, is limited to the tip of the cell, which enables these cells to invade the surrounding substrate and to reach a target. Tip-growing plant cells are surrounded by the stiff polysaccharidic wall that regulates the growth and elongation of these cells, a mechanism that is very different from non-walled cells. Understanding the regulation of the cell wall mechanical properties in controlling growth and cellular functioning of the pollen tube, a rapidly growing plant cell, is the goal of this project. The pollen tube carries sperm cells from the pollen grain to the ovule for fertilization and on its way from the stigma towards ovary the pollen tube physically invades the stylar transmitting tissue of the flower. To reach its target it also has to change its growth direction multiple times. To assess the behavior of growing pollen tubes, an in vitro experimental system based on lab-on-chip (LOC) technology and MEMS (microelectro-mechanical systems) was designed. Using these devices we measured a variety of physical properties characterizing the pollen tube of Camellia, such as growth velocity, invasive growth and dilating force. In one of the experimental set-ups the tubes were exposed to slit-shaped openings made of elastic PDMS (polydimethylsiloxane) material allowing us to measure the force a pollen tube exerts to dilate the growth substrate. This invasion capacity is crucial for pollen tubes to allow them to enter narrow intercellular spaces within the pistillar tissues. In other assays we used the microfluidic set-up to test whether pollen tubes can elongate in air and whether they have a directional memory. One of the applications that the lab is interested in is the investigation of intracellular processes such as the motion of fluorescently labelled organelles or macromolecules while the pollen tubes grow within the LOC devices. To prove that the devices are compatible with high-resolution optical microscopy and fluorescence microscopy, I used the styryl dye FM1-43 to label the endomembrane system of Camellia japonica pollen tubes. Observation of the vesicle cone, an aggregation of endocytic and exocytic vesicles in the apical cytoplasm of the pollen tube tip, did not pose any problems in pollen tubes located within the LOC. However, the particular dye in question adhered to the sidewalls of the LOC microfluidic network, making viewing of pollen tubes close to the sidewalls difficult because of the highly fluorescent signal of the wall. This property of the dye might be useful to image the network geometry when operating in fluorescence mode.

No description available.