CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / In this study were characterized biochemical and physiological mechanisms arising from photoinhibition that act in the modulation of photochemical activity and oxidative protection, helping to reduce photo oxidative damage in response to drought and high light stresses in cashew plants. The seedlings were obtained from seeds and grown in substrates by mixing sand and vermiculite (ratio 1:1) in plastic bags, with a volume of 2 liters. Drought stress was imposed by withholding the water supply to the plants ( 20 days) in greenhouse conditions. For exposure to light treatments and recovery to the light effect, the plants were placed in a chamber with controlled conditions of relative humidity (60% Â5) and temperature (30ÂC Â2). The plants subjected to drought stress showed a marked decrease in photosynthesis when exposed to excess light (combination of drought with high luminosity), compared with those irrigated. This higher sensitivity of CO2 fixation to excess light on plants under drought was associated with a higher intensity of damage to the photochemical apparatus, as indicated by measures of effective quantum efficiency and apparent electron transport rate. The data show that the reduction of photosynthetic activity in response to excess light, has been attributed in part to process photoinhibition occurred under these conditions as shown by a drastic reduction in potential maximum quantum efficiency of PSII (given by Fv/Fm ratio). The results also suggest that the intense photoinhibition, triggered by excess light, may have assisted in photoprotection, because under these conditions there was no oxidative damage, as indicated by the absence of changes in H2O2 content and lipid peroxidation (TBARS content). This photochemistry protection, assigned to photoinhibition in this study, is enhanced due to non-occurrence of dissipation of excess energy through non-photochemical quenching (NPQ), because this mechanism did not show significant changes after long periods of exposure to excessive light. However, the energy dissipation through NPQ in response to short time of exposure to excessive light, observed here indicates that when the PSII activity is normal this mechanism is essential to the protection photochemistry. The role of photoinhibition for photo oxidative protection can be attributed to the effect of this process on reducing the activity of PSII and consequent lower photochemical activity, resulting in lower electron transfer. This suggestion is also reiterated in this study based on the reduction of the content of D1 protein, a major component of structural and functional PSII, and plastocyanin (PC), another major carrier of electrons. The modulation these proteins content may have contributed to restrict the formation of ROS and consequent oxidative damage under conditions inducing photo oxidatives stress such as drought associated with high luminosities, in this species. / No presente estudo foram caracterizados mecanismos bioquÃmicos e fisiolÃgicos decorrentes da fotoinibiÃÃo e que atuam na modulaÃÃo da atividade fotoquÃmica e da proteÃÃo oxidativa, auxiliando na reduÃÃo de danos fotoxidativos, em reposta aos estresses de seca e luminosidade elevada em cajueiro. As mudas foram obtidas a partir de sementes e cultivadas em substrato composto pela mistura de areia e vermiculita (proporÃÃo 1:1) em sacos plÃsticos, com volume de 2 L. O estresse hÃdrico foi aplicado pela suspenÃÃo da rega (Â20 dias) em condiÃÃes de casa de vegetaÃÃo. Para a exposiÃÃo aos tratamentos de luminosidade e de recuperaÃÃo ao efeito da luz, as plantas foram acondicionadas em cÃmara com condiÃÃes controladas de umidade relativa (60% Â5) e temperatura (30ÂC Â2). As plantas submetidas ao estresse hÃdrico apresentaram uma intensa reduÃÃo da fotossÃntese quando expostas ao excesso de luz (combinaÃÃo de seca com luminosidade elevada), se comparadas com aquelas irrigadas. Essa maior sensibilidade da fixaÃÃo de CO2 ao excesso de luz nas plantas sob seca foi relacionada com uma maior intensidade de danos no aparato fotoquÃmico, conforme indicado pelas medidas de eficiÃncia quÃntica efetiva e taxa aparente de transporte de elÃtrons. A reduÃÃo da atividade fotossintÃtica, em resposta ao excesso de luz, foi atribuÃda em parte ao processo de fotoinibiÃÃo ocorrido nessas condiÃÃes, conforme demonstrado pela drÃstica reduÃÃo da eficiÃncia quÃntica potencial mÃxima do PSII (dada pela relaÃÃo Fv/Fm). Os resultados sugerem tambÃm que a intensa fotoinibiÃÃo, desencadeada pelo excesso de luz, pode ter auxiliado na fotoproteÃÃo, pois nessas condiÃÃes nÃo ocorreu danos oxidativos, conforme indicado pela ausÃncia de mudanÃas no conteÃdo de H2O2 e na peroxidaÃÃo lipÃdica (conteÃdo de TBARS). Essa proteÃÃo fotoquÃmica, atribuÃda a fotoinibiÃÃo nesse estudo, à reforÃada devido a nÃo ocorrÃncia de dissipaÃÃo do excesso de energia por meio do quenching nÃo fotoquÃmico (NPQ), pois esse mecanismo nÃo apresentou mudanÃas significativas apÃs longos perÃodos de exposiÃÃo ao excesso de luz. No entanto, a dissipaÃÃo de energia por meio do NPQ em respostas a curtos perÃodos de exposiÃÃo ao excesso de luz, aqui observado, indica que quando a atividade do PSII està normal esse mecanismo à essencial para a proteÃÃo fotoquÃmica. O papel da fotoinibiÃÃo para a proteÃÃo fotoxidativa pode ser atribuido ao efeito desse processo na reduÃÃo da atividade dos PSII e consequente menor atividade fotoquÃmica, o que resultaria na menor transferÃncia de elÃtrons. Essa sugestÃo à ainda reinterada no presente estudo com base na reduÃÃo do conteÃdo da proteina D1, um dos principais componentes estrutural e funcional do PSII, e da plastocianina (PC), outro importante carreador de elÃtrons. A modulaÃÃo do conteÃdo dessas proteÃnas pode ter contribuÃdo para restringir a formaÃÃo de EROs e consequente danos oxidativos sob condiÃÃes indutoras de estresse fotoxidativos, como a seca associada com luminosidades elevadas, nessa espÃcie.

A queilite actínica (QA) é uma doença que afeta a semimucosa labial, principalmente inferior, causada pela exposição crônica à radiação solar ultravioleta (UV). É uma lesão potencialmente maligna extremamente frequente e considerada precursora da grande maioria dos cânceres de lábio, em pacientes não fumantes. A etiologia da QA permite medidas preventivas de fotoproteção solar, porém grande parte da população não as utiliza em função do desconhecimento do risco potencial e falta de informação. De outro lado se acredita que o dano causado ao lábio é irreversível e que a adoção de medidas fotoprotetoras apenas limita o dano e que quadros de displasia intensa deveriam ser tratados de forma cirúrgica radical. O objetivo principal deste estudo foi avaliar o efeito do uso de fotoprotetor labial, na forma de bastão, sobre parâmetros clínicos de severidade e grau de displasia histológica por meio de acompanhamento clínico e investigações microscópicas sucessivas. Foram selecionados pacientes que procuraram a Clínica de Diagnóstico Oral da FOUSP e apresentavam sinais clínicos sugestivos de QA. Os pacientes foram orientados quanto às condições de participação no trabalho de pesquisa e assinaram termo de consentimento livre e esclarecido. Após a confirmação de QA, em sequência ao procedimento de biópsia e análise histopatológica, os pacientes foram efetivamente incluídos no grupo de pesquisa. O local da biópsia incisional foi escolhido a partir do exame clínico e teste do azul de toluidina. Os pacientes foram orientados quanto ao uso do fotoprotetor e de barreiras físicas, sendo acompanhados a cada três meses para reavaliação clínica e reforço das medidas de fotoproteção. Após pelo menos seis meses de uso do fotoprotetor uma nova biópsia incisional foi realizada para avaliação histopatológica do quadro. Os espécimes de biópsia dos dois momentos foram analisados inicialmente por diversos patologistas (via rotina clínica-laboratório) e posteriormente por uma única patologista, mais especializada nessa área, cega em relação aos resultados anteriores. Vinte pacientes compuseram a casuística do trabalho, 12 homens e 8 mulheres, com idade média de 63 anos. De acordo com a análise histopatológica realizada via rotina do laboratório de patologia cirúrgica, dos 20 pacientes, dez apresentaram melhora das displasias e do quadro clínico; quatro permaneceram com as mesmas displasias, porém com melhora do quadro clínico; seis apresentaram piora do quadro histológico, porém houve melhora do quadro clínico em quatro deles. A análise realizada pela única patologista produziu resultados bastante diversos, registrando piora dos graus de displasia do primeiro para o segundo momento. Concluímos que a utilização do fotoprotetor produz melhora dos sinais clínicos exibidos pelos pacientes com QA e que os parâmetros clínicos não correspondem aos sinais de displasia histopatológica. Trata-se de doença ainda pouco reconhecida e valorizada tanto pela população quanto pelos profissionais da área de saúde com responsabilidade sobre essa área anatômica e estudos adicionais são requeridos para melhor compreensão da doença, normalização dos critérios de displasia microscópica e estabelecimento de características preditivas em relação à evolução carcinomatosa da doença. / Actinic cheilitis (AC) is an injury that mainly affects the lower lip vermilion, and it is caused by chronic exposure to ultraviolet light. It is a very frequent potentially malignant disorder and it is considered the precursor of most lip cancers, in non-smoker patients. The AC etiology provides preventive measures of sun light protection, but most people do not use it because are unaware of the potential risks and lacking knowledge. On the other hand it is believed that the damaged caused to the lip is irreversible and the introduction of photoprotective measures just contain the damage and cases of severe dysplasia should be treated with radical surgery. The main purpose of this study was to evaluate the use of sunscreen lip balm in stick form, under clinical parameters of severity and degree of histological dysplasia by clinical follow-up and sequential microscopic researches. Patients selected were those who sought Clínica de Diagnóstico Oral in FOUSP and presented suggested signs of AC were selected. They were informed about the research terms of participation as well as signed a free and informed consent term. After confirm the diagnosis of AC with biopsy procedure and histopathological analysis, patients were included in the research group. The incisional biopsy site was selected by clinical exam and toluidine blue test. Patients were instructed about the use of sunscreen lip balm and physical protection, all of them had follow up appointments every three months to clinical evaluation and reinforcement of the use the use of lip sunscreen. After at least six months of lip sunscreen use, a new incisional biopsy was performed for histopathological evaluation. The biopsy specimens of the two procedures were initially analyzed by several pathologists (via laboratory routine) and later by a single blinded pathologist, more specialized in this field. Twenty patients were included in the sample of the study, 12 men and 8 women with a mean age of 63 years. According to histopathological analysis by laboratory routine, ten out of the twenty patients showed improvement in dysplasia and clinical signs; four remained with the same dysplasias, but with improvement of clinical signs; six had worsening results in histopathological analysis, however four of them presented improvement of clinical signs. The analysis conducted by the single pathologist produced very different results, registering worsening degrees of dysplasia from the first to the second procedure. In conclusion the use of sunscreen lip balm produces improvement of clinical signs on the patients with AC as well as the clinical parameters do not match with the signs of histopathological dysplasia. It is a poorly recognized and undervalued disease by both population and healthy professionals with responsibility for this anatomic area. Additional studies are required for better understanding of the disease, standardization of the criteria of microscopic dysplasia and establishment of predictive features to the progression of carcinoma.

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-06-14T22:48:14Z No. of bitstreams: 1 TESE S?NIA CARINE COVA COSTA.pdf: 4450540 bytes, checksum: 273e33d63aa35b23e7686b53ad4e5b56 (MD5) / Made available in DSpace on 2016-06-14T22:48:14Z (GMT). No. of bitstreams: 1 TESE S?NIA CARINE COVA COSTA.pdf: 4450540 bytes, checksum: 273e33d63aa35b23e7686b53ad4e5b56 (MD5) Previous issue date: 2015-12-17 / Solar radiation is the main factor in the appearance of skin diseases. Preventive measures against skin photoaging are necessary and one of the ways to avoid it is to use sunscreen. The genus Marcetia (Melastomataceae) is endemic of rocky fields in northeastern Brazil and are adapted to high sunlight conditions due to bioproduction of flavonoids. The initial goal of this work was to evaluate the antioxidant activities, photoprotection (UVB/UVA) and toxicity of ethanolic extracts of M. taxifolia, M. macrophylla and M. latifolia. Thus, it was investigated the potential photoprotection of the extracts incorporated at 5, 10, 20 and 30% by polawax? lotion. All tests were performed in vitro. The formulations were evaluated in the physicochemical standpoint. In addition it was held HPLC-DAD for identification and quantification of flavonoids. The spectrophotometric method was used to determine the total level of flavonoids (TFC), DPPH? (antioxidant activity) and photoprotective activity (UVB/UVA). The evaluation of toxicity was made by means of the HET-CAM test, and hemolysis rate. The most promising extract was fractionated. Photoprotective formulations have been developed (5, 10, 20 and 30%), which also had their sunscreen profile UVB / UVA evaluated. The M. taxifolia showed higher quercetin content, with 55.78 g/Kg and 168 ?g/mL, following the studies of HPLC-DAD and TFT. All Marcetia ssp extracts had an antioxidant activity around 95%. Likewise, the three species had good results to SPF and UVA photoprotection. The species that has better value SPF was M. macrophylla (20.25) and UVA protection was M. taxifolia (86.04%), but these species have a higher toxic potential related to M. latifolia, which also had a good value SPF (13.12) and UVA (78.09%). The toxicity results show that this species is more secure and is considered an irritant and of weak hemolysis rate (23.51%), while the other species had a hemolysis rate ? 50%. Given these results EEML was fractionated into five fractions (MLFR02, MLFR03, MLFR04, MLFR05, MLFR06). After testing, MLFR02 showed good UVB sunscreen activity (17,52) and UVA (87.49%), but the safest was MLFR02 beyond presenting results in a high SPF value (37.82) when incorporated into the emulsion which makes it suitable for individuals who are very sensitive to sunburn. / A radia??o solar ? o principal fator de surgimento de patologias t?picas. Medidas preventivas contra o fotoenvelhecimento cut?neo s?o necess?rias e umas das formas ? o uso de fotoprotetores. O g?nero Marcetia (Melastomataceae) ? end?mico dos campos rupestres do nordeste brasileiro e s?o adaptadas as condi??es de alta incid?ncia solar devido ? bioprodu??o de flavonoides. Este trabalho teve como objetivo inicial avaliar as atividades antioxidante, fotoprotetora (UVB/UVA) e toxicidade dos extratos etan?licos de M. taxifolia, M. macrophylla e M. latifolia. Em seguida, foi investigado o potencial fotoprotetor dos extratos incorporados a 5, 10, 20 e 30% em lo??o polawax?. Todos os testes foram realizados in vitro. As formula??es foram avaliadas do ponto de vista f?sico-qu?mico. Em adi??o realizou-se CLAE-DAD para identifica??o e quantifica??o dos flavonoides. O m?todo espectrofotom?trico foi usado para determina??o do teor total de flavonoides (TFC), m?todo DPPH? (atividade antioxidante) e atividade fotoprotetora (UVB/UVA). A avalia??o da toxicidade foi feita por meio do teste HET-CAM e hem?lise. O extrato mais promissor foi fracionado. Foram desenvolvidas formula??es fotoprotetoras (5, 10, 20 e 30%), as quais tamb?m tiveram seu perfil fotoprotetor UVB/UVA avaliados. A M. taxifolia apresentou maior teor de quercetina, com 55,78 g/Kg e 168 ?g/mL, conforme os estudos de CLAE-DAD e TFT. Todos os extratos de Marcetia ssp. tiveram uma atividade antioxidante em torno de 95%. Da mesma forma que as tr?s esp?cies tiveram bons resultados de FPS e fotoprote??o UVA. A esp?cie que apresentou melhor valor de FPS foi a M. macrophylla (20,25) e prote??o UVA foi a M. taxifolia (86,04%), por?m estas esp?cies tem um potencial t?xico superior a M. latifolia, que tamb?m teve um bom valor de FPS (13,12) e prote??o UVA (78,09%). Os resultados de toxicidade mostram que esta esp?cie foi a mais segura, sendo considerada um irritante fraco e com uma taxa de hem?lise de 23,51%, enquanto as outras esp?cies tiveram a taxa de hem?lise ? 50%. Diante destes resultados o EEML foi fracionado em cinco fra??es (MLFR02, MLFR03, MLFR04, MLFR05, MLFR06). Ap?s os ensaios, a MLFR02 apresentou boa atividade fotoprotetora UVB (FPS: 17, 52) e UVA (87,49%), por?m a mais segura foi a MLFR02, al?m de apresentar um alto valor FPS (37,82) quando incorporada ? emuls?o o que a faz ser indicada para indiv?duos muito sens?veis a queimadura solar.

A radiação solar ultravioleta (RUV) pode induzir efeitos à pele devidos a sua ação direta ou indireta, por meio da geração de radicais livres. Esses efeitos podem provocar diversas lesões na pele humana como o câncer de pele. No Brasil, segundo o Instituto Nacional do Câncer (INCA, 2012), este tipo de câncer corresponde a 25% de todos os tumores diagnosticados. Como medida profilática de proteção da pele contra os efeitos da radiação solar pode-se citar o uso de protetores solares, produtos tópicos adicionados de filtros solares UV sintéticos com propriedades de absorção e reflexão dos raios solares, e como medida preventiva é recomendado o uso de fotoquimioprotetores, produtos tópicos ou de administração oral incorporados de extratos vegetais ou substancias naturais isoladas com atividades antioxidante e/ou sequestradora de radicais livres e atividade anti-inflamatória. Os protetores solares são considerados produtos OTC, em alguns países, e por isso devem ter sua eficácia comprovada por métodos in vitro ou in vivo padronizados. Assim, o presente trabalho teve como objetivo investigar o potencial fotoprotetor e/ou fotoquimioprotetor do extrato etanólico do epicarpo de Garcinia brasiliensis usando métodos in vitro e in vivo, respectivamente. O extrato foi caracterizado quimicamente por medida dos teores de flavonoides, polifenois e lipídios e funcionalmente pela determinação da atividade antioxidante e/ou sequestradora de radicais livres por diferentes métodos in vitro. A citotoxidade e fotoestabilidade do extrato, como também, o potencial fotoprotetor do extrato e das formulações adicionadas deste em diferentes concentrações foram avaliados in vitro por medida da viabilidade celular de cultura de células de fibroblastos (L929). A eficácia fotoprotetora e/ou fotoquimioprotetora da formulação adicionada do extrato foi testada in vivo por medida das quantidades de GSH endógeno e das interleucinas IL-1? e TNF-?, como também, pela medida da atividade da mieloperoxidase, usando os camundongos hairless, como modelo animal. Os teores de flavonoides e polifenois de 3,4 mg EQ/g e 69,84 mg EAG/g, respectivamente, foram menores àqueles de outros extratos vegetais. Os menores teores de flavonoides e polifenois refletiram na menor atividade antioxidante desse extrato que apresentou valores de IC50 de 47,47 ?g/mL e 425,06 ?g/mL para atividade antioxidante determinada pelos métodos de DPPHo e peroxidação lipídica, respectivamente. O teor de lipídio encontrado foi de 45%, isto sugere que esse extrato deve ser armazenado em condições controladas para minimizar a sua instabilidade por meio da oxidação dos lipídios por reações oxidativas. Os estudos de citotoxidade mostraram que o extrato na concentração de 25 ?g/mL diminuiu em 40% a viabilidade das células L929. A citotoxidade do extrato foi maior quando exposto à radiação UVA que à UVB, sugerindo que este extrato pode ser mais fotoinstável à radiação UVA. Nos testes de fotoproteção empregando culturas de células, o extrato na concentração de 100 mg/mL e formulação adicionada de 20% de extrato aumentaram a viabilidade das células L929 expostas à radiação UVB na mesma proporção àquela do protetor solar comercial com FPS 15. Nos testes in vivo, a formulação adicionada de 20% de extrato mostrou eficácia fotoprotetora, protegeu o GSH da depleção, não permitiu o aumento da atividade da mieloperoxidase e das quantidades das citocinas, IL-1? e TNF- ?, na pele exposta à radiação UVB. / The solar ultraviolet radiation (UVR) can induce harmfull effects to the skin by direct action or through the generation of free radicals. These effects can cause various skin lesions such as skin cancer. According to the National Institute of Cancer (INCA, 2012) this type of cancer accounts for 25% of all tumors diagnosed in Brazil. In order to protect the skin against the effects of solar radiation it is recommended the use of sunscreens and topical products added to synthetic sunscreens with properties of absorption and reflection of solar rays. Moreover it is increasing the interest in the use of photochemoprotectors including topical or oral products incorporated with plant extracts or natural substances isolated with antioxidant and/or free radical scavenging and anti-inflammatory activity. Sunscreens are considered OTC products, in some countries, and therefore must have proven effective for in vitro or in vivo standardized. Thus, the present study aimed to investigate the photochemical/photoprotective potential of the ethanolic extract of the Garcinia brasiliensis epicarp using in vitro and in vivo methods, respectively. The extract was chemically characterized by measuring the levels of flavonoids, polyphenols and lipids and functionally by determining the antioxidant activity and/or free radical scavenging using different methods in vitro. The cytotoxicity and photostability of the extract and the photoprotective potential of the extract and formulations added extract with different concentrations of the extract were assessed in vitro by measurement of cell viability using cell culture of fibroblasts (L929). The photochemical/protoprotective effect of the formulation added with the extract was tested in vivo by measuring the amounts of endogenous GSH and interleukins IL-1? and TNF-?, besides by measuring myeloperoxidase activity using hairless mice as an animal model. The determined levels of flavonoids and polyphenols of 3.4 mg EQ/g and 69.84 mg GAE/g, respectively, were considered lower than those observed in other plant extracts. The lower levels of flavonoids and polyphenols reflected in lower antioxidant potential of the extract which showed IC50 values of 47.47 and 425.06 mg/mL for antioxidant activity determined by DPPHo and lipid peroxidation methods, respectively. The lipid content was found to be 45%, which suggests that this extract must be stored under controlled conditions to minimize their instability by oxidation of the lipids by oxidative reactions. Cytotoxicity studies showed that the extract at a concentration of 25 mg/mL decreased in 40% the viability of L929 cells. The cytotoxicity of the extract was higher when exposed to UVA than to UVB, suggesting that this extract might be more photoinstable to UVA radiation. In photoprotection tests employing cell culture the extract (100 mg/mL) and the formulation added with 20% of the extract increased the viability of L929 cells exposed to UVB radiation at the same rate to that observed when it was used a commercial sunscreen with an SPF of 15. In vivo results showed that the formulation added with 20% of the extract showed a photoprotective effect when observed the reduction of GSH depletion in treated mice as such as the reduction of myeloperoxidase activity and amounts of cytokines IL-1? and TNF-? in treated skin exposed to radiation UVB in comparison to the non-treated irradiated control.

Apesar de vários avanços no combate ao câncer, a incidência do câncer de pele tipo melanoma e a mortalidade relacionada a essa doença tem aumentado. Considerando-se que a radiação ultravioleta (UV) é o principal agente causador de diversos danos à pele, inclusive o câncer de pele, é de grande importância medir de forma adequada as propriedades fotoprotetoras dos filtros solares. Diante dos problemas provocados pelo uso de filtros solares, as pesquisas têm se voltado no sentido de encontrar produtos naturais com propriedades antioxidantes visto que já foi demonstrado que muitos desses agentes naturais possuem efeitos anticarcinogênico, e antimutagênico. Assim, um dos objetivos desse trabalho foi a avaliação de três formulações fotoprotetoras comerciais por meio de parâmetros bioquímicos não comumente utilizados, mas que refletem o efeito dessas formulações no sistema antioxidante natural da pele e também no processo inflamatório induzido pela radiação UV. Esses efeitos foram mensurados in vivo em camundongos sem pelos, utilizando-se como marcadores o antioxidante não enzimático glutationa reduzida (GSH), enzima antioxidante superóxido dismutase (SOD), a enzima mieloperoxidase (MPO) e as citocinas IL-1? e TNF-?. Outro importante objetivo desse estudo foi avaliar o efeito de um extrato de soja biotransformado (ESB) pelo fungo A. awamori em células de melanoma humano das linhagens 451LU e A375, altamente metastáticas, e estudar os mecanismos de ação pelos quais o extrato induz a morte celular por apoptose nestas células e também avaliar o potencial desse extrato para a prevenção e tratamento do câncer de pele. Os resultados mostraram que com relação ao processo inflamatório induzido pela radiação UVB, verificou-se que o FPS, apesar de avaliar somente o eritema, é um bom indicador do nível de proteção da pele, uma vez que todas as formulações apresentaram um potencial protetor contra o aumento da atividade da MPO e liberação das citocinas pró-inflamatórias IL-1? e TNF-?. No entanto, as formulações não forneceram proteção contra a depleção do antioxidante endógeno GSH e, apesar de possuírem mesmo FPS 15 essas formulações apresentaram diferentes níveis de proteção com relação à redução da atividade da enzima SOD induzida pela radiação UV. Os resultados referentes ao estudo do ESB mostraram que o tratamento das células de melanoma altamente invasivas com o extrato resultou em inibição do crescimento/viabiliade das células associado com a indução de apoptose. As análises revelaram que o ESB resultou em indução da clivagem de PARP e ativação das caspases-3, -7 e -8; aumento da expressão de TNF-R2 e da expressão de TRAIL e do receptor DR4. Além disso, o tratamento das células de melanoma com o extrato ESB aumentou a fosforilação e ativação de IKK, degradação de I?B? e translocação de p65/NF?B para o núcleo. Apesar de ser geralmente aceito que a ativação do NF-?B seja responsável pela resistência à apoptose, neste estudo foi demonstrado que a estimulação da via do NF-?B é necessária pela indução da apoptose mediada pelo extrato ESB. Finalmente, conclui-se que as formulações fotoprotetoras devem ser avaliadas de forma mais profunda, empregando-se diferentes métodos a fim de se garantir formulações mais eficazes tanto contra os danos induzidos tanto pela radiação UVB quanto pela radiação UVA. Além disso, esses estudos identificaram uma atividade anticâncer do extrato ESB que é altamente relevante para a quimioprevenção/quimioterapia contra o câncer de pele tipo melanoma. / Despite several advances in fighting cancer, the incidence of melanoma type skin cancer and the mortality related to this disease have increased. Considering that ultraviolet radiation (UV) is the main causative agent of various skin damages, including skin cancer, it is of great importance to adequately measure the photoprotective properties of sunscreens. Considering the problems caused by the use of sunscreens, researches have been focused towards finding natural products with antioxidant properties as it has been shown that many of these natural agents possess anticarcinogenic and antimutagenic effects. Thus, an objective of this study was to evaluate three marketed photoprotective formulations through biochemical parameters not commonly used, but which reflect the effect of these formulations on the skin\'s natural antioxidant system and also in the inflammatory process induced by UV radiation. These effects were measured in vivo in hairless mice, employing as markers reduced glutathione (GSH), a non-enzymatic antioxidant; superoxide dismutase (SOD), an antioxidant enzyme; myeloperoxidase (MPO) enzyme and IL-1? and TNF-? cytokines. Another important objective of this study was to evaluate the effect of a biotransformed soy extract (BSE) by the A. awamori fungus against 451LU and A375 human melanoma cell strains, highly metastatic, and to study the action mechanisms by which the extract induces cell death by apoptosis in these cells; in addition it was intended to evaluate the potential of this extract for the prevention and treatment of skin cancer. The results demonstrated that regarding the inflammatory process induced by UVB irradiation, it was found that the FPS, although only assessing the erythema, is a good indicator of the level of skin protection, since all formulations showed a protector potential against the increased MPO activity and the release of IL-1? and TNF-? pro-inflammatory cytokines. Nevertheless, the formulations did not provide protection against the depletion of the GSH endogenous antioxidant and, despite having the same nominal SPF (SPF=15), these formulations showed different levels of protection with respect to the reduction of SOD activity induced by UV radiation. The results of the BSE study demonstrated that the treatment of highly invasive melanoma cells with the extract resulted in the cell growth/viability inhibition associated with the induction of apoptosis. The analysis revealed that BSE resulted in induction of PARP cleavage and activation of caspase-3, -7 and -8, increased expression of TNF-R2 and expression of TRAIL and DR4 receptor. Furthermore, the treatment of melanoma cells with BSE extract increased phosphorylation and activation of IKK, degradation of I?B? and translocation of p65/NF?B to the nucleus. Although it is generally accepted that the activation of NF-kB is responsible for resistance to apoptosis, this study demonstrated that the stimulation of NF-?B is required for the induction of apoptosis mediated by BSE extract. Finally, it is concluded that the photoprotective formulations should be more deeply evaluated, using different methods in order to ensure more effective formulations against damages induced both by UVB radiation and UVA radiation. In addition, these studies identified an anticancer activity of the BSE extract that is highly relevant to chemoprevention/chemotherapy against melanoma type skin cancer.

As invasões por espécies exóticas vêm acarretando a homogeneização das comunidades naturais tornando-se; atualmente, a segunda principal causa da perda da biodiversidade. Entre os domínios brasileiros mais afetados está o Cerrado, que possui mais de 11 fitofisionomias e 33% de toda biodiversidade vegetal do país. As alterações pela atividade humana foram facilitadas em decorrência das áreas de Cerrado estarem dispostas em quase todo o território nacional e, na fisionomia de campo sujo, em particular, pela facilidade de mecanização e consequentemente pelo emprego da agricultura em larga escala. Dessa forma, foram inseridas gramíneas exóticas africanas para a melhoria da qualidade e produtividade do forrageio. Essas gramíneas se ajustaram tão bem em áreas de campo sujo que se expandiram desordenadamente e conduziram a um desequilíbrio estrutural e funcional destas áreas. O objetivo deste estudo foi investigar os padrões de utilização de recursos em gramíneas nativas e invasoras em um campo sujo levando em conta os períodos de maior e menor disponibilidade hídrica e os possíveis efeitos das variáveis microclimáticas sobre as respostas fisiológicas de gramíneas nativas e invasoras. A área de estudo localiza-se no Parque Estadual do Juquery, município de Franco da Rocha, Estado de São Paulo. As espécies utilizadas para o estudo foram as nativas: Tristachya leiostachya, Imperata brasiliensis, Axonopus pressus e Axonopus siccus. E as invasoras: Urochloa brizantha e Melinis minutiflora. As respostas fisiológicas frente às flutuações entre os períodos chuvoso e seco foram obtidas através de análises de trocas gasosas, análise de fluorescência e de medições das variáveis microclimáticas ao longo de 23 meses entre 8:00 e 12:00. Os resultados indicaram que gramíneas nativas investem 16% menos em fotoproteção do que gramíneas invasoras, sendo estas mais sensíveis aos fotodanos. No entanto, gramíneas nativas investem 13% a mais na síntese de clorofila total e se equivalem na capacidade de assimilação de carbono (A) e quanto as taxas de transporte de elétrons (ETR) indicando uma aprovável equivalência no uso da luz que pode estar associada a maiores taxas de eficiência no uso do nitrogênio em nativas tanto no período chuvoso (70%) quanto no seco (70%), além da ausência de diferença estatística no conteúdo de fósforo foliar por massa seca (Pmg/ms) e na eficiência no uso deste recurso (EUP). A condutância estomática (gs) e transpiração (E) foram respectivamente 22 e 60% maiores nas gramíneas nativas, por isso, a eficiência no uso da água foi 60% menor nestas em comparação às invasoras, tanto no período chuvoso quanto no seco. Tal regulação da condutância provavelmente esteve relacionada ao conteúdo de nitrogênio foliar que foi 100% maior nas invasoras no período chuvoso e 85% maior no período seco. Como esperado, gramíneas nativas apresentaram respostas de menor sensibilidade à seca em comparação às invasoras. Gramíneas invasoras, por sua vez, não corroboraram a expectativa de maior oportunismo em relação às nativas no período chuvoso quanto a captação de recursos, assim como, diferentemente do esperado, não se mostraram tão sensíveis à seca devido a um comportamento conservador no uso da água / Invasions by alien species are causing the homogenization of natural communities, becoming; currently the second leading cause of biodiversity loss. And among the most affected areas are the Brazilian Cerrado, which has more than 11 vegetation types and 33 % of all the country\'s biodiversity. The changes were facilitated by human activity due to the Cerrado areas are arranged in almost all the national territory. And in the face of dirty field, in particular, the ease of mechanization and consequently the employment of agriculture. Thus, African exotic grasses to improve the quality and productivity of foraging were inserted. These grasses have adjusted so well in areas of Cerrado dirty field that expanded wildly and led to a structural and functional imbalance of these areas. The aim of this study was to investigate the patterns of resource use of native grasses and weeds in a field Cerrado dirty taking into account periods of high and low water availability and the possible effects of microclimatic variables on the physiological responses of native and invasive grasses . The study area is located in the Juquery State Park, city of Franco da Rocha, State of Sao Paulo. The species used for the study were native: Tristachya leiostachya , Imperata brasiliensis , Axonopus pressus and Axonopus siccus. And the invaders: Urochloa brizantha and Melinis minutiflora. The physiological responses to fluctuations between wet and dry periods were obtained from analyzes of gas exchange, fluorescence analysis and measurements of microclimate variables over 23 months between 8:00 am and 12:00 am. The results indicate that native grasses Invest 16 % less than photoprotection grass weeds, which are more sensitive to photodamage. However, native grasses invest 13 % more in the synthesis of chlorophyll and are equivalent in capacity to carbon assimilation (A) and on the rate of electron transport (ETR) indicating an approvable equivalence in the use of light that can be associated with higher rates of nitrogen use efficiency in native both in the rainy season (70%) and the dry (70 %). Besides the lack of statistical difference in the content of phosphorus of leaf dry mass (Pmg/ms) and efficient use of this resource (EUP). The stomatal conductance (gs ) and transpiration ( E) were respectively 22 and 60 % higher in native grasses , so ; efficiency in water use was 60 % lower compared to these invasive both in the rainy season as in the dry. Such regulation conductance probably was related to leaf N content that was 100 % higher in invasive in the rainy season and 85 % higher in the dry season. As expected, responses of native grasses showed lower sensitivity to drought compared to invasive. Invasive grasses in tur ; does not support the expectation of greater opportunism in relation to native in the rainy season as fundraising , as well as , unlike expected, were not as sensitive to drought due to a more conservative behavior in water use

Strong light can cause damage and be lethal for photosynthetic organisms. An increase of thermal dissipation of excess absorbed energy at the level of photosynthetic antenna is one of the processes protecting against deleterious effects of light. In cyanobacteria, a soluble photoactive carotenoid binding protein, Orange Carotenoid Protein (OCP) mediates this process. The photoactivated OCP by interacting with the core of phycobilisome (PB; the major photosynthetic antenna of cyanobacteria) triggers the photoprotective mechanism, which decreases the energy arriving at the reaction centres and PSII fluorescence. The excess energy is dissipated as harmless heat. To regain full PB capacity in low light intensities, theFluorescence Recovery Protein (FRP) is required. FRP accelerates the deactivation of OCP.In this work, I present my input in the understanding of the mechanism underlying the OCPrelated photoprotection. I further characterized the FRP of Synechocystis PCC6803, the model organism in our studies. I established that the Synechocystis FRP is shorter than what it was proposed in Cyanobase and it begins at Met26. Our results also revealed the great importance of a high OCP to FRP ratio for existence of photoprotection. The most remarkable achievement of this thesis is the in vitro reconstitution of the OCPrelated mechanism using isolated OCP, PB and FRP. I demonstrated that light is only needed for OCP photoactivation but OCP binding to PB is light independent. Only the photoactivated OCP is able to bind the PB and quench all its fluorescence. Based on our in vitro experiments we proposed a molecular model of OCP-related photoprotection. The in vitro reconstituted system was applied to examine the importance of a conserved salt bridge (Arg155-Glu244) between the two domains of OCP and showed that this salt bridge stabilises the inactive form of OCP. During photoactivation this salt bridge is broken and Arg155 is involved in the interaction between the OCP and the PB. The site of OCP binding in the core of a PB wasalso investigated with the in vitro reconstituted system. Our results demonstrated that the terminal energy emitters of the PB are not needed and that the first site of fluorescence quenching is an APC trimer emitting at 660 nm. Finally, we characterised the properties of excited states of the carotenoid in the photoactivated OCP showing that one of these states presents a very pronounced charge transfer character that likely has a principal role in energy dissipation. Our results strongly suggested that the OCP not only induces thermal energy dissipation but also acts as the energy dissipator.

Στα φύλλα κάποιων φυτικών ειδών παρουσιάζεται παροδική ερυθρότητα, λόγω συσσώρευσης ανθοκυανινών, η οποία μπορεί να είναι τόσο έντονη που να καλύπτεται το χρώμα της χλωροφύλλης. Δεδομένου ότι απορροφούν και στο ορατό φάσμα (κυρίως στην πράσινη και ελαφρώς στη μπλε και κίτρινη περιοχή) οι ανθοκυανίνες πρακτικώς λειτουργούν ως φίλτρα, αφού απορροφούν μέρος της προσπίπτουσας φωτοσυνθετικά ενεργής ακτινοβολίας και ανταγωνίζονται τις χλωροφύλλες στην απορρόφηση του φωτός. Εξ αιτίας αυτής της ιδιότητάς τους, ένας από τους ρόλους που τους έχει αποδοθεί είναι η φωτοπροστατευτική δράση, ενώ παράλληλα (και ανεξαρτήτως ρόλου που επιτελούν) έχει προταθεί ότι διαμορφώνουν ένα ιδιαίτερο μικροπεριβάλλον σκιάς στο εσωτερικό του φύλλου. Προκειμένου να διερευνηθεί η πιθανή συνεισφορά των ανθοκυανινών στη φωτοπροστασία αλλά και στην επαγωγή σκιόφιλων χαρακτήρων, στην παρούσα διατριβή παρακολουθήσαμε την πορεία των φωτοσυνθετικών και φωτοπροστατευτικών χαρακτηριστικών, παράλληλα με τη μεταβολή της ερυθρότητας, σε φύλλα του ίδιου είδους που διαφέρουν ως προς το ανθοκυανικό περιεχόμενο. Εξετάστηκαν πέντε είδη, τρία ως κύρια πειραματόφυτα (Cistus creticus L., Photinia x fraseri Dress και Quercus coccifera L.) και δύο ως συμπληρωματικά στον προσδιορισμό της στοιχειομετρίας των δύο φωτοσυστημάτων (Ricinus communis L., Rosa sp. L.). Στο C. creticus, η παροδική ερυθρότητα εμφανίζεται στα ώριμα φύλλα και σχετίζεται με αβιοτικούς περιβαλλοντικούς παράγοντες, συγκεκριμένα το συνδυασμό χαμηλών θερμοκρασιών και υψηλών εντάσεων φωτός. Στα υπόλοιπα, η παροδική συσσώρευση ανθοκυανινών επάγεται από οντογενετικούς παράγοντες (νεαρά κόκκινα φύλλα που πρασινίζουν με την ωρίμανση). Στα P. x fraseri και R. communis, η χρωματική ποικιλομορφία αφορά φύλλα διαφορετικής ηλικίας, που ανήκουν όμως στο ίδιο άτομο (νεαρά κόκκινα-ώριμα πράσινα). Tα υπόλοιπα τρία είδη εμφανίζουν ενδο-ειδική ποικιλομορφία ως προς τον ανθοκυανικό χαρακτήρα, και επομένως συγκρίνονται φύλλα ίδιας κάθε φορά φυσιολογικής ηλικίας, που ανήκουν σε άτομα διαφορετικών φαινοτύπων. Στην περίπτωση που οι ανθοκυανίνες λειτουργούν φωτοπροστατευτικά, αναμένεται τα φύλλα που τις περιέχουν να αντιμετωπίζουν μικρότερο κίνδυνο φωτοαναστολής και να έχουν μικρότερη ανάγκη για μη-φωτοχημική απόσβεση σε σύγκριση με τα αντίστοιχα πράσινα. Ωστόσο, από τις μετρήσεις του in vivo φθορισμού της χλωροφύλλης σε προ-σκοτεινιασμένα δείγματα (OJIP-ανάλυση) δεν διαπιστώθηκε τα ανθοκυανικά φύλλα να διαθέτουν κάποιο συγκριτικό πλεονέκτημα όσον αφορά στη φωτοσυνθετική τους λειτουργία. Αντιθέτως, τα κόκκινα φύλλα των ειδών P. x fraseri και C. creticus εκτός του ότι παρουσιάζουν ελαφρώς, αλλά στατιστικώς σημαντικά, χαμηλότερες τιμές μέγιστης φωτοχημικής απόδοσης του PSII (Fv/Fm) συναντούν και σαφώς μεγαλύτερους περιορισμούς στα μετέπειτα στάδια ηλεκτρονιακής ροής και μετατροπής της ενέργειας σε σχέση με τα αντίστοιχα πράσινα. Και στις δυο περιπτώσεις είναι πιθανό να συμβαίνει απενεργοποίηση κάποιων λειτουργικών ενεργών κέντρων του PSII. Στο Q. coccifera, τα όμοιας ηλικίας φύλλα των δύο φαινοτύπων δεν παρουσιάζουν διαφορές στις ανωτέρω παραμέτρους. Οι μετρήσεις φθορισμού της χλωροφύλλης κάτω από συνθήκες ακτινικού φωτός έδειξαν ότι τα κόκκινα φύλλα έχουν όμοιες (P. x fraseri και C. creticus) ή χαμηλότερες (Q. coccifera) τιμές τρέχουσας φωτοχημικής απόδοσης (YII) και αντίστοιχα όμοιες ή υψηλότερες τιμές μη-φωτοχημικής απόσβεσης (YNPQ). Ωστόσο, λόγω της απορρόφησης των ανθοκυανινών, οι χλωροπλάστες των κόκκινων φύλλων δέχονται πραγματική ένταση φωτός χαμηλότερη της προσπίπτουσας, και επομένως τα ανωτέρω αποτελέσματα είναι αντίθετα των αναμενόμενων. Διαφωτιστικές προς αυτή την κατεύθυνση είναι οι μετρήσεις φθορισμού της κάτω (πράσινης) φυλλικής επιφάνειας σε φωτιζόμενα φύλλα των δύο φαινοτύπων του C. creticus. Σ’ αυτήν την περίπτωση, έχοντας παρακάμψει το πρόβλημα της απορρόφησης των ανθοκυανινών, τα φύλλα του κόκκινου φαινοτύπου εμφανίζουν υψηλότερη ανάγκη μη-φωτοχημικής απόσβεσης (YNPQ) και υψηλότερη ευαισθησία έναντι της φωτοαναστολής (YNΟ), παρ’ όλη τη θεωρούμενη προστασία των υπερκείμενων ανθοκυανινών της άνω επιφανείας. Η μεγαλύτερη ανάγκη μη φωτοχημικής απόσβεσης των κόκκινων φύλλων διαφαίνεται και από την υψηλότερη επένδυση σε συστατικά του κύκλου των ξανθοφυλλών (P. x fraseri) ή την καλύτερη λειτουργικότητα του κύκλου (C. creticus), σε συνθήκες έντονου φωτισμού. Μάλιστα, κατά την καταπονητική περίοδο του χειμώνα ο κόκκινος φαινότυπος του C. creticus εμφανίζει μείωση των περιεχομένων χλωροφυλλών, πιθανόν σε μια προσπάθεια περαιτέρω ελάττωσης της απορροφούμενης ενέργειας διεγέρσεως, παρ’ όλη την ύπαρξη του ανθοκυανικού φίλτρου. Με βάση τα ανωτέρω ευρήματα, η υπόθεση του φωτοπροστατευτικού ρόλου των ανθοκυανινών δεν ενισχύεται, εκτός εάν υποτεθεί είτε ότι ο στόχος για την προστασία δεν συνδέεται με τη φωτοσύνθεση είτε ότι τα κόκκινα φύλλα εάν δεν τις διέθεταν θα ήταν σε πολύ πιο δυσμενή θέση, σε σύγκριση πάντα με τα πράσινα. Όσον αφορά στη συνεισφορά των ανθοκυανινών στην επαγωγή σκιόφιλων χαρακτήρων βρέθηκαν κάποιες ισχυρές ενδείξεις προς αυτήν την κατεύθυνση, ανεξάρτητα από τον παράγοντα που επάγει τη συσσώρευσή τους. Έτσι, και στα πέντε είδη που εξετάστηκαν, παρατηρήθηκε αύξηση της σχετικής αναλογίας PSII/PSI στα κόκκινα φύλλα, η οποία είναι στατιστικά σημαντική (εκτός από την περίπτωση του Q. coccifera) και βαίνει μειούμενη με τη μείωση των περιεχομένων ανθοκυανινών. Αύξηση της αναλογίας PSII/PSI έχει συσχετισθεί με την ποιοτική αλλοίωση του φωτός σε συνθήκες σκιάς και στοχεύει στην εξισορροπημένη διέγερση των δύο φωτοσυστημάτων. Από τον τρόπο προσδιορισμού της (ως F686/F735), η ανωτέρω αναλογία δεν κάνει διάκριση μεταξύ φωτοσυλλεκτικής κεραίας και ενεργών κέντρων των δύο φωτοσυστημάτων. Μία άλλη παράμετρος, που θεωρείται τυπικός δείκτης σκιοφιλίας και μετρήθηκε στο σύνολο των πειραματοφύτων, είναι η αναλογία Chl a/b. Μειωμένη αναλογία Chl a/b σε συνθήκες σκιάς υποδεικνύει αύξηση των φωτοσυλλεκτικών κεραιών σε σχέση με τα ενεργά κέντρα. Στατιστικά σημαντική μείωση της ανωτέρω αναλογίας βρέθηκε στα κόκκινα φύλλα των ειδών C. creticus, Q. coccifera και Rosa sp.. Στα P. x fraseri και R. communis δεν παρατηρήθηκαν στατιστικά σημαντικές διαφορές μεταξύ κόκκινων και πράσινων φύλλων. Τέλος, στα είδη C. creticus, P. x fraseri και Q. coccifera προσδιορίσθηκε και η παράμετρος ABS/RC (όπως προκύπτει από την OJIP-ανάλυση), όπου παρατηρήθηκε στατιστικώς σημαντική αύξηση στα κόκκινα φύλλα των δύο πρώτων ειδών. Στο Q. coccifera η ίδια τάση δεν είναι στατιστικά σημαντική. Αύξηση της αναλογίας ABS/RC, η οποία αποτελεί θα λέγαμε έναν λειτουργικό περισσότερο δείκτη, μπορεί να αποδοθεί σε αυξημένο μέγεθος της φωτοσυλλεκτικής κεραίας ή/και σε μείωση του αριθμού των λειτουργικών ενεργών κέντρων του PSII. Από το συνδυασμό των παραπάνω αποτελεσμάτων διαφαίνεται ότι στα είδη C. creticus, Rosa sp. και Q. coccifera η επίδραση των ανθοκυανινών εντοπίζεται κυρίως σε αύξηση του μεγέθους της φωτοσυλλεκτικής κεραίας. Στα P. x fraseri και R. communis, η αύξηση του λόγου PSII/PSI αντανακλά πιθανώς μια αύξηση των ενεργών κέντρων του PSII. / Leaves of some plant species appear transiently red because of the accumulation of anthocyanins, at levels sufficient to mask the green chlorophyll color. Given that leaf anthocyanins absorb also in the visible spectrum (strongly in the green and less in the blue-violet and yellow region), they act as sunscreens attenuating part of the photosynthetically active radiation and hence they compete with chlorophylls for photon capture. Due to this attribute, one of the ascribed roles of leaf anthocyanins is the photoprotection of the photosynthetic mesophyll. Additionally (and regardless of the proposed role) it has been suggested that they shape a particular shade microenvironment in the leaf interior. In order to investigate these two hypotheses, in the present study we monitored the course of photosynthetic and photoprotective characteristics in leaves of the same species with different anthocyanic content. Five species have been used, three of them as main experimental material (Cistus creticus L., Photinia x fraseri Dress και Quercus coccifera L.) and two additional (Ricinus communis L., Rosa sp. L.) for the assessment of the stoichiometry of the two photosystems. In Cistus creticus (L.) transient redness is induced in mature leaves by abiotic environmental factors, i.e. the combination of low temperatures and high light intensity during winter. In the rest species redness is developmentally determined (young red leaves which become red upon maturation). In P. x fraseri and R. communis the color variation concerns leaves of different age from the same individual (comparison of young red and mature green). The rest three species show intra-species variation of the anthocyanic trait. Thus, leaves of the same physiological age from different individuals and phenotypes (occupying the same habitat) were compared. The photoprotective hypothesis of leaf anthocyanins entails that red leaves would be less sensitive against photoinhibition and have a reduced need of non-photochemical quenching, compared to their green counterparts. However, according to our chlorophyll fluorescence measurements with dark adapted samples (OJIP-analysis), anthocyanic leaves did not display a comparative advantage in their photosynthetic function. On the contrary, red leaves of P. x fraseri and C. creticus, apart from their slightly, yet statistically significant, lower maximum PSII yield (Fv/Fm), they also confront higher limitations in the further steps of excitation energy processing and its transformation compared to greens. In both species, a transformation of active PSII centers to non-QA -reducing ones, could be inferred. In Q. coccifera, no differences were observed between leaves of the same physiological age from the two phenotypes in the above parameters. Moreover, chlorophyll fluorescence measurements in light acclimated samples have shown that red leaves have similar (P. x fraseri και C. creticus) or lower (Q. coccifera) PSII effective yield (YII) and similar or higher corresponding non-photochemical energy quenching (YNPQ). It has to be noted, however, that the actual PAR levels penetrating to the red leaf mesophyll are in fact lower compared to their green counterparts, due to anthocyanin absorption of the white and blue actinic light used during these measurements. Accordingly, for the same incident PAR, the opposite trend was expected in red leaves. In C. creticus, measurements performed in the lower leaf side by-pass this problem, since anthocyanins accumulate only in the palisade mesophyll (of the upper side) and the abaxial leaf surface is always green. In that case, red leaves showed a higher need for non-photochemical quenching (YNPQ) and a higher vulnerability to photoinhibition (YNΟ), in spite of the supposed photoprotective function of the overlying anthocyanins. The trend for an enhanced need of non-photochemical dissipation in red leaves is indicated also by the higher investment in “xanthophyll cycle” components (P. x fraseri) and/or the lower EPS values (P. x fraseri and C. creticus) during midday. In addition, during the superimposed winter stress, red leaves of C. creticus proceed to a Chl loss, possibly as an attempt to decrease further the absorbed excitation energy, in spite of the anthocyanic screen. The above results weaken the photoprotective hypothesis for leaf anthocyanins, unless it is assumed either that photosynthesis is not the target for protection or that red leaves would be in a worse position, compared to greens, if anthocyanins were absent. Some of our results support the shade acclimation hypothesis in red leaves, irrespectively of the factor that induces the accumulation of anthocyanins. In all tested species, red leaves display a higher, statistically significant, relative PSII/PSI ratio compared to greens (except of Q. coccifera, where the same was observed as a trend). PSII/PSI ratio declines in parallel with the decrease of anthocyanin accumulation. A higher PSII/PSI ratio is considered as an acclimation to the altered light quality under shade conditions in order to adjust the excitation pressure of two photosystems. Chl a/b was statistically lower in red leaves of C. creticus, Q. coccifera και Rosa sp., while in P. x fraseri and R. communis no differences were observed. A decrease in Chl a/b ratio is a typical shade acclimation feature, indicating an increased ratio of light harvesting antennae per reaction center. Finally, another parameter indicative of shade acclimation is the mean antenna size (calculated as ABS/RC ratio), which was considerably higher in red leaves of C. creticus and P. x fraseri (again in Q. coccifera only a similar trend was observed). Yet, according to the JIP-analysis the antenna size is expressed per active RC, hence the increased ABS/RC ratio could be the combined effect of an increase in the antenna size and a decrease in active PSII centers. The combination of the above results indicates that anthocyanin accumulation in C. creticus, Rosa sp. and Q. coccifera contributes mainly to a higher relative size of LHC. In the case of P. x fraseri and R. communis, the enhanced PSII/PSI ratio of red leaves reflects rather an increase of PSII centers.

Παρά τη σημαντική της συνεισφορά στο συνολικό κέρδος σε άνθρακα των φυτών και τις λειτουργικές της ιδιαιτερότητες, η φωτοσύνθεση βλαστού δεν έχει μελετηθεί στην έκταση που της αναλογεί. Για το λόγο αυτό εφαρμόσαμε ένα συνδυασμό ανατομικών και φυσιολογικών μεθόδων για το χαρακτηρισμό του φωτοσυνθετικού μηχανισμού των πράσινων μίσχων και των στελεχών του άνθους του μονοκοτυλήδονου γεώφυτου Zantedeschia aethiopica και των πράσινων βλαστών του δικοτυλήδονου ημιξυλώδους Dianthus caryophyllus, σε σύγκριση με τα αντίστοιχα φύλλα. Οι μίσχοι και τα στελέχη του άνθους του Z. aethiopica και οι βλαστοί του D. caryophyllus διαθέτουν όλα τα ανατομικά χαρακτηριστικά ενός φωτοσυνθετικά αποδοτικού οργάνου, όπως σημαντικό αριθμό στομάτων με τυπικούς υποστομάτιους θαλάμους, χλωρεγχυματικά κύτταρα παρόμοιας μορφολογίας με τα δρυφακτοειδή κύτταρα των φύλλων, επαρκείς μεσοκυττάριους χώρους και σημαντικό ποσοστό ελεύθερων κυτταρικών τοιχωμάτων. Ωστόσο, η διάταξη των δρυφακτοειδών κυττάρων των μίσχων/στελεχών του Z. aethiopica είναι ασυνήθιστη, καθώς διευθετούνται παράλληλα με τον κατά μήκος άξονα των οργάνων. Επιπλέον, οι μίσχοι/στελέχη επέδειξαν φωτοσυνθετικά χαρακτηριστικά που προσομοιάζουν με εκείνα φύλλων σε συνθήκες καταπόνησης, όπως μειωμένο περιεχόμενο/ενεργότητα της Rubisco, αυξημένο ρυθμό του κύκλου C2 και αυξημένη κυκλική ροή ηλεκτρονίων γύρω από το PSI. Τα χαρακτηριστικά αυτά φαίνεται πως είναι εγγενή στα συγκεκριμένα φωτοσυνθετικά όργανα, εξυπηρετώντας την αυξημένη αζωτοδεσμευτική ικανότητα του είδους, την ποιοτική ρύθμιση του περιεχομένου τους σε αμινοξέα, την αποκαρβοξυλίωση C4-οργανικών οξέων του διαπνευστικού ρεύματος και την ταχεία επαγωγή της μη-φωτοχημικής απόσβεσης. Σε αντίθεση με το Z. aethiopica, η φωτοσυνθετική απόδοση των βλαστών του D. caryophyllus βρέθηκε ανώτερη αυτής των φύλλων, ως αποτέλεσμα των υψηλότερων ρυθμών του κύκλου C3 και μιας πιθανής οργανο-ειδικής ποικιλότητας του παράγοντα εξειδίκευσης της Rubisco. Η μειωμένη ένταση του προσπίπτοντος φωτός in vivo, λόγω του κάθετου προσανατολισμού των βλαστών, ενδεχομένως να οδηγεί σε χαμηλότερα επίπεδα φωτοπροστασίας σε σύγκριση με τα φύλλα και στην υιοθέτηση μιας στρατηγικής βελτιστοποίησης του ρυθμού καθήλωσης C, η οποία πιθανώς περιλαμβάνει και την καθήλωση CO2, που προέρχεται από την αποκαρβοξυλίωση C4-οργανικών οξέων του διαπνευστικού ρεύματος. / Despite its significant contribution to the net carbon gain of plants and its distinct functional properties, stem photosynthesis has not yet received adequate scientific attention. For this reason, a combination of anatomical and physiological methods was used to characterize the photosynthetic machinery of the green petioles and pedicels of the monocotyledonous geophyte Zantedeschia aethiopica and the green stems of the dicotyledonous semi-woody species Dianthus caryophyllus, in comparison to the corresponding leaves. Both the green petioles/pedicels of Z. aethiopica and the green stems of D. caryophyllus possess all the anatomical prerequisites of an actively photosynthesizing organ i.e. considerable number of stomata with typical underlying substomatal chambers, chlorenchyma cells which are similar to the leaf palisade chlorenchyma cells and considerable amount of both intercellular spaces and palisade free cell walls. Yet, the palisade cells of Z. aethiopica petioles/pedicels show a peculiar arrangement with their long axis parallel to the longitudinal organ axis. Furthermore, petiole/pedicel photosynthetic characteristics resemble those of leaves under adversity i.e. reduced Rubisco activity/content, high photorespiration rates and significant cyclic electron flow around PSI. It is concluded that these are innate attributes of petiole/pedicel photosynthesis serving particular functions like the increased nitrogen fixing activity of the species, the qualitative adjustment of the petiole/pedicel amino acid content, the active decarboxylation of C4-organic acids and the rapid induction of non-photochemical quenching. Stem photosynthesis in D. caryophyllus was more efficient than leaf photosynthesis, as a result of the greater rates of stem C3 cycle and a possible organ-specific variation of the specificity factor of Rubisco. In general, D. caryophyllus stems display a photosynthetic pattern of optimal carbon assimilation in the expense of photoprotection. It could be hypothesized that this kind of adaptation could be due to the vertical orientation of stems, which results in lower incident light intensities in vivo and may include the use of C4-organic acids coming up with the transpiration stream as an additional carbon source.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Plantas de pinhÃo-manso (Jatropha curcas) e de mamona (Ricinus communis) tÃm sido exploradas agronomicamente para fins de produÃÃo de biocombustÃveis, principalmente em regiÃes secas e quentes do semiÃrido do nordeste brasileiro. Estas espÃcies sÃo nativas de regiÃes tropicais e evoluÃram em resposta Ãs condiÃÃes abiÃticas adversas como alta temperatura e luz, seca e salinidade. Neste trabalho, partimos da principal hipÃtese de que plantas jovens de Jatropha curcas e de Ricinus communis possuem respostas anÃlogas de aclimataÃÃo da fotossÃntese e nos mecanismos de fotoproteÃÃo em resposta Ãs condiÃÃes de estresses abiÃticos. Para isso, os principais objetivos deste trabalho foram conhecer, analisar, descrever e discutir as principais respostas da fotossÃntese e os principais mecanismos de fotoproteÃÃo, como a dissipaÃÃo de excesso de energia na forma de calor, fotorrespiraÃÃo, drenos alternativos de elÃtrons e o metabolismo antioxidativo em plantas jovens de pinhÃomanso e mamona submetidas à condiÃÃes de estresses abiÃticos. Este trabalho foi divido em quatro capÃtulos. O capitulo I trata de uma revisÃo de literatura e estado da arte dos principais tÃpicos abordados ao longo do estudo. O capÃtulo II, na forma de artigo, teve como objetivo principal conhecer e discutir as principais respostas das trocas gasosas e fotoquÃmica dessas duas espÃcies em resposta a variaÃÃes nas condiÃÃes ambientais como o aumento de luz, concentraÃÃo interna de CO2, dÃficit de pressÃo de vapor (DPV), temperatura foliar e ao longo de um dia tÃpico em condiÃÃes de uma regiÃo semiÃrida. Foi claramente demonstrado nesse estudo que plantas de R. communis, quando bem hidratadas, possuem uma maior eficiÃncia fotossintÃtica, dada principalmente pela sua alta taxa de transpiraÃÃo e condutÃncia estomÃtica em comparaÃÃo a plantas jovens de J. curcas. No entanto, em condiÃÃo de seca, seja por suspenÃÃo de rega ou alto dÃficit de pressÃo de vapor, plantas jovens de J. curcas se mostraram mais eficientes na assimilaÃÃo de CO2 quando comparadas com R. communis. Os dados demonstraram ainda que as duas espÃcies estudadas possuem diferentes respostas aclimatativas da fotossÃntese sob condiÃÃes estressantes ou Ãtimas durante a fase inicial de crescimento. O capÃtulo III teve como objetivo demonstrar as diferenÃas nas principais respostas aclimatativas dessas duas espÃcies em condiÃÃo de seca e sua relaÃÃo com a tolerÃncia a esse estresse entre as duas espÃcies estudadas. Foi demonstrado que ambas as espÃcies apresentaram limitaÃÃes estomÃticas e metabÃlicas da fotossÃntese em condiÃÃo de seca, e que essas duas espÃcies apresentam diferentes respostas em termos de dissipaÃÃo de excesso de energia e drenos alternativos de elÃtrons para aliviar a produÃÃo de espÃcies reativas do oxigÃnio no cloroplasto, prevenindo a foto-oxidaÃÃo. As plantas de mamona sÃo mais sensÃveis à seca do que plantas jovens de pinhÃo manso. AlÃm disso, o quenching nÃo fotoquÃmico (NPQ) à um importante mecanismo para a tolerÃncia à seca de J. curcas enquanto que R. communis por nÃo possuir um NPQ tÃo eficiente necessita investir em outros drenos alternativos de elÃtrons para dissipar o excesso de energia. No quarto e Ãltimo capÃtulo, foram avaliadas as respostas aclimatativas da fotossÃntese de plantas jovens de pinhÃo manso e de mamona submetidas ao estresse salino. O tratamento salino imposto aumentou o dano de membrana apenas em folhas de pinhÃo-manso. O conteÃdo de osmÃlitos orgÃnicos compatÃveis aumentou em ambas as espÃcies expostas à salinidade. Plantas de mamona apresentaram, principalmente, restriÃÃes estomÃticas da fotossÃntese, devido à reduÃÃo na pressÃo parcial interna de CO2 (Ci) e por nÃo apresentar reduÃÃo na atividade de Rubisco. No entanto, plantas de pinhÃo-manso expostas à salinidade apresentaram restriÃÃes estomÃticas e metabÃlicas na fotossÃntese, demonstrado pelo aumento do Ci e restriÃÃo na atividade de Rubisco. Plantas de mamona expostas à salinidade apresentaram maior assimilaÃÃo de nitrato e maior fotorrespiraÃÃo, comparada com plantas de pinhÃo-manso sob condiÃÃo de estresse salino. No entanto, o pinhÃo-manso apresentou maior dissipaÃÃo e excesso de energia na forma de calor (NPQ). Como conclusÃo, nossos dados sugerem que as duas espÃcies estudadas empregam diferentes mecanismos para dissipar o excesso de energia na cadeia transportadora de elÃtrons (CTE) do cloroplasto, prevenindo a fotoinibiÃÃo e danos foto-oxidativos. / Plants of Jatropha curcas and Ricinus communis have been exploited for agronomic production of biofuels, especially in hot and dry regions of semiarid at northeastern Brazil. These species are native to tropical and evolved in response to adverse abiotic conditions such as high temperature, drought, salinity and light. In this work, we start with the main hypothesis that saplings of Jatropha curcas and Ricinus communis have analogous mechanisms of acclimation of photosynthesis and photoprotection in response to abiotic stress conditions. For this, the main objectives of this work were to analyze, describe and discuss responses of photosynthesis and important photoprotection mechanisms such as dissipation of excess energy as heat, photorespiration, alternative electron sinks and antioxidant metabolism in young plants of physic nut and castor bean subjected to abiotic stress conditions. This work was divided into four chapters. The chapter I is a review of the literature and state of art of the main topics covered throughout the study. Chapter II, in the form of paper, aimed to meet and discuss the main responses of gas exchange and photochemistry of these two species in response to changes in environmental conditions such as increased lighting, internal CO2 concentration, vapor pressure deficit, leaf temperature and over a typical day in terms of a semiarid region. It has been clearly demonstrated in this experiment that R. communis plants, when well hydrated, have a higher photosynthetic efficiency given mainly by its high transpiration rate and stomatal conductance compared to young plants of J. curcas. However, in dry condition, by watering suspension or high DPV, J. curcas young plants are more efficient in CO2assimilation compared with R. communis. The data showed that the two species have different responses of photosynthesis under optimal or stressful conditions during the early growth stages. Chapter III aimed to demonstrate the differences in the main responses of these two species under drought conditions and its relation to stress tolerance between the two studied species. It has been shown that both species showed stomatal and metabolic limitations of photosynthesis under drought conditions. And that these two species showed different responses in terms of excess energy dissipation and alternative electron sinks of CTE to alleviate the chloroplast ROS production, preventing photo-oxidation. In addition, it has been shown that castor bean plants are more sensitive to drought than J. curcas. Moreover, the NPQ is an important mechanism for drought tolerance of J. curcas whereas R. communis for not having a so efficient NPQ need to invest in other alternative electron sinks to dissipate the excess energy. In the fourth and final chapter, we evaluated the responses of photosynthesis of J. curcas and R. commnuis young plants exposed to salt stress. The salt treatment increased membrane damage only in leaves of J. curcas. The content of organic compatible osmolytes increased in both species exposed to salinity. Castor bean plants had mainly stomatal limitations of photosynthesis due to fall in Ci and by the maintaining in Rubisco activity. However, J. curcas plants exposed to salinity showed stomatal and metabolic restrictions on photosynthesis, demonstrated by the increase in Ci and a drop in Rubisco activity. Castor bean plants exposed to salinity showed higher nitrate assimilation and photorespiration, compared with J. curcas plants under salt stress condition. However, J. curcas had higher dissipation and excess energy as heat (NPQ). In conclusion, our data suggest that both species employ different mechanisms to dissipate excess energy in the CTE of the chloroplast, preventing photoinhibition and photo-oxidative damage.