The RCg2 promoter was identified in a search for root-specific genes to combat the rice water weevil (RWW) but expressed at low frequency (~10%). Spatial expression of RCg2 was investigated using two reporter constructs YXA (RCg2-gus-ocs) and YXB (RCg2-gus-RCg2) that included 1.6 kb of the RCg2 5' sequence fused to the ?-glucuronidase (gus) coding region. YXB plants were generated via Agrobacterium-mediated transformation but only 8 of 158 plants analyzed showed strong GUS activity despite the presence of an intact construct. Reactivation of RCg2 gene in rice was investigated by treatment of R0 and R1 of YXB transgenic plants with 5-azacytidine. Reactivation of RCg2-gus was observed in some transgenic plants indicating different mechanisms involved in the gene silencing of the YXB lines. DNA methylation analysis, northern blotting, RT-PCR and small RNA analysis supported the conclusion that PTGS and TGS are present in the silenced plants. Promoter analysis in silico and using promoter deletion assays predicted that the RCg2 promoter contains a complex region that includes miRNA homologs, MITEs and repetitive sequences. The high frequency of promoter-related silencing suggests functional interactions of these elements of the transgene and the homologous endogenous gene. To identify key elements contributing to the root-preferential expression of RCg2 and the high frequency of silencing observed in transgenic (YXB) lines, several RCg2 promoter deletion constructs were designed. These include 5' deletions MC1, MC2, MC4, MC7 and MC8 and internal deletions MC5, MC11, MC12 and MC13. The frequency with which silencing was encountered in populations of the deletion mutants was used to characterize the effects of various promoter elements. Deletion of the region from -406 to -208 (compared MC11 to YXB, and MC13 to MC1) revealed that region contains a negative element. Among 36 independent transformants, 33% with MC11 expressed GUS and 85% with MC13 showed GUS expression. Comparing MC7 transgenic plants to MC1 revealed that the region ?888 to ?729 is another negative regulatory element, and comparing MC11 to MC12, the proportion of expression of transgenic plants indicated the region ?729 to ?406 is a positive regulatory element.

The RCg2 promoter was identified in a search for root-specific genes to combat the rice water weevil (RWW) but expressed at low frequency (~10%). Spatial expression of RCg2 was investigated using two reporter constructs YXA (RCg2-gus-ocs) and YXB (RCg2-gus-RCg2) that included 1.6 kb of the RCg2 5' sequence fused to the ?-glucuronidase (gus) coding region. YXB plants were generated via Agrobacterium-mediated transformation but only 8 of 158 plants analyzed showed strong GUS activity despite the presence of an intact construct. Reactivation of RCg2 gene in rice was investigated by treatment of R0 and R1 of YXB transgenic plants with 5-azacytidine. Reactivation of RCg2-gus was observed in some transgenic plants indicating different mechanisms involved in the gene silencing of the YXB lines. DNA methylation analysis, northern blotting, RT-PCR and small RNA analysis supported the conclusion that PTGS and TGS are present in the silenced plants. Promoter analysis in silico and using promoter deletion assays predicted that the RCg2 promoter contains a complex region that includes miRNA homologs, MITEs and repetitive sequences. The high frequency of promoter-related silencing suggests functional interactions of these elements of the transgene and the homologous endogenous gene. To identify key elements contributing to the root-preferential expression of RCg2 and the high frequency of silencing observed in transgenic (YXB) lines, several RCg2 promoter deletion constructs were designed. These include 5' deletions MC1, MC2, MC4, MC7 and MC8 and internal deletions MC5, MC11, MC12 and MC13. The frequency with which silencing was encountered in populations of the deletion mutants was used to characterize the effects of various promoter elements. Deletion of the region from -406 to -208 (compared MC11 to YXB, and MC13 to MC1) revealed that region contains a negative element. Among 36 independent transformants, 33% with MC11 expressed GUS and 85% with MC13 showed GUS expression. Comparing MC7 transgenic plants to MC1 revealed that the region ?888 to ?729 is another negative regulatory element, and comparing MC11 to MC12, the proportion of expression of transgenic plants indicated the region ?729 to ?406 is a positive regulatory element.

O arsênio (As) é um semimetal,amplamente distribuído em toda a crosta terrestre, podendo ser encontrado em formas inorgânicas: arsenato (As5+) e arsenito (As3+) e orgânicas como a arsenobetaína (AsB), dimetil-arsênio (DMA) monometil-arsênio (MMA). As formas inorgânicas de As são mais tóxicas que as orgânicas. Patologias como hipertensão, diabetes e vários tipos de câncer estão associados com a exposição ao As inorgânico. Dentre as muitas fontes de exposição a este elemento químico, o arroz (Oryza sativa L.), tem sido destacado como uma das maiores fontes de exposição em populações não expostas diretamente ao As presente na água. Neste sentido, o objetivo deste trabalho foi avaliar a bioacessibilidade in vitro do As presente no arroz e avaliar em camundongos Swiss o acúmulo do semimetal nos tecidos bem como, possíveis alterações nos parâmetros redox em fígado e músculo decorrente do consumo de arroz contendo As. Para isto, na primeira etapa do estudo, o cultivar de arroz BR IRGA 409 foi plantado e divido em 2 grupos onde o primeiro foi chamado de As (-) (sem adição de As no solo) e outro plantado em solo contaminado com As na concentração de 10 mg/Kg, chamado de As (+). Após a colheita, foi verificado que o arroz do grupo As (+) apresentava uma maior concentração de As total no grão. Foram realizados testes de bioacessibilidade que demonstraram uma alta bioacessibilidade do As presente no arroz, principalmente das formas inorgânicas. Foram preparadas duas rações com o arroz plantado para administrar em 2 grupos de camundongos Swiss. Após o tratamento crônico por 100 dias, os amimais foram eutanasiados e coletados órgãos para avaliar o acúmulo do metaloide. Os tecidos que apresentaram um maior acúmulo de As foram bexiga, pelo, rim, baço, testículo, pele e fígado. Além disso, foram realizadas biópsias de músculo e tecido permeabilizados e determinação de parâmetros redox. Não foram observados diferenças estatísticas nas respirações do músculo e fígado. No entanto, observou-se, um aumento na formação de espécies reativas de oxigênio no fígado no grupo As (+), na presença de piruvato. Também foi demonstrado que nos animais expostos a uma maior concentração de As através da dieta ocorreu alterações na atividade enzimática e aumento da peroxidação lipídica. Finalmente, os resultados deste estudo demonstraram que o As inorgânico acumulado nos grãos de arroz se apresentam bioacessiveis e após a exposição pela dieta se distribuem por vários tecidos, levando a alterações em parâmetros redox no fígado. / Arsenic (As) is a metalloid, widely distributed throughout the Earth\'s crust. Arsenic. It can be found in inorganic forms such as (As5+) and arsenite (As3+) and organic compounds such as arsenobetaine (AsB), dimethyl-arsenic (DMA) and monomethylarsenic (MMA). Inorganic forms of As are more toxic than organic forms. Pathologies such as hypertension, diabetes and various types of cancer are associated with exposure to As inorganic. Among the many sources of exposure to this chemical element, rice (Oryza sativa L.) has been reported as the major source of human exposure in populations not exposed directly to As present in the water. In this sense, the objective of this study was to evaluate the in vitro bioaccessibility of As present in rice and to evaluate in Swiss mice the accumulation of semimetal tissues as well as possible changes in the redox parameters in liver and muscle of these animals by consumption of rice containing As by diet. For this, in the first stage of the study, rice cultivar BR IRGA 409 was planted and divided into 2 groups where the first was called As (-) (without addition of As in soil) and another planted in soil contaminated with As in concentration of 10 mg / kg, called As (+). After harvest, it was verified that the rice of the group As (+) had a higher concentration of As total in the grain. Bioaccessibility tests were performed that demonstrated a high bioaccessibility of As present in rice, mainly inorganic forms. Two feed were prepared with the planted rice to be administered in 2 groups of Swiss mice. After the chronic treatment for 100 days, the animals were euthanized and organs were collected to evaluate the accumulation of the metalloid. The tissues that presented a greater accumulation of As were bladder, hair, kidney, spleen, testicle, skin and liver. In addition, permeabilized muscle and tissue biopsies were performed and redox parameters were determined. No changes were observed on muscle and liver breathings. However, there is an increase in the formation of reactive oxygen species in the liver in the As (+) group in the presence of pyruvate. It has been also demonstrated that in animals exposed to a higher concentration of As through diet there were changes in enzymatic activity and increased lipid peroxidation. Finally, the results of this study demonstrated that the As inorganic accumulated in the rice grains are bioaccessible and after dietary exposure they are distributed through several tissues, leading to changes in redox parameters in the liver.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Estudar a eficiÃncia do uso da Ãgua (EUA), a eficiÃncia econÃmica e os indicadores de rentabilidade na cultura do arroz (Oryza sativa, L.), foram os principais objetivos deste trabalho, realizado no PerÃmetro Irrigado de Morada Nova, CearÃ, no perÃodo de julho a dezembro de 2003. Estabeleceu-se a cultura do arroz cultivar EPAGRI 109, em unidades de solo com texturas areia-franca, franca e argilo-siltosa, sendo esta, em duas Ãreas, as quais denominaram-se I e II. Utilizaram-se calhas Parshall e sifÃes de plÃstico como instrumentos para mediÃÃo e aplicaÃÃo de Ãgua aos tabuleiros. O sistema de irrigaÃÃo utilizado foi inundaÃÃo. Os dados utilizados na anÃlise econÃmica foram de levantamentos de custos e receitas pertinentes à cada uma das unidades avaliadas. O perÃodo de irrigaÃÃo do cultivo de arroz para as condiÃÃes de solo e clima no Distrito de IrrigaÃÃo Morada Nova situa-se em torno de 120 dias, perÃodo este que deve ser tomado como referÃncia para o planejamento da irrigaÃÃo. A eficiÃncia de uso da Ãgua para os solos de textura leve apresentou valores mÃdios de 0,2 kg.m-3; jà para os solos de textura pesada, de 0,43 kg.m-3. A eficiÃncia de aplicaÃÃo de Ãgua na unidade textural argilo-siltosa, solo adequado ao cultivo de arroz apresentou um valor mÃdio de 66%. Na unidade textural areia franca, porÃm, solo sem aptidÃo ao cultivo do arroz, a eficiÃncia de aplicaÃÃo foi apenas de 35%, considerando-se em ambos os casos, somente os eventos de irrigaÃÃo sem dÃficit. A rentabilidade lÃquida de cada mil m3 , utilizando a metodologia de cobranÃa de Ãgua derivada e aplicada, mostrou-se superior nos solos argilo-siltosos com valores entre R$ 179,0 e R$ 94,0, enquanto os solos de textura mais leve esta rentabilidade nÃo ultrapassou os R$ 58,0. A receita lÃquida obtida em 1,0 ha de arroz na unidade textural areia franca (R$1.900,00), comparativamente ao valor obtido na unidade textural argilo-siltosa (R$2.400,00), incentiva o cultivo de arroz em solos sem aptidÃo para a cultura, porquanto o sistema de cobranÃa de Ãgua atualmente em vigor, leva em consideraÃÃo a Ãrea irrigada e nÃo o volume de Ãgua aplicada. A anÃlise da rentabilidade nas unidades texturais areia franca e argilo-siltosa, demonstrou a viabilidade do cultivo do arroz para ambas as unidades, em base aos critÃrios convencionais da anÃlise de investimento, porÃm, simulando-se uma remuneraÃÃo mensal do produtor no valor de R$ 240,0, o plano de cultivo na unidade textural areia-franca à inviÃvel, conforme os resultados obtidos: relaÃÃo benefÃcio custo (B/C) 0,98; valor presente lÃquido (VPL) -603,9 e taxa interna de retorno (TIR) 3,5%. Na unidade textural argilo-siltosa, porÃm, os indicadores se mostraram viÃveis: B/C 1,145, VPL R$ 4.204,1 e TIR 60,33%. / The main objective of this study was to determine the water use efficiency, the economic efficiency and the profit indexes for rice (Oryza sativa, L.) in the Morada Nova Irrigation District, state of CearÃ, Brazil, from July to December, 2003. EPAGRI 109 cultivar was cropped in three different soil units: sandyloam, silt and clay loam, the last two called units I and II, respectively. Parshall flumes and siphon tubes were used to measure and apply water to the field basins. The irrigation system used was basin irrigation (inundation). Data used for the economical analysis were obtained from costs and revenues surveyed in each plot evaluated. Irrigation period for planning for the soil and climate conditions of Morada Nova was 120 days. The water use efficiency for sandy soils presented average values of 0.2 kg.m-3; in the case of heavy soils such value was 0.43 kg.m-3. The water application efficiency for clay-loam soils was 66% in average, whereas for sandy-loam was 35%, considering, in both cases, irrigation without deficit. Net profit for a thousand cubic meter, using diverted and applied water methodology, showed superiority for clay-loam soils with values between R$179,00 and R$94,00, while for sandy soils the values were less than R$58,00. Profit analysis for sandy-loam and clay-loam showed feasibility for both soil units, based on conventional criteria of investment analysis, but considering in the simulation a minimum wage of R$240,00/worker, crop plan for the sandy-loam unit was not feasible, according to the obtained results: cost-benefit relation (B/C) equal to 0.98; net present value (VPL) of â 603.9 and âinternal rate of returnâ (TIR) equal to 3.5%. For the case of clay-loam soil the indexes presented feasibility: B/C = 1.145; VPL = R$4.204,10 and TIR = 60.33%.

COLARES, Daniel Santana. Análise técnico-econômica do cultivo do arroz no perímetro irrigado Morada Nova, Ceará. 2004. 58 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia Agrícola, Fortaleza-CE, 2004. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-06-20T12:57:34Z No. of bitstreams: 1 2004_dis_dscolares.pdf: 448942 bytes, checksum: 78b6b3820fccc6db2bddef9b9ec5db7a (MD5) / Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-06-20T13:00:02Z (GMT) No. of bitstreams: 1 2004_dis_dscolares.pdf: 448942 bytes, checksum: 78b6b3820fccc6db2bddef9b9ec5db7a (MD5) / Made available in DSpace on 2016-06-20T13:00:02Z (GMT). No. of bitstreams: 1 2004_dis_dscolares.pdf: 448942 bytes, checksum: 78b6b3820fccc6db2bddef9b9ec5db7a (MD5) Previous issue date: 2004 / The main objective of this study was to determine the water use efficiency, the economic efficiency and the profit indexes for rice (Oryza sativa, L.) in the Morada Nova Irrigation District, state of Ceará, Brazil, from July to December, 2003. EPAGRI 109 cultivar was cropped in three different soil units: sandyloam, silt and clay loam, the last two called units I and II, respectively. Parshall flumes and siphon tubes were used to measure and apply water to the field basins. The irrigation system used was basin irrigation (inundation). Data used for the economical analysis were obtained from costs and revenues surveyed in each plot evaluated. Irrigation period for planning for the soil and climate conditions of Morada Nova was 120 days. The water use efficiency for sandy soils presented average values of 0.2 kg.m-3; in the case of heavy soils such value was 0.43 kg.m-3. The water application efficiency for clay-loam soils was 66% in average, whereas for sandy-loam was 35%, considering, in both cases, irrigation without deficit. Net profit for a thousand cubic meter, using diverted and applied water methodology, showed superiority for clay-loam soils with values between R$179,00 and R$94,00, while for sandy soils the values were less than R$58,00. Profit analysis for sandy-loam and clay-loam showed feasibility for both soil units, based on conventional criteria of investment analysis, but considering in the simulation a minimum wage of R$240,00/worker, crop plan for the sandy-loam unit was not feasible, according to the obtained results: cost-benefit relation (B/C) equal to 0.98; net present value (VPL) of – 603.9 and “internal rate of return” (TIR) equal to 3.5%. For the case of clay-loam soil the indexes presented feasibility: B/C = 1.145; VPL = R$4.204,10 and TIR = 60.33%. / Estudar a eficiência do uso da água (EUA), a eficiência econômica e os indicadores de rentabilidade na cultura do arroz (Oryza sativa, L.), foram os principais objetivos deste trabalho, realizado no Perímetro Irrigado de Morada Nova, Ceará, no período de julho a dezembro de 2003. Estabeleceu-se a cultura do arroz cultivar EPAGRI 109, em unidades de solo com texturas areia-franca, franca e argilo-siltosa, sendo esta, em duas áreas, as quais denominaram-se I e II. Utilizaram-se calhas Parshall e sifões de plástico como instrumentos para medição e aplicação de água aos tabuleiros. O sistema de irrigação utilizado foi inundação. Os dados utilizados na análise econômica foram de levantamentos de custos e receitas pertinentes à cada uma das unidades avaliadas. O período de irrigação do cultivo de arroz para as condições de solo e clima no Distrito de Irrigação Morada Nova situa-se em torno de 120 dias, período este que deve ser tomado como referência para o planejamento da irrigação. A eficiência de uso da água para os solos de textura leve apresentou valores médios de 0,2 kg.m-3; já para os solos de textura pesada, de 0,43 kg.m-3. A eficiência de aplicação de água na unidade textural argilo-siltosa, solo adequado ao cultivo de arroz apresentou um valor médio de 66%. Na unidade textural areia franca, porém, solo sem aptidão ao cultivo do arroz, a eficiência de aplicação foi apenas de 35%, considerando-se em ambos os casos, somente os eventos de irrigação sem déficit. A rentabilidade líquida de cada mil m3 , utilizando a metodologia de cobrança de água derivada e aplicada, mostrou-se superior nos solos argilo-siltosos com valores entre R$ 179,0 e R$ 94,0, enquanto os solos de textura mais leve esta rentabilidade não ultrapassou os R$ 58,0. A receita líquida obtida em 1,0 ha de arroz na unidade textural areia franca (R$1.900,00), comparativamente ao valor obtido na unidade textural argilo-siltosa (R$2.400,00), incentiva o cultivo de arroz em solos sem aptidão para a cultura, porquanto o sistema de cobrança de água atualmente em vigor, leva em consideração a área irrigada e não o volume de água aplicada. A análise da rentabilidade nas unidades texturais areia franca e argilo-siltosa, demonstrou a viabilidade do cultivo do arroz para ambas as unidades, em base aos critérios convencionais da análise de investimento, porém, simulando-se uma remuneração mensal do produtor no valor de R$ 240,0, o plano de cultivo na unidade textural areia-franca é inviável, conforme os resultados obtidos: relação benefício custo (B/C) 0,98; valor presente líquido (VPL) -603,9 e taxa interna de retorno (TIR) 3,5%. Na unidade textural argilo-siltosa, porém, os indicadores se mostraram viáveis: B/C 1,145, VPL R$ 4.204,1 e TIR 60,33%.

COLARES, Daniel Santana. Análise técnico-econômica do cultivo do arroz no perímetro irrigado Morada Nova, Ceará. 2004. 58 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2004. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-17T17:44:13Z No. of bitstreams: 1 2004_dis_dscolares.pdf: 455698 bytes, checksum: cb31059ac73e1be646455f36520e8374 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-07-21T20:08:09Z (GMT) No. of bitstreams: 1 2004_dis_dscolares.pdf: 455698 bytes, checksum: cb31059ac73e1be646455f36520e8374 (MD5) / Made available in DSpace on 2016-07-21T20:08:09Z (GMT). No. of bitstreams: 1 2004_dis_dscolares.pdf: 455698 bytes, checksum: cb31059ac73e1be646455f36520e8374 (MD5) Previous issue date: 2004 / The main objective of this study was to determine the water use efficiency, the economic efficiency and the profit indexes for rice (Oryza sativa, L.) in the Morada Nova Irrigation District, state of Ceará, Brazil, from July to December, 2003. EPAGRI 109 cultivar was cropped in three different soil units: sandyloam, silt and clay loam, the last two called units I and II, respectively. Parshall flumes and siphon tubes were used to measure and apply water to the field basins. The irrigation system used was basin irrigation (inundation). Data used for the economical analysis were obtained from costs and revenues surveyed in each plot evaluated. Irrigation period for planning for the soil and climate conditions of Morada Nova was 120 days. The water use efficiency for sandy soils presented average values of 0.2 kg.m-3; in the case of heavy soils such value was 0.43 kg.m-3. The water application efficiency for clay-loam soils was 66% in average, whereas for sandy-loam was 35%, considering, in both cases, irrigation without deficit. Net profit for a thousand cubic meter, using diverted and applied water methodology, showed superiority for clay-loam soils with values between R$179,00 and R$94,00, while for sandy soils the values were less than R$58,00. Profit analysis for sandy-loam and clay-loam showed feasibility for both soil units, based on conventional criteria of investment analysis, but considering in the simulation a minimum wage of R$240,00/worker, crop plan for the sandy-loam unit was not feasible, according to the obtained results: cost-benefit relation (B/C) equal to 0.98; net present value (VPL) of – 603.9 and “internal rate of return” (TIR) equal to 3.5%. For the case of clay-loam soil the indexes presented feasibility: B/C = 1.145; VPL = R$4.204,10 and TIR = 60.33%. / Estudar a eficiência do uso da água (EUA), a eficiência econômica e os indicadores de rentabilidade na cultura do arroz (Oryza sativa, L.), foram os principais objetivos deste trabalho, realizado no Perímetro Irrigado de Morada Nova, Ceará, no período de julho a dezembro de 2003. Estabeleceu-se a cultura do arroz cultivar EPAGRI 109, em unidades de solo com texturas areia-franca, franca e argilo-siltosa, sendo esta, em duas áreas, as quais denominaram-se I e II. Utilizaram-se calhas Parshall e sifões de plástico como instrumentos para medição e aplicação de água aos tabuleiros. O sistema de irrigação utilizado foi inundação. Os dados utilizados na análise econômica foram de levantamentos de custos e receitas pertinentes à cada uma das unidades avaliadas. O período de irrigação do cultivo de arroz para as condições de solo e clima no Distrito de Irrigação Morada Nova situa-se em torno de 120 dias, período este que deve ser tomado como referência para o planejamento da irrigação. A eficiência de uso da água para os solos de textura leve apresentou valores médios de 0,2 kg.m-3; já para os solos de textura pesada, de 0,43 kg.m-3. A eficiência de aplicação de água na unidade textural argilo-siltosa, solo adequado ao cultivo de arroz apresentou um valor médio de 66%. Na unidade textural areia franca, porém, solo sem aptidão ao cultivo do arroz, a eficiência de aplicação foi apenas de 35%, considerando-se em ambos os casos, somente os eventos de irrigação sem déficit. A rentabilidade líquida de cada mil m3 , utilizando a metodologia de cobrança de água derivada e aplicada, mostrou-se superior nos solos argilo-siltosos com valores entre R$ 179,0 e R$ 94,0, enquanto os solos de textura mais leve esta rentabilidade não ultrapassou os R$ 58,0. A receita líquida obtida em 1,0 ha de arroz na unidade textural areia franca (R$1.900,00), comparativamente ao valor obtido na unidade textural argilo-siltosa (R$2.400,00), incentiva o cultivo de arroz em solos sem aptidão para a cultura, porquanto o sistema de cobrança de água atualmente em vigor, leva em consideração a área irrigada e não o volume de água aplicada. A análise da rentabilidade nas unidades texturais areia franca e argilo-siltosa, demonstrou a viabilidade do cultivo do arroz para ambas as unidades, em base aos critérios convencionais da análise de investimento, porém, simulando-se uma remuneração mensal do produtor no valor de R$ 240,0, o plano de cultivo na unidade textural areia-franca é inviável, conforme os resultados obtidos: relação benefício custo (B/C) 0,98; valor presente líquido (VPL) -603,9 e taxa interna de retorno (TIR) 3,5%. Na unidade textural argilo-siltosa, porém, os indicadores se mostraram viáveis: B/C 1,145, VPL R$ 4.204,1 e TIR 60,33%.

O arsênio (As) é um elemento não essencial ao homem, encontrado na natureza nas formas inorgânicas (As-i) e orgânicas (As-o). As espécies inorgânicas, arsenito e arsenato (As3+ e As5+), são as mais tóxicas, podendo interferir em reações bioquímicas, estado redox das células, formação de trifosfato de adenosina (ATP) e gerar danos oxidativos, ocasionando proliferação celular e câncer. O As-i pode sofrer metilação no organismo e no ambiente, gerando metabólitos que são menos reativos com componentes do tecido e mais facilmente excretados na urina, principalmente ácido monometilarsônico (MMA) e ácido dimetilarsínico (DMA). O As-i é encontrado no arroz (Oryza sativa L.), principalmente quando o cultivo ocorre pelo método irrigado, que leva a uma maior mobilização de elementos presentes no solo. Neste estudo, foram avaliadas 6 diferentes cultivares brasileiras de arroz quanto à predileção pela captação de As (EPAGRI 109, EPAGRI 108, SCS BRS Tiotaka, SCS 114 Andosan, Maranhão e Cáqui). Para cada cultivar foram plantados grupos controles (não expostos, n=4) e expostos (n=4). No grupo exposto, para cada kg de solo, foram adicionados 10 mg de As5+. Nos grupos controle não adicionou-se As5+, sendo submetidos às mesmas condições de solo, irrigação, temperatura e umidade. Após a completa maturação das plantas foram feitas determinações de As total (As-t) em raízes, solo, colmos e grãos por espectrometria de massas com plasma indutivamente acoplado (ICP-MS) e a especiação química de As nos grãos foi feita por HPLC-ICP-MS. Uma elevada capacidade de captação do As foi observada na seguinte ordem crescente: grãos<colmos<solo<raízes, sendo as concentrações médias dos grupos controle de 0,06; 0,32; 3,29 e 0,65 mg kg-1 e nos grupos expostos com médias de 0,54; 5,96; 13,5 e 95,48 mg kg-1. EPAGRI 108 foi a cultivar que menos acumulou As-t nos grãos, tanto nos grupos controle (0,05±0,005 mg kg-1) quanto nos grupos expostos (0,36±0,08 mg kg-1) apresentando também menores fatores de transferência (FTsolo-grão, FTraíz-grão, FTcolmo-grão) e concentrações de As-o nos grupos controle (0,015 mg kg-1) e expostos (0,13 mg kg-1). Entre as cultivares de arroz branco, Andosan (exposto) foi a que acumulou maiores quantidades de As-t (0,515±0,15 mg kg-1) e de Aso (0,37 mg kg-1 ou 72% do As-t) nos grãos. Esta mesma cultivar, entre os grupos controle, foi uma das que apresentou maiores porcentagens de As-i (65%) em relação ao As-t. EPAGRI 109 (controle) foi a cultivar de arroz branco com maior As-t e As-i no grãos (0,07±0,008 e 0,04 mg kg-1 respectivamente) e maior FTsolo-grãos (0,216). Nas plantas expostas a 10 mg Kg-1 As5+ no solo foi observada uma correlação positiva entre As-t (solo) x As-t e As-o (grãos) evidenciando o aumento da captação de As e transporte de As-o para as partes aéreas. Os elementos essenciais Co e Mn diminuíram significativamente em alguns cultivares sob alta exposição apresentando correlação negativa As-t (raíz) x Co (grãos). Os elementos tóxicos Cd e Pb, sob alta exposição ao As foram em geral menos captados pela planta. / Arsenic (As) is a nonessential element to man, found in the environment in inorganic (As-i) and organic forms (As-o). Inorganic species, arsenite and arsenate (As3+ and As5+) are the most toxic, and may interfere in biochemical reactions, cellular redox status, formation of adenosine triphosphate (ATP) and generate oxidative damage leading to cell proliferation and cancer. As-i can be methylated in the body and in the environment generating metabolites which are less reactive with components of organisms and more easily excreted in the urine, mainly monomethylarsonous acid (MMA) and dimethylarsinous acid (DMA). As-i is found in rice (Oryza sativa L.), especially when the crop is flooded, which leads to greater mobilization of elements present in the soil. In this study, Brazilian rice varieties were evaluated and the predilection for As uptake in 6 different cultivars (EPAGRI 109, EPAGRI 108, BRS Tiotaka SCS, SCS 114 Andosan, Maranhão and Cáqui). For each cultivar it were planted controls (untreated, n = 4) and exposed (n = 4). In the group exposed, for each kg of soil was added 10 mg of As5+. Control groups were not added As5+, being submitted to the same conditions of soil, irrigation, temperature and humidity. After complete plant maturation were made determinations of the total Arsenic (As-t) in soil, roots, shoots and grains were performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and the chemical speciation of the grains was performed by HPLC-ICP-MS. A high As uptake ability was observed in the following order: grain<shoot<soil<roots, and the average concentrations of control groups were 0.06; 0.32; 3.29 and 0.65 mg kg-1 and the average exposed groups were 0.54; 5.96; 13.5 and 95.48 mg kg-1. EPAGRI 108 was the cultivar less accumulated As-t both control groups (0.05 ± 0.005 mg kg-1) as the exposed group (0.36 ± 0.08 mg kg-1) also presenting the lowest FTsoil-grain, FTroot-grain, FTshoot-grain, concentrations of As-o in the control (0.015 mg kg-1) and exposed group (0.13 mg kg-1). Among the white rice cultivars, Andosan (exposed) accumulated larger amounts of As-t (0.515 ± 0.15 mg kg-1) and As-o (0.37 mg kg-1 or 72% As-t) in grains. This same cultivar was the one who had higher percentages of As-i (65%) compared to As-t, between the control group. EPAGRI 109 (control) was the white rice cultivar with high As-t and As-i in grain (0.07±0,008 and 0,04 mg kg-1 respectively) between the control group and higher FTsoil-grain (0,216). In high As exposure, it was observed a positive correlation between As-t (soil) x As-t and As-o(grains) highlighting the increased As uptake and the transport of As-o to the aerial parts. The essential elements Co and Mn decreased significantly in some cultivars under high exposure and showed negative correlation between As-t (root) x Co (grain). Toxic elements, Cd and Pb under high As exposure were generally less uptake by plant

Rice (Oryza sativa L.) is an important crop cultivated worldwide, and abiotic stresses limit its productivity. Different approaches were carried out to understand the mechanisms of rice defense responses against abiotic stresses, mainly drought. The NADPH-generating enzymes engaged in response to dehydration and salt stresses during the seedling stage of Nipponbare cultivar were analyzed. Enzyme activities of 6-phosphogluconate dehydrogenase (6PGDH), NADP-dependent aldehyde dehydrogenase, NADP-malic enzyme (NADP-ME) in leaves, and 6PGDH in roots were significantly increased in response to dehydration stress. NADP-ME and NADP-glutamate dehydrogenase activities in roots increased significantly in response to salt stress. These results suggest the involvement of NADPH-generating enzymes in plant responses to dehydration and salinity stresses, and the increased demands of NADPH in plants under abiotic stress can be furnished by enhanced activities of NADPH-producing enzymes. Also, a dehydration-induced protein was detected and identified as serine-hydroxymethyltransferase. This result indicates that serine-hydroxymethyltransferase can play a key role in regulating dehydration response in rice. Moreover, comparative proteomic analyses of CL163 (drought-tolerant), Cheniere (drought-sensitive), and Rex (moderately-drought-sensitive) rice varieties were performed. Drought-responsive proteome changes were profiled in leaves and roots at the seedling stage in response to drought stress imposed by polyethylene glycol (PEG-6000). Eighteen significantly differentially expressed proteins were identified by mass spectrometry. Elongate factor1 alpha and 17.9-kDa classI heat shock protein appear to have different expression patterns between CL163 and Cheniere, which may be attributable to the difference in drought response of the two rice varieties. Furthermore, a compendium of 103 drought resistance genes in rice was compiled to construct and analyze networks formed by associations between genes/proteins and to identify the most significant genes, biological processes/pathways. Genes were classified based on gene ontology and protein class into 26 groups. Forty-two genes were classified as transcription factors. Proteins encoded by the genes were localized in 8 subcellular locations and classified into three classes. Two pathways from KEGG whose genes were overrepresented in the compendium were identified. Gene expression, network presenting pairwise interactions between genes/proteins, and co-expression network were constructed. This study provides a systematic view of the crucial genes that can be contributing collectively to drought tolerance.