The mitochondrial NAD+ transporter (NDT1) plays important roles in cellular NAD+ homeostasis in \u3ci\u3eArabidopsis thaliana\u3c/i\u3e

Nicotinamide adenine dinucleotide (NAD+) is an essential coenzyme required for all living organisms. In eukaryotic cells, the final step of NAD+ biosynthesis is exclusively cytosolic. Hence, NAD+ must be imported into organelles to support their metabolic functions. Three NAD+ transporters belonging to the mitochondrial carrier family (MCF) have been biochemically characterized in plants. AtNDT1 (At2g47490), focus of the current study, AtNDT2 (At1g25380), targeted to the inner mitochondrial membrane, and AtPXN (At2g39970), located in the peroxisomal membrane. Although AtNDT1 was presumed to reside in the chloroplast membrane, subcellular localization experiments with green fluorescent protein (GFP) fusions revealed that AtNDT1 locates exclusively in the mitochondrial membrane in stably transformed Arabidopsis plants. To understand the biological function of AtNDT1 in Arabidopsis, three transgenic lines containing an antisense construct of AtNDT1 under the control of the 35S promoter alongside a T-DNA insertional line were evaluated. Plants with reduced AtNDT1 expression displayed lower pollen viability, silique length, and higher rate of seed abortion. Furthermore, these plants also exhibited an increased leaf number and leaf area concomitant with higher photosynthetic rates and higher levels of sucrose and starch. Therefore, lower expression of AtNDT1 was associated with enhanced vegetative growth but severe impairment of the reproductive stage. These results are discussed in the context of the mitochondrial localization of AtNDT1 and its important role in the cellular NAD+ homeostasis for both metabolic and developmental processes in plants

Educação em saúde como forma de prevenção do câncer do colo do útero

Cervical cancer is the type of cancer that most kills women in the world. This study aimed to analyze the scientific evidence of health education to prevent cervical cancer. This is an integrative review of the literature, carried out through the databases of the BVS and PUBMED, in which the following guiding question was used: “What scientific evidence points to health education as a way of preventing cervical cancer?”. Studies available in full, in portuguese, english and spanish, published from 2017 to 2022 were used. Ten studies were selected to compose this review. According to the studies analyzed, it was identified that the triggering factors of cervical cancer are early sexual intercourse, unprotected sexual intercourse, multiple sexual partners, HPV infections, and use of hormonal contraceptives. Health education activities such as lectures, conversation circles, home visits are relevant, as they bring knowledge to women about the neoplasm, encouraging the practice of self-care, as well as helping to deconstruct stigmas and fears related to the Pap smear. It was evidenced that the scarcity of information about CC and the ways to prevent the disease cause fears and apprehensions for many women, which contributes to a delay in carrying out the Pap smear. Thus, health education strategies, with clarification of doubts about the disease and forms of prevention, addressing the availability of health services for early screening, are essential measures to break the taboo associated with performing the test.El cáncer de cuello uterino es el tipo de cáncer que más mata a las mujeres en el mundo. Este estudio tuvo como objetivo analizar la evidencia científica de la educación en salud como una forma de prevención del cáncer de cuello uterino. Se trata de una revisión integrativa de la literatura, realizada a través de las bases de datos de la BVS y PUBMED, en la que se utilizó la siguiente pregunta orientadora: “¿Qué evidencia científica apunta a la educación en salud como forma de prevención del cáncer de cuello uterino? ¿útero?”. Se utilizaron estudios disponibles en su totalidad, en portugués, inglés y español, publicados entre 2017 y 2022. Se seleccionaron diez estudios para componer esta revisión. De acuerdo con los estudios analizados, se identificó que los factores desencadenantes del cáncer de cuello uterino son el inicio temprano de la vida sexual, las relaciones sexuales sin protección, las múltiples parejas sexuales, las infecciones por VPH y el uso de anticonceptivos hormonales. Las actividades de educación en salud, como charlas, círculos de conversación, visitas domiciliarias, son relevantes, ya que acercan el conocimiento a las mujeres sobre la neoplasia, incentivando la práctica del autocuidado, además de ayudar a deconstruir estigmas y miedos relacionados con el Papanicolaou. Se evidenció que la escasez de informaciones sobre CC y formas de prevención de la enfermedad provocan temores y aprensiones en muchas mujeres, lo que contribuye a la demora en la realización del Papanicolaou. Así, las estrategias de educación en salud, con aclaración de dudas sobre la enfermedad y formas de prevención, abordando la disponibilidad de los servicios de salud para realizar el tamizaje precoz, son medidas esenciales para romper el tabú asociado al examen.O câncer de colo de útero é o tipo de câncer que mais mata mulheres no mundo. Este estudo teve por objetivo, analisar as evidências científicas da educação em saúde como forma de prevenção do câncer de colo de útero. Trata-se de uma revisão integrativa da literatura, realizada através das bases de dados da BVS e da PUBMED, na qual se utilizou a seguinte questão norteadora: “Quais as evidências científicas apontam para educação em saúde como forma de prevenção do câncer de colo de útero?”. Utilizaram-se estudos disponíveis na íntegra, nos idiomas português, inglês e espanhol, publicados de 2017 a 2022. Foram selecionados 10 estudos para compor esta revisão. Conforme os estudos analisados, foi identificado que os fatores desencadeantes do câncer de colo do útero são, início da vida sexual precoce, relação sexual desprotegida, múltiplos parceiros sexuais, infecções pelo HPV, e uso de contraceptivos hormonais. As atividades de educação em saúde como palestras, rodas de conversas, visitas domiciliares se mostram relevantes, pois levam conhecimento para as mulheres acerca da neoplasia, incentivando a prática do autocuidado, bem como auxilia na desconstrução de estigmas e receios relacionados ao exame citopatológico. Evidenciou-se que a escassez de informações sobre o CCU e as formas de prevenção da doença provocam medos e receios para muitas mulheres, no qual contribui para um retardo na realização do exame citopatológico. Assim, estratégias de educação em saúde, com esclarecimento de dúvidas sobre a doença e as formas de prevenção, abordando a disponibilidade dos serviços de saúde para realização do rastreamento precoce, são medidas imprescindíveis para quebrar o tabu associado à realização do exame

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

O papel da compartimentalização e das dinâmicas de NAD+ em Arabidopsis thaliana

Nicotinamide adenine dinucleotide (NAD+) is a fundamental coenzyme required to regulate plant central metabolism and redox status homeostasis. Plants produce NAD+ via de novo and salvage pathways. Despite early steps of the two pathways occur in different subcellular compartments, de novo in chloroplasts and salvage in cytosol, both pathways produce the final product NAD+ exclusively in the cytosol. Thus, NAD+ must be imported into organelles to drive biological processes inside them. In Arabidopsis thaliana, three genes have been identified as NAD+ carriers, namely NDT1 (At2g47490) and NDT2 (At1g25380), both targeted to the inner mitochondrial membrane, and the peroxisomal transporter PXN (At2g39970). The previous functional characterization of NDT1, NDT2 and PXN have revealed their importance for seed production and quality, seedling establishment, photosynthesis, metabolism, stomatal density and stomatal conductance. To extend our knowledge on the importance of NAD+ dynamics, we used mutants for NAD+ transport and focused in comprehend: (1) how altered NAD + distribution affects stomatal development in cotyledons, (2) the crosstalk between NAD+ transport and elevated atmospheric CO2 concentration and (3) NAD + dynamics in vivo under different environmental cues. The results indicate that NAD negatively regulates stomatal development in cotyledons of Arabidopsis. Seedlings with reduced expression of mitochondrial (NDT1 and NDT2) and peroxisomal (PXN) NAD+ transporter genes displayed reduced numbers of stomata lineage cells and reduced stomatal density. Furthermore, cotyledons of wild- type seedlings treated with exogenous NAD+ and cotyledons of mutant plants with reduced NAD+ breakdown capacity also exhibited reduced stomatal number. Impaired NAD+ transport and the exogenous NAD+ feeding were further associated with the induction of abscisic acid (ABA)-responsive genes. Additionally, NAD+ feeding of aba- 2 and ost1 seedlings, impaired in ABA synthesis and ABA signaling, respectively, did not impact on stomatal number, whereas the inhibition of ABA synthesis rescued the stomatal phenotype in NAD+ carrier mutants. Moreover, in vivo measurement of ABA dynamics in seedlings of an ABA-specific optogenetic reporter - ABAleon2.1 treated with NAD+ showed increases in ABA content, suggesting that NAD+ impacts on stomatal development through ABA synthesis and signaling. The results demonstrate that intracellular NAD+ homeostasis is essential for normal stomatal development, and provide a link between central metabolism and developmental plasticity. Posteriorly, NAD+ carrier mutants were grown under elevated CO2 concentrations and overall results showed that, under high CO2 , the mutants displayed reductions in total biomass and leaf number compared to the control under ambient CO2 . Furthermore, higher levels of photorespiratory intermediates such as glutamate and glycine were found in the mutant lines under elevated CO2 . Moreover, mutant lines produced much less seeds than wild-type plants regardless of CO2 concentration, demonstrating that NAD+ compartmentalization is fundamental during reproductive phase in both ambient and high CO2 concentration. With the aim to deeper study NAD + dynamics, we transformed wild-type and a ndt1 mutant line with the Peredox-mCherry sensor that permits the measuring of cytosolic NADH dynamics in vivo. The cytosol of ndt1 mutant lines presented higher levels of NADH/NAD + compared to the control line. Additionally, increased cytosolic levels of NADH/NAD+ in leaves of ndt1 mutants was observed upon the exogenous feeding of sugars and tricarboxylic acid (TCA) cycle intermediates. Surprisingly, light, mitochondrial electron transport chain (mETC) inhibitors and oxygen deprivation treatment did not show significant differences in cytosolic NADH/NAD+ content in ndt1 mutants compared to wild-type. The results provide evidence of disruption of NAD+ balance among organelles in ndt1 mutants and show the power of this technique to follow NADH dynamics in vivo. Collectively, the data presented provide different inputs to show that, not only NAD+ metabolism, but also NAD+ distribution across organelles, are fundamental to drive essential biological processes in plants. Furthermore, this study proposes a direct link between central metabolism and early developmental process such as stomatal development. Keywords: Nicotinamide adenine dinucleotide. NAD+ transport. Metabolism. Development.Nicotinamide adenina dinucletídeo (NAD+) é uma coenzima fundamental para a regulação do metabolismo central e do estado redox celular. Plantas produzem NAD+ através das vias de novo e salvamento. Apesar de começarem em diferentes compartimentos, de novo nos cloroplastos e salvamento no citosol ambas as vias sintetizam NAD+ como produto final no citosol. Desta forma, o NAD+ precisa ser importado pelas organelas para exercer suas funções no interior das mesmas. Em Arabidopsis três genes foram identificados como transportadores de NAD+ sendo dois localizados na membrana interna da mitocôndria NDT1 (At2g4790) e NDT2 (At1g25380) e um na membrana do peroxissomo PXN (At2g39970). A caracterização funcional dos genes NDT1, NDT2 e PXN revelou a importância a importância desses genes para a produção e qualidade de sementes, estabelecimento de plântulas, fotossíntese, metabolismo e regulação do número de estômatos e condutância estomática. Para aumentar nosso conhecimento sobre a importância das dinâmicas de NAD+, utilizamos mutantes para o transporte de NAD+ e nos focamos em compreender: (1) como a distribuição de NAD+ afeta o desenvolvimento estomático em cotilédones, (2) a interação entre transporte de NAD+ e altas concentrações de gás carbônico e (3) dinâmicas de NAD+ in vivo em diferentes situações ambientais. Os resultados indicam que o NAD+ regula negativamente o desenvolvimento estomático em cotilédones de Arabidopsis. Plântulas com reduzida expressão dos transportadores de NAD+ mitocondriais (NDT1 e NDT2) e do peroxissomo (PXN) apresentaram reduzidos números de células formadoras de estômatos e densidade estomática. Além disso, cotilédones tratados com NAD+ de forma exógena e cotilédones de plantas com reduzida capacidade de mobilização de NAD+ também exibiram menor densidade estomática. O impedimento de transporte de NAD+ e o tratamento exógeno com NAD+ foram associados com a indução de genes responsivos ao hormônio ABA. Adicionalmente, o tratamento de NAD+ em mutantes para a síntese (aba-2) e sinalização (ost1) de ABA não impactou o número de estômatos enquanto o uso de um inibidor da biossíntese de ABA recuperou o fenótipo de estômatos dos mutantes para o transporte de NAD+ . Ademais, a mensuração in vivo das dinâmicas de ABA em plântulas do sensor de ABA (ABA-specific optogenetic repórter – ABAleon2.1) tratadas com NAD+ mostraram aumentos nos níveis de ABA, sugerindo que o NAD+ impacta o número estomático através da síntese e sinalização de ABA. Os resultados demonstraram que a homeostase intracelular de NAD+ é essencial para o correto desenvolvimento estomático e fornece uma ligação entre o metabolismo central e a plasticidade do desenvolvimento. Posteriormente crescemos os mutantes para o transporte de NAD+ em elevadas concentrações de CO2 e em geral os resultados mostraram que as plantas mutantes apresentaram menor biomassa e número de folhas que o controle em altas concentrações de CO2 . Adicionalmente, plantas mutantes acumularam intermediários da fotorrespiração, tais como glutamato e glicina em alto CO2 . Além disso, plantas mutantes produziram muito menos sementes que plantas WT em resposta ao CO2 , demonstrando que a compartimentalização do NAD+ é fundamental durante a fase reprodutiva em condição ambiente e de alto CO2 . Com o objetivo de estudar as dinâmicas de NAD+ transformamos plantas controle e plantas com reduzida expressão do gene NDT1 com o sensor de NAD+ chamado Peredox-mCherry que permite a mensuração da dinâmica de NADH/NAD+ no citosol in vivo. O citosol das plantas mutantes ndt1 apresentaram maiores níveis de NADH/NAD+ comparado com o citosol de plantas controle. Adicionalmente, aumentos nos níveis de NADH/NAD+ em folhas de ndt1 foram observados após o tratamento destas com açúcares e intermediários do ciclo dos ácidos tricarboxílicos. Surpreendentemente, os tratamentos com luz, inibidores da cadeia de transporte mitocondrial e indução de estresse por oxigênio não apresentaram diferenças significativas nos teores de NADH/NAD+ entre mutantes e plantas controle. Os resultados apresentam evidência do desbalanço de NAD+ entre as organelas em plantas mutantes e mostra ainda como essa técnica é valiosa para estudar as dinâmicas de NADH in vivo. Coletivamente, os dados apresentados mostram que não apenas o metabolismo do NAD+ é fundamental para regular processos biológicos essenciais, mas também sua distribuição entre organelas. Além disso, este estudo propõem uma ligação direta entre o metabolismo central e processos iniciais de desenvolvimento como o desenvolvimento estomático. Palavras-chave: Nicotinamida adenina dinucleotídeo. Transporte de NAD+ . Metabolismo. Desenvolvimento.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

A influência da via Target of Rapamycin (TOR) no metabolismo de amido em Arabidopsis thaliana

Plant growth and development are maintained by a complex network controlled by environmental factors including the availability of water, light and nutrients and by several signaling pathways. One of the most important signaling pathways, conserved in eukaryotes, is the kinase Target of Rapamycin (TOR). Various lines of evidence point out that TOR plays a fundamental role in carbon and nitrogen balance, acting as an essential regulator on central metabolism by controlling growth and biomass production. Starch is the major form of carbon storage and its content is negatively correlated with growth. Transgenic lines with reduced expression of TOR gene or components of the TOR complex present a clear starch excess phenotype. However, it remained to be elucidated whether the accumulation of starch is due to increased synthesis, impaired degradation or both. In this work, Arabidopsis seedlings treated with the specific ATP-competitive inhibitor of TOR kinase AZD-8055 showed a starch excess phenotype right after 4 hours of treatment and the accumulation of starch was proved to be due to an augmentation in the rate of starch synthesis. Furthermore, TOR- inhibited plants presented an average increase of 20-30% in their starch content at the end of day when compared to control. Metabolite profiling analysis showed that TOR– inhibited plants exhibited broad changes in the levels of sucrose, fructose, glucose, maltose, mannose and orthophosphate, which are associated directly or indirectly with starch metabolism. In addition, a correlation between the amount of mannose, orthophosphate and increased starch content was noticed in AZD-treated plants. Gene expression analysis of AGPase subunits showed significant changes only from 18 and 24h after treatment. Although TOR inhibited plants displayed higher content of the active form of AGPase (monomer), enzymatic activity assays revealed that changes in AGPase activity might occur as secondary effect of TOR inhibition and might be not related to the starch excess phenotype observed 4 hours after AZD-treament. Since several enzymes related to starch metabolism are subject to redox regulation, the levels of glutathione were measured to verify the redox environment of the cells. TOR- inhibited plants showed changes in the pools of glutathione, mainly in its reduced form, and the redox state of the cells tended to be more reduced. Together, these results indicate the participation of TOR signalling on starch metabolism but the mechanistic behind this process need further studies.O crescimento e o desenvolvimento vegetal são controlados por uma complexa rede metabólica controlada por fatores ambientais, incluindo a disponibilidade de água, nutrientes e luz, e por várias vias de sinalização. Uma das mais importantes vistas de sinalização, conservada em eucariotos, é a kinase Target of Rapamycin (TOR). Várias linhas de evidência demonstram que TOR exerce um papel fundamental no balanço de carbono e nitrogênio, agindo como um regulador essencial do metabolismo central, controlando o crescimento e a produção de biomassa. O amido é a principal forma de armazenamento de carbono e seu conteúdo é correlacionado negativamente com crescimento. Linhas transgênicas com expressão reduzida do gene TOR ou dos componentes do complexo apresentam um claro fenótipo de acúmulo de amido. No entanto, ainda não é elucidado se o acúmulo de amido é devido a um aumento na síntese, decréscimo na degradação ou ambos. Neste trabalho, plântulas de Arabidopsis tratadas com o inibidor químico específico de TOR AZD-8055, que age no sítio de ligação do ATP no domínio quinase de TOR, mostraram um fenótipo de acúmulo de amido logo após 4 horas de tratamento e este acúmulo é devido a um aumento nas taxas de síntese deste polímero. Além disso, plântulas onde TOR estava inibida apresentaram um aumento em torno de 30-40% em seu conteúdo de amido em comparação ao controle. Análise de perfil metabólico em plântulas com inibição de TOR apresentaram mudanças nos níveis de sacarose, frutose, glicose, maltose, manose e fosfato inorgânico. Todos estes metabólitos estão correlacionados direta ou indiretamente com o metabolismo de amido. Uma correlação entre o teor de manose, fosfato inorgânico e aumento de amido foi notável em plantas tratadas com AZD-8055. Análise de expressão gênica de subunidades da AGPase apresentou mudanças significativas nos pontos 18 e 24 horas após o tratamento com o inibidor. Atividade catalítica máxima da AGPase foi determinada nos pontos 2, 4, 6, 10 e 24 horas após a administração de AZD-8055. No entanto, a atividade só foi estatisticamente diferente entre tratamentos nos pontos 4 e 24 horas. Immunoblotting para esta enzima mostrou que após 4 horas de inibição da via TOR, o conteúdo de AGPase em sua forma dimérica tendeu a ser maior em plantas controle. Além disso, o teor total de AGPase e seu conteúdo na forma monomérica foram maiores em plantas tratadas com AZD-8055 após 6 horas de tratamento na luz. Sabendo que várias enzimas relacionadas ao metabolismo do amido são reguladas pelo potencial redox da célula, os níveis de glutationa foram mensurados para verificar o potencial redox celular. Plantas tratadas com AZD-8055 apresentaram mudanças na quantidade total de glutationa, pincipalmente na sua forma reduzida e o potencial redox da célula tendeu a ficar mais reduzido. Em conjunto, estes resultados indicam a participação de TOR no metabolismo do amido, mas o exato mecanismo por trás disso ainda está longe de ser elucidado.Fundação de Amparo à Pesquisa do Estado de Minas Gerai

Shifting paradigms and novel players in Cys-based redox regulation and ROS signaling in plants - and where to go next.

Meyer AJ, Dreyer A, Ugalde JM, Feitosa-Araujo E, Dietz K-J, Schwarzlander M. Shifting paradigms and novel players in Cys-based redox regulation and ROS signaling in plants - and where to go next. Biological Chemistry. 2021;402(3):399–423.Cys-based redox regulation was long regarded a major adjustment mechanism of photosynthesis and metabolism in plants, but in the recent years, its scope has broadened to most fundamental processes of plant life. Drivers of the recent surge in new insights into plant redox regulation have been the availability of the genome-scale information combined with technological advances such as quantitative redox proteomics and in vivo biosensing. Several unexpected findings have started to shift paradigms of redox regulation. Here, we elaborate on a selection of recent advancements, and pinpoint emerging areas and questions of redox biology in plants. We highlight the significance of (1) proactive H2O2 generation, (2) the chloroplast as a unique redox site, (3) specificity in thioredoxin complexity, (4) how to oxidize redox switches, (5) governance principles of the redox network, (6) glutathione peroxidase-like proteins, (7) ferroptosis, (8) oxidative protein folding in the ER for phytohormonal regulation, (9) the apoplast as an unchartered redox frontier, (10) redox regulation of respiration, (11) redox transitions in seed germination and (12) the mitochondria as potential new players in reductive stress safeguarding. Our emerging understanding in plants may serve as a blueprint to scrutinize principles of reactive oxygen and Cys-based redox regulation across organisms. © 2020 Andreas J. Meyer et al., published by De Gruyter, Berlin/Boston

First report of interaction of nematophagous fungi on Libyostrongylus douglassii (Nematoda: Trichostrongylidae) Primeiro relato da interação de fungos nematófagos sobre Libyostrongylus douglassii (Nematoda: Trichostrongilidae)

Libyostrongylus douglassii is a gastrointestinal nematode parasite of ostriches that can cause up to 50% mortality in young birds. The objective of this study was to compare the predatory capacity of two isolates of the predatory fungi Duddingtonia flagrans (AC001 and CG722 isolates) and one of Arthrobotrys cladodes (CG719) on infective larvae (L3) of L. douglassii under laboratory conditions, in 2% water-agar medium. The results showed that the fungi tested were effective in preying upon the L3 of L. douglassii (P 0.05) during the seven days of experimental testing. In comparison with the control, without fungus, there were significant decreases (P Libyostrongylus douglassii &#233; um nemat&#243;ide parasito gastrintestinal de avestruzes que pode causar at&#233; 50% de mortalidade em aves jovens. O objetivo deste trabalho foi comparar a capacidade predat&#243;ria de dois isolados de fungos predadores Duddingtonia flagrans (isolados AC001 e CG722) e um Arthrobotrys cladodes (CG719) sobre larvas infectantes (L3) de L. douglassii em condi&#231;&#245;es laboratoriais, em meio &#225;gar&#8211;&#225;gua 2%. Os resultados demonstraram que os fungos testados foram eficientes em predar as L3 de L. douglassii (P 0,05) durante os sete dias do ensaio experimental. Em compara&#231;&#227;o ao controle, sem fungo, houve uma redu&#231;&#227;o significativa (P < 0,05) de 85,2% (AC001); 81,2% (CG722) e 89,2% (C719) na m&#233;dia de L3 recuperadas nas placas do grupo tratado com os isolados testados. No presente trabalho, os tr&#234;s isolados de fungos predadores D. flagrans (AC001 e CG722) e A. cladodes (CG719) foram eficientes na destrui&#231;&#227;o in vitro das L3 de L. douglassii

Biochemical and functional characterization of a mitochondrial citrate carrier in Arabidopsis thaliana

A homolog of the mitochondrial succinate/fumarate carrier from yeast (Sfc1p) has been found in the Arabidopsis genome, named AtSFC1. The AtSFC1 gene was expressed in Escherichia coli, and the gene product was purified and reconstituted in liposomes. Its transport properties and kinetic parameters demonstrated that AtSFC1 transports citrate, isocitrate and aconitate and, to a lesser extent, succinate and fumarate. This carrier catalyzes a fast counter-exchange transport as well as a low uniport of substrates, exhibits a higher transport affinity for tricarboxylates than dicarboxylates, and is inhibited by pyridoxal 5'-phosphate and other inhibitors of mitochondrial carriers to various degrees. Gene expression analysis indicated that the AtSFC1 transcript is mainly present in heterotrophic tissues, and fusion with a green-fluorescent protein localized AtSFC1 to the mitochondria. Furthermore, 35S-AtSFC1 antisense lines were generated and characterized at metabolic and physiological levels in different organs and at various developmental stages. Lower expression of AtSFC1 reduced seed germination and impaired radicle growth, a phenotype that was related to reduced respiration rate. These findings demonstrate that AtSFC1 might be involved in storage oil mobilization at the early stages of seedling growth and in nitrogen assimilation in root tissue by catalyzing citrate/isocitrate or citrate/succinate exchanges