bluuebunny/crossref_metadata_2025 huggingface dataset:
Variação espaço-temporal de parâmetros biofísicos e da evapotranspiração em plantios de eucalipto
Authors: Sabino Marlus , Bouvié Luana , Silva Junior Anísio Alfredo da , Machado Nadja Gomes , Biudes Marcelo Sacardi
Published: June 2020

Avaliou-se a variação espaço-temporal dos parâmetros biofísicos em plantios de Eucalyptus sp, na transição Cerrado-Amazônia Mato-Grossense, por meio de sensoriamento remoto. A área localiza-se no município de Lucas do Rio Verde-MT, sendo composta por talhões de E. urophylla, E. urograndis, mata nativa e solo exposto. As imagens foram adquiridas no site do U. S. Geological Survey referentes aos meses de fevereiro 2015/16 e janeiro 2017 (estação chuvosa) e junho 2015-2017 (estação seca). O Índice de Vegetação da Diferença Normalizada (NDVI), albedo da superfície (α); temperatura da superfície (Ts); Saldo de Radiação (Rn) e evapotranspiração (ET) foram calculados em etapas do modelo R-SSEB. Os plantios de Eucalipto, comparado a floresta nativa, apresentaram aumento de 3% a 4% nos valores de NDVI, Ts, Rn e ET. A exposição de solo provocou aumento do albedo (69% a 109%) e da Ts (14% a 34%) e redução do NDVI (63% a 58%), do Rn (13% a 20%) e da ET (57% a 26%), nos períodos de chuva e seca, respectivamente. Conclui-se que as mudanças no uso e ocupação do solo alteraram os parâmetros biofísicos e a evapotranspiração, sendo estas mais acentuadas em áreas desmatadas do que em áreas com cultivo de Eucalipto.
Garcinia macrophylla e Clusia grandiflora (CLUSIACEAE LINDL.): ensaios antioxidantes e georreferenciamento na Estação Ecológica do Jari.
Authors: Fernandes Wilson Bruno Conceição , Silva Luan Patrick dos Santos , Ripardo Filho Haroldo Silva
Published: June 2020

As plantas são uma excelente fonte de metabólitos secundários detentores de atividade biológica. Esses produtos naturais tem potencial para serem empregados em diferentes setores da indústria, como a de alimentos, agroquímica, farmacêutica, de cosméticas e perfumaria. Dentre as atividades apresentadas pelos metabólitos secundários de plantas, encontra-se a antioxidante, compostos com essas características são procurados pelas indústrias de alimentos e farmacêutica, para produção de conservantes, suplementos alimentares e medicamentos. Com base no pressuposto acima, o presente trabalho teve como objetivo avaliar a atividade antioxidante de espécies da família Clusiaceae, encontradas na estação ecológica do Jari, assim como georreferenciar essas espécies dentro da Área de Proteção Permanente. As espécies envolvidas nesse estudo foram a Garcinia macrophilla, popularmente conhecida como bacuripari e Clusia grandiflora, que possui o nome popular de cebola “braba”. Os ensaios antioxidantes foram realizados com o extrato etanólico das raízes das duas plantas, pela técnica de bioautografia. Os resultados dos ensaios, atestaram que os extratos de ambas espécies são ativos e que possuem várias substâncias antioxidantes em sua composição. Com relação ao georreferenciamento, foram produzidos mapas de distribuição espacial, que contribui para a localização das espécies na Estação Ecológica do Jari.
Residual lignin from biomass pretreatment for 2G ethanol production as an adsorbent in dye removal
Authors: Avancini Anita Ribas , Lemões Juliana Silva , Matoso Ester Schiavon , Cruz Nidria Dias , Silva Sérgio Delmar dos Anjos , Silva Cláudia Fernanda Lemons
Published: June 2020

Liquid waste from some industrial activities generates a serious environmental impact due to the presence of dyes. However, during the production process of second-generation ethanol, a lignin-rich residue is generated, which may be able to absorb the dyes in the waste. The goal of this work was to test the potential of lignin as a dye-removal adsorbent. Two quantities of precipitated lignin (200 and 500 mg) were tested as adsorbents by contact with Methylene Blue, Eriochrome Black T, and Bromocresol Green dyes. Kinetics curves for the adsorption capacity (Q) of lignin quantities were constructed and the percentage of removal of each dye was calculated. The Q of the three dyes increased with contact time and was higher in the 200-mg treatment; however, the strongest dye removal was presented by the 500-mg treatment. The maximum removal achieved was 84.77% with 500 mg lignin in the methylene blue solution and the minimum was 21.32% with 200 mg in the Bromocresol green solution. Therefore, it is concluded that lignin has potential as an adsorbent, as increased quantities are more efficient in removing dyes.
Controle de custos na produção do gado de corte: um estudo de caso em uma propriedade rural de Santa Catarina
Authors: Domenico Daniela Di , Magro Cristian Bau Dal , Zanin Antonio , Martini Raphael
Published: June 2020

O estudo teve como objetivo relacionar e analisar os custos na atividade da pecuária de corte em uma propriedade rural do Oeste Catarinense. A pesquisa se classifica quanto aos objetivos como exploratória, quanto aos procedimentos como documental, e quanto a abordagem do problema de caráter quantitativo. Os controles da contabilidade rural e da contabilidade de custos, quando implantados têm como meta auxiliar o empresário rural na tomada de decisão, obtendo um real controle de suas entradas, gastos e custos, envolvidos na atividade da pecuária, tendo, assim, maior controle e gestão da atividade. Os resultados apontaram que com o uso dos controles fornecidos pela contabilidade rural e contabilidade de custos, é possível que o proprietário rural obtenha a real situação econômica e financeira da propriedade, e seus respectivos custos e despesas, os quais irão contribuir com a tomada de decisão em busca de melhor lucratividade.
Analisando a percepção dos agricultores de três municípios da região noroeste do Rio Grande do Sul sobre a oferta de produtos e serviços agrícolas
Authors: Kunkel Cristina , Andrioli Mônica , Visentini Monize Sâmara
Published: June 2020

Este trabalho visa identificar, em municípios na região de Santa Rosa-RS, como os agricultores percebem a estrutura comercial no setor de máquinas e implementos agrícolas, que os atende e fornece subsídios para o desenvolvimento de suas atividades. Para tanto, elaborou-se um estudo descritivo e quantitativo, utilizando o método survey para a coleta dos dados com 65 agricultores dos municípios de Alecrim, Cândido Godói e Santo Cristo. Dentre os resultados da pesquisa, identificou-se que a maioria dos respondentes prefere realizar a manutenção do seu maquinário em suas propriedades ao invés de concessionárias. Os agricultores de Cândido Godói e de Santo Cristo utilizam mais os serviços oferecidos por empresas do município em que residem do que os agricultores de Alecrim. Com relação aos motivos que levam esses agricultores a escolher um estabelecimento comercial, tem-se destaque para a qualidade dos produtos e do atendimento oferecidos. Esses resultados são interessantes para empresas da região, a fim de melhorar sua oferta de produtos e serviços, bem como buscar maior competitividade. Também são relevantes para futuros empreendedores, que tenham interesse de atuação neste ramo.
Análise da dinâmica energética de Agroecossistemas
Authors: Menezes Neto Jayme Bezerra de Menezes , Mattos Jorge Luiz Schirmer de , Caporal Francisco Roberto
Published: June 2020

O objetivo desta revisão bibliográfica é apresentar um conjunto de ferramentas metodológicas úteis para as análises da dinâmica biofísica de agroecossistemas. Essas metodologias envolvem o cálculo dos Retornos de Energia Investida (REIs), que são indicadores de eficiência energética construídos a partir da quantificação e classificação da Produtividade Primária Líquida (PPL) e do consumo de insumos externos. Esses indicadores expressam não só o custo de energia da biomassa líquida produzida em benefício da sociedade, mas também possibilitam a coleta de informações sobre mudanças estruturais nos agroecossistemas que afetam a manutenção dos serviços ecossistêmicos por eles promovidos. O assunto foi abordado a partir do enfoque teórico-metodológico do Metabolismo Social Agrário e da perspectiva agroecológica. Com isso, buscou-se demonstrar que o uso de um conjunto de REIs proporciona uma análise mais profunda sobre a relação entre o fluxo energético, a manutenção dos elementos de fundo e a capacidade dos agroecossistemas de gerarem serviços ambientais.
Etapas históricas na formação da identidade internacional de Argentina e Brasil
Authors: Bertollo Adriana Bitencourt
Published: June 2020

O presente ensaio surgiu a partir de avaliação proposta na disciplina de História da América Latina, aulas do curso de Mestrado em Direito das Relações Internacionais e da Integração na América Latina, ministrado pela Universidad De La Empresa, em Montevidéu, Uruguai. O trabalho partiu da interessante visão abordada na disciplina, sobre a formação da identidade internacional dos países e como tal identidade influencia a tomada de decisões políticas. Pretende, ainda, o presente estudo, demonstrar a evolução histórica na formação dessa identidade por ambos os países, desde uma visão mais isolada, até a busca pelo (desejável) fortalecimento regional de laços.
Capacidade à luz do Estatuto da Pessoa com Deficiência
Authors: Borges Pedro Pereira , Souza Lucas Augusto da Silva de
Published: June 2020

A temática do presente estudo foi a personalidade e a capacidade das pessoas com deficiência. O objetivo geral deste artigo foi analisar as mudanças trazidas pela Lei nº 13.146/2015 para as pessoas com deficiência no que se refere à capacidade das pessoas naturais. Os objetivos específicos são verificar os conceitos de capacidade na história, identificar os mecanismos que motivaram a criação da lei, verificar as alterações em relação ao Código Civil e abordar as consequências das mudanças no âmbito prático. O tipo de pesquisa foi bibliográfico e procurou apresentar como resultado que toda mudança em ensino e em infraestrutura, seja nos locais públicos, privados ou em meios de transporte ainda precisam ser assumidos pela sociedade em geral se o objetivo for incluir as pessoas com deficiência e dar-lhes a possibilidade de se tornarem pessoas independentes.
O caráter transnacional da proteção ambiental
Authors: Alves Matheus de Araújo , Vinhal Luiza Cardoso Boaventura
Published: June 2020

As questões relacionadas ao Direito Ambiental no âmbito internacional estão em constante construção e com cada vez mais importância. Diante das variadas catástrofes ambientais, do consumo descontrolado dos recursos naturais e a degradação causada pelas ações do ser humano, a preocupação com o futuro do planeta e da sobrevivência de suas espécies crescem significativamente. Dentre os conceitos que são influenciados por essas questões está o da soberania que, se antes se referia a um poder absoluto e irrestrito de um país, agora só condiz com a realidade quando os Estados agirem de acordo com os limites do Direito Internacional. Por outro lado, deve-se também garantir ao ser humano o direito ao desenvolvimento. Só que, para isso, deve-se atentar às regras de sustentabilidade, pois o desenvolvimento humano só será possível se este for, primeiramente, sustentável.
Des vies de francophones dans le Nouvel-Ontario. Analyse descriptive et interprétation relationnelle
Authors: Laflamme Simon
Published: June 2020

L’étude de
Simon Laflamme
, sa huitième dans nos Cahiers, porte sur des entretiens qui ont été réalisés, il y a une vingtaine d’années, auprès de francophones d’une communauté du nord-est de l’Ontario. Ces données, analysées dans une optique relationnelle par Pierre Bouchard, avaient montré que les activités auxquelles s’adonnent les individus ont peu à voir avec les principes d’intention et d’intérêt qui animent la plupart des théories en sciences humaines. L’analyse récente d’un échantillon de ces entretiens qui a été opérée par Claude Vautier, toujours dans une perspective relationnelle, a permis de trialectiser les notions de système, d’individu et d’événement. Il a semblé utile à Simon Laflamme de revenir vers ces données pour deux raisons : d’abord, pour les traiter en marge d’une hypothèse théorique afin de découvrir ce qu’elles révèlent sur la vie de francophones en situation minoritaire ; ensuite, pour interroger les conclusions théoriques précédentes à la lumière de ce travail empirique. Pour aborder nouvellement les données, l’auteur a eu recours à la textométrie, soit aux logiciels Alceste et Lexico. Ces analyses ont mis en évidence l’engagement communautaire, la vie familiale, le rapport au travail et le loisir. Sur le plan théorique, elles ont rappelé l’importance, pour les théories en sciences humaines, de combiner liberté et détermination, conscient et inconscient, raison et émotion, individu et société, dialectiques qui échappent aux théories dans lesquelles est à l’oeuvre un acteur rationnel, conscient, stratégique, guidé par l’intérêt.
The formation of the national idea of Chinese environmental culture
Authors: Varakina Margarita Igorevna , Trofimova Elizaveta Sergeevna , Levchenko Yaroslava Aleksandrovna
Published: June 2020

This article examines the formation of a new environmental culture that promotes a positive spiritual transformation of the individual. The analysis of the environmental culture in China shows that in the center of the eco-ethical system of Confucianism is a social person, follower of environmentally moral behavior. China’s future is impossible without sustainable development of society, where positive environmental imperatives play a serious role. This paper shows the role of the Chinese leadership in the formation of a new radical and global policy that has new challenges for social thinking, the problems of environmental development of society and a new environmental strategy. The findings suggest that the problem of getting out of the environmental crisis can be solved through formation of environmental culture, as it includes all the material and spiritual values created by humanity in the process of socio-natural interactions.
Skd3 (human ClpB) is a potent mitochondrial protein disaggregase that is inactivated by 3-methylglutaconic aciduria-linked mutations
Authors: Cupo Ryan R , Shorter James
Published: June 2020

Cells have evolved specialized protein disaggregases to reverse toxic protein aggregation and restore protein functionality. In nonmetazoan eukaryotes, the AAA+ disaggregase Hsp78 resolubilizes and reactivates proteins in mitochondria. Curiously, metazoa lack Hsp78. Hence, whether metazoan mitochondria reactivate aggregated proteins is unknown. Here, we establish that a mitochondrial AAA+ protein, Skd3 (human ClpB), couples ATP hydrolysis to protein disaggregation and reactivation. The Skd3 ankyrin-repeat domain combines with conserved AAA+ elements to enable stand-alone disaggregase activity. A mitochondrial inner-membrane protease, PARL, removes an autoinhibitory peptide from Skd3 to greatly enhance disaggregase activity. Indeed, PARL-activated Skd3 solubilizes α-synuclein fibrils connected to Parkinson’s disease. Human cells lacking Skd3 exhibit reduced solubility of various mitochondrial proteins, including anti-apoptotic Hax1. Importantly, Skd3 variants linked to 3-methylglutaconic aciduria, a severe mitochondrial disorder, display diminished disaggregase activity (but not always reduced ATPase activity), which predicts disease severity. Thus, Skd3 is a potent protein disaggregase critical for human health.
Effects of Stellera chamaejasme removal on the nutrient stoichiometry of S. chamaejasme-dominated grasslands in the Qinghai–Tibetan plateau
Authors: Song Meiling , Wang Yuqin , Bao Gensheng , Wang Hongsheng , Yin Yali , Li Xiuzhang , Zhang Chunping
Published: June 2020

Background

Stoichiometric relations drive powerful constraints in several fundamental ecosystem processes. However, limited studies have been conducted on the ecological stoichiometry of plants after the change of community composition induced by Stellera chamaejasme removal in alpine grassland in the Qinghai–Tibetan Plateau.

Methods

We investigated the effects of S. chamaejasme removal on ecological stoichiometry by estimating the C:N:P stoichiometry in species, functional group and community levels of the ecosystem. The interactions between different species, functional groups and correlation with soil nutrient, responding to S. chamaejasme removal were also analyzed.

Results

For the plants that became dominant after S. chamaejasme removal (SR), N content decreased and their C:N increased. S. chamaejasme removal significantly affected the nutrient stoichiometry of different functional groups. Specifically, Gramineae in the SR sites had decreased N content and N:P, and increased C:N; however, forbs had increased N content, C:P and N:P and decreased P content and C:N. At the community level, N content was lower and C:N higher in SR communities compared to CK. The N content of the plant community was positively correlated with soil total N content. S. chamaejasme removal could change the nutrient balance from species level, to functional group level, and to community level. Thus, supplementary measures might be cooperated with S. chamaejasme removal for the recovery of S. chamaejasme-dominated degraded grassland. These results provide insight into the role of S. chamaejasme in ecological protection and conservation, and the conclusions from this study could be used to develop effective and sustainable measures for S. chamaejasme control in the Qinghai–Tibetan Plateau.
Life in a harsh environment: the effects of age, sex, reproductive condition, and season on hair cortisol concentration in a wild non-human primate
Authors: Garber Paul A. , McKenney Anna , Bartling-John Evelyn , Bicca-Marques Júlio César , De la Fuente María Fernanda , Abreu Filipa , Schiel Nicola , Souto Antonio , Phillips Kimberley A.
Published: June 2020

Hair cortisol concentration (HCC) provides a long-term retrospective measure of hypothalamic–pituitary–adrenal axis activity, and is increasingly used to assess the life history, health and ecology of wild mammals. Given that sex, age, season and pregnancy influence HCC, and that it may indicate ongoing stress, we examined HCC in common marmosets (Callithrix jacchus) naturally inhabiting a hot and dry semi-desert like habitat, Caatinga, in northeastern Brazil. We trapped, measured, weighed, marked and collected shaved hair from the back of the neck of 61 wild marmosets during the wet and dry seasons. Using enzyme immunoassay, we found that HCC was higher in the dry season compared with the wet season among all age/sex classes. Females had significantly higher HCC than males, juveniles had higher HCC than adults, and reproductively active adult females and non-pregnant/non lactating adult females did not differ in HCC. There were no interaction effects of sex, age, group, or season on HCC. The magnitude of the effect of this extremely hot and dry environment (average yearly rainfall was only 271 mm) on HCC in common marmosets is difficult to ascertain as these animals are also experiencing a variety of other stressors. However, the elevated HCC seen in common marmosets during the 5–8 month dry season, suggests these primates face an extended period of heat, water and possibly nutritional stress, which appears to result in a high rate of juvenile mortality.
Modelling fatality curves of COVID-19 and the effectiveness of intervention strategies
Authors: Vasconcelos Giovani L. , Macêdo Antônio M.S. , Ospina Raydonal , Almeida Francisco A.G. , Duarte-Filho Gerson C. , Brum Arthur A. , Souza Inês C.L.
Published: June 2020

The main objective of the present article is twofold: first, to model the fatality curves of the COVID-19 disease, as represented by the cumulative number of deaths as a function of time; and second, to use the corresponding mathematical model to study the effectiveness of possible intervention strategies. We applied the Richards growth model (RGM) to the COVID-19 fatality curves from several countries, where we used the data from the Johns Hopkins University database up to May 8, 2020. Countries selected for analysis with the RGM were China, France, Germany, Iran, Italy, South Korea, and Spain. The RGM was shown to describe very well the fatality curves of China, which is in a late stage of the COVID-19 outbreak, as well as of the other above countries, which supposedly are in the middle or towards the end of the outbreak at the time of this writing. We also analysed the case of Brazil, which is in an initial sub-exponential growth regime, and so we used the generalised growth model which is more appropriate for such cases. An analytic formula for the efficiency of intervention strategies within the context of the RGM is derived. Our findings show that there is only a narrow window of opportunity, after the onset of the epidemic, during which effective countermeasures can be taken. We applied our intervention model to the COVID-19 fatality curve of Italy of the outbreak to illustrate the effect of several possible interventions.
The scope of moderate pressure changes for kinetic and equilibrium studies of biochemical systems
Authors: Davis J.S. , Gutfreund H.
Published: July 2002

… but fertility is the result not of exactness but of seeing new problems where none have been seen before, and of finding new ways of solving them…' Karl Popper, Unended Quest (p. 25, Fontana/ Collins Edition)
Regulation of pathways of glucose metabolism in kidney
Authors: Steer Keith A. , Sochor Milena , Gonzalez Ana-Maria , Patricia McLean
Published: July 2002

The pentose phosphate pathway operates at an elevated level in rat kidney following induction of diabetes and in the compensatory hypertrophy following unilateral nephrectomy in control and alloxan‐diabetic rats, as shown by the yields of 14Co2 from [1‐14C]glucose, [6‐14C]glucose and 3H2O yields from [2‐3H]glucose. The elevated flux through the pentose phosphate pathway is correlated with the increased RNA content and weight of the kidney. The direct utilization of NADPH for reductive synthetic reactions and the potential for indirect utilization via the sorbitol route and the linked transhydrogenase reactions of the glucuronate‐xylulose pathway, for NADH and ATP generation, are also discussed.
Vinculin localization in cardiac muscle
Authors: Koteliansky V.E. , Gneushev G.N.
Published: July 2002

Vinculin isolated from chicken cardiac muscle crossreacts with antibodies against smooth muscle vinculin. Antibodies to vinculin were used for localization of vinculin in cardiac muscle by indirect immunofluorescence method. In cardiac muscle vinculin was localized in intercalated discs and near plasma membrane at the cell periphery between external myofibrils and sarcolemma. It was suggested that vinculin plays an important role in myofibril—sarcolemma interaction in cardiac muscle
Islet‐activating protein discriminates the antilipolytic mechanism of insulin from that of other antilipolytic compounds
Authors: Kather Horst , Aktor Klaus , Schulz Günter , Jakobs Karl H.
Published: July 2002

In vivo administration of islet‐activating protein to rats resulted in an increase in fat cell lipolysis in vitro, which was associated with almost complete resistance of adipocytes towards the antilipolytic effects of N
6‐phenylisopropyladenosine, prostaglandin E2 and nicotinic acid. Concomitantly, the inhibitory effects of these compounds on adenylate cyclase activity in membranes were impaired. In contrast, the antilipolytic action of insulin was not only preserved, but even augmented in cells from rats treated with islet‐activating protein. The data suggest that insulin exerts its antilipolytic effects via mechanisms which are different from those involved in the effects of prostaglandin E2, N
6‐phenylisopropyladenosine and nicotinic acid.
Effect of S‐100 protein on microtubule assembly—disassembly
Authors: Endo Toyoshi , Hidaka Hiroyoshi
Published: July 2002

S‐100 protein was examined for its ability to affect microtubule assembly—disassembly in vitro. Addition of S‐100 protein inhibited microtubule assembly in a dose‐dependent manner in the presence of Ca2+, but this effect was not observed in the presence of 2 mM EGTA. The interaction of microtubule proteins with S‐100 protein was also demonstrated by Ca+‐dependent affinity chromatography on S‐100 protein—Sepharose. The proteins bound to the Sepharose column comigrated with tubulin as judged by sodium dodecyl sulfate—polyacrylamide gel electrophoresis. These results might suggest a possible physiological role of S‐100 protein in the microtubule assembly—disassembly system.
NMR analyses on the molecular mechanism of the conformational rigidity of 2‐thioribothymidine, a modified nucleoside in extreme thermophile tRNAs
Authors: Yamamoto Yuriko , Yokoyama Shigeyuki , Miyazawa Tatsuo , Watanabe Kimitsuna , Higuchi Shigesada
Published: July 2002

1H‐NMR analyses have been made on the conformations of 2‐thioribothymidine (s2T), 2‐thiodeoxyribothymidine (s2dT), as well as ribothymidine (T) and deoxyribothymidine (dT). s2T and s2dT exclusively take the anti form rather than the syn form. The C3'‐endo‐gg form of the sugar moiety is remarkably stabilized on modification of T to s2T, but not on modification of dT to s2dT. The steric effects of the 2‐thiocarbonyl group and the 2'‐hydroxyl group cause the rigidity of the C3'‐endo‐gg form of s2T. Such rigidity of s2T probably contributes to the thermostability of 2‐thiopyrimidine polyribonucleotides and extreme thermophile tRNAs.
Adrenergic regulation of ureogenesis in hepatocytes from adrenalectomized rats
Authors: Hernández-Sotomayor S.M.Teresa , García-Sáinz J.Adolfo
Published: July 2002

In hepatocytes from control rats, the ureogenic action of epinephrine is mainly mediated through α1‐adrenoceptors and the effect is independent of the presence of extracellular calcium. In hepatocytes from adrenalectomized rats, both α1‐ and β‐adrenoceptors are involved in the action of epinephrine. Furthermore, the α1‐adrenergic‐mediated stimulation of ureogenesis in these cells is dependent on the presence of extracellular calcium. Our results indicate that glucocorticoids modulate the calcium dependency of α1‐adrenergic effects and are consistent with our suggestion that two pathways are involved in the transduction of the α1‐adrenergic signal.
A putative primer for the replication of cauliflower mosaic virus by reverse transcription is virion‐associated
Authors: Turner David S. , Covey Simon N.
Published: July 2002

We have isolated, from a cauliflower mosaic virus (CaMV) preparation, an RNA species (75 nucleotides) covalently linked to the 5′‐end of the CaMV DNA fragment (sa‐DNA) which is complementary to the CaMV 35 S RNA transcript 5′‐end. Site‐specific cleavage located a unique m7G residue in the RNA moiety of sa‐DNA suggesting that it is host cell tRNAmet
i sa‐DNA is reminiscent of retrovirus ‘strong‐stop“ DNA and is evidence fo the reverse transcription model of CaMV replication.
Effects of analogues of adenosine and methyl xanthines on insulin sensitivity in soleus muscle of the rat
Authors: Budohoski Leszek , John Challis R.A. , McManus Bronwyn , Newsholme Eric A.
Published: July 2002

The concentration of insulin that produces half‐maximal stimulation of glycolysis by stripped soleus muscle preparations is markedly increased by the adenosine analogues, 2‐chloroadenosine and N
6‐phenylisopropyladenosine, but is markedly decreased by the methyl xanthine analogue, 8‐phenyltheophylline. 2‐Chloroadenosine increases the concentration of insulin required to stimulate glycolysis half maximally, from about 100 to 2000 μunits/ml. 8‐Phenyltheophylline decreases this concentration of insulin from about 100 to 10 μunits/ml, an effect which is similar to that produced either by addition of adenosine deaminase to the medium or to exercise‐training of the donor animals for 4 weeks.
Muscle gelsolin: isolation from heart tissue and characterization as an integral myofibrillar protein
Authors: Rouayrenc J.F. , Fattoum A. , Gabrion J. , Audemard E. , Kassab R.
Published: July 2002

A 92‐kDa polypeptide present in rabbit and dog cardiac muscle was purified to homogeneity and some of its properties were investigated using biochemical and cytochemical approaches. The protein was found to be similar, if not identical to macrophage gelsolin; it cross‐reacts immunologically with anti‐rabbit macrophage gelsolin antibody, has a Ca2+‐sensitive shortening effect on the actin filaments as judged by the high shear viscometry and sedimentation experiments, and has a similar amino acid composition. In addition, immunoblot and SDS polyacrylamide gel analysis of cardiac muscle extracts obtained at high and low ionic strength showed that this protein is tightly bound to myofibrils, both in the absence and presence of Ca2+, in ventricular as well as in atrial muscle cells. Indirect immunofluorescence microscopy revealed a striated gelsolin staining pattern analogous to that previously observed for the skeletal muscle gelsolin, suggesting that in the muscle cell this protein is sharing the same localisation as actin. Because of its severing and nucleating properties the gelsolin may play a major role in the organization, assembly and turnover of the thin filaments within the muscle cells.
ADP binds similarly to rigor muscle myofibrils and to actomyosin‐subfragment one
Authors: Johnson Robert E. , Adams Patricia H.
Published: July 2002

The binding of Mg2+ ADP to both rabbit skeletal and bovine cardiac myofibrils has been studied at two different temperatures. In each case a single class of binding sites was observed with a binding constant very close to that reported for the analogous actomyosin‐subfragment one but much weaker than that seen with the analogous myosin subfragment one alone. These findings are discussed in terms of the constraints on the myosin cross‐bridges imposed by the regular array of thick and thin filaments found in myofibrils.
Evidence that biosynthesis of platelet‐activating factor (paf‐acether) by human neutrophils occurs in an intracellular membrane
Authors: Ribbes Gérard , Ninio Ewa , Fontan Pascal , Record Michel , Chap Hugues , Benveniste Jacques , Douste-Blazy Louis
Published: July 2002

Human polymorphonuclear leukocytes (PMN) were incubated in the absence or presence of the calcium ionophore A23187 (6μM) for 10 min at 37°C. They were then lysed by nitrogen cavitation and fractionated using Percoll gradients. Three major fractions of increasing density corresponding to plasma membrane, intracellular membranes and secretory granules were detected using [3H]concanavalin A, NADH‐dehydrogenase and β‐D‐glucuronidase as respective markers. In both cases, the acetyltransferase activity responsible for biosynthesis of paf‐acether (platelet‐activating factor of 1‐O‐alkyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine) was detected in the intermediary fraction, the enzyme activity being increased 3‐4‐fold in stimulated cells. From the comparison with the distribution of various markers, it is concluded that in human PMN the final step of paf‐acether assembly occurs in an intracellular membrane, possibly the endoplasmic reticulum.
Calcium‐activated, phospholipid‐dependent protein kinase in cultured rat mesangial cells
Authors: Orita Yoshimasa , Fujiwara Yoshihiro , Ochi Satoshi , Tanaka Yoshimu , Kamada Takenobu
Published: July 2002

The analysis of the 100000 × g supernatant fraction of cultured rat glomerular mesangial cells with DEAE‐cellulose ion‐exchange chromatography revealed a large peak showing the activity of a protein kinase (protein kinase C) which depended on phospholipid and diolein as well as Ca2+ Furthermore, it was shown that angiotensin II (AII) (10−6 M) induced rapid hydrolysis of phosphatidylinositol 4,5‐bisphosphate, leading to production of diacylglycerol rich in arachidonic acid, in the cultured rat mesangial cells. These results suggest that activation of protein kinase C resulting from enhancement of phosphoinositide metabolism may be important as an intracellular regulatory mechanism of AII upon cultured mesangial cells.
2‐5A‐dependent endoribonuclease activity and effects of A2'p5'A2'p5'A (2‐5A core) in mouse pancreatic islets
Authors: Rhodes Christopher J. , Taylor Keith W.
Published: July 2002

Glucose‐stimulated (pro)insulin biosynthesis is markedly inhibited is mouse pancreatic islets incubated with micromolar concentrations of 2‐5A ‘core’, (A2'p5'A2'p5'A). Total protein synthesis was also reduced, but to a lesser extent, while insulin release and total insulin content of the islets was untouched by 2‐5A ‘core’. Evidence is given for the presence of a 2‐5A‐dependent endoribonuclease which mediates these effects.
Regulation of platelet cytosolic free calcium by cyclic nucleotides and protein kinase C
Authors: MacIntyre D.E. , Bushfield M. , Shaw A.M.
Published: July 2002

PAF elicits a rapid, concentration‐dependent elevation of platelet cytosolic free calcium ([Caf]), measured by quin2. Elevation of [Caf] is transient, and the rate of reversal increases with agonist concentration. Adenylate cyclase stimulants (PGI2, PGD2) and 8‐bromo cAMP; a guanylate cyclase stimulant (sodium nitroprusside) and 8‐bromo cGMP; and a protein kinase C stimulant (phorbol myristate acetate) block the elevation of [Caf] induced by PAF, and accelerate its reversal. These results suggest that cAMP, cGMP and 1,2‐diacylglycerol (DAG) could act as second messengers to regulate [Caf] in platelets. As PAF is known to stimulate platelet phosphoinositide hydrolysis (ergo DAG formation) but fails to elevate platelet cAMP or cGMP, it is proposed that DAG, via activation of protein kinase C, may act as an endogenous modulator of platelet [Caf]: an action that contributes to the role of DAG as a bi‐directional regulator of platelet reactivity.
Sympathetic neurons extend neurites in a culture medium containing cyanide and dinitrophenol but not iodoacetate
Authors: Wakade Arun R. , Prat John C. , Wakade Taruna D.
Published: July 2002

A culture medium circulated through the rat heart and supplemented with insulin, transferrin and nerve growth factor leads to a massive proliferation of neurite outgrowth from neurons of peripheral sympathetic ganglia of the chick embryo. Addition of 1 mM cyanide or 50 μM dinitrophenol to such medium for 2 days had no adverse effect on the neurite outgrowth and ATP content of these neurons. However, 0.5 μM iodoacetate lowered ATP content 65% without affecting the number of surviving neurons up to 2 days. Only when ATP content was reduced to 80% by 2.5 μM iodoacetate was the number of surviving neurons significantly reduced (30%). It is concluded that the glycolytic pathway is the major route of ATP synthesis in embryonic sympathetic neurons maintained in culture, and only a small fraction of ATP is utilized for the survival and neurite extension.
Acetylcholine stimulates phosphatidylinositol turnover at nicotinic receptors of cultured myotubes
Authors: Adamo Sergio , Zani Bianca Maria , Nervi Clara , Senni Maria Immacolata , Molmaro Mario , Eusebi Fabrizio
Published: July 2002

Acetylcholine treatment of [3H]inositol pre‐labelled cultured chick embryo myotubes results in the stimulation of phosphatidylinositol breakdown, as shown by the measurement of inositol‐1‐phosphate accumulating in the presence of lithium. The described effect is dependent on agonist concentration and incubation time, and is inhibited by tubocurarine and α‐bungarotoxin. The activation of phosphatidylinositol breakdown by acetylcholine at extrajunctional nicotinic receptors is likely to be involved in the modulation of the functional activity of the receptor.
Ion transport in rat liver mitochondria: the effect of the incubation medium osmolarity
Authors: Novgorodov S.A. , Yaguzhinsky L.A.
Published: July 2002

Mitochondria
Ion transport
ATPase
Osmolarity
Free radical reaction
A potential biochemical explanation for the genesis of porphyria cutanea tarda
Authors: Mukerji S.K. , Pimstone N.R. , Tan K.T.
Published: July 2002

Familial porphyria cutanea tarda (PCT) is a photocutaneous disease in which subnormal activity of uroporphyrinogen decarboxylase is observed both in the liver and red cells. Hepatic iron plays a key role in the genesis of overt biochemical and clinical PCT. In this report, we have studied the properties of 10000‐fold purified erythrocyte uroporphyrinogen decarboxylase preparations from two familial PCT patients and a non‐porphyric control subject. The apparent Michaelis constants (K
m), determined by using uroporphyrinogen III substrate, were approx. 3.2‐times higher for the enzyme from the diseased subjects (K
m = ~1.0 μM) as compared to the normal (K
m = 0.3 μM). Though both abnormal and normal enzymes were inhibited progressively with increasing concentrations of iron, the enzymes from diseased subjects exhibited greater susceptibility e.g. 0.1 mM Fe2+ inhibited the former about 50% and the latter about 20%. These observations suggest that (i) the inherent biochemical defect in PCT is the reduced enzyme‐substrate affinity and (ii) the intrinsic abnormal conformation renders the PCT enzyme particularly susceptible to inhibition by iron.
Rapid exchange of histones H2A and H2B in sea urchin embryo chromatin
Authors: Schwager S. , Retief J.D. , de Groot P. , von Holt C.
Published: July 2002

Chromatin from sea urchin blastula and gastrula was partially digested with micrococcal nuclease and separated electrophoretically in two dimensions into various nucleosome fractions and their component histones. After labelling of the embryos with radioactive lysine the various isohistones of the H2A and H2B group in all nucleosome fractions had incorporated approximately twice as much the radioactivity as the histones H2 and H4. The results are interpreted in terms of a labile nucleosome structure during transcription.
Codon reading patterns in Saccharomyces cerevisiae mitochondria based on sequences of mitochondrial tRNAs
Authors: Sibler Annie-Paule , Dirheimer Guy , Martin Robert P.
Published: July 2002

The sequences of Saccharomyces cerevisiae mitochondrial tRNA1
Arg, tRNA2
Arg, tRNAGly, tRNA2
Lys tRNALeu and tRNAPro are reported. Special structural features were found in tRNAPro, which has A8, C21, A48 instead of the constant residues U8, A21 and pyrimidine 48, and in tRNA2
Lys, which has a U excluded from basepairing and bulging out from the TΨC stem. The tRNA1
Arg, tRNA2
Lys and tRNALeu, which belong to two‐codon families ending in a purine, have a modified uridine in the wobble position, which prevents misreading of C and U. It is likely to be 5‐carboxymethylaminomethyluridine. tRNAGly and tRNAPro have an unmodified uridine in the wobble position allowing the reading of all four codons of a four‐codon family. However, tRNA2
Arg, which is a minor species and belongs to the CGN four‐codon family, has an unmodified A in the wobble position. This very unusual feature raises the problem of the mechanism by which the codons CGA, CGG and CGC are recognized.
The heparin‐binding site(s) of histidine‐rich glycoprotein as suggested by sequence homology with antithrombin III
Authors: Koide Takehiko , Foster Donald , Odani Shoji
Published: July 2002

A high degree of sequence homology has been found between the N‐terminal region of histidine‐rich glycoprotein (HRG) and that of antithrombin III (AT III) where the putative heparin‐binding site of AT HI is located. The amino acid residue at the position corresponding to Arg‐47 of AT III that is essential for the heparin‐binding was also arginine (Arg 23 and 78) in the homologous sequences of HRG. These observations strongly suggest that the heparin‐binding sites of HRG and AT III are evolutionarily related. There was no apparent sequence similarity between the remaining about 70% portions of the two proteins.
Hydrophobic photolabelling of pertussis toxin subunits interacting with lipids
Authors: Montecucco Cesare , Tomasi Maurizio , Schiavo Giampietro , Rappuoli Rino
Published: July 2002

The hydrophobic surfaces presumably involved in the membrane interaction of pertussis toxin have been mapped by a new detergent‐binding assay. This is based on the interdispersion among detergent micelles of trace amounts of radioactive photoreactive phospholipid analogues, able to cross‐link to the protein thereby labelling its detergent‐binding domains. The assay has proven to be very sensitive. Subunits B1, B2 and B3 of pertussis toxin were found to interact with the lipid micelles suggesting that they may be involved in the membrane penetration step of the intoxication process.
Do the higher oxidation states of the photosynthetic O2‐evolving system contain bound H2O?
Authors: Radmer Richard , Ollinger Otto
Published: July 2002

A modified mass spectrometer was used to determine whether the higher oxidation states of the photosynthetic O2‐evolving system contain substrate water that is not freely exchangeable with the external medium. Our data indicated that the higher oxidation states contain no appreciable bound, non‐exchangeable H2O. This suggests that H2O oxidation takes place via a rapid, concerted, all‐or‐none mechanism rather than by a mechanism involving stable, partially oxidized, H2O‐derived intermediates. These findings set definite constraints on possible mechanisms of O2 evolution.
α1‐Adrenergic activation of brown adipocytes leads to an increased formation of inositol polyphosphates
Authors: Nånberg Eewa , Putney James
Published: July 2002

α1‐Adrenergic activation of isolated brown adipocytes causes a rapid mobilization of intracellular Ca2+. The cells also respond with an increased turnover of inositol lipids. The present work demonstrates that α1 adrenergic stimulation of brown adipocytes results in phospholipase C‐mediated breakdown of phosphatidylinositol bisphosphate to form inositol trisphosphate. The rate of appearance of inositol trisphosphate is sufficiently rapid for it to mediate or contribute to Ca2+ mobilization in these cells.
Chromogranins, widespread in endocrine and nervous tissue, bind Ca2+
Authors: Reiffen Felicitas U. , Gratzl Manfred
Published: July 2002

The proteinaceous components of the secretory vesicle contents isolated from bovine adrenal medulla bind Ca2+ (number of binding sites, 152 ± 52 nmol Ca2+ per mg protein; dissociation constant, 54 ± 8 μM (n = 5)). SDS‐polyacrylamide gel electrophoresis and 45Ca2+binding of the proteins following their separation and blotting on nitrocellulose revealed that Ca2+ binds to chromogranins. Moreover, it was shown that the chromogranins, like other known Ca2+‐binding proteins, can be specifically stained with a cationic carbocyanine dye. The Ca2+‐binding function of the chromogranins described here, in conjunction with recent findings concerning Ca2+ transport across chromaffin vesicle membranes and the widespread distribution of chromogranins in many different endocrine and nerve cells, points to the general importance of these proteins in the metabolism ofCa2+.
Localisation of the main immunogenic region of the nicotinic acetylcholine receptor
Authors: Barkas T. , Gabriel J.-M. , Juillerat M. , Kokla A. , Tzartos S.J.
Published: July 2002

The nicotinic acetylcholine receptor from Torpedo marmorata was digested using papain and the reaction products separated by SDS gel electrophoresis and characterised by immunoblotting using labelled α‐bungarotoxin, polyclonal antibodies to synthetic peptides and monoclonal antibodies to the main immunogenic region (MIR). Using this approach, it was possible to show that the MIR is located N‐terminal to all or part of peptide 151–169 (peptide P1) of the α‐chain and that papain cleaves the α‐chain between Asn 141 and peptide P1.
Time‐resolved measurements of fluorescence from reaction centres of Rhodopseudomonas viridis and the effect of menaquinone reduction
Authors: Hörber J.K.H. , Göbel W. , Ogrodnik A. , Michel-Beyerle M.E. , Cogdell R.J.
Published: July 2002

The kinetics of the fluorescence emitted by the ‘special pair’ of bacteriochlorophyll b molecules in reaction centres from Rhodopseudomonas viridis was recorded in the near infrared, with a time resolution of 1 ns. In nonreduced reaction centres two decay components were resolved with lifetimes of <0.5 and 2.5 ns. Upon reduction of the menaquinone electron acceptor three decay components were detected with lifetimes of < 0.5, 2.5 and 15ns.
Impairment of Na+/H+ exchange underlies inhibitory effects of Na+‐free media on leukocyte function
Authors: Nasmith Patricia E. , Grinstein Sergio
Published: July 2002

Inhibition of activation has been reported when neutrophils are suspended in Na+‐free media. We considered the possibility that impairment of cellular pH (pHi) regulation due to elimination of Na+/H+ exchange underlies this effect. In the absence of Na+, the phorbol ester‐induced respiratory burst was partially inhibited and a concomitant cytoplasmic acidification recorded. Using nigericin/K+ to clamp pHi we demonstrated that the acidification accounts for the inhibition of O2 uptake. Moreover, in Na+‐free media, relieving the acidification by means of ionophores restored maximal O2 consumption. It was concluded that Na+ is not directly involved in signal transduction during stimulation. Instead, omission of Na+ affects neutrophile activation indirectly, by impairing pHi regulation.
Malic enzyme levels are increased by the activation of NADPH‐consuming pathways: detoxification processes
Authors: Ayala Antonio , F-Lobato María , Machado Alberto
Published: July 2002

The administration to rats of either t‐butyl hydroperoxide or phénobarbital, compounds that are metabolized through detoxification processes, produces an increase in specific activity of the NADPH‐consuming enzymes, glutathione reductase and NADPH‐cytochrome c reductase. These compounds also produce a very significant increase in the specific activity of malic enzyme. Immunoprecipitation with a specific antibody for malic enzyme indicates that specific activity changes are the result of corresponding changes in the amounts of enzyme protein present. The administration of 1,3‐bis(chloroethyl(‐1‐nitrosourea (a glutathione reductase inhibitor) together with t‐butyl hydroperoxide abolishes any stimulation of malic enzyme activity. These results indicate that an increase in NADPH consumption induces the synthesis of malic enzyme. Alternatively, a protection of enzyme degradation cannot be rigorously excluded.
Membrane fusion induced by influenza virus hemagglutinin requires protein bound fatty acids
Authors: Lambrecht Bernd , Schmidt Michael F.G.
Published: July 2002

The low pH‐dependent fusion of lipid membranes induced by two types of the fatty acylated influenza viral hemagglutinin has been studied by use of an energy transfer assay. When protein bound fatty acids were released from the hemagglutinin by hydroxylamine treatment viral fusion activity was inhibited. The extent of fusion inhibition correlates with the amount of fatty acids cleaved from the hemagglutinin. Virosomes prepared from fowl plague virus containing fatty acid free hemagglutinin showed a much lower fusion activity than control virosomes containing fatty acylated hemagglutinin. The hydroxylamine treatment applied has no detectable effects on the virus other than fatty acid release from its spike glycoproteins. These results support our previous hypothesis that protein bound fatty acids are involved in the induction of membrane fusion by the influenza hemagglutinin.
ATP‐induced calcium mobilization and inositol 1,4,5‐trisphosphate formation in H‐35 hepatoma cells
Authors: Horstman Debra A. , Tennes Karin A. , Putney James W.
Published: July 2002

Addition of ATP (but not epinephrine, angiotensin II, vasopressin, or platelet‐activating factor) to H‐35 hepatoma cells whose cellular lipids have been pre‐labelled with [3H]inositol, causes a rapid increase in [3H]inositol trisphosphate. In H‐35 cells pre‐incubated in the presence of 45Ca2+, ATP causes a similarly rapid release of 45Ca2+. The concentration‐effect relationships for inositol trisphosphate formation and Ca2+ efflux are similar to those reported previously for differentiated hepatocytes. These results demonstrate that at least one of the Ca2+‐mobilizing receptors normally found on hepatocytes is functionally retained in the H‐35 hepatoma cell line and thus could provide a useful model for the study of these receptor mechanisms in liver.