286 research outputs found

    Distribuição e estratégia reprodutiva de duas espécies de bagres (Siluriformes, Ariidae) em um estuário do Sudeste do Brasil, Atlântico Oeste Tropical

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    Os ecossistemas estuarinos representam ambientes únicos e de suma importância para reprodução e desenvolvimento de várias espécies, dentre elas, os bagres marinhos da Família Ariidae, que despertaram um grande interesse pela sua abundância e importância na cadeia trófica. Este trabalho teve como objetivo descrever a distribuição espaço-temporal e estratégia reprodutiva dos bagres Genidens genidens e Cathorops spixii na APA de Conceição da Barra, litoral norte do Espírito Santo. As amostragens foram realizadas mensalmente entre agosto/2014 e julho/2015, em marés de quadratura, utilizando-se de rede de arrasto com portas em quatro áreas ao longo do gradiente salino do estuário. Também foram coletados parâmetros abióticos (salinidade, temperatura, oxigênio dissolvido e turbidez) antes de cada amostragem. Através da análise macroscópica e corroboração com cortes histológicos das gônadas, determinou-se o sexo, período reprodutivo, época de desova e tamanho de primeira maturação (L50). Estimou-se a fecundidade absoluta e a relação entre o número total de ovos e larvas na cavidade orofaringeana (NOL) e o comprimento total (CT) dos exemplares incubadores, além de associar as variáveis ambientais que influenciam na distribuição das espécies. Foram coletados 1569 exemplares de G. genidens e 2180 exemplares de C. spixii. Não foi observada diferença significativa na proporção sexual geral de ambas espécies. O L50 para fêmeas e machos de G. genidens e C. spixii foram de 163 mm e 161mm; e 145 mm e 146 mm, respectivamente. O período reprodutivo foi baseado na presença de ovários nos estádios capaz de desovar e hidratado, nos maiores valores de Índice gonodossomárico (IGS) e Fator de condição (ΔK), compreendendo os meses de setembro a dezembro para ambas. G. genidens apresentou período de desova mais extenso ocorrendo entre os meses de outubro a fevereiro, enquanto C. spixii de dezembro a fevereiro. As duas espécies apresentaram relação linear fraca entre NOL e o CT. A fecundidade absoluta variou de 7 a 28 ovócitos, demonstrando boas relações lineares com o CT para G. genidens, enquanto C. spixii variou de 17 a 44 ovócitos, demonstrando relações lineares fracas. As variáveis ambientais que apresentaram correlações positivas na distribuição de G. genidens foram profundidade e turbidez, enquanto a salinidade apresentou correlação negativa. Para C. spixii as correlações positivas foram observadas para temperatura, turbidez e profundidade e negativas para salinidade. Sobre G. genidens indivíduos juvenis apresentaram maior densidade na área mais interna do estuário; sub-adultos na porção mais interna e intermediária e os indivíduos adultos na porção intermediária, enquanto C. spixii juvenis apresentaram maiores densidades na área mais interna e intermediária do estuário; sub-adultos na porção externa e adultos na porção interna e intermediária, demonstrando que essas espécies utilizam esse ambiente de formas distintas. No Brasil, decretos de proteção aos bagres da Família Ariidae foram fixados na Portaria N° 42 de 18/10/84, pela SUDEPE, que define o período do defeso nos estados do RS, SC, PR e SP, entre 1° de janeiro a 31 de março. Sugere-se a implementação de período de defesa também no estado do ES, para o período de novembro a fevereiro, no sentido de que esta portaria contemple, além do período de incubação, também os períodos de maturação final das gônadas

    Human Adaptability for Deep Space Missions: An Exploratory Study

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    The present qualitative study conducts in-depth interviews with astronauts and other subject matter experts in order to shed light on human adaptability in extreme environments. Deep space travel will entail a range of highly stressful conditions to which astronauts must adapt. Feelings of isolation will be increased, as the space traveler is farther from Earth for longer periods of time. Daily life will take place in small and confined areas, for durations extending into years. The dangers of the extreme environment of space are ever-present, and failure of critical equipment or components can lead to death. Astronauts will need to function more autonomously, with diminished support from Earth. It is thus important to select and train future astronauts who are able to adapt to such extreme and variable conditions and continue to function effectively. Subject matter experts identify the central adaptive challenges faced by crewmembers, and what are the key individual attributes associated with human adaptability. Results also point to organizational factors, as well as several coping and resource strategies that can be applied to improve human adaptability to extreme environments and missions. These results can be used to inform selection and training programs, as well as the design of space vehicles, systems, and habitats in order to enhance astronaut adaptive task performance

    Defining and Evaluating a Decision Support System (DSS) for the Precise Pest Management of the Mediterranean Fruit Fly, Ceratitis capitata, at the Farm Level

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    A Decision Support System (DSS) was developed and evaluated to control the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedermann), by incorporating a semi-automatic pest monitoring and a precision targeting approach in multi-varietal orchards. The DSS consists of three algorithms. DSS1, based on the degree days calculation, defines when the traps should be deployed in the field initiating the medfly population monitoring. DSS2 defines the areas to be treated and the type of treatment based on the number of adult medfly captures, harvesting time, and phenological stage of the host cultivar. DSS3 defines the spraying procedure considering the technical registration properties of the selected insecticide (e.g., withholding period and efficacy duration time) and weather conditions. The DSS was tested in commercial orchard conditions near Rome, central Italy, with a randomized complete blocks experimental design, comparing DSS-assisted and conventional management. In the DSS-assisted plots, a semi-automatic adult medfly monitoring system was deployed, composed of real-time, wireless electronic traps. The output of the functioning DSS is a map of spraying recommendation, reporting the areas to be treated and the treatment type (bait or cover insecticide spraying). The farmer was left free to follow, or not, the DSS indications. The first medfly captures were observed on June 30, whereas the DD threshold was reached on July 3 when the DSS started to operate. The field test produced 29 DSS decisions from July 3 to September 1 and confirmed that medfly management using the DSS substantially reduced the number of pesticide applications, the treated area, and the volumes of pesticide utilization. No significant differences in infested fruit were observed between DSS-assisted and conventional management. The level of acceptance of the DSS by the farmer was 78%. This evidence confirmed the requirement of fully involving farmers and pest managers during the evaluation process of DSS

    Deadzone-Quadratic Penalty Function for Predictive Extended Cruise Control with Experimental Validation

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    Battery Electric Vehicles have high potentials for the modern transportations, however, they are facing limited cruising range. To address this limitation, we present a semi-autonomous ecological driver assistance system to regulate the velocity with energy-efficient techniques. The main contribution of this paper is the design of a real-time nonlinear receding horizon optimal controller to plan the online cost-effective cruising velocity. Instead of conventional L2-norms, a deadzone-quadratic penalty function for the nonlinear model predictive controller is proposed. Obtained field experimental results demonstrate the effectiveness of the proposed method for a semi-autonomous electric vehicle in terms of real-time energy-efficient velocity regulation and constraints satisfaction

    Acute hyperglycemia abolishes cardioprotection by remote ischemic perconditioning

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    BACKGROUND: Remote ischemic perconditioning (RIPerC) has a promising therapeutic insight to improve the prognosis of acute myocardial infarction. Chronic comorbidities such as diabetes are known to interfere with conditioning interventions by modulating cardioprotective signaling pathways, such as e.g., mTOR pathway and autophagy. However, the effect of acute hyperglycemia on RIPerC has not been studied so far. Therefore, here we investigated the effect of acute hyperglycemia on cardioprotection by RIPerC. METHODS: Wistar rats were divided into normoglycemic (NG) and acute hyperglycemic (AHG) groups. Acute hyperglycemia was induced by glucose infusion to maintain a serum glucose concentration of 15-20 mM throughout the experimental protocol. NG rats received mannitol infusion of an equal osmolarity. Both groups were subdivided into an ischemic (Isch) and a RIPerC group. Each group underwent reversible occlusion of the left anterior descending coronary artery (LAD) for 40 min in the presence or absence of acute hyperglycemia. After the 10-min LAD occlusion, RIPerC was induced by 3 cycles of 5-min unilateral femoral artery and vein occlusion and 5-min reperfusion. After 120 min of reperfusion, infarct size was measured by triphenyltetrazolium chloride staining. To study underlying signaling mechanisms, hearts were harvested for immunoblotting after 35 min in both the NG and AHG groups. RESULTS: Infarct size was significantly reduced by RIPerC in NG, but not in the AHG group (NG + Isch: 46.27 +/- 5.31 % vs. NG + RIPerC: 24.65 +/- 7.45 %, p < 0.05; AHG + Isch: 54.19 +/- 4.07 % vs. 52.76 +/- 3.80 %). Acute hyperglycemia per se did not influence infarct size, but significantly increased the incidence and duration of arrhythmias. Acute hyperglycemia activated mechanistic target of rapamycine (mTOR) pathway, as it significantly increased the phosphorylation of mTOR and S6 proteins and the phosphorylation of AKT. In spite of a decreased LC3II/LC3I ratio, other markers of autophagy, such as ATG7, ULK1 phopsphorylation, Beclin 1 and SQSTM1/p62, were not modulated by acute hyperglycemia. Furthermore, acute hyperglycemia significantly elevated nitrative stress in the heart (0.87 +/- 0.01 vs. 0.50 +/- 0.04 microg 3-nitrotyrosine/mg protein, p < 0.05). CONCLUSIONS: This is the first demonstration that acute hypreglycemia deteriorates cardioprotection by RIPerC. The mechanism of this phenomenon may involve an acute hyperglycemia-induced increase in nitrative stress and activation of the mTOR pathway

    Standardizing Visual Control Devices for Tsetse Flies: West African Species Glossina tachinoides, G. palpalis gambiensis and G. morsitans submorsitans

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    Here we describe field trials designed to standardize tools for the control of Glossina tachinoides, G. palpalis gambiensis and G.morsitans submorsitans in West Africa based on existing trap/target/bait technology. Blue and black biconical and monoconical traps and 1 m2 targets were made in either phthalogen blue cotton, phthalogen blue cotton/polyester or turquoise blue polyester/viscose (all with a peak reflectance between 450–480 nm) and a black polyester. Because targets were covered in adhesive film, they proved to be significantly better trapping devices than either of the two trap types for all three species (up to 14 times more for G. tachinoides, 10 times more for G. palpalis gambiensis, and 6.5 times for G. morsitans submorsitans). The relative performance of the devices in the three blue cloths tested was the same when unbaited or baited with a mixture of phenols, 1-octen-3-ol and acetone. Since insecticide-impregnated devices act via contact with flies, we enumerated which device (traps or targets) served as the best object for flies to land on by also covering the cloth parts of traps with adhesive film. Despite the fact that the biconical trap proved to be the best landing device for the three species, the difference over the target (20–30%) was not significant. This experiment also allowed an estimation of trap efficiency, i.e. the proportion of flies landing on a trap that are caught in its cage. A low overall efficiency of the biconical or monoconical traps of between 11–24% was recorded for all three species. These results show that targets can be used as practical devices for population suppression of the three species studied. Biconical traps can be used for population monitoring, but a correction factor of 5–10 fold needs to be applied to captures to compensate for the poor trapping efficiency of this device for the three species

    Role of water in Protein Aggregation and Amyloid Polymorphism

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    A variety of neurodegenerative diseases are associated with the formation of amyloid plaques. Our incomplete understanding of this process underscores the need to decipher the principles governing protein aggregation. Most experimental and simulation studies have been interpreted largely from the perspective of proteins: the role of solvent has been relatively overlooked. In this Account, we provide a perspective on how interactions with water affect folding landscapes of Aβ\beta monomers, Aβ1622\beta_{16-22} oligomer formation, and protofilament formation in a Sup35 peptide. Simulations show that the formation of aggregation-prone structures (N^*) similar to the structure in the fibril requires overcoming high desolvation barrier. The mechanism of protofilament formation in a polar Sup35 peptide fragment illustrates that water dramatically slows down self-assembly. Release of water trapped in the pores as water wires creates protofilament with a dry interface. Similarly, one of the main driving force for addition of a solvated monomer to a preformed fibril is the entropy gain of released water. We conclude by postulating that two-step model for protein crystallization must also hold for higher order amyloid structure formation starting from N^*. Multiple N^* structures with varying water content results in a number of distinct water-laden polymorphic structures. In predominantly hydrophobic sequences, water accelerates fibril formation. In contrast, water-stabilized metastable intermediates dramatically slow down fibril growth rates in hydrophilic sequences.Comment: 27 pages, 4 figures; Accounts of Chemical Research, 201

    Structure-Based Design of Non-Natural Amino Acid Inhibitors of Amyloid Fibrillation

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    Many globular and natively disordered proteins can convert into amyloid fibers. These fibers are associated with numerous pathologies1 as well as with normal cellular functions2,3, and frequently form during protein denaturation4,5. Inhibitors of pathological amyloid fibers could serve as leads for therapeutics, provided the inhibitors were specific enough to avoid interfering with normal processes. Here we show that computer-aided, structure-based design can yield highly specific peptide inhibitors of amyloid formation. Using known atomic structures of segments of amyloid fibers as templates, we have designed and characterized an all D-amino acid inhibitor of fibrillation of the tau protein found in Alzheimer’s disease, and a non-natural L-amino acid inhibitor of an amyloid fiber that enhances sexual transmission of HIV. Our results indicate that peptides from structure-based designs can disrupt the fibrillation of full-length proteins, including those like tau that lack fully ordered native structures.We thank M.I. Ivanova, J. Corn, T. Kortemme, D. Anderson, M.R. Sawaya, M. Phillips, S. Sambashivan, J. Park, M. Landau, Q. Zhang, R. Clubb, F. Guo, T. Yeates, J. Nowick, J. Zheng, and M.J. Thompson for discussions, HHMI, NIH, NSF, the GATES foundation, and the Joint Center for Translational Medicine for support, R. Peterson for help with NMR experiments, E. Mandelkow for providing tau constructs, R. Riek for providing amyloid beta, J. Stroud for amyloid beta preparation. Support for JK was from the Damon Runyon Cancer Research Foundation, for HWC by the Ruth L. Kirschstein National Research Service Award, for JM from the programme for junior-professors by the ministry of science, Baden-Württemberg, and for SAS by a UCLA-IGERT bioinformatics traineeship

    Comparative effectiveness of antihypertensive medication for primary prevention of cardiovascular disease: systematic review and multiple treatments meta-analysis

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    Background: We conducted a systematic review of evidence from randomized controlled trials to answer the following research question: What are the relative effects of different classes of antihypertensive drugs in reducing the incidence of cardiovascular disease outcomes for healthy people at risk of cardiovascular disease? Methods: We searched MEDLINE, EMBASE, AMED (up to February 2011) and CENTRAL (up to May 2009), and reference lists in recent systematic reviews. Titles and abstracts were assessed for relevance and those potentially fulfilling our inclusion criteria were then assessed in full text. Two reviewers made independent assessments at each step. We selected the following main outcomes: total mortality, myocardial infarction and stroke. We also report on angina, heart failure and incidence of diabetes. We conducted a multiple treatments meta-analysis using random-effects models. We assessed the quality of the evidence using the GRADE-instrument. Results: We included 25 trials. Overall, the results were mixed, with few significant dif-ferences, and with no drugclass standing out as superior across multiple outcomes. The only significant finding for total mortality based on moderate to high quality evidence was that beta-blockers (atenolol) were inferior to angiotensin receptor blockers (ARB) (relative risk (RR) 1.14; 95% credibility interval (CrI) 1.02 to 1.28). Angiotensin converting enzyme (ACE)- inhibitors came out inferior to calcium-channel blockers (CCB) regarding stroke-risk (RR 1.19; 1.03 to 1.38), but superior regarding risk of heart failure (RR 0.82; 0.69 to 0.94), both based on moderate quality evidence. Diuretics reduced the risk of myocardial infarction compared to beta-blockers (RR 0.82; 0.68 to 0.98), and lowered the risk of heart failure compared to CCB (RR 0.73; 0.62 to 0.84), beta-blockers (RR 0.73; 0.54 to 0.96), and alpha-blockers (RR 0.51; 0.40 to 0.64). The risk of diabetes increased with diuretics compared to ACE-inhibitors (RR 1.43; 1.12 to 1.83) and CCB (RR 1.27; 1.05 to 1.57). Conclusion: Based on the available evidence, there seems to be little or no difference between commonly used blood pressure lowering medications for primary prevention of cardiovascular disease. Beta-blockers (atenolol) and alpha-blockers may not be first-choice drugs as they were the only drug-classes that were not significantly superior to any other, for any outcomes
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