733 resultados para Gall wasps


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Traditionally, ice-binding proteins (IBPs), also known as antifreeze proteins (AFPs), have been defined by two universal activities: ice recrystallization inhibition and thermal hysteresis. However, there remains the possibility IBPs have other complementary functions given the diversity found within this protein group. This thesis explores some of these in both natural and applied settings, in the hopes of furthering our understanding of this remarkable group of proteins. Plant IBPs could function as part of a defensive strategy against ice nucleators produced by certain pathogens. To assess this hypothesis, recombinant IBPs from perennial ryegrass and purple false brome were combined with the ice nucleation protein (INP) from the plant pathogen, Pseudomonas syringae. Strikingly, the plant proteins depressed the freezing point of the bacterial INP, while a fish AFP could not, nor did the INPs have any effect on IBP activity. Thus, the interaction between these two different proteins suggests a role in plant defensive strategies against pathogenic bacteria as another IBP function. In addition, the potential use of hyperactive insect IBPs in organ preservation was investigated. Current kidney preservation techniques involve storing the organ at 4 °C for a maximum of 24 h prior to transplantation. Extending this “safe” time would have profound effects on renal transplants, however, ischemic injury is prevalent when storage periods are prolonged. Experiments described here allowed subzero preservation for 72 h with the addition of a beetle IBP to CryoStasis® solution. Kidneys stored using the traditional technique for 24 h and the method developed here for 72 h showed similar levels of biomarker enzymes, underscoring the potential utility of insect IBPs for future transplant purposes. Finally, IBP function in the freeze-tolerant gall fly, Eurosta solidaginis, was examined. Larvae representing the mid-autumn stage displayed ice-binding activity, suggesting an IBP is being expressed, possibly as a protective measure against freezing damage when fall temperatures can unpredictably drop. IBP activity was also observed in the larvae’s host plant, Solidago spp. Mass spectrometry analysis of ice-affinity purified plant extracts provided three candidate pathogenesis-related proteins that could be responsible for the detected activity, further demonstrating additional functions of IBPs.

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A representative collection of hydrothermal manifestations was sampled practically from all hydrothermal mounds of the Broken Spur hydrothermal vent field with use of the Mir manned submersibles during three cruises of R/V Akademik Mstislav Keldysh. Mineral associations characteristic for different morphological types of sulfide ores from hydrothermal pipes, plates, and diffusers are assessed. Particular attention is paid to distribution of minor elements and their distribution patterns determined by mineralogical zonation. Measured isotopic composition of sulfur in sulfide minerals varies from 0.4 to 5.2 per mil that indicates their similarity with ores from the Snake Pit vent field and is related to dilution of hot ore-bearing solutions by seawater and reduction of water sulfate ions to H2S with heavy isotopic composition.

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To increase our understanding of the formation of students' intentions to found an own firm, research needs to systematically integrate theory of planned behavior, resource-based view, and family business literature. To date, however, an explicit and systematic integration of these perspectives cannot be found. We attempt to close this gap by explicitly investigating founding intentions of students with family business background. More specifically, we examine how the provision of human, social, and financial resources by the family affects students' desirability and feasibility perceptions, and ultimately founding intentions. Our analysis based on a sample of 14'290 students from 26 countries reveals that both desirability and feasibility perceptions mediate the relationships between all three types of resources and founding intentions. Interestingly, the provision of financial resources is negatively related to both desirability and feasibility perceptions. These findings illustrate the research potential of a combination of theory of planned behavior with the resource-based view, especially in the family business context. Our study thus offers valuable contributions to literature on career choices, theory of planned behavior, and family business, as well as to practice.

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Mode of access: Internet.

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Each play has special t.p.

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General introduction.--Chronological table.--Acharnians.--Knights.--Clouds.--Wasps.--Peace.--Birds.--Frogs.--Plutus.

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Iron gall ink annotations throughout.