共查询到20条相似文献,搜索用时 15 毫秒
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B. Hayden C. Harrod S. M. Thomas A. P. Eloranta J.‐P. Myllykangas A. Siwertsson K. Prbel R. Knudsen P.‐A. Amundsen K. K. Kahilainen 《Ecology letters》2019,22(5):807-816
Climate change and the intensification of land use practices are causing widespread eutrophication of subarctic lakes. The implications of this rapid change for lake ecosystem function remain poorly understood. To assess how freshwater communities respond to such profound changes in their habitat and resource availability, we conducted a space‐for‐time analysis of food‐web structure in 30 lakes situated across a temperature‐productivity gradient equivalent to the predicted future climate of subarctic Europe (temperature +3°C, precipitation +30% and nutrient +45 μg L?1 total phosphorus). Along this gradient, we observed an increase in the assimilation of pelagic‐derived carbon from 25 to 75% throughout primary, secondary and tertiary consumers. This shift was overwhelmingly driven by the consumption of pelagic detritus by benthic primary consumers and was not accompanied by increased pelagic foraging by higher trophic level consumers. Our data also revealed a convergence of the carbon isotope ratios of pelagic and benthic food web endmembers in the warmest, most productive lakes indicating that the incorporation of terrestrial derived carbon into aquatic food webs increases as land use intensifies. These results, reflecting changes along a gradient characteristic of the predicted future environment throughout the subarctic, indicate that climate and land use driven eutrophication and browning are radically altering the function and fuelling of aquatic food webs in this biome. 相似文献
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Philippe Huneman 《Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences》2006,37(4):649
Kant’s analysis of the concept of natural purpose in the Critique of judgment captured several features of organisms that he argued warranted making them the objects of a special field of study, in need of a special regulative teleological principle. By showing that organisms have to be conceived as self-organizing wholes, epigenetically built according to the idea of a whole that we must presuppose, Kant accounted for three features of organisms conflated in the biological sciences of the period: adaptation, functionality and conservation of forms. Kant’s unitary concept of natural purpose was subsequently split in two directions: first by Cuvier’s comparative anatomy, that would draw on the idea of adaptative functions as a regulative principle for understanding in reconstituting and classifying organisms; and then by Goethe’s and Geoffroy’s morphology, a science of the general transformations of living forms. However, such general transformations in nature, objects of an alleged ‘archaeology of nature’, were thought impossible by Kant in §80 of the Critique of judgment. Goethe made this ‘adventure of reason’ possible by changing the sense of ‘explanation’: scientific explanation was shifted from the investigation of the mechanical processes of generation of individual organisms to the unveiling of some ideal transformations of types instantiated by those organisms. 相似文献
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Recently, two quite different approaches exemplifying ‘bottom-up’ and ‘top-down’ philosophies have shed new light on basal ganglia function. In vitro work using organotypic co-cultures has implicated the subthalamic nucleus (STN) and the external segment of the globus pallidus (GPe) as pacemakers for low-frequency bursting that is reminiscent of the activity produced in Parkinsonian tremor. A circuit essential for avian song learning has been identified as part of the basal ganglia with surprisingly well conserved cellular details; investigation of this system may help to address general issues of basal ganglia function. 相似文献
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DNA is recognized as a nanomaterial, not as a biological material, in the research field of nanotechnology. This article reviews recent research on nanowires, nanoarchitectures, computing, aptamers, biocatalysts, devices, and machines using DNA. In these works, the characteristics of DNA including facile synthesis by the solid-phase method, self-assembly, electro-conductivity, information elements, amplification, switching, molecular recognition, and catalytic functions, were appropriately applied. Multiple functions of DNA could be used simultaneously, and activated independently, by molecular switching. Therefore, the combinations of functional sequences of DNA can produce unique materials. It is obvious that the DNA molecule is one of the most promising functional nanomaterials. However, the application of DNA molecules is still under study because of the big gap that exists between theory and practice. We eagerly anticipate a ‘coming out’ of DNA due to breakthroughs in nanobiotechnology. 相似文献
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Sharyn A. Endow Robert J. Fletterick 《BioEssays : news and reviews in molecular, cellular and developmental biology》1998,20(2):108-112
Ncd, a kinesin-related microtubule motor protein that moves the ‘wrong’ way on microtubules, towards the minus ends, has now been made to move like kinesin, towards plus ends, by fusing regions from outside the kinesin motor domain to the Ncd motor.1,2 Since it is the kinesin motor domain that binds to and moves on the microtubule, the finding that regions outside the motor domain can confer directionality of Ncd movement is remarkable—it implies a structural basis for motor polarity. Here we consider this finding from a structural point of view and discuss the implications for motor function and evolution. BioEssays 20:108–112, 1998. © 1998 John Wiley & Sons, Inc. 相似文献
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Edwige J. F. Souleyre David Chagné Xiuyin Chen Sumathi Tomes Rebecca M. Turner Mindy Y. Wang Ratnasiri Maddumage Martin B. Hunt Robert A. Winz Claudia Wiedow Cyril Hamiaux Susan E. Gardiner Daryl D. Rowan Ross G. Atkinson 《The Plant journal : for cell and molecular biology》2014,78(6):903-915
The ‘fruity’ attributes of ripe apples (Malus × domestica) arise from our perception of a combination of volatile ester compounds. Phenotypic variability in ester production was investigated using a segregating population from a ‘Royal Gala’ (RG; high ester production) × ‘Granny Smith’ (GS; low ester production) cross, as well as in transgenic RG plants in which expression of the alcohol acyl transferase 1 (AAT1) gene was reduced. In the RG × GS population, 46 quantitative trait loci (QTLs) for the production of esters and alcohols were identified on 15 linkage groups (LGs). The major QTL for 35 individual compounds was positioned on LG2 and co‐located with AAT1. Multiple AAT1 gene variants were identified in RG and GS, but only two (AAT1‐RGa and AAT1‐GSa) were functional. AAT1‐RGa and AAT1‐GSa were both highly expressed in the cortex and skin of ripe fruit, but AAT1 protein was observed mainly in the skin. Transgenic RG specifically reduced in AAT1 expression showed reduced levels of most key esters in ripe fruit. Differences in the ripe fruit aroma could be perceived by sensory analysis. The transgenic lines also showed altered ratios of biosynthetic precursor alcohols and aldehydes, and expression of a number of ester biosynthetic genes increased, presumably in response to the increased substrate pool. These results indicate that the AAT1 locus is critical for the biosynthesis of esters contributing to a ‘ripe apple’ flavour. 相似文献
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Paolo Heywood 《The journal of the Royal Anthropological Institute》2015,21(4):855-871
This article addresses a classic ethnographic problem in the study of Italy: how is it that people can subscribe simultaneously to seemingly contradictory ideologies, such as Catholicism and Communism? It does so by describing examples from Italy's ‘showcase city’ of the left, ‘Red Bologna’, in which to be ‘red’ is ubiquitous but each person's ‘red’ is a different thing: being ‘red’ (differently) is the idiom in which real political distinctions are expressed over issues like religion or immigration. In parallel, I discuss the relationship between the ‘field’ as a location and the ‘field’ as a conceptual topic. My account replicates internal ethnographic differences at the analytical level by highlighting the differences between being left‐wing in Bologna and its meaning as a concept in anthropology. Hence the ‘equivocal location’: a field‐site that is productively different, from what an inexperienced ethnographer expected from it, from conceptual discussions in anthropology, and from itself. 相似文献
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Ting Yang Geert Stoopen Manus Thoen Gerrie Wiegers Maarten A. Jongsma 《Plant biotechnology journal》2013,11(7):875-882
Herbivore‐induced plant volatiles are often involved in direct and indirect plant defence against herbivores. Linalool is a common floral scent and found to be released from leaves by many plants after herbivore attack. In this study, a linalool/nerolidol synthase, FaNES1, was overexpressed in the plastids of chrysanthemum plants (Chrysanthemum morifolium). The volatiles of FaNES1 chrysanthemum leaves were strongly dominated by linalool, but they also emitted small amount of the C11‐homoterpene, (3E)‐4,8‐dimethyl‐1,3,7‐nonatriene, a derivative of nerolidol. Four nonvolatile linalool glycosides in methanolic extracts were found to be significantly increased in the leaves of FaNES1 plants compared to wild‐type plants. They were putatively identified by LC‐MS‐MS as two linalool–malonyl–hexoses, a linalool–pentose–hexose and a glycoside of hydroxy–linalool. A leaf‐disc dual‐choice assay with western flower thrips (WFT, Frankliniella occidentalis) showed, initially during the first 15 min of WFT release, that FaNES1 plants were significantly preferred. This gradually reversed into significant preference for the control, however, at 20–28 h after WFT release. The initial preference was shown to be based on the linalool odour of FaNES1 plants by olfactory dual‐choice assays using paper discs emitting pure linalool at similar rates as leaf discs. The reversal of preference into deterrence could be explained by the initial nonvolatile composition of the FaNES1 plants, as methanolic extracts were less preferred by WFT. Considering the common occurrence of linalool and its glycosides in plant tissues, it suggests that plants may balance attractive fragrance with ‘poor taste’ using the same precursor compound. 相似文献
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Sverre Molland 《The Australian journal of anthropology》2011,22(2):236-254
For several years, aid programs in the Mekong region have taken an increasing interest in cross‐border mobility and human trafficking and its relationship with development. More recently, there has been an increasing interest in the identification of trafficked victims and the investigation, arrest and prosecution of traffickers. Whereas anti‐trafficking programs ubiquitously define themselves as being in a battle with traffickers, this article argues that although they are not homologous social actors, both engage in acts of bad faith. The article elaborates this argument by drawing attention to the recruitment process within the Lao sex industry as well as to the way in which aid programs attempt to identify trafficked victims. It concludes that imaginary aspects of development underpin a simultaneous disjuncture yet enable the social reproduction of the life worlds of ‘traffickers’ and ‘anti‐traffickers’ alike. 相似文献
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Lucie H. Salwiczek Redouan Bshary 《Ethology : formerly Zeitschrift fur Tierpsychologie》2011,117(11):939-948
In recent years evidence has accumulated that at least some animals can remember the ‘what’, ‘where’ and ‘when’ of personal experiences. Currently, evidence for such ability is taxonomically restricted to birds and mammals. Here, we demonstrate for the first time that cleaner wrasses Labroides dimidiatus are able to remember when they interacted with what after a single event. In nature, cleaners remove ectoparasites from other reef fishes, so‐called clients. Clients are depleted, non‐stationary food patches at the end of an interaction and replenished only after a delay. In our experiments, we presented twelve cleaners every 2.5 min, a choice between two of a total of four plates with different colours and patterns. One plate was always accessible but contained a non‐preferred food item while the other three contained a preferred food item, but allowed a next feeding event only after 5, 10 or 15 min. Thus, to maximise food intake, cleaners had to remember for each choice when they had last interacted with which plate. When confronted with two plates offering preferred food, cleaners showed an overall significant preference for the plate that allowed access during the trial. For six cleaners, the preference was significant. Also, on trials involving the always accessible plate, cleaners discriminated between trials in which they had to eat the non‐preferred food and trials on which they could eat the preferred food. In conclusion, cleaners are able to track the ‘when’ and ‘what’ (or possibly ‘who’) within a biologically meaningful time period. 相似文献
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NICO TASSI 《The journal of the Royal Anthropological Institute》2012,18(2):285-310
In the Christian tradition, representing the divine has often been considered both an impossible and yet necessary endeavour rooted in the human need in certain moments of weakness to visualize God. In this article, based on research findings from fieldwork carried out with urban indigenous groups in La Paz, Bolivia, I suggest that the articulation of local and Catholic representational traditions and practices has produced an understanding of the religious image not so much as an object of detached contemplation or a reference to a religious symbol but rather as an energized element which physically shapes the relationship and exchange between the material and the spiritual world. I suggest that through a study of Andean religious images we may be able to produce an alternative ontological perspective on the relationship between the spiritual, material, and living worlds.