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JANNE E. SØREIDE EVA LEU JØRGEN BERGE MARTIN GRAEVE STIG FALK‐PETERSEN 《Global Change Biology》2010,16(11):3154-3163
The Arctic bloom consists of two distinct categories of primary producers, ice algae growing within and on the underside of the sea ice, and phytoplankton growing in open waters. Long chain omega‐3 fatty acids, a subgroup of polyunsaturated fatty acids (PUFAs) produced exclusively by these algae, are essential to all marine organisms for successful reproduction, growth, and development. During an extensive field study in the Arctic shelf seas, we followed the seasonal biomass development of ice algae and phytoplankton and their food quality in terms of their relative PUFA content. The first PUFA‐peak occurred in late April during solid ice cover at the onset of the ice algal bloom, and the second PUFA‐peak occurred in early July just after the ice break‐up at the onset of the phytoplankton bloom. The reproduction and growth of the key Arctic grazer Calanus glacialis perfectly coincided with these two bloom events. Females of C. glacialis utilized the high‐quality ice algal bloom to fuel early maturation and reproduction, whereas the resulting offspring had access to ample high‐quality food during the phytoplankton bloom 2 months later. Reduction in sea ice thickness and coverage area will alter the current primary production regime due to earlier ice break‐up and onset of the phytoplankton bloom. A potential mismatch between the two primary production peaks of high‐quality food and the reproductive cycle of key Arctic grazers may have negative consequences for the entire lipid‐driven Arctic marine ecosystem. 相似文献
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Cd uptake by intact wheat plants 总被引:7,自引:0,他引:7
J. SMEYERS-VERBEKE M. DE GRAEVE M. FRANCOIS R. DE JAEGEREf† D. L. MASSART 《Plant, cell & environment》1978,1(4):291-296
Abstract. An investigation of the uptake of Cd by intact wheat plants has been carried out. The accumulation of Cd in the roots as a function of time and external Cd concentration was determined. Since the transport of Cd to the grains and shoots was found to be small, only uptake into the root was examined further. An appreciable fraction of the Cd absorbed by the roots can be desorbed and consequently constitutes the freely diffusible and exchangeable fraction.
The effect of temperature and of metabolic inhibitors on the absorption provides evidence that another Cd fraction is taken up by metabolically mediated processes. The absorption of this Cd fraction was found to be inhibited by Cu and Zn. The inhibitory effect of Cu and Zn on Cd absorption was comparable. 相似文献
The effect of temperature and of metabolic inhibitors on the absorption provides evidence that another Cd fraction is taken up by metabolically mediated processes. The absorption of this Cd fraction was found to be inhibited by Cu and Zn. The inhibitory effect of Cu and Zn on Cd absorption was comparable. 相似文献
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KATRIEN DE GRAEVE 《Bioethics》2010,24(7):365-372
The concept of ‘intimate citizenship’ stresses the right of people to choose how they organize their personal lives and claim identities. Support and interest groups are seen as playing an important role in the pursuit of recognition for these intimate choices, by elaborating visible and positive cultures that invade broader public spheres. Most studies on intimate citizenship take into consideration the exclusions these groups encounter when negotiating their differences with society at large. However, much less attention is paid to the ways in which these groups internalize the surrounding ideologies, identity categories and hierarchies that pervade society and constrain their recognition as full citizens. In contrast, this paper aims to emphasize the reproduction of otherness within alternative spheres of life, and to reveal the ambiguities and complexities involved in their dialectic relationship with society at large. To address this issue, the paper focuses on the role that ‘adoption cultures’ of Flemish adoptive parents with children from Ethiopia play in the pursuit of being recognized as ‘proper’ families and full citizens. The ethnographic research among adoptive parents and adoption professionals shows a defensive discourse and action that aims at empowering against potential problems, as well as a tendency to other the adoptive child by pathologizing its non‐normativity. By showing the strong embeddedness of adoptive families' practices of familial and cultural construction in larger cultural frames of selfing and othering, characterized by biologism and nativism, one begins to understand the limits of their capacity to realize full citizenship. 相似文献
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