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JAN CROSTHWAITE 《Bioethics》1995,9(4):361-379
Philosophers, particularly moral philosophers, are increasingly being involved in public decision-making in areas which are seen to raise ethical issues. For example, Dame Mary Warnock chaired the ‘Committee of Inquiry into Human Fertilization and Embryology’ in the UK in 1982–4; the Philosophy Department at Auckland was commissioned by the Auckland Regional Authority to report on the ethical aspects of fluoridating the public water supply in 1990; and many of us are serving on ethics committees of various sorts. Not only are philosophers actually being called on or consulted, but many of us would argue that a philosophical contribution in such areas is essential. The involvement of moral philosophers in public policy decisions raises a question of professional ethics, viz, what role should a philosopher's own moral perspective or judgements play in the advice s/he gives, or contribution s/he makes, to public decision-making on ethical issues. Like most problems in professional ethics, this prompts reflection on the nature of the profession, and in particular on the expertise we take moral philosophy to offer. It also prompts reflection on how processes of public decision making in ethically problematic areas should be understood. I explore these issues in this paper. 相似文献
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JAN PAWLOWSKI MARIA HOLZMANN JOSÉ F. FAHRNI PAMELA HALLOCK 《The Journal of eukaryotic microbiology》2001,48(3):362-367
Large miliolid foraminifers bear various types of algal endosymbionts including chlorophytes, dinoflagellates, rhodophytes, and diatoms. Symbiosis plays a key role in the adaptation of large foraminifera to survival and growth in oligotrophic seas. The identity and diversity of foraminiferal symbionts, however, remain largely unknown. In the present work we use ribosomal DNA (rDNA) sequences to identify chlorophyte endosymbionts in large miliolid foraminifera of the superfamily Soritacea. Partial 18S and complete Internal Transcribed Spacer (ITS) rDNA sequences were obtained from symbionts of eight species representing all genera of extant chlorophyte-bearing Soritacea. Phylogenetic analysis of the sequences confirms the previous fine structure-based identification of these endosymbionts as belonging to the genus Chlamydomonas. All foraminiferal symbionts form a monophyletic group closely related to Chlamydomonas noctigama. The group is composed of seven types identified in this study, including one previously morphologically described species, Chlamydomonas hedleyi. Each of these types can be considered as a separate species, based on the comparison of genetic differences observed between other established Chlamydomonas species. Several foraminiferal species share the same symbiont type, but only one species, Archaias angulatus, was found to bear more than one type. 相似文献
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1. We assessed the role of cyanobacterial–bacterial consortia (Gloeotrichia echinulata phycospheres) for net changes in inorganic carbon, primary production (PP) and secondary production in Lake Erken (Sweden). 2. At the time of sampling, large colonies of G. echinulata formed a massive bloom with abundances ranging from 102 colonies L?1 in the pelagic zone to 5000 colonies L?1 in shallow bays. These colonies and their surrounding phycospheres contributed between 17 and 92% of total PP, and phycosphere‐associated bacteria contributed between 8.5 and 82% of total bacterial secondary production. PP followed a diurnal cycle, whereas bacterial production showed no such pattern. Over a 24 h period, carbon dioxide measurements showed that the phycospheres were net autotrophic in the top layer of the water column, whereas they were net heterotrophic below 2 m depth. 3. Sequencing and phylogenetic analysis of 16S rRNA genes of attached bacteria revealed a diverse bacterial community that included populations affiliated with Proteobacteria, Bacteriodetes, Acidobacteria, Fusobacteria, Firmicutes, Verrucomicrobia, and other Cyanobacteria. 4. Compared with their planktonic counterparts, bacteria associated with cyanobacterial phycospheres had lower affinity for arginine, used as a model compound to assess uptake of organic compounds. 5. Extrapolation of our data to the water column of lake Erken suggests that microorganisms that were not associated with cyanobacteria dominated CO2 production at the ecosystem scale during our experiments, as CO2 fixation balanced CO2 production in the cyanobacterial phycospheres. 相似文献
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KIM VAN DER LINDE JAN G. SEVENSTER 《Biological journal of the Linnean Society. Linnean Society of London》2006,87(1):115-125
The ecological trade-off between developmental time and starvation resistance, acting in a heterogeneous environment, can promote the coexistence of competing species. Heterogeneity results from variation in the vegetation that influences both abiotic (e.g. temperature, humidity) and biotic (e.g. fruit availability during the year) aspects of the environment. In this study, we investigated whether differences between collection sites have led to local differentiation of the two life-history traits underlying the coexistence model: developmental time and starvation resistance. Drosophila were collected from four collection sites, ranging from grassland to secondary forest, along a transect of 15 km. The microclimatic and vegetation differences among these collection sites were considerable. For developmental time, different species showed similar genetic responses to the (habitat) differences between the different collection sites. The shortest developmental times were found in the secondary forest populations and the agricultural area populations, the longest in the grassland populations, and the forest edge populations were intermediate. However, there was no correlation between the habitat ranking based on disturbance and canopy cover, and the ranking of the developmental times. Furthermore, the data did not confirm the generality of the positive correlation between developmental time and starvation underlying the coexistence model. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87 , 115–125. 相似文献