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101.
Anthony Preen 《Biological conservation》2004,118(2):205-218
The marine mammals of Saudi Arabia, Bahrain, Qatar and the United Arab Emirates (UAE) were censussed by three strip-transect aerial surveys. The Arabian Gulf supports a population of ca. 5800 dugongs (Dugong dugon), which is the largest known outside Australia. The most important habitats occur (1) around Murawah Island (UAE), (2) between Qatar and Bahrain and (3) between Qatar and the UAE. Surveys of the UAE were repeated 13 years apart. The two estimates of the dugong population were not significantly different, suggesting a stable population of ca. 3000 between 1986 and 1999. In the region between Kuwait and Oman, the Indian Ocean bottlenose dolphin (Tursiops aduncus) is the most common cetacean (71% of groups and individuals), followed by the Indo-Pacific humpback dolphin (Sousa chinensis; 27%) and finless porpoise (Neophocaena phocaenoides; 2%). The estimates of cetacean abundance in the UAE differed significantly between 1986 and 1999 and indicate a population decline of 71%. At least two die-offs of marine mammals occurred between these surveys. The countries of the southern Gulf are developed and affluent and are well positioned to take a lead in marine conservation in the region. A coordinated series of protected areas could greatly enhance the long-term prospects for marine mammals and other components of biodiversity in the region. 相似文献
102.
Mitton-Fry RM Anderson EM Hughes TR Lundblad V Wuttke DS 《Science (New York, N.Y.)》2002,296(5565):145-147
The essential Cdc13 protein in the yeast Saccharomyces cerevisiae is a single-stranded telomeric DNA binding protein required for chromosome end protection and telomere replication. Here we report the solution structure of the Cdc13 DNA binding domain in complex with telomeric DNA. The structure reveals the use of a single OB (oligonucleotide/oligosaccharide binding) fold augmented by an unusually large loop for DNA recognition. This OB fold is structurally similar to OB folds found in the ciliated protozoan telomere end-binding protein, although no sequence similarity is apparent between them. The common usage of an OB fold for telomeric DNA interaction demonstrates conservation of end-protection mechanisms among eukaryotes. 相似文献
103.
Beeson TD Mastracchio A Hong JB Ashton K Macmillan DW 《Science (New York, N.Y.)》2007,316(5824):582-585
The asymmetric alpha-addition of relatively nonpolar hydrocarbon substrates, such as allyl and aryl groups, to aldehydes and ketones remains a largely unsolved problem in organic synthesis, despite the wide potential utility of direct routes to such products. We reasoned that well-established chiral amine catalysis, which activates aldehydes toward electrophile addition by enamine formation, could be expanded to this important reaction class by applying a single-electron oxidant to create a transient radical species from the enamine. We demonstrated the concept of singly occupied molecular orbital (SOMO) activation with a highly selective alpha-allylation of aldehydes, and we here present preliminary results for enantioselective heteroarylations and cyclization/halogenation cascades. 相似文献
104.
Equivalent effects of snake PLA2 neurotoxins and lysophospholipid-fatty acid mixtures 总被引:1,自引:0,他引:1
Rigoni M Caccin P Gschmeissner S Koster G Postle AD Rossetto O Schiavo G Montecucco C 《Science (New York, N.Y.)》2005,310(5754):1678-1680
Snake presynaptic phospholipase A2 neurotoxins (SPANs) paralyze the neuromuscular junction (NMJ). Upon intoxication, the NMJ enlarges and has a reduced content of synaptic vesicles, and primary neuronal cultures show synaptic swelling with surface exposure of the lumenal domain of the synaptic vesicle protein synaptotagmin I. Concomitantly, these neurotoxins induce exocytosis of neurotransmitters. We found that an equimolar mixture of lysophospholipids and fatty acids closely mimics all of the biological effects of SPANs. These results draw attention to the possible role of local lipid changes in synaptic vesicle release and provide new tools for the study of exocytosis. 相似文献
105.
Anthony Winson 《Agriculture and Human Values》2008,25(4):499-511
To understand the phenomenon of the rapidly increasing prevalence of overweight and obese children and youth, it is especially
important to examine the school food environment, the role of structural factors in shaping this environment, and the resulting
nutrition and health outcomes. The paper examines research on school food environments in the US and Canada. It notes evidence
of widespread availability of poor nutrition products in both environments and delineates reasons for the situation, and examines
initiatives presently being undertaken in a number of jurisdictions in both countries to encourage healthy eating in schools.
Empirical data are presented from a pilot study of high schools in the Canadian province of Ontario. The study documents the
extent of student purchasing of nutrient-poor foods and beverages, and the structural factors internal and external to the
school that appear responsible for the availability of such products in food environments in this critical institutional sphere.
The paper also examines positive local initiatives in high schools that seek to encourage healthy eating in schools.
Anthony Winson PhD is a professor in the department of sociology and anthropology at the University of Guelph. He has written on agriculture, food and rural development, and restructuring issues related to Canada and the Third World for more than 20 years. Among his books are The Intimate Commodity: Food and the Development of the Agro-Industrial Complex in Canada (Garamond 1993) and, more recently, Contingent Work, Disrupted Lives (University of Toronto 2002, with Belinda Leach) which examines economic restructuring, the changing world of work, and the factors underlying sustainability in small manufacturing-dependent rural communities in several regions of Ontario. This book won the John Porter Book Prize of the Canadian Sociology and Anthropology Association for 2003. Dr. Winson’s current work is focused on the analysis of factors shaping the contemporary Canadian food environment and their role in producing what has been termed the “epidemic of obesity.” Particular attention is being paid to supermarkets and schools as part of broader-ranging research on the political economic context of the food environment. 相似文献
Anthony WinsonEmail: |
Anthony Winson PhD is a professor in the department of sociology and anthropology at the University of Guelph. He has written on agriculture, food and rural development, and restructuring issues related to Canada and the Third World for more than 20 years. Among his books are The Intimate Commodity: Food and the Development of the Agro-Industrial Complex in Canada (Garamond 1993) and, more recently, Contingent Work, Disrupted Lives (University of Toronto 2002, with Belinda Leach) which examines economic restructuring, the changing world of work, and the factors underlying sustainability in small manufacturing-dependent rural communities in several regions of Ontario. This book won the John Porter Book Prize of the Canadian Sociology and Anthropology Association for 2003. Dr. Winson’s current work is focused on the analysis of factors shaping the contemporary Canadian food environment and their role in producing what has been termed the “epidemic of obesity.” Particular attention is being paid to supermarkets and schools as part of broader-ranging research on the political economic context of the food environment. 相似文献
106.
Collective action processes in complex, multiple-use common-pool resources (CPRs) have only recently become a focus of study. When CPRs evolve into more complex systems, resource use by separate user groups becomes increasingly interdependent. This implies, amongst others, that the institutional framework governing resource use has to be re-negotiated to avoid adverse impacts associated with the increased access of any new stakeholders, such as overexploitation, alienation of traditional users, and inter-user conflicts. The establishment of platforms for resource use negotiation is a way of dealing with complex natural resource management problems. Platforms arise when stakeholders perceive the same resource management problem, realize their interdependence in solving it, and come together to agree on action strategies for solving the problem (Röling, 1994). This article sets the scene for a discussion in this Special Issue about the potential of nested platforms for resource use negotiation in facilitating collective action in the management of complex, multiple-use CPRs. The article has five objectives. First, we define collective action in the context of this paper. Second, we discuss the importance of collective action in multiple-use CPRs. Third, we introduce the concept of platforms to coordinate collective action by multiple users. Fourth, we address some issues that emerge from evidence in the field regarding the role and potential of nested platforms for managing complex CPRs. Finally, we raise five discussion statements. These will form the basis for the collection of articles in this special issue. 相似文献
107.
Anesthesia of Artemia larvae: method for quantitative study 总被引:2,自引:0,他引:2
A B Robinson K F Manly M P Anthony J F Catchpool L Pauling 《Science (New York, N.Y.)》1965,149(689):1255-1258
Potency of anesthetics is quantitatively measured with laboratory-hatched larvae of the brine shrimp Artemia salina. Statistical fluctuations are minimized in that 100,000 animals are used to determine a single median anesthetic dose value. The technique was developed to study molecular mechanisms of general anesthesia. 相似文献
108.
Yankovskaya V Horsefield R Törnroth S Luna-Chavez C Miyoshi H Léger C Byrne B Cecchini G Iwata S 《Science (New York, N.Y.)》2003,299(5607):700-704
The structure of Escherichia coli succinate dehydrogenase (SQR), analogous to the mitochondrial respiratory complex II, has been determined, revealing the electron transport pathway from the electron donor, succinate, to the terminal electron acceptor, ubiquinone. It was found that the SQR redox centers are arranged in a manner that aids the prevention of reactive oxygen species (ROS) formation at the flavin adenine dinucleotide. This is likely to be the main reason SQR is expressed during aerobic respiration rather than the related enzyme fumarate reductase, which produces high levels of ROS. Furthermore, symptoms of genetic disorders associated with mitochondrial SQR mutations may be a result of ROS formation resulting from impaired electron transport in the enzyme. 相似文献
109.
110.