Heterogeneous reaction probabilities, solubilities, and the physical state of cold volcanic aerosols     

Toon O  Browell E  Gary B  Lait L  Livingston J  Newman P  Pueschel R  Russell P  Schoeberl M  Toon G  Traub W  Valero FP  Selkirk H  Jordan J 《Science (New York, N.Y.)》1993,261(5125):1136-1140

On 19 January 1992, heterogeneous loss of HNO(3), ClNO(3), and HCl was observed in part of the Mount Pinatubo volcanic cloud that had cooled as a result of forced ascent. Portions of the volcanic cloud froze near 191 kelvin. The reaction probability of ClNO(3) and the solubility of HNO(3) were close to laboratory measurements on liquid sulfuric acid. The magnitude of the observed loss of HCl suggests that it underwent a heterogeneous reaction. Such reactions could lead to substantial loss of HCl on background sulfuric acid particles and so be important for polar ozone loss.  相似文献   

A single IGF1 allele is a major determinant of small size in dogs   总被引：3，自引：0，他引：3  

Sutter NB  Bustamante CD  Chase K  Gray MM  Zhao K  Zhu L  Padhukasahasram B  Karlins E  Davis S  Jones PG  Quignon P  Johnson GS  Parker HG  Fretwell N  Mosher DS  Lawler DF  Satyaraj E  Nordborg M  Lark KG  Wayne RK  Ostrander EA 《Science (New York, N.Y.)》2007,316(5821):112-115

The domestic dog exhibits greater diversity in body size than any other terrestrial vertebrate. We used a strategy that exploits the breed structure of dogs to investigate the genetic basis of size. First, through a genome-wide scan, we identified a major quantitative trait locus (QTL) on chromosome 15 influencing size variation within a single breed. Second, we examined genetic variation in the 15-megabase interval surrounding the QTL in small and giant breeds and found marked evidence for a selective sweep spanning a single gene (IGF1), encoding insulin-like growth factor 1. A single IGF1 single-nucleotide polymorphism haplotype is common to all small breeds and nearly absent from giant breeds, suggesting that the same causal sequence variant is a major contributor to body size in all small dogs.  相似文献   

Architecture of succinate dehydrogenase and reactive oxygen species generation   总被引：1，自引：0，他引：1  

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   

Island biology and ecosystem functioning in epiphytic soil communities     

Wardle DA  Yeates GW  Barker GM  Bellingham PJ  Bonner KI  Williamson WM 《Science (New York, N.Y.)》2003,301(5640):1717-1720

Although island attributes such as size and accessibility to colonizing organisms can influence community structure, the consequences of these for ecosystem functioning are little understood. A study of the suspended soils of spatially discrete epiphytes or treetop "islands" in the canopies of New Zealand rainforest trees revealed that different components of the decomposer community responded either positively or negatively to island size, as well as to the tree species that the islands occurred in. This in turn led to important differences between islands in the rates of ecosystem processes driven by the decomposer biota. This system serves as a model for better understanding how attributes of both real and habitat islands may affect key ecosystem functions through determining the community structure of organisms that drive these functions.  相似文献   

Regulation of bone mass in mice by the lipoxygenase gene Alox15     

Klein RF  Allard J  Avnur Z  Nikolcheva T  Rotstein D  Carlos AS  Shea M  Waters RV  Belknap JK  Peltz G  Orwoll ES 《Science (New York, N.Y.)》2004,303(5655):229-232

The development of osteoporosis involves the interaction of multiple environmental and genetic factors. Through combined genetic and genomic approaches, we identified the lipoxygenase gene Alox15 as a negative regulator of peak bone mineral density in mice. Crossbreeding experiments with Alox15 knockout mice confirmed that 12/15-lipoxygenase plays a role in skeletal development. Pharmacologic inhibitors of this enzyme improved bone density and strength in two rodent models of osteoporosis. These results suggest that drugs targeting the 12/15-lipoxygenase pathway merit investigation as a therapy for osteoporosis.  相似文献   

Firearms, violence, and self-protection     

Kleck GD 《Science (New York, N.Y.)》2005,309(5741):1675-6; author reply 1675-6

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Biomedicine. Every joint has a silver lining     

Firestein GS 《Science (New York, N.Y.)》2007,315(5814):952-953

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From the editors     

Paul B. Thompson  Keith M. Moore  William M. Rivera  Gary P. Green  Joel Schor  et al. 《Agriculture and Human Values》1991,8(3):1-2

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Regulation of blood and lymphatic vascular separation by signaling proteins SLP-76 and Syk     

Abtahian F  Guerriero A  Sebzda E  Lu MM  Zhou R  Mocsai A  Myers EE  Huang B  Jackson DG  Ferrari VA  Tybulewicz V  Lowell CA  Lepore JJ  Koretzky GA  Kahn ML 《Science (New York, N.Y.)》2003,299(5604):247-251

Lymphatic vessels develop from specialized endothelial cells in preexisting blood vessels, but the molecular signals that regulate this separation are unknown. Here we identify a failure to separate emerging lymphatic vessels from blood vessels in mice lacking the hematopoietic signaling protein SLP-76 or Syk. Blood-lymphatic connections lead to embryonic hemorrhage and arteriovenous shunting. Expression of slp-76 could not be detected in endothelial cells, and blood-filled lymphatics also arose in wild-type mice reconstituted with SLP-76-deficient bone marrow. These studies reveal a hematopoietic signaling pathway required for separation of the two major vascular networks in mammals.  相似文献   

Microwave sounding units and global warming     

Gary BL  Keihm SJ 《Science (New York, N.Y.)》1991,251(4991):316-317

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