Counting low-copy number proteins in a single cell     

Huang B  Wu H  Bhaya D  Grossman A  Granier S  Kobilka BK  Zare RN 《Science (New York, N.Y.)》2007,315(5808):81-84

We have designed a microfluidic device in which we can manipulate, lyse, label, separate, and quantify the protein contents of a single cell using single-molecule fluorescence counting. Generic labeling of proteins is achieved through fluorescent-antibody binding. The use of cylindrical optics enables high-efficiency (approximately 60%) counting of molecules in micrometer-sized channels. We used this microfluidic device to quantify beta2 adrenergic receptors expressed in insect cells (SF9). We also analyzed phycobiliprotein contents in individual cyanobacterial cells (Synechococcus sp. PCC 7942) and observed marked differences in the levels of specific complexes in cell populations that were grown under nitrogen-depleted conditions.  相似文献   

Bioethics. Is biomedical research too dangerous to pursue?     

Caplan A 《Science (New York, N.Y.)》2004,303(5661):1142

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Immunology. The toll of cathepsin K deficiency     

Krieg AM  Lipford GB 《Science (New York, N.Y.)》2008,319(5863):576-577

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Comparative genomics of trypanosomatid parasitic protozoa     

El-Sayed NM  Myler PJ  Blandin G  Berriman M  Crabtree J  Aggarwal G  Caler E  Renauld H  Worthey EA  Hertz-Fowler C  Ghedin E  Peacock C  Bartholomeu DC  Haas BJ  Tran AN  Wortman JR  Alsmark UC  Angiuoli S  Anupama A  Badger J  Bringaud F  Cadag E  Carlton JM  Cerqueira GC  Creasy T  Delcher AL  Djikeng A  Embley TM  Hauser C  Ivens AC  Kummerfeld SK  Pereira-Leal JB  Nilsson D  Peterson J  Salzberg SL  Shallom J  Silva JC  Sundaram J  Westenberger S  White O  Melville SE  Donelson JE  Andersson B  Stuart KD  Hall N 《Science (New York, N.Y.)》2005,309(5733):404-409

A comparison of gene content and genome architecture of Trypanosoma brucei, Trypanosoma cruzi, and Leishmania major, three related pathogens with different life cycles and disease pathology, revealed a conserved core proteome of about 6200 genes in large syntenic polycistronic gene clusters. Many species-specific genes, especially large surface antigen families, occur at nonsyntenic chromosome-internal and subtelomeric regions. Retroelements, structural RNAs, and gene family expansion are often associated with syntenic discontinuities that-along with gene divergence, acquisition and loss, and rearrangement within the syntenic regions-have shaped the genomes of each parasite. Contrary to recent reports, our analyses reveal no evidence that these species are descended from an ancestor that contained a photosynthetic endosymbiont.  相似文献   

Bond-selective control of a heterogeneously catalyzed reaction     

Killelea DR  Campbell VL  Shuman NS  Utz AL 《Science (New York, N.Y.)》2008,319(5864):790-793

Energy redistribution, including the many phonon-assisted and electronically assisted energy-exchange processes at a gas-metal interface, can hamper vibrationally mediated selectivity in chemical reactions. We establish that these limitations do not prevent bond-selective control of a heterogeneously catalyzed reaction. State-resolved gas-surface scattering measurements show that the nu1 C-H stretch vibration in trideuteromethane (CHD3) selectively activates C-H bond cleavage on a Ni(111) surface. Isotope-resolved detection reveals a CD3:CHD2 product ratio > 30:1, which contrasts with the 1:3 ratio for an isoenergetic ensemble of CHD3 whose vibrations are statistically populated. Recent studies of vibrational energy redistribution in the gas and condensed phases suggest that other gas-surface reactions with similar vibrational energy flow dynamics might also be candidates for such bond-selective control.  相似文献   

Comment on "How the horned lizard got its horns"     

Agosta SJ  Dunham AE 《Science (New York, N.Y.)》2004,306(5694):230; author reply 230

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Oscillating systems. On emerging coherence     

Winfree AT 《Science (New York, N.Y.)》2002,298(5602):2336-2337

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Isotopic evidence for massive oxidation of organic matter following the great oxidation event     

Kump LR  Junium C  Arthur MA  Brasier A  Fallick A  Melezhik V  Lepland A  Crne AE  Luo G 《Science (New York, N.Y.)》2011,334(6063):1694-1696

The stable isotope record of marine carbon indicates that the Proterozoic Eon began and ended with extreme fluctuations in the carbon cycle. In both the Paleoproterozoic [2500 to 1600 million years ago (Ma)] and Neoproterozoic (1000 to 542 Ma), extended intervals of anomalously high carbon isotope ratios (δ(13)C) indicate high rates of organic matter burial and release of oxygen to the atmosphere; in the Neoproterozoic, the high δ(13)C interval was punctuated by abrupt swings to low δ(13)C, indicating massive oxidation of organic matter. We report a Paleoproterozoic negative δ(13)C excursion that is similar in magnitude and apparent duration to the Neoproterozoic anomaly. This Shunga-Francevillian anomaly may reflect intense oxidative weathering of rocks as the result of the initial establishment of an oxygen-rich atmosphere.  相似文献   

Demonstrating decline of an iconic species under sustained indigenous harvest – The pig-nosed turtle (Carettochelys insculpta) in Papua New Guinea     

Carla C. Eisemberg  Mark Rose  Benedict Yaru  Arthur Georges 《Biological conservation》2011,144(9):2282-2288

Papua New Guinea has astonishing biological and cultural diversity which, coupled with a strong community reliance on the land and its biota for subsistence, add complexity to monitoring and conservation and in particular, the demonstration of declines in wildlife populations. Many species of concern are long-lived which provides additional challenges for conservation. We provide, for the first time, concrete evidence of a substantive decline in populations of the pig-nosed turtle (Carettochelys insculpta); an important source of protein for local communities. Our study combined matched village and market surveys separated by 30 years, trends in nesting female size, and assessment of levels and efficacy of harvest, each of which was an essential ingredient to making a definitive assessment of population trends. Opportunities for an effective response by local communities to these declines needs to consider both conservation and fisheries perspectives because local communities consider the turtle a food resource, whereas the broader global community views it as a high priority for conservation. Our study in the Kikori region is representative of harvest regimes in most rivers within the range of the species in Papua New Guinea, and provides lessons for conservation of many other wildlife species subject to harvest.  相似文献   

Efficacy of spinosad and methoprene,applied alone or in combination,against six stored-product insect species     

Christos G. Athanassiou  Frank H. Arthur  Nickolas G. Kavallieratos  James E. Throne 《Journal of pest science》2011,84(1):61-67

Efficacy of the insecticides spinosad and methoprene, applied alone or in combination to wheat, was evaluated against six stored-product insect species, Rhyzopertha dominica, Sitophilus oryzae, S. granarius, Cryptolestes ferrugineus, Oryzaephilus surinamensis, and Liposcelis bostrychophila. The concentrations of the insecticides were 0.1 and 0.5 ppm for spinosad and 1 and 5 ppm for methoprene. Parental mortality of R. dominica was 100% on wheat treated with either rate of spinosad, with no progeny production in any combination treatment. Parental mortality of S. oryzae did not exceed 62%, and progeny production was not reduced by any insecticide treatment. All S. granarius adults exposed on wheat treated with spinosad alone at 0.5 ppm were killed, but parental mortality was reduced when methoprene was added. Progeny production was reduced in treatments containing spinosad. Mortality of adult C. ferrugineus was 97% or greater in treatments containing spinosad, but adult mortality of O. surinamensis and L. bostrychophila was not reduced by insecticide treatments. The specific combinations of spinosad and methoprene evaluated in our study would have no benefit over spinosad used alone for control of any of the six species tested.  相似文献