George C. Williams profile. Stretching the limits of evolutionary biology     

Zimmer C 《Science (New York, N.Y.)》2004,304(5675):1235-1236

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农杆菌介导转化为目的的水稻组培体系的建立   总被引：2，自引：2，他引：2  

段承俐  萧凤回  Carl RathuS  Ian Godwin 《西南大学学报(自然科学版)》2001,23(6):527-531

高效可靠的组培再生体系是水稻农杆菌遗传转化的基础。该试验通过对培养基类型、光照条件和水稻基因型的研究,发现富含脯氨酸的N6D培养基能明显促进愈伤组织的生长,光照条件也可显著改善其生长。Calrose76和合系41号被证实为易于组培高效再生的粳稻品种,该高效组培体系的为云南栽培良种合系41号的进一步农杆菌转化体系的建立铺平了道路。  相似文献   

The effect of diurnal correction on satellite-derived lower tropospheric temperature   总被引：1，自引：0，他引：1  

Mears CA  Wentz FJ 《Science (New York, N.Y.)》2005,309(5740):1548-1551

Satellite-based measurements of decadal-scale temperature change in the lower troposphere have indicated cooling relative to Earth's surface in the tropics. Such measurements need a diurnal correction to prevent drifts in the satellites' measurement time from causing spurious trends. We have derived a diurnal correction that, in the tropics, is of the opposite sign from that previously applied. When we use this correction in the calculation of lower tropospheric temperature from satellite microwave measurements, we find tropical warming consistent with that found at the surface and in our satellite-derived version of middle/upper tropospheric temperature.  相似文献   

Selective charging of tRNA isoacceptors explains patterns of codon usage     

Elf J  Nilsson D  Tenson T  Ehrenberg M 《Science (New York, N.Y.)》2003,300(5626):1718-1722

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Modulation of postendocytic sorting of G protein-coupled receptors   总被引：1，自引：0，他引：1  

Whistler JL  Enquist J  Marley A  Fong J  Gladher F  Tsuruda P  Murray SR  Von Zastrow M 《Science (New York, N.Y.)》2002,297(5581):615-620

Recycling of the mu opioid receptor to the plasma membrane after endocytosis promotes rapid resensitization of signal transduction, whereas targeting of the delta opioid receptor (DOR) to lysosomes causes proteolytic down-regulation. We identified a protein that binds preferentially to the cytoplasmic tail of the DOR as a candidate heterotrimeric GTP-binding protein (G protein)-coupled receptor-associated sorting protein (GASP). Disruption of the DOR-GASP interaction through receptor mutation or overexpression of a dominant negative fragment of GASP inhibited receptor trafficking to lysosomes and promoted recycling. The GASP family of proteins may modulate lysosomal sorting and functional down-regulation of a variety of G protein-coupled receptors.  相似文献   

Improved learning in a large-enrollment physics class     

Deslauriers L  Schelew E  Wieman C 《Science (New York, N.Y.)》2011,332(6031):862-864

We compared the amounts of learning achieved using two different instructional approaches under controlled conditions. We measured the learning of a specific set of topics and objectives when taught by 3 hours of traditional lecture given by an experienced highly rated instructor and 3 hours of instruction given by a trained but inexperienced instructor using instruction based on research in cognitive psychology and physics education. The comparison was made between two large sections (N = 267 and N = 271) of an introductory undergraduate physics course. We found increased student attendance, higher engagement, and more than twice the learning in the section taught using research-based instruction.  相似文献   

Leading the charge to virtual meetings     

Dolci WW  Boldt MS  Dodson KE  Pilcher CB 《Science (New York, N.Y.)》2011,331(6018):674

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Spain's Ramón y Cajal Program     

Axness C  Tornero P  Ricote J  Algueró M 《Science (New York, N.Y.)》2003,300(5616):52-53

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The proteasome of Mycobacterium tuberculosis is required for resistance to nitric oxide     

Darwin KH  Ehrt S  Gutierrez-Ramos JC  Weich N  Nathan CF 《Science (New York, N.Y.)》2003,302(5652):1963-1966

The production of nitric oxide and other reactive nitrogen intermediates (RNI) by macrophages helps to control infection by Mycobacterium tuberculosis (Mtb). However, the protection is imperfect and infection persists. To identify genes that Mtb requires to resist RNI, we screened 10,100 Mtb transposon mutants for hypersusceptibility to acidified nitrite. We found 12 mutants with insertions in seven genes representing six pathways, including the repair of DNA (uvrB) and the synthesis of a flavin cofactor (fbiC). Five mutants had insertions in proteasome-associated genes. An Mtb mutant deficient in a presumptive proteasomal adenosine triphosphatase was attenuated in mice, and exposure to proteasomal protease inhibitors markedly sensitized wild-type Mtb to RNI. Thus, the mycobacterial proteasome serves as a defense against oxidative or nitrosative stress.  相似文献   

Oceanography. What is the thermohaline circulation?     

Wunsch C 《Science (New York, N.Y.)》2002,298(5596):1179-1181

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