Serine-7 of the RNA polymerase II CTD is specifically required for snRNA gene expression     

Egloff S  O'Reilly D  Chapman RD  Taylor A  Tanzhaus K  Pitts L  Eick D  Murphy S 《Science (New York, N.Y.)》2007,318(5857):1777-1779

RNA polymerase II (Pol II) transcribes genes that encode proteins and noncoding small nuclear RNAs (snRNAs). The carboxyl-terminal repeat domain (CTD) of the largest subunit of mammalian RNA Pol II, comprising tandem repeats of the heptapeptide consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7, is required for expression of both gene types. We show that mutation of serine-7 to alanine causes a specific defect in snRNA gene expression. We also present evidence that phosphorylation of serine-7 facilitates interaction with the snRNA gene-specific Integrator complex. These findings assign a biological function to this amino acid and highlight a gene type-specific requirement for a residue within the CTD heptapeptide, supporting the existence of a CTD code.  相似文献   

A soldier's view of the USAMRIID     

Blanchard M 《Science (New York, N.Y.)》2002,297(5584):1122

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Fluorescence-force spectroscopy maps two-dimensional reaction landscape of the holliday junction     

Hohng S  Zhou R  Nahas MK  Yu J  Schulten K  Lilley DM  Ha T 《Science (New York, N.Y.)》2007,318(5848):279-283

Despite the recent advances in single-molecule manipulation techniques, purely mechanical approaches cannot detect subtle conformational changes in the biologically important regime of weak forces. We developed a hybrid scheme combining force and fluorescence that allowed us to examine the effect of subpiconewton forces on the nanometer scale motion of the Holliday junction (HJ) at 100-hertz bandwidth. The HJ is an exquisitely sensitive force sensor whose force response is amplified with an increase in its arm lengths, demonstrating a lever-arm effect at the nanometer-length scale. Mechanical interrogation of the HJ in three different directions helped elucidate the structures of the transient species populated during its conformational changes. This method of mapping two-dimensional reaction landscapes at low forces is readily applicable to other nucleic acid systems and their interactions with proteins and enzymes.  相似文献   

White fat progenitor cells reside in the adipose vasculature   总被引：1，自引：0，他引：1  

Tang W  Zeve D  Suh JM  Bosnakovski D  Kyba M  Hammer RE  Tallquist MD  Graff JM 《Science (New York, N.Y.)》2008,322(5901):583-586

White adipose (fat) tissues regulate metabolism, reproduction, and life span. Adipocytes form throughout life, with the most marked expansion of the lineage occurring during the postnatal period. Adipocytes develop in coordination with the vasculature, but the identity and location of white adipocyte progenitor cells in vivo are unknown. We used genetically marked mice to isolate proliferating and renewing adipogenic progenitors. We found that most adipocytes descend from a pool of these proliferating progenitors that are already committed, either prenatally or early in postnatal life. These progenitors reside in the mural cell compartment of the adipose vasculature, but not in the vasculature of other tissues. Thus, the adipose vasculature appears to function as a progenitor niche and may provide signals for adipocyte development.  相似文献   

Genetics. DNA patenting and licensing     

Henry MR  Cho MK  Weaver MA  Merz JF 《Science (New York, N.Y.)》2002,297(5585):1279

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Product differentiation via corporate social responsibility: consumer priorities and the mediating role of food labels     

Marco?Costanigro  Oana?Deselnicu  Dawn?Thilmany?McFaddenEmail author 《Agriculture and Human Values》2016,33(3):597-609

This article examines quantitatively the determinants of purchase decisions based on corporate social responsibility (CSR), adopting a hierarchical conceptual model of decision making where the key factors are personal concern, information availability and financial considerations. We use best–worst methods to assess consumer priorities (personal concern) for CSR activities in milk production; and elicit consumer interpretation of four labels (organic, Validus, Colorado Proud and rBST free) in terms of CSR and other outcomes (information availability). We then elicit willingness to pay (WTP) for the labels (financial considerations), and estimate regression models to determine how predictive each label perceptual profile is of WTP for milk. Animal welfare and sustainable agricultural practices are the most important activities, and milk labels do convey CSR-related messages. With the exception of the pair animal welfare-Validus, the link between CSR messages and WTP is tenuous. The discussion emphasizes the central role of each label’s perceptual profile in triggering product differentiation among consumers.  相似文献   

Orangutan cultures and the evolution of material culture     

van Schaik CP  Ancrenaz M  Borgen G  Galdikas B  Knott CD  Singleton I  Suzuki A  Utami SS  Merrill M 《Science (New York, N.Y.)》2003,299(5603):102-105

Geographic variation in some aspects of chimpanzee behavior has been interpreted as evidence for culture. Here we document similar geographic variation in orangutan behaviors. Moreover, as expected under a cultural interpretation, we find a correlation between geographic distance and cultural difference, a correlation between the abundance of opportunities for social learning and the size of the local cultural repertoire, and no effect of habitat on the content of culture. Hence, great-ape cultures exist, and may have done so for at least 14 million years.  相似文献   

Environmental economics. Development and conservation goals in World Bank projects     

Kareiva P  Chang A  Marvier M 《Science (New York, N.Y.)》2008,321(5896):1638-1639

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Stochastic pulse regulation in bacterial stress response     

Locke JC  Young JW  Fontes M  Hernández Jiménez MJ  Elowitz MB 《Science (New York, N.Y.)》2011,334(6054):366-369

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Graduate students' teaching experiences improve their methodological research skills     

Feldon DF  Peugh J  Timmerman BE  Maher MA  Hurst M  Strickland D  Gilmore JA  Stiegelmeyer C 《Science (New York, N.Y.)》2011,333(6045):1037-1039

Science, technology, engineering, and mathematics (STEM) graduate students are often encouraged to maximize their engagement with supervised research and minimize teaching obligations. However, the process of teaching students engaged in inquiry provides practice in the application of important research skills. Using a performance rubric, we compared the quality of methodological skills demonstrated in written research proposals for two groups of early career graduate students (those with both teaching and research responsibilities and those with only research responsibilities) at the beginning and end of an academic year. After statistically controlling for preexisting differences between groups, students who both taught and conducted research demonstrate significantly greater improvement in their abilities to generate testable hypotheses and design valid experiments. These results indicate that teaching experience can contribute substantially to the improvement of essential research skills.  相似文献