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171.
The diatom flora of Cowboy Hot Spring, Mono County, California, was studied. Two habitats, one at 37C and one at 41C, were examined. Fifty-six taxa were identified from our samples. These taxa were mostly broadly distributed forms, and no endemic species were encountered. The dominant taxon was Nitzschia frustulum, followed by Achnanthes gibberula, Achnanthes exigua, Nitzschia hantzschiana , and Navicula cincta . 相似文献
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By the middle of the nineteenth century, the opinion of science, as well as of philosophy and even religion, was, at least in Britain, firmly in the camp of the plurality of worlds, the view that intelligent life exists on other celestial bodies. William Whewell, considered an expert on science, philosophy and religion (among other areas), would have been expected to support this position. Yet he surprised everyone in 1853 by publishing a work arguing strongly against the plurality view. This was even stranger given that he had endorsed pluralism twenty years earlier in his contribution to the Bridgewater Treatises. In this paper I show that the shift in Whewell’s view was motivated by three factors: the influence of Richard Owen’s theory of archetypes on Whewell’s view of the argument from design, and Whewell’s perception of the need to strengthen such arguments in light of evolutionary accounts of human origins; important developments in his view of philosophy and his role as a scientific expert; and new findings in astronomy. An examination of the development of Whewell’s position provides a lens through which we can view the interplay of theology, philosophy and science in the plurality of worlds debate. 相似文献
175.
Deciphering the evolution and metabolism of an anammox bacterium from a community genome 总被引:15,自引:0,他引:15
Strous M Pelletier E Mangenot S Rattei T Lehner A Taylor MW Horn M Daims H Bartol-Mavel D Wincker P Barbe V Fonknechten N Vallenet D Segurens B Schenowitz-Truong C Médigue C Collingro A Snel B Dutilh BE Op den Camp HJ van der Drift C Cirpus I van de Pas-Schoonen KT Harhangi HR van Niftrik L Schmid M Keltjens J van de Vossenberg J Kartal B Meier H Frishman D Huynen MA Mewes HW Weissenbach J Jetten MS Wagner M Le Paslier D 《Nature》2006,440(7085):790-794
Anaerobic ammonium oxidation (anammox) has become a main focus in oceanography and wastewater treatment. It is also the nitrogen cycle's major remaining biochemical enigma. Among its features, the occurrence of hydrazine as a free intermediate of catabolism, the biosynthesis of ladderane lipids and the role of cytoplasm differentiation are unique in biology. Here we use environmental genomics--the reconstruction of genomic data directly from the environment--to assemble the genome of the uncultured anammox bacterium Kuenenia stuttgartiensis from a complex bioreactor community. The genome data illuminate the evolutionary history of the Planctomycetes and allow us to expose the genetic blueprint of the organism's special properties. Most significantly, we identified candidate genes responsible for ladderane biosynthesis and biological hydrazine metabolism, and discovered unexpected metabolic versatility. 相似文献
176.
The activity of the ribosomal dissociation factor and the formation in vitro of free 60S and 40S subunits increased in the first 12--48 h after partial hepatectomy. This suggests an accelerated reconversion into active subunits of ribosomes that complete a translation cycle in the early phases of liver regeneration. 相似文献
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Wiesmann C Katschke KJ Yin J Helmy KY Steffek M Fairbrother WJ McCallum SA Embuscado L DeForge L Hass PE van Lookeren Campagne M 《Nature》2006,444(7116):217-220
The complement system is a key part of the innate immune system, and is required for clearance of pathogens from the bloodstream. After exposure to pathogens, the third component of the complement system, C3, is cleaved to C3b which, after recruitment of factor B, initiates formation of the alternative pathway convertases. CRIg, a complement receptor expressed on macrophages, binds to C3b and iC3b mediating phagocytosis of the particles, but it is unknown how CRIg selectively recognizes proteolytic C3-fragments and whether binding of CRIg to C3b inhibits convertase activation. Here we present the crystal structure of C3b in complex with CRIg and, using CRIg mutants, provide evidence that CRIg acts as an inhibitor of the alternative pathway of complement. The structure shows that activation of C3 induces major structural rearrangements, including a dramatic movement (>80 A) of the thioester-bond-containing domain through which C3b attaches to pathogen surfaces. We show that CRIg is not only a phagocytic receptor, but also a potent inhibitor of the alternative pathway convertases. The structure provides insights into the complex macromolecular structural rearrangements that occur during complement activation and inhibition. Moreover, our structure-function studies relating the structural basis of complement activation and the means by which CRIg inhibits the convertases provide important clues to the development of therapeutics that target complement. 相似文献
179.
Solt LA Wang Y Banerjee S Hughes T Kojetin DJ Lundasen T Shin Y Liu J Cameron MD Noel R Yoo SH Takahashi JS Butler AA Kamenecka TM Burris TP 《Nature》2012,485(7396):62-68
Synchronizing rhythms of behaviour and metabolic processes is important for cardiovascular health and preventing metabolic diseases. The nuclear receptors REV-ERB-α and REV-ERB-β have an integral role in regulating the expression of core clock proteins driving rhythms in activity and metabolism. Here we describe the identification of potent synthetic REV-ERB agonists with in vivo activity. Administration of synthetic REV-ERB ligands alters circadian behaviour and the circadian pattern of core clock gene expression in the hypothalami of mice. The circadian pattern of expression of an array of metabolic genes in the liver, skeletal muscle and adipose tissue was also altered, resulting in increased energy expenditure. Treatment of diet-induced obese mice with a REV-ERB agonist decreased obesity by reducing fat mass and markedly improving dyslipidaemia and hyperglycaemia. These results indicate that synthetic REV-ERB ligands that pharmacologically target the circadian rhythm may be beneficial in the treatment of sleep disorders as well as metabolic diseases. 相似文献
180.
MA Deardorff M Bando R Nakato E Watrin T Itoh M Minamino K Saitoh M Komata Y Katou D Clark KE Cole E De Baere C Decroos N Di Donato S Ernst LJ Francey Y Gyftodimou K Hirashima M Hullings Y Ishikawa C Jaulin M Kaur T Kiyono PM Lombardi L Magnaghi-Jaulin GR Mortier N Nozaki MB Petersen H Seimiya VM Siu Y Suzuki K Takagaki JJ Wilde PJ Willems C Prigent G Gillessen-Kaesbach DW Christianson FJ Kaiser LG Jackson T Hirota ID Krantz K Shirahige 《Nature》2012,489(7415):313-317