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A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the equatorial Pacific Ocean 总被引:70,自引:0,他引:70
Coale KH Johnson KS Fitzwater SE Gordon RM Tanner S Chavez FP Ferioli L Sakamoto C Rogers P Millero F Steinberg P Nightingale P Cooper D Cochlan WP Landry MR Constantinou J Rollwagen G Trasvina A Kudela R 《Nature》1996,383(6600):495-501
The seeding of an expanse of surface waters in the equatorial Pacific Ocean with low concentrations of dissolved iron triggered a massive phytoplankton bloom which consumed large quantities of carbon dioxide and nitrate that these microscopic plants cannot fully utilize under natural conditions. These and other observations provide unequivocal support for the hypothesis that phytoplankton growth in this oceanic region is limited by iron bioavailability. 相似文献
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A PHD finger of NURF couples histone H3 lysine 4 trimethylation with chromatin remodelling 总被引:1,自引:0,他引:1
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How broadly tuned olfactory receptors equally recognize their agonists. Human OR1G1 as a test case 总被引:1,自引:1,他引:0
Landry Charlier Jérémie Topin Catherine Ronin Soo-Kyung Kim William A. Goddard III Roman Efremov Jér?me Golebiowski 《Cellular and molecular life sciences : CMLS》2012,69(24):4205-4213
The molecular features that dominate the binding mode of agonists by a broadly tuned olfactory receptor are analyzed through a joint approach combining cell biology, calcium imaging, and molecular modeling. The odorant/receptor affinities, estimated through statistics accrued during molecular dynamics simulations, are in accordance with the experimental ranking. Although in many systems receptors recognize their target through a network of oriented interactions, such as H-bonding, the binding by broadly tuned olfactory receptors is dominated by non-polar terms. We show how such a feature allows chemicals belonging to different chemical families to similarly activate the receptors through compensations of interactions within the binding site. 相似文献
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E. Sick N. Niederhoffer K. Takeda Y. Landry J.-P. Gies 《Cellular and molecular life sciences : CMLS》2009,66(7):1271-1282
Mast cells play pivotal roles in allergic and inflammatory processes via distinct activation pathways. Mucosal and serosal mast cells are activated by the IgE/FcɛRI pathway, while only serosal mast
cells are activated by basic secretagogues. We show that CD47 receptors are expressed on rat peritoneal mast cells. 4N1K,
a peptide agonist of CD47, rapidly caused exocytosis. Such exocytosis required increased intracellular calcium and was inhibited
by pertussis toxin and an antibody against the βγ dimer of a Gi protein. Cooperation with integrins and glycosylphosphatidylinositol-anchored proteins was necessary, since anti-integrin
antibodies and pretreatment with phosphatidylinositol-phospholipase C reduced exocytosis. Depletion of membrane cholesterol
inhibited exocytosis and decreased CD47 in lipid rafts, consistent with a CD47/integrin/Gi protein complex being located in rafts. An anti-CD47 antibody inhibited exocytosis induced by 4N1K and by mastoparan and
spermine, suggesting that basic secretagogues might target CD47. We propose that 4N1K-stimulated mast cell exocytosis involves
a CD47/integrin/Gi protein complex.
Received 8 December 2008; received after revision 12 January 2009; accepted 29 January 2009 相似文献
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The proteins DnaK (hsp70) and GroEL (cpn60) from Escherichia coli are prototypes of two classes of molecular chaperones conserved throughout evolution. The analysis of transferred nuclear Overhauser effects in two-dimensional NMR spectra is ideally suited to determine chaperone-bound conformations of peptides. The peptide vsv-C (amino-acid sequence KLIGVLSSLFRPK) stimulates the ATPase of BiP and Hsc70 (ref. 3) and the intrinsic ATPase of DnaK. The affinity of the vsv-C peptide for DnaK is greatly reduced in the presence of ATP. Here we analyse transferred nuclear Overhauser effects and show that the peptide is in an extended conformation while bound to DnaK but is helical when bound to GroEL. NMR also indicates that the mobility of the peptide backbone is reduced more by binding to DnaK than by binding to GroEL, whereas the side chains are less mobile when bound to GroEL. 相似文献
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