Bursts, rays, and jets     

Rowan L  Coontz R 《Science (New York, N.Y.)》2001,291(5501):65

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HOMING,MIGRATION AND INSTINCT     

Rowan W 《Science (New York, N.Y.)》1945,102(2643):210-211

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The Arabidopsis circadian clock incorporates a cADPR-based feedback loop     

Dodd AN  Gardner MJ  Hotta CT  Hubbard KE  Dalchau N  Love J  Assie JM  Robertson FC  Jakobsen MK  Gonçalves J  Sanders D  Webb AA 《Science (New York, N.Y.)》2007,318(5857):1789-1792

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Nest inheritance is the missing source of direct fitness in a primitively eusocial insect     

Leadbeater E  Carruthers JM  Green JP  Rosser NS  Field J 《Science (New York, N.Y.)》2011,333(6044):874-876

Animals that cooperate with nonrelatives represent a challenge to inclusive fitness theory, unless cooperative behavior is shown to provide direct fitness benefits. Inheritance of breeding resources could provide such benefits, but this route to cooperation has been little investigated in the social insects. We show that nest inheritance can explain the presence of unrelated helpers in a classic social insect model, the primitively eusocial wasp Polistes dominulus. We found that subordinate helpers produced more direct offspring than lone breeders, some while still subordinate but most after inheriting the dominant position. Thus, while indirect fitness obtained through helping relatives has been the dominant paradigm for understanding eusociality in insects, direct fitness is vital to explain cooperation in P. dominulus.  相似文献   

Medulloblastoma growth inhibition by hedgehog pathway blockade     

Berman DM  Karhadkar SS  Hallahan AR  Pritchard JI  Eberhart CG  Watkins DN  Chen JK  Cooper MK  Taipale J  Olson JM  Beachy PA 《Science (New York, N.Y.)》2002,297(5586):1559-1561

Constitutive Hedgehog (Hh) pathway activity is associated with initiation of neoplasia, but its role in the continued growth of established tumors is unclear. Here, we investigate the therapeutic efficacy of the Hh pathway antagonist cyclopamine in preclinical models of medulloblastoma, the most common malignant brain tumor in children. Cyclopamine treatment of murine medulloblastoma cells blocked proliferation in vitro and induced changes in gene expression consistent with initiation of neuronal differentiation and loss of neuronal stem cell-like character. This compound also caused regression of murine tumor allografts in vivo and induced rapid death of cells from freshly resected human medulloblastomas, but not from other brain tumors, thus establishing a specific role for Hh pathway activity in medulloblastoma growth.  相似文献   

beta -Helical polymers from isocyanopeptides     

Cornelissen JJ  Donners JJ  de Gelder R  Graswinckel WS  Metselaar GA  Rowan AE  Sommerdijk NA  Nolte RJ 《Science (New York, N.Y.)》2001,293(5530):676-680

Polymerization of isocyanopeptides results in the formation of high molecular mass polymers that fold in a proteinlike fashion to give helical strands in which the peptide chains are arranged in beta-sheets. The beta-helical polymers retain their structure in water and unfold in a cooperative process at elevated temperatures. The peptide architecture in these polymers is a different form of the beta-helix motif found in proteins. Unlike their natural counterparts, which contain arrays of large beta-sheets stacked in a helical fashion, the isocyanopeptide polymers have a central helical core that acts as a director for the beta-sheet-like arrangement of the peptide side arms. The helical structure of these isocyanopeptide polymers has the potential to be controlled through tailoring of the side branches and the hydrogen-bonding network present in the beta-sheets.  相似文献   

Acknowledgements     

Joe Wisniewski  R. Neil Sampson 《Water, air, and soil pollution》1993,70(1-4):xii-xii

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Experimental closure of footpaths in a woodland national nature reserve in Scotland     

Neil G. Bayfield  Graham M. Bathe 《Biological conservation》1982,22(3):229-237

Visitors' reactions to six types of path barrier were recorded both by observation and by means of a questionnaire survey. ‘Natural’ barriers such as logs or branches were not very effective. A plank with notice was the most efficient barrier, and also the type most preferred by visitors. Barbed wire was effective but disliked by visitors. Few people objected to the closure of paths. Children and bird watchers took less notice of barriers than did other categories of visitors.  相似文献   

Multi-parameter fingerprinting of sediment deposition in a small gullied catchment in SE Australia   总被引：4，自引：0，他引：4  

A. K. Krause  S. W. Franks  J. D. Kalma  R. J. Loughran  J. S. Rowan 《CATENA》2003,53(4):327-348

The determination of relative contributions of potential sediment sources is an important step in the development of management strategies to combat soil erosion. In a 1.2 km² gullied catchment in southeastern New South Wales, multi-parameter fingerprinting of sediment deposited in successive downstream pools has identified gully walls as the dominant sediment source when the grazed pasture surface was the only other potential source. The median fractional contributions remained relatively steady in the successive downstream pools, with the gully walls responsible for between 90% and 98% of the pool sediment. This result was achieved despite the ratio of the source areas varying considerably between successive nested subareas. Reliability bounds on the predictions, accounting for limited sampling of sources, were well constrained and varied between 5.4% and 13.8%. Downstream of an unsealed road crossing, sediment from the road source dominated the pool sediments such that contributions from the pasture surface and gully sources could not be determined.  相似文献   

Mechanisms of Gastrointestinal Ischemia-Reperfusion Injury and Potential Therapeutic Interventions: A Review and Its Implications in the Horse   总被引：2，自引：0，他引：2  

Rustin M. Moore  William W. Muir  D. Neil Granger 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1995,9(3):115-132

Restoration of blood flow after a period of intestinal ischemia is necessary to maintain cell function and viability; however, the reintroduction of oxygen can initiate a cascade of events that exacerbates tissue injury. Intestinal I-R injury is manifested as increased microvascular and mucosal permeability, and mucosal necrosis. Reperfusion injury begins with the accumulation of hypoxanthine from ATP metabolism and the conversion of XDH to XO during ischemia. Upon reperfusion, the XO catalyzes the conversion of hypoxanthine to superoxide radicals in the presence of oxygen. Superoxide radicals are further reduced to highly reactive hydroxyl radicals, which initiate lipid peroxidation. Lipoperoxidation causes functional and structural alterations in cell membrane lipids and can release numerous inflammatory mediators, which exacerbate tissue damage. Neutrophils are recruited into tissues during ischemia and on reperfusion; then they undergo degranulation and release destructive products (proteases and OFRs), which mediate further tissue injury. A limited number of experimental studies in the gastrointestinal tract of horses have shown I-R injury. Additional studies are necessary to further elucidate and sequence the precise pathophysiologic mechanisms occuring in the equine intestine during I-R. Therapy should be focused on prevention of I-R injury by pharmacologic or chemical inhibition or modification of these pathophysiologic pathways. Selected pharmacologic agents or drug combinations may offer novel, scientifically relevant and yet practical approaches to alleviating intestinal I-R injury in horses. This may improve survival of horses with naturally acquired intestinal strangulation obstruction.  相似文献