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Spatial heterogeneity in species composition constrains plant community responses to herbivory and fertilisation
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![点击此处可从《Ecology letters》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dorothee Hodapp Elizabeth T. Borer W. Stanley Harpole Eric M. Lind Eric W. Seabloom Peter B. Adler Juan Alberti Carlos A. Arnillas Jonathan D. Bakker Lori Biederman Marc Cadotte Elsa E. Cleland Scott Collins Philip A. Fay Jennifer Firn Nicole Hagenah Yann Hautier Oscar Iribarne Johannes M. H. Knops Rebecca L. McCulley Andrew MacDougall Joslin L. Moore John W. Morgan Brent Mortensen Kimberly J. La Pierre Anita C. Risch Martin Schütz Pablo Peri Carly J. Stevens Justin Wright Helmut Hillebrand 《Ecology letters》2018,21(9):1364-1371
Environmental change can result in substantial shifts in community composition. The associated immigration and extinction events are likely constrained by the spatial distribution of species. Still, studies on environmental change typically quantify biotic responses at single spatial (time series within a single plot) or temporal (spatial beta diversity at single time points) scales, ignoring their potential interdependence. Here, we use data from a global network of grassland experiments to determine how turnover responses to two major forms of environmental change – fertilisation and herbivore loss – are affected by species pool size and spatial compositional heterogeneity. Fertilisation led to higher rates of local extinction, whereas turnover in herbivore exclusion plots was driven by species replacement. Overall, sites with more spatially heterogeneous composition showed significantly higher rates of annual turnover, independent of species pool size and treatment. Taking into account spatial biodiversity aspects will therefore improve our understanding of consequences of global and anthropogenic change on community dynamics. 相似文献
154.
This investigation examined the hypothesis that acute heavy resistance exercise (AHRE) would increase overnight concentrations of circulating human growth hormone (hGH). Ten men (22 +/- 1 yr, 177 +/- 2 cm, 79 +/- 3 kg, 11 +/- 1% body fat) underwent two overnight blood draws sampled every 10 min from 1700 to 0600: a control and an AHRE condition. The AHRE was conducted from 1500 to 1700 and was a high-volume, multiset exercise bout. Three different immunoassays measured hGH concentrations: the Nichols immunoradiometric assay (Nichols IRMA), National Institute of Diabetes and Digestive and Kidney Diseases radioimmunoassay (NIDDK RIA), and the Diagnostic Systems Laboratory immunofunctional assay (DSL IFA). The Pulsar peak detection system was used to evaluate the pulsatility profile characteristics of hGH. Maximum hGH was lower in the exercise (10.7 microg/l) vs. the control (15.4 microg/l) condition. Mean pulse amplitude was lower in the exercise vs. control condition when measured by the Nichols IRMA and the DSL IFA. A differential pattern of release was also observed after exercise in which hGH was lower in the first half of sleep but higher in the second half. We conclude that AHRE does influence the temporal pattern of overnight hGH pulsatility. Additionally, because of the unique molecular basis of the DSL IFA, this influence does have biological relevance because functionally intact molecules are affected. 相似文献
155.
Nimodipine confers clinical improvement in two models of experimental autoimmune encephalomyelitis
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![点击此处可从《Journal of neurochemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jens Ingwersen Lorenzo De Santi Britta Wingerath Jonas Graf Barbara Koop Reiner Schneider Christina Hecker Friederike Schröter Mary Bayer Anna Dorothee Engelke Michael Dietrich Philipp Albrecht Hans‐Peter Hartung Pasquale Annunziata Orhan Aktas Tim Prozorovski 《Journal of neurochemistry》2018,146(1):86-98
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M Kraemer R Tournaire V Dejong N Montreau D Briane C Derbin B Binétruy 《Cell growth & differentiation》1999,10(3):193-200
The comparative tumorigenicity in rats and nude mice of cell lines derived from FR3T3 and transformed by either c-jun, ras, SV40 lt, or bovine papilloma virus type 1 (BPV1) oncogenes was investigated. c-Jun-transformed cells were as tumorigenic and metastatic as Ras-transformed cells. Latencies were short, and numerous pulmonary metastases were observed in all injected animals. In contrast, tumors induced by s.c. injection of SV40-transformed cells developed slower, and none of the animals who received injections i.v. presented with metastases. BPV1-transformed cells had an intermediate tumorigenic and metastatic activity. Microvessels present in the different tumors were revealed by immunostaining with Griffonia (Bandeiraea) Simplicifolia lectin 1. Tumors obtained with c-Jun-transformed cells exhibited more neovascularization than those induced by the other oncogenes. By comparison to FR3T3 cells or SV40- or BPV1-transformed cells, c-Jun-transformed fibroblasts repress the antiangiogenic thrombospondin-1 and SPARC genes, whereas we found that they express higher levels of gene expression of the angiogenic vascular endothelial growth factor. Finally, as compared with cells before passage in animals, thrombospondin-1, SPARC, and VEGF gene expression was also deregulated in cell lines isolated from primary tumors induced by BPV1-transformants. Our results indicate that the high transforming potential of c-Jun, evidenced as soon as transformation is established in vitro, correlates with deregulation of gene expression of both angiogenic and antiangiogenic factors leading to rapid neovascularization of tumors. 相似文献
160.
The Gag Domains Required for Avian Retroviral RNA Encapsidation Determined by Using Two Independent Assays
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![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Eun-gyung Lee Ashly Yeo Brian Kraemer Marvin Wickens Maxine L. Linial 《Journal of virology》1999,73(8):6282-6292
The Rous sarcoma virus (RSV) Gag precursor polyprotein is the only viral protein which is necessary for specific packaging of genomic RNA. To map domains within Gag which are important for packaging, we constructed a series of Gag mutations in conjunction with a protease (PR) active-site point mutation in a full-length viral construct. We found that deletion of either the matrix (MA), the capsid (CA), or the protease (PR) domain did not abrogate packaging, although the MA domain is likely to be required for proper assembly. A previously characterized deletion of both Cys-His motifs in RSV nucleocapsid protein (NC) reduced both the efficiency of particle release and specific RNA packaging by 6- to 10-fold, consistent with previous observations that the NC Cys-His motifs played a role in assembly and RNA packaging. Most strikingly, when amino acid changes at Arg 549 and 551 immediately downstream of the distal NC Cys-His box were made, RNA packaging was reduced by more than 25-fold with no defect in particle release, demonstrating the importance of this basic amino acid region in packaging. We also used the yeast three-hybrid system to study avian retroviral RNA-Gag interactions. Using this assay, we found that the interactions of the minimal packaging region (Mpsi) with Gag are of high affinity and specificity. Using a number of Mpsi and Gag mutants, we have found a clear correlation between a reporter gene activation in a yeast three-hybrid binding system and an in vivo packaging assay. Our results showed that the binding assay provides a rapid genetic assay of both RNA and protein components for specific encapsidation. 相似文献