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251.
252.
Hongbing Sun Allison Brown Jorge Coppen Paul Steblein 《Wetlands Ecology and Management》2007,15(1):63-79
This multi-year study evaluated the response of invasive Phragmites australis to changes in pore water geochemistry associated with tidal enhancement, alone or in combination with other prescribed management
regimes used by the US Fish and Wildlife Service. A pilot study was conducted prior to the treatment experiment that showed
a negative correlation between the growth of Phragmites and cation concentrations in a transitional vegetation zone. In the targeted 535-acre brackish-water impoundment (East Pool)
where Phragmites dominated, the soil water chemistry was changed by introducing tidal salt water through water control structures in June
of 1999. Soil profiles, pH, salinity and cation concentration data in addition to Phragmites height and density data were collected both before and after the treatments were imposed, where possible. It was generally
observed that a soil water salinity above ∼28 would be needed to maintain the reduction of Phragmites and to support its replacement by salt marsh species. In the tidal water manipulated experimental macroplots, the soil water
salinity changed from 7.1 to 32 on average between 1999 and 2001. The reduction of the average height of Phragmites ranged from 25% to 84% for different treatment combinations, while untreated sites exhibited a slight increases in height.
The reduction in average live density ranged from 51% to 87% for different treatment combinations. The greatest reduction
of Phragmites density and height resulted when tidal enhancement was followed by a prescribed burn in the winter. Also, significant negative
correlations were observed between Phragmites height and the main cations associated with tidal salt water including Mg2+, Na+ and K+ and to a lesser extent Ca2+. pH did not change drastically with the introduction of tidal water over the period of 1999–2001 and did not appear to play
a significant role in changing the growth of Phragmites. A reduction of soil adhesiveness associated with the decay of Phragmites roots was observed after a two month period in 2001 when plants were submerged in standing water. This points to the need
to maintain tidal exchange to promote a gradual transition from a Phragmites-dominated system to a Spartina-dominated system. Towards the end of the growing season in 2001, Spartina patens and Distichlis spicata had begun to ramify into the center of the island patches. 相似文献
253.
Soil Organic Phosphorus Transformations During Pedogenesis 总被引:2,自引:0,他引:2
Benjamin L. Turner Leo M. Condron Sarah J. Richardson Duane A. Peltzer Victoria J. Allison 《Ecosystems》2007,10(7):1166-1181
Abstract
Long-term changes in soil phosphorus influence ecosystem development and lead to a decline in the productivity of forests
in undisturbed landscapes. Much of the soil phosphorus occurs in a series of organic compounds that differ in their availability
to organisms, but changes in the relative abundance of these compounds during pedogenesis remain unknown. We used alkaline
extraction and solution phosphorus-31 nuclear magnetic resonance spectroscopy to assess the chemical nature of soil organic
phosphorus along a 120,000-year post-glacial chronosequence at Franz Josef, New Zealand. Inositol phosphates, DNA, phospholipids,
and phosphonates accumulated rapidly during the first 500 years of soil development characterized by nitrogen limitation of
biological productivity, but then declined slowly to low concentrations in older soils characterized by intense phosphorus
limitation. However, the relative contribution of the various compounds to the total organic phosphorus varied along the sequence
in dramatic and surprising ways. The proportion of inositol hexakisphosphate, conventionally considered to be relatively recalcitrant
in the environment, declined markedly in older soils, apparently due to a corresponding decline in amorphous metal oxides,
which weather to crystalline forms during pedogenesis. In contrast, the proportion of DNA, considered relatively bioavailable
in soil, increased continually throughout the sequence, due apparently to incorporation within organic structures that provide
protection from biological attack. The changes in soil organic phosphorus coincided with marked shifts in plant and microbial
communities, suggesting that differences in the forms and bioavailability of soil organic phosphorus have ecological significance.
Overall, the results strengthen our understanding of phosphorus transformations during pedogenesis and provide important insight
into factors regulating the composition of soil organic phosphorus. 相似文献
254.
Matthew B. Dugas Susannah R. Halbrook Allison M. Killius Jillian F. del Sol Corinne L. Richards‐Zawacki 《Ethology : formerly Zeitschrift fur Tierpsychologie》2015,121(8):813-822
The phenomenon of aposematism, or the pairing of antipredator defence with conspicuous or distinctive signals, serves as an excellent example of how traits act in concert to shape fitness. Not only does this complex phenotype require the integration of multiple traits, it alters the fitness pay‐offs of yet others. The protection offered by aposematism may, for example, reduce the costs associated with foraging or sexual display. Thus, well‐protected aposematic lineages should be bolder, more active and less likely to respond to perceived threats of predation than more cryptic lineages. Comparisons of differently coloured morphs of the polytypic strawberry poison frog (Oophaga pumilio) have supported the predicted behavioural correlates of aposematism, with the exception of those regarding responsiveness to simulated predators. We tested the key prediction that aposematic coloration will be associated with reduced sensitivity to predators in two polymorphic O. pumilio populations. The novel approach of studying polymorphic populations allowed us to assess the effect of colour in the absence of potentially confounding habitat differences. We found that colour was associated with the probability that a frog would attempt escape and the distance at which it fled, but only in one population, and not in the predicted direction. An overall comparison of the two populations superficially supported our predictions, but this pattern actually arose because frogs occupying higher perches were less likely to respond, a pattern that may reflect the value of high perches and the costs associated with returning to them after attempted escape. These results highlight the complexity of the relationship between predators and prey, the challenges associated with understanding how and why traits are correlated, and the intimate ties between behaviour and morphological evolution. 相似文献
255.
Pulsed light is a nonthermal processing technology recognized by the FDA for killing microorganisms on food surfaces, with cumulative fluences up to 12 J cm−2. In this study, we investigated its efficacy for inactivating murine norovirus 1 (MNV-1) as a human norovirus surrogate in phosphate-buffered saline, hard water, mineral water, turbid water, and sewage treatment effluent and on food contact surfaces, including high-density polyethylene, polyvinyl chloride, and stainless steel, free or in an alginate matrix. The pulsed-light device emitted a broadband spectrum (200 to 1,000 nm) at a fluence of 0.67 J cm−2 per pulse, with 2% UV at 8 cm beneath the lamp. Reductions in viral infectivity exceeded 3 log10 in less than 3 s (5 pulses; 3.45 J cm−2) in clear suspensions and on clean surfaces, even in the presence of alginate, and in 6 s (11 pulses; 7.60 J cm−2) on fouled surfaces except for stainless steel (2.6 log10). The presence of protein or bentonite interfered with viral inactivation. Analysis of the morphology, the viral proteins, and the RNA integrity of treated MNV-1 allowed us to elucidate the mechanisms involved in the antiviral activity of pulsed light. Pulsed light appeared to disrupt MNV-1 structure and degrade viral protein and RNA. The results suggest that pulsed-light technology could provide an effective alternative means of inactivating noroviruses in wastewaters, in clear beverages, in drinking water, or on food-handling surfaces in the presence or absence of biofilms. 相似文献
256.
Zhixiang Tong Aniruddh Solanki Allison Hamilos Oren Levy Kendall Wen Xiaolei Yin Jeffrey M Karp 《The EMBO journal》2015,34(8):987-1008
Derived from any somatic cell type and possessing unlimited self-renewal and differentiation potential, induced pluripotent stem cells (iPSCs) are poised to revolutionize stem cell biology and regenerative medicine research, bringing unprecedented opportunities for treating debilitating human diseases. To overcome the limitations associated with safety, efficiency, and scalability of traditional iPSC derivation, expansion, and differentiation protocols, biomaterials have recently been considered. Beyond addressing these limitations, the integration of biomaterials with existing iPSC culture platforms could offer additional opportunities to better probe the biology and control the behavior of iPSCs or their progeny in vitro and in vivo. Herein, we discuss the impact of biomaterials on the iPSC field, from derivation to tissue regeneration and modeling. Although still exploratory, we envision the emerging combination of biomaterials and iPSCs will be critical in the successful application of iPSCs and their progeny for research and clinical translation. 相似文献
257.
258.
Dalil Hannani Marie Vétizou David Enot Sylvie Rusakiewicz Nathalie Chaput David Klatzmann Melanie Desbois Nicolas Jacquelot Nadège Vimond Salem Chouaib Christine Mateus James P Allison Antoni Ribas Jedd D Wolchok Jianda Yuan Philip Wong Michael Postow Andrzej Mackiewicz Jacek Mackiewicz Dirk Schadendorff Dirk Jaeger Alan J Korman Keith Bahjat Michele Maio Luana Calabro Michele WL Teng Mark J Smyth Alexander Eggermont Caroline Robert Guido Kroemer Laurence Zitvogel 《Cell research》2015,25(2):208-224
The cytotoxic T lymphocyte antigen-4 (CTLA-4)-blocking antibody ipilimumab induces immune-mediated long-term control of metastatic melanoma in a fraction of patients. Although ipilimumab undoubtedly exerts its therapeutic effects via immunostimulation, thus far clinically useful, immunologically relevant biomarkers that predict treatment efficiency have been elusive. Here, we show that neutralization of IL-2 or blocking the α and β subunits of the IL-2 receptor (CD25 and CD122, respectively) abolished the antitumor effects and the accompanying improvement of the ratio of intratumoral T effector versus regulatory cells (Tregs), which were otherwise induced by CTLA-4 blockade in preclinical mouse models. CTLA-4 blockade led to the reduction of a suppressive CD4+ T cell subset expressing Lag3, ICOS, IL-10 and Egr2 with a concomitant rise in IL-2-producing effector cells that lost FoxP3 expression and accumulated in regressing tumors. While recombinant IL-2 improved the therapeutic efficacy of CTLA-4 blockade, the decoy IL-2 receptor α (IL-2Rα, sCD25) inhibited the anticancer effects of CTLA-4 blockade. In 262 metastatic melanoma patients receiving ipilimumab, baseline serum concentrations of sCD25 represented an independent indicator of overall survival, with high levels predicting resistance to therapy. Altogether, these results unravel a role for IL-2 and IL-2 receptors in the anticancer activity of CTLA-4 blockade. Importantly, our study provides the first immunologically relevant biomarker, namely elevated serum sCD25, that predicts resistance to CTLA-4 blockade in patients with melanoma. 相似文献
259.
Dongmei Cheng Allison Weckerle Yi Yu Lijun Ma Xuewei Zhu Mariana Murea Barry I. Freedman John S. Parks Gregory S. Shelness 《Journal of lipid research》2015,56(8):1583-1593
Two APOL1 gene variants, which likely evolved to protect individuals from African sleeping sickness, are strongly associated with nondiabetic kidney disease in individuals with recent African ancestry. Consistent with its role in trypanosome killing, the pro-death APOL1 protein is toxic to most cells, but its mechanism of cell death is poorly understood and little is known regarding its intracellular trafficking and secretion. Because the liver appears to be the main source of circulating APOL1, we examined its secretory behavior and mechanism of toxicity in hepatoma cells and primary human hepatocytes. APOL1 is poorly secreted in vitro, even in the presence of chemical chaperones; however, it is efficiently secreted in wild-type transgenic mice, suggesting that APOL1 secretion has specialized requirements that cultured cells fail to support. In hepatoma cells, inducible expression of APOL1 and its risk variants promoted cell death, with the G1 variant displaying the highest degree of toxicity. To explore the basis for APOL1-mediated cell toxicity, endoplasmic reticulum stress, pyroptosis, autophagy, and apoptosis were examined. Our results suggest that autophagy represents the predominant mechanism of APOL1-mediated cell death. Overall, these results increase our understanding of the basic biology and trafficking behavior of circulating APOL1 from the liver. 相似文献
260.
Considering species richness and rarity when selecting optimal survey traps: comparisons of semiochemical baited flight intercept traps for Cerambycidae in eastern North America
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Kevin J. Dodds Jeremy D. Allison Daniel R. Miller Ryan P. Hanavan Jon Sweeney 《Agricultural and Forest Entomology》2015,17(1):36-47
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