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Dr. Rosemarie Wolfram 《Journal of pest science》1952,25(5):73-75
Ohne Zusammenfassung 相似文献
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Climate trends and global crop production since 1980 总被引:14,自引:0,他引:14
Efforts to anticipate how climate change will affect future food availability can benefit from understanding the impacts of changes to date. We found that in the cropping regions and growing seasons of most countries, with the important exception of the United States, temperature trends from 1980 to 2008 exceeded one standard deviation of historic year-to-year variability. Models that link yields of the four largest commodity crops to weather indicate that global maize and wheat production declined by 3.8 and 5.5%, respectively, relative to a counterfactual without climate trends. For soybeans and rice, winners and losers largely balanced out. Climate trends were large enough in some countries to offset a significant portion of the increases in average yields that arose from technology, carbon dioxide fertilization, and other factors. 相似文献
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Nahuel Fittipaldi Troy E. Fuller Janet F. Teel Thomas L. Wilson Thaddeus J. Wolfram David E. Lowery Marcelo Gottschalk 《Veterinary microbiology》2009,139(3-4):310-317
Streptococcus suis is an important swine pathogen and a zoonotic agent. Differences in virulence have been noted among the 33 described serotypes, serotype 2 being considered the most virulent. In this study, we aimed at assessing the serotype distribution and the production of virulence-associated markers by strains recovered from diseased pigs in the United States (U.S.). Results showed that among the 100 strains evaluated, serotype 3 (20% of the isolates) and serotype 2 (17%) were the most prevalent. We then investigated the presence in these isolates of the genes sly, epf and mrp, encoding the virulence-associated markers suilysin (SLY), extracellular factor (EF) and muramidase-released (MRP) protein, respectively. The effective production of the markers by the strains was also verified. Results showed that the presence of the gene did not always correlate with actual expression of the respective protein. In the case of MRP, this was due, in most cases, to frameshift mutations at the 5′ end of the gene resulting in premature stop codons. The most prevalent phenotypes among U.S. strains were MRP+EF−SLY− (40%) and MRP−EF−SLY+ (35%). Serotype distribution greatly differed from that reported in several European countries, as did the production of virulence markers, particularly for serotype 2. On the other hand, our results for the U.S. S. suis isolates are similar to those reported for Canadian strains, suggesting a common status in North America. 相似文献
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Correlations between leaf abscisic acid concentration ([ABA]), stomatal conductance (gs), rate of stomatal opening in response to an increase in leaf water potential (si), shoot hydraulic conductance (L) and photosynthetic characteristics were examined in saplings of six temperate deciduous tree species: Acer platanoides L., Padus avium Mill., Populus tremula L., Quercus robur L., Salix caprea L. and Tilia cordata Mill. Species-specific values of foliar [ABA] were negatively related to the mean values of gs, si, L and light- and CO2- saturated net photosynthesis (P(max)), thus providing strong correlative evidence of a scaling of foliar gas exchange and hydraulic characteristics with leaf endogenous [ABA]. In addition, we suggest that mean gs, si, L and Pmax for mature leaves may partly be determined by the species-specific [ABA] during leaf growth. The most drought-intolerant species had the lowest [ABA] and the highest gs, suggesting that interspecific differences in [ABA] may be linked to differences in species-specific water-use efficiency. Application of high concentrations of exogenous ABA led to large decreases in gs, si and P(max), further underscoring the direct role of ABA in regulating stomatal opening and photosynthetic rate. Exogenous ABA also decreased L, but the decreases were considerably smaller than the decreases in gs, si and Pmax. Thus, exogenous ABA predominantly affected the stomata directly, but modification of L by ABA may also be an important mechanism of ABA action. We conclude that interspecific variability in endogenous [ABA] during foliage growth and in mature leaves provides an important factor explaining observed differences in L, gs, si and Pmax among temperate deciduous tree species. 相似文献
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Recombination of human mitochondrial DNA 总被引:1,自引:0,他引:1
Kraytsberg Y Schwartz M Brown TA Ebralidse K Kunz WS Clayton DA Vissing J Khrapko K 《Science (New York, N.Y.)》2004,304(5673):981
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The influence of the VAM fungi Glomus macrocarpum and G. manihotis on shoot dry weight and P contents in the shoots of various graminaceous species was studied in pot culture experiments. The treatments included fertilization with different rock phosphates, four soil pH levels (pH 4.5, 5.5, 6.5, 7.5) and four soil temperatures (20, 25, 30, 35°C). The rock phosphate treatments were compared with soluble phosphate (mono calcium phosphate, MCP) and with a check (no P fertilizer, OP). Increases of shoot dry weight up to 143% could be found with mycorrhizal Triticum aestivum using Kodjari rock phosphate as P source. In the presence of VAM, Sorghum bicolor and T. aestivum fertilized with any of the rock phosphates, except Kola, produced yields comparable with those of plants fertilized with MCP, at soil pH 5.5 to 7.5 and at 25°C soil temperature. As the soil pH increased from 5.5 to 7.5 dry weight declined. Likewise, yields decreased with increasing soil temperature and at 35°C VAM showed no effect in all treatments. 相似文献