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The role of silicon (Si) in alleviating the effects of biotic and abiotic stresses, including defence against insect herbivores, in plants is widely reported. Si defence against insect herbivores is overwhelmingly studied in grasses (especially the cereals), many of which are hyper-accumulators of Si. Despite being neglected, legumes such as soybean (Glycine max) have the capacity to control Si accumulation and benefit from increased Si supply. We tested how Si supplementation via potassium, sodium or calcium silicate affected a soybean pest, the native budworm Helicoverpa punctigera Wallengren (Lepidoptera: Noctuidae). Herbivory reduced leaf biomass similarly in Si-supplemented (+Si) and non-supplemented (–Si) plants (c. 29 and 23%, respectively) relative to herbivore-free plants. Both Si supplementation and herbivory increased leaf Si concentrations. In relative terms, herbivores induced Si uptake by c. 19% in both +Si and –Si plants. All Si treatments reduced H. punctigera relative growth rates (RGR) to a similar extent for potassium (−41%), sodium (−49%) and calcium (−48%) silicate. Moreover, there was a strong negative correlation between Si accumulation in leaves and herbivore RGR. To our knowledge, this is only the second report of Si-based herbivore defence in soybean; the rapid increase in leaf Si following herbivory being indicative of an induced defence. Taken together with the other benefits of Si supplementation of legumes, Si could prove an effective herbivore defence in legumes as well as grasses.
In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.
Rectal colonization with multidrug-resistant Enterobacteriaceae was found in 23 of 94 consecutively enrolled international patients hospitalized at Mayo Clinic, Rochester, Minnesota. No carbapenemase producers were detected. Twenty-one isolates were extended-spectrum β-lactamase-producing Escherichia coli. Colonization was associated with gastrointestinal disease and central venous catheter placement within the antecedent year.
Introduction
Plant-mediated indirect interactions between phytophagous insects
There is increasing interest in the consequences of indirect interactions for community structure and function (Wootton 1994). Herbivory by one phytophagous species has the potential to affect other herbivores exploiting the same plant, hence plants are able to mediate indirect interactions between organisms that exploit them, even if these organisms are spatially or temporally separated (Masters and Brown 1997). For example, root-feeding herbivores may impact on the performance of foliar feeding insects (Gange and Brown 1989, Masters and Brown 1992), while herbivores feeding early in the season affect the growth and development of those feeding later (West 1985, Harrison and Karban 1986). Many such interactions are mediated by damage-induced changes in the chemical composition of the shared host plant (Hartley and Jones 1997, Karban and Baldwin 1997), particularly increases in secondary compounds (Hartley and Lawton 1987, Haukioja et al. 1990), but there are also cases where alterations in the nutrient levels within the host explain the impact of one insect herbivore on another (McClure 1980, Denno et al. 2000). Thus both changes in nutrient and in secondary compounds have been associated with detrimental effects on other phytophagous insects and may underpin competitive indirect interactions between herbivores (Denno et al. 1995).
The importance of competitive interactions between phytophagous insects has been re-evaluated in recent years.
Thermal properties of a number of new Ca-based bulk metallic glasses are reported and discussed here. The compositional range of the new metallic glasses follows the formula:
CaA(Y,Ln)B(Mg,Sn)C(Ga,Zn,Al,Ag)D(Cu,Ni)E,
where A ranges from 0.40 to 0.70, B = 0 to 0.25, C = 0 to 0.25, D = 0 to 0.35, E = 0 to 0.35, A+B+C+D+E=1, and Ln represents the La group elements. The alloys have been developed based on specific criteria predicted from Senkov-Miracle topological and thermodynamic models for metallic glass formation, which narrow the compositional range for searching new metallic glasses.
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