Browsing by Subject "Populus"

Now showing 1 - 4 of 4
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    3-Acyl dihydroflavonols from poplar resins collected by honey bees are active against the bee pathogens Paenibacillus larvae and Ascosphaera apis
    (Elsevier, 2017) Wilson, Michael B.; Pawlus, Alison D.; Brinkman, Doug; Gardner, Gary; Hegeman, Adrian D.; Spivak, Marla; Cohen, Jerry D.
    Honey bees, Apis mellifera, collect antimicrobial plant resins from the environment and deposit them in their nests as propolis. This behavior is of practical concern to beekeepers since the presence of propolis in the hive has a variety of benefits, including the suppression of disease symptoms. To connect the benefits that bees derive from propolis with particular resinous plants, we determined the identity and botanical origin of propolis compounds active against bee pathogens using bioassay-guided fractionation against the bacterium Paenibacillus larvae, the causative agent of American foulbrood. Eleven dihydro-flavonols were isolated from propolis collected in Fallon, NV, including pinobanksin-3-octanoate. This hitherto unknown derivative and five other 3-acyl-dihydroflavonols showed inhibitory activity against both P. larvae (IC50 ¼ 17e68 mM) and Ascosphaera apis (IC50 ¼ 8e23 mM), the fungal agent of chalkbrood. A structure-activity relationship between acyl group size and antimicrobial activity was found, with longer acyl groups increasing activity against P. larvae and shorter acyl groups increasing activity against A. apis. Finally, it was determined that the isolated 3-acyl-dihydroflavonols originated from Populus fremontii, and further analysis showed these compounds can also be found in other North American Populus spp.
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    POPGROW : a model for Populus coppice stand development.
    (University of Minnesota, 1983-01) Lenarz, J. E.; Ek, Alan R.
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    Resource assessment and analysis of aspen-dominated ecosystems in the Lake States.
    (2010-08) Domke, Grant Michael
    Utilization of renewable resources for energy in the United States has increased substantially over the past decade. These increases have been driven by energy policy aimed at reducing dependence on foreign oil, boosting economic development, and curbing fossil fuel emissions. In recent years, state governments have passed laws mandating further reductions in energy consumption and greenhouse gas emissions, and increases in energy conservation and use of renewables. Such legislation and pending federal action has led to renewed interest in the use of forest-derived biomass for energy production. There are a variety of sources of forest-derived biomass in the Lake States and much debate over the carbon costs or benefits associated with the utilization of this material for energy. The aspen forest type is dominated by the most commercially utilized tree species in the region (Populus tremuloides and to a much lesser extent, P. grandidentata and P. balsamifera) and occupies more than 10 million acres of timberland in Michigan, Minnesota, and Wisconsin. Aspen is a short-lived, fast-growing tree species, which typically regenerates from adventitious suckers following harvest or stand-replacing disturbance, making it ideally suited for biomass production. This dissertation describes: 1) the status and trends of aspen-dominated ecosystems in the Lake States, 2) an analysis of biomass production potential in native and hybrid aspen communities in northern Minnesota, 3) a model framework for the estimation of carbon flows associated with the procurement and utilization of harvest residues for energy, and 4) the development of a spreadsheet-based model for rapid estimation of biomass availability.