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Willow Trees (willow + tree)
Selected AbstractsCarbon-14 radiosynthesis of combretastatin A-1 (CA1) and its corresponding phosphate prodrug (CA1P)JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 14 2009Rodney T. Brown Abstract The natural product combretastatin A-1 (CA1) is isolated from the African bush willow tree, a member of the Combretaceae family. CA1 has important medicinal value, due in part to its ability to inhibit tubulin assembly. The prodrug combretastatin A-1 diphosphate (CA1P; OXi4503) is currently in human Phase I clinical trials as a vascular disrupting agent. This paper describes the carbon-14 radiosynthesis of [4,- 14C]CA1 and the corresponding phosphate prodrug salt [4,- 14C]CA1P in high specific activity (55,mCi/mmol). The carbon-14 label was introduced by methylation of the C-4, protected phenolic moiety of the CA1 precursor following removal of the tert -butyldimethylsilyl protecting group in the presence of [14C]methyl iodide. This was accomplished in excellent yield without significant Z to E isomerization. The [14C]-precursor ((Z)-1-[3,,[4,- 14C],5,-trimethoxyphenyl]-2-[2,,3,-di-[(isopropyl)oxy]-4,-methoxyphenyl] ethene) was subjected to a de- isopropylation reaction with TiCl4. The tetrabenzyl phosphate derivative of the resulting diol was prepared using fresh dibenzyl phosphite. Debenzylation with trimethylsilylbromide, followed by hydrolysis of the trimethylsilyl ester and adjustment of the pH with dilute aqueous hydrochloric acid yielded [4,- 14C]CA1P with an overall radiochemical yield of 8.4%. Copyright © 2009 John Wiley & Sons, Ltd. [source] The effects of the invasive Argentine ant (Linepithema humile) and the native ant Prenolepis imparis on the structure of insect herbivore communities on willow trees (Salix lasiolepis)ECOLOGICAL ENTOMOLOGY, Issue 6 2008JULIE P. NYGARD Abstract 1.,We examined the relative effects of the invasive Argentine ant, Linepithema humile, and a common native ant, Prenolepis imparis, on the community of herbivorous insects occurring on willow trees, Salix lasiolepis in Northern California, U.S.A. 2.,Using paired control and treatment branches from which we excluded ants and other non-volant predators, we found that effects of Argentine ants on the herbivore community were generally similar to those of P. imparis. Argentine ants and P. imparis suppressed the damage by skeletonising insects by 50%, but had little effect on most other external-feeding or internal-feeding guilds. 3.,The abundance of aphids was 100% greater in the presence of Argentine ants, but there was no effect on aphid numbers in the presence of P. imparis. Late season aphid numbers were substantially higher in the presence of Argentine ants, but not P. imparis. 4.,The effects of Argentine ants on skeletonising insects and aphids combined with the overwhelming abundance of Argentine ant workers, suggests that they may have substantial, but often overlooked, effects on the herbivore communities on other plant species in or near riparian habitats in which they invade. [source] Organic carbon biostimulates rapid rhizodegradation of perchlorateENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2008Dawit D. Yifru Abstract Previous hydroponics and field studies identified phytodegradation and rhizodegradation as the two main mechanisms by which plants metabolize perchlorate. Plant uptake and phytodegradation of perchlorate is a slower and undesired process that poses ecological risks resulting from phytoaccumulation of some fraction of the perchlorate. Meanwhile, rhizodegradation is a more rapid and favored process involving perchlorate-degrading bacteria utilizing dissolved organic carbon (DOC) as a carbon and energy (electron) source to rapidly degrade perchlorate to innocuous chloride. In the present study, rhizodegradation of perchlorate by willow trees (Salix nigra) was biostimulated using electron sources obtained from natural and artificial carbon sources. In bioreactors provided with carbon sources as 500 mg/L DOC, 25 to 40 mg/L of initial perchlorate concentrations were removed to below the ion chromatography method detection limit of 2 ,g/L in approximately 9 d. For planted controls provided with no electron donors, the time required for the complete removal of the same doses of perchlorate was up to 70 d. Enhancement of rhizodegradation by organic carbon reduced the phytoaccumulated fraction of perchlorate by an order of magnitude from approximately 430 to 20 mg/ kg. The implication of the present study is that the high fraction uptake and phytoaccumulation of perchlorate in agricultural products and the recycling of perchlorate into the ecosystem can be significantly curtailed by supplying electron donors derived from organic carbon sources to the root zone of plants. [source] The impact of the aphids Tuberolachnus salignus and Pterocomma salicis on willow treesANNALS OF APPLIED BIOLOGY, Issue 2 2001C MATILDA COLLINS Summary The effect of two species of stem-feeding aphid on the yield, phenology and water-use of soil-grown and hydroponic-cultured willow were investigated. The effects of Pterocomma salicis were less marked than those of Tuberolachnus salignus. The latter reduced not only the above and below-ground growth of trees made during and subsequent to infestation, but also altered the mass of previously developed woody tissue. The negative effects of T. salignus on the shoots and roots of established and establishing trees were drastic and were both quantitative and qualitative. They were also observed to reduce the survival of infested trees. P. salicis had negative effects on the growth of roots and shoots during infestation, but the influence of this species did not persist nor did it influence previous growth. [source] | ||||||||||