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Davis, CA, United States

Brennan J.C.,University of California at Davis | Denison M.S.,University of California at Davis | Holstege D.M.,University of California at Davis | Magiatis P.,National and Kapodistrian University of Athens | And 4 more authors.
BMC Complementary and Alternative Medicine | Year: 2013

Background: The plant genus Fallopia is well-known in Chinese traditional medicine and includes many species that contain bioactive compounds, namely phytoestrogens. Consumption of phytoestrogens may be linked to decreased incidence of breast and prostate cancers therefore discovery of novel phytoestrogens and novel sources of phytoestrogens is of interest. Although phytoestrogen content has been analyzed in the rhizomes of various Fallopia sp., seeds of a Fallopia sp. have never been examined for phytoestrogen presence.Methods: Analytical chemistry techniques were used with guidance from an in vitro estrogen receptor bioassay (a stably transfected human ovarian carcinoma cell line) to isolate and identify estrogenic components from seeds of Fallopia convolvulus. A transiently transfected human breast carcinoma cell line was used to characterize the biological activity of the isolated compounds on estrogen receptors (ER) α and β.Results: Two compounds, emodin and the novel flavan-3-ol, (-)-epiafzelechin-3-O-p-coumarate (rhodoeosein), were identified to be responsible for estrogenic activity of F. convolvulus seed extract. Absolute stereochemistry of rhodoeosein was determined by 1 and 2D NMR, optical rotation and circular dichroism. Emodin was identified by HPLC/DAD, LC/MS/MS, and FT/ICR-MS. When characterizing the ER specificity in biological activity of rhodoeosein and emodin, rhodoeosein was able to exhibit a four-fold greater relative estrogenic potency (REP) in breast cells transiently-transfected with ERβ as compared to those transfected with ERα, and emodin exhibited a six-fold greater REP in ERβ-transfected breast cells. Cell type-specific differences were observed with rhodoeosein but not emodin; rhodoeosein produced superinduction of reporter gene activity in the human ovarian cell line (> 400% of maximum estradiol [E2] induction) but not in the breast cell line.Conclusion: This study is the first to characterize the novel flavan-3-ol compound, rhodoeosein, and its ability to induce estrogenic activity in human cell lines. Rhodoeosein and emodin may have potential therapeutic applications as natural products activating ERβ, and further characterization of rhodoeosein is necessary to evaluate its selectivity as a cell type-specific ER agonist. © 2013 Brennan et al.; licensee BioMed Central Ltd. Source

Kesich A.,One Shields Avenue
Journal of Physics: Conference Series | Year: 2012

Thermal suppression of quarkonium production in heavy-ion collisions, due to Debye screening of the quark-antiquark potential, has been proposed as a clear signature of quark-gluon plasma (QGP) formation. At RHIC energies, the γ meson is a clean probe of the early system thanks to negligible levels of enhancement from bb̄ recombination and non-thermal suppression from co-mover absorption. We report on our measurement of the γ → e +e- cross section in Au+Au collisions at √s NN=200 GeV. We compute the Nuclear Modification Factor by comparing these results to p+p collisions. In order to have a complete assessment of both hot and cold nuclear matter effects on Upsilon production we also report on results from d+Au collisions. Source

Greco B.J.,One Shields Avenue | Brown T.K.,California State University, San Marcos | Andrews J.R.M.,San Diego Zoo Global | Swaisgood R.R.,San Diego Zoo Global | Caine N.G.,California State University, San Marcos
Animal Cognition | Year: 2013

Social learning is a more efficient method of information acquisition and application than trial and error learning and is prevalent across a variety of animal taxa. Social learning is assumed to be important for elephants, but evidence in support of that claim is mostly anecdotal. Using a herd of six adult female African bush elephants (Loxodonta africana africana) at the San Diego Zoo's Safari Park, we evaluated whether viewing a conspecific's interactions facilitated learning of a novel task. The tasks used feeding apparatus that could be solved in one of two distinct ways. Contrary to our hypothesis, the method the demonstrating animal used did not predict the method used by the observer. However, we did find evidence of social learning: After watching the model, subjects spent a greater percentage of their time interacting with the apparatus than they did in unmodeled trials. These results suggest that the demonstrations of a model may increase the motivation of elephants to explore novel foraging tasks. © 2012 Springer-Verlag Berlin Heidelberg. Source

Dyer A.R.,University of South Carolina | Hardison J.L.,One Shields Avenue | Rice K.J.,University of California at Davis
Plant Ecology | Year: 2012

Seasonal resource availability may act as a constraint on plant phenology and thereby influence the range of growth responses observed among populations of annual species, especially those occupying a wide range of environments. We compared a mesic and a xeric population of the non-native, annual grass, Bromus tectorum, to examine phenology in response to interspecific competition and water availability. Using a target-neighborhood approach, we assessed how phenological patterns of the two populations affected morphological and growth responses to enhanced resource availability represented by late-season soil moisture. The xeric population exhibited a highly constrained phenology and was unable to extend the growing season despite available soil resources. Because of the low phenotypic variation, allocation to reproduction was similar across resource conditions. In contrast, the mesic population flowered later and showed a more opportunistic phenology in response to late-season water availability. The mesic population was not able to maintain consistent reproductive allocation at low resource levels. The responses of the two populations to late-season water availability were not affected by the density of neighboring plants. We suggest that post-introduction selection pressure on B. tectorum in the xeric habitat has resulted in a more fixed phenology which limits opportunistic response to unpredictable, particularly late-season resource availability. Opportunistic and fixed responses represent contrasting strategies for optimizing fitness in temporally varying environments and, while both play important roles for ensuring reproductive success, these results suggest that local adaptation to temporal resource variation may reflect a balance between flexible and inflexible phenology. © 2011 Springer Science+Business Media B.V. Source

Lu J.,One Shields Avenue | Aydin C.,One Shields Avenue | Liang A.J.,Chevron | Chen C.-Y.,Chevron | And 4 more authors.
ACS Catalysis | Year: 2012

Zeolite HSSZ-53, which has 1-dimensional channels with 14-ring extra-large pores, was used as a support for a molecular iridium complex synthesized from Ir(C 2H 4) 2(C 5H 7O 2) and characterized with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and atomic-resolution aberration-corrected scanning transmission electron microscopy (STEM). The spectra show that Ir(C 2H 4) 2(C 5H 7O 2) reacted readily with the bridging OH groups of the zeolite, leading to the removal of C 5H 7O 2 ligands and the formation of mononuclear Ir(C 2H 4) 2 complexes bonded to the zeolite by Ir-O bonds at the framework aluminum sites. STEM images confirm the spectra, showing site-isolated iridium centers within the zeolite channels, with no evidence of iridium clusters. The samples constitute a highly uniform, well-defined array of essentially molecular catalytic species in a highly uniform, confined environment, allowing precise investigations of the chemistry of the iridium complex in the absence of solvents. IR spectra show that the supported Ir(C 2H 4) 2 complexes were converted to Ir(C 2H 5) 2, Ir(CO) 2, Ir(CO)(C 2H 4), and Ir(CO)(C 2H 4) 2 as various mixtures of H 2, CO, and C 2H 4 reacted with the sample. The sample was tested as a catalyst for ethylene hydrogenation and for H-D exchange in the reaction of H 2 + D 2. The data, combined with results reported for isostructural iridium complexes bonded to zeolite HY and to MgO, demonstrate how the catalytic activity can be tuned by choice of the support, with the support being characterized as a ligand with electron-donating or electron-withdrawing properties. The results demonstrate that the rate of ethylene hydrogenation catalyzed by the supported iridium complexes is limited by H 2 activation when the iridium is electron rich (on the MgO support), whereas the rate-limiting step is C 2H 4 adsorption when the iridium is electron deficient (on either zeolite support). © 2012 American Chemical Society. Source

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