304 research outputs found
Micropropagation Of Agapanthus Umbellatus Var. Minor By Using Two Systems Of Multiplication
For conventional micropropagation methods, semisolidified medium (SM) is used; the use of this medium requires intense manipulation of the cultures and skilled labor. Systems that use liquid medium show equal or better efficiency of the multiplication process, besides reducing the cost for the elimination of agar. In this study, we evaluated the mass propagation of Agapanthus umbellatus var. minor two in vitro multiplication systems (SM system and temporary immersion system [SIT]). The plant material was grown in MS medium supplemented with 6-benzylaminopurine (6-BA; 0.0, 8.9, 17.8, and 35.6 μM). The data obtained in this study demonstrate that the two systems used were efficient for the multiplication phase of this species. However, we recommend SIT in view of its reuse in the process of multiplication and rooting. Moreover, simple construction, low cost of the culture medium, and low cost of the bioreactors and the fact that agar is not required qualify this system as an efficient alternative for large-scale micropropagation of Agapanthus umbellatus var. minor. We recommend 17.8 μM 6-BA for the SM system and 8.9 μM 6-BA for SIT.3752923293
Partial characterization and anticoagulant activity of a heterofucan from the brown seaweed Padina gymnospora
The brown algae Padina gymnospora contain different fucans. Powdered algae were submitted to proteolysis with the proteolytic enzyme maxataze. The first extract of the algae was constituted of polysaccharides contaminated with lipids, phenols, etc. Fractionation of the fucans with increasing concentrations of acetone produced fractions with different proportions of fucose, xylose, uronic acid, galactose, and sulfate. One of the fractions, precipitated with 50% acetone (v/v), contained an 18-kDa heterofucan (PF1), which was further purified by gel-permeation chromatography on Sephadex G-75 using 0.2 M acetic acid as eluent and characterized by agarose gel electrophoresis in 0.05 M 1,3 diaminopropane/acetate buffer at pH 9.0, methylation and nuclear magnetic resonance spectroscopy. Structural analysis indicates that this fucan has a central core consisting mainly of 3-ß-D-glucuronic acid 1-> or 4-ß-D-glucuronic acid 1 ->, substituted at C-2 with alpha-L-fucose or ß-D-xylose. Sulfate groups were only detected at C-3 of 4-alpha-L-fucose 1-> units. The anticoagulant activity of the PF1 (only 2.5-fold lesser than low molecular weight heparin) estimated by activated partial thromboplastin time was completely abolished upon desulfation by solvolysis in dimethyl sulfoxide, indicating that 3-O-sulfation at C-3 of 4-alpha-L-fucose 1-> units is responsible for the anticoagulant activity of the polymer.Universidade Federal do Rio Grande do Norte Departamento de Bioquímica Laboratório de GlicobiologiaUniversidade Federal do Rio Grande do Norte Departamento de Bioquímica Laboratório de Biotecnologia de Polímeros NaturaisUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de BioquímicaUNIFESP, EPM, Depto. de BioquímicaSciEL
Open charm production in relativistic nucleus-nucleus collisions
We calculate excitation functions for open charm mesons in reactions
from AGS to RHIC energies within the HSD transport approach which is based on
string, quark, diquark () and hadronic degrees
of freedom. The open charm cross sections from and reactions are
fitted to results from PYTHIA and scaled in magnitude to the available
experimental data. From our dynamical calculations we find an approximate
-scaling for pions, kaons, -mesons and -- when discarding
final state elastic scattering of kaons and -mesons with pions -- in
central collisions of at 160 AGeV (with an apparent slope of
176 MeV) without employing the assumption of a Quark-Gluon Plasma (QGP). We
demonstrate that this result is essentially due to a relative -scaling in
collisions at 17.3 GeV. At lower bombarding energies of
25 AGeV a suppression of -mesons by a factor of 10 relative to
a global -scaling with slope 143 MeV is expected. However, when
incorporating attractive -meson self energies as suggested by QCD sum rules,
an approximate -scaling is regained even at 25 AGeV. The effects of
-meson rescattering and charmonium absorption are discussed, furthermore,
with respect to rapidity and transverse mass distributions in central
collisions of at 25, 160 AGeV and 21.3 ATeV.Comment: 46 pages, LaTeX, including 19 postscript figures, to be published in
Nucl. Phys.
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
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