963 research outputs found
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HORMESIS AND A CHEMICAL RAISON DâEÌTRE FOR SECONDARY PLANT METABOLITES
In plants, accumulation in specific compartments and huge structural diversity of secondary metabolites is one trait that is not understood yet. By exploring the diverse abiotic and biotic interactions of plants above- and belowground, we provide examples that are characterized by nonlinear effects of the secondary metabolites. We propose that redox chemistry, specifically the reduction of reactive oxygen species (ROS) and, in their absence, reduction of molecular oxygen by the identical secondary metabolite, is an important component of the hormetic effects caused by these compounds. This is illustrated for selected phenols, terpenoids, and alkaloids. The redox reactions are modulated by the variable availability of transition metals that serve as donors of electrons in a Fenton reaction mode. Low levels of ROS stimulate growth, cell differentiation, and stress resistance; high levels induce programmed cell death. We propose that provision of molecules that can participate in this redox chemistry is the raison dâeÌtre for secondary metabolites. In this context, the presence or absence of functional groups in the molecule is more essential than the whole structure. Accordingly, there exist no constraints that limit structural diversity. Redox chemistry is ubiquitous, from the atmosphere to the soil
The NMDA antagonist ketamine and the 5-HT agonist psilocybin produce dissociable effects on structural encoding of emotional face expressions
Rationale: Both glutamate and serotonin (5-HT) play a key role in the pathophysiology of emotional biases. Recent studies indicate that the glutamate N-methyl-d-aspartate (NMDA) receptor antagonist ketamine and the 5-HT receptor agonist psilocybin are implicated in emotion processing. However, as yet, no study has systematically compared their contribution to emotional biases. Objectives: This study used event-related potentials (ERPs) and signal detection theory to compare the effects of the NMDA (via S-ketamine) and 5-HT (via psilocybin) receptor system on non-conscious or conscious emotional face processing biases. Methods: S-ketamine or psilocybin was administrated to two groups of healthy subjects in a double-blind within-subject placebo-controlled design. We behaviorally assessed objective thresholds for non-conscious discrimination in all drug conditions. Electrophysiological responses to fearful, happy, and neutral faces were subsequently recorded with the face-specific P100 and N170 ERP. Results: Both S-ketamine and psilocybin impaired the encoding of fearful faces as expressed by a reduced N170 over parieto-occipital brain regions. In contrast, while S-ketamine also impaired the encoding of happy facial expressions, psilocybin had no effect on the N170 in response to happy faces. Conclusion: This study demonstrates that the NMDA and 5-HT receptor systems differentially contribute to the structural encoding of emotional face expressions as expressed by the N170. These findings suggest that the assessment of early visual evoked responses might allow detecting pharmacologically induced changes in emotional processing biases and thus provides a framework to study the pathophysiology of dysfunctional emotional biase
Assessing the occurrence of the novel zoonotic variegated squirrel bornavirus 1 in captive squirrels in Germany âA prevalence study
The newly described zoonotic variegated squirrel bornavirus 1 (VSBVâ1) in German squirrel holdings has been associated with the death of three private owners and one zoo animal caretaker (confirmed cases). Epidemiological investigations were severely impeded by the general lack of data on holdings of the putative reservoir hosts, the family Sciuridae. To fill this lack of data for detailed epidemiological investigations of the captive squirrel population, a register of private and zoological squirrel holdings was established. The findings show a broad variety of kept species and their frequency distribution. By contacting the different stakeholders via Webâbased social groups and societies, information passed in both directions so that disease awareness could be raised and participants could be recruited for further studies. Crossâsectional studies revealed a prevalence of VSBVâ1âpositive subpopulations of 0% (95% CI 0%â6.2%) among private squirrel collections and 1.9% (95% CI: 0%â9.9%) among zoos in Germany. The approach presented here can be transferred to other populations of nonâtraditional pets, which may be equally difficult to monitor, in the case of an emerging zoonotic infectious disease.Peer Reviewe
Direct Observation and Anisotropy of the Contribution of Gap nodes in the Low Temperature Specific Heat of YBa_2Cu_3O_7
The specific heat due to line nodes in the superconducting gap of YBa2Cu3O7
has been obscured up to now by magnetic terms of extrinsic origin, even for
high quality crystals. We report the specific heat of a new single crystal
grown in a non-corrosive BaZrO3 crucible, for which paramagnetic terms are
reduced to less than one spin-1/2 center for 20'000 Cu atoms. The contribution
of line nodes shows up directly in the difference C(B,T) - C(0,T) at fixed
temperatures (T < 5 K) as a function of the magnetic field parallel to the
c-axis (B<=14 T). These data illustrate the smooth crossover from C propotional
to T^2 at low fields to C propotional to TB^1/2 at high fields, and provide new
values for gap parameters which are quantitatively consistent with tunneling
spectroscopy and thermal conductivity in the framework of dx^2-y^2 pairing
symmetry. Data for B along the nodal and antinodal directions in the ab-plane
are also provided. The in-plane anisotropy predicted in the clean limit is not
observed.Comment: 29 pages(using Revtex style), 14 postscript figures, submitted to
Phys. Rev. B Content of the file changed after replacin
Cadherin-11 localizes to focal adhesions and promotes cell-substrate adhesion
Cadherin receptors have a well-established role in cellâcell adhesion, cell polarization and differentiation. However, some cadherins also promote cell and tissue movement during embryonic development and tumour progression. In particular, cadherin-11 is upregulated during tumour and inflammatory cell invasion, but the mechanisms underlying cadherin-11 stimulated cell migration are still incompletely understood. Here, we show that cadherin-11 localizes to focal adhesions and promotes adhesion to fibronectin in Xenopus neural crest, a highly migratory embryonic cell population. Transfected cadherin-11 also localizes to focal adhesions in different mammalian cell lines, while endogenous cadherin-11 shows focal adhesion localization in primary human fibroblasts. In focal adhesions, cadherin-11 co-localizes with ÎČ1-integrin and paxillin and physically interacts with the fibronectin-binding proteoglycan syndecan-4. Adhesion to fibronectin mediated by cadherin-11/syndecan-4 complexes requires both the extracellular domain of syndecan-4, and the transmembrane and cytoplasmic domains of cadherin-11. These results reveal an unexpected role of a classical cadherin in cellâmatrix adhesion during cell migration
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Comparative selective retention of particle size classes in the gastrointestinal tract of ponies and goats
There is a discrepancy in the literature on potential digesta separation mechanisms in horses, with both a selective retention of fine and of large particles postulated in different publications. To assess the net effect of such mechanisms, we fed ponies on a hay-only diet a pulse dose of whole (unchopped) marked hay together with a solute marker, collected faeces on a regular basis, measured marker concentrations in whole faeces and in their large (2.0-16 mm), medium (0.5-1.0 mm) and small (0.063-0.25 mm) particle fraction, and calculated the corresponding mean retention times (MRT). For comparison, the same experiment was performed in goats. In goats, as expected, MRTsolute (35 h) was significantly shorter than MRTparticle (51 h); only a very small fraction of particle marker was excreted as large particles (2%); and the MRT of these large particles was significantly shorter than that of small particles (with a relevant difference of 8.6 h), indicating that those few large particles that escape the rumen do so mostly soon after ingestion. In ponies, MRTsolute (24 h) did not differ from MRTparticle (24 h); a higher fraction of particle marker was excreted as large particles (5%); and the MRT of these large particles was longer than that of small particles (but with a non-relevant difference of less than 1 h). These results indicate that no relevant net separation of digesta phases occurs in horses, and that selective particle retention mechanisms in the large intestine are unlikely to represent important characteristics of the horse's digestive physiology
Plant chemicals and the sexual behavior of male tephritid fruit flies
Plant compounds affect insects in many different ways. In addition to being a food source, plants also contain secondary metabolites that may have positive and negative impacts on insects. The influence of these compounds on sexual behavior, in particular, has been the focus of many recent studies. Here, we review the existing literature on the effects of plant compounds on the sexual behavior of tephritid fruit fly males. We put special focus on polyphagous species whose males congregate in leks, where females exert strong mate selection. We first summarize the main findings related to plant compounds that increase male signaling behavior and attraction of females and consequently increase mating frequency, a phenomenon that has been recorded mainly for species of Anastrepha and Ceratitis. In other tephritid species, males are attracted to phenylpropanoids produced by plants (such as methyl eugenol or raspberry ketone) that, upon encounter, are consumed and sequestered by males. These compounds, or metabolic derivatives, which normally have negligible nutritional value, are included in the pheromone and also confer advantages in a sexual context: enhanced female attraction and improved male mating success. These phenomena have been reported for several Bactrocera species as well as for Zeugodacus cucurbitae. Because many tephritid species are serious pests, the effect of plant compounds on male behavior has been explored for potential incorporation into control strategies such as the sterile insect technique (SIT). We conclude noting several factors, such as age and nutrition during larval and adult stage, that modulate the effect of plant compounds on male mating behavior as well as some prominent gaps that preclude a thorough understanding of the plant-mediated enhancement of male sexual performance and hence limit our ability to effectively utilize phytochemicals in pest control strategies.Instituto de GenĂ©ticaFil: Segura, Diego Fernando. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de GenĂ©tica. Laboratorio de GenĂ©tica de Insectos de Importancia EconĂłmica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Belliard, Silvina A. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de GenĂ©tica. Laboratorio de GenĂ©tica de Insectos de Importancia EconĂłmica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Vera, MarĂa Teresa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de TucumĂĄn. Facultad de AgronomĂa y Zootecnia; ArgentinaFil: Bachmann, Guillermo Enrique. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de GenĂ©tica. Laboratorio de GenĂ©tica de Insectos de Importancia EconĂłmica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Ruiz, MarĂa Josefina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de TucumĂĄn. Facultad de AgronomĂa y Zootecnia; ArgentinaFil: Jofre-Barud, Flavia. Instituto Nacional de TecnologĂa Agropecuaria (INTA). EstaciĂłn Experimental Agropecuaria San Juan; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: FernĂĄndez, Patricia. Instituto Nacional de TecnologĂa Agropecuaria (INTA). EstaciĂłn Experimental Agropecuaria Delta del ParanĂĄ; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Lopez, M. Liza. Instituto Nacional de TecnologĂa Agropecuaria (INTA). EstaciĂłn Experimental Agropecuaria San Juan; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Shelly, Todd E. United States Department of Agriculture. Animal and Plant Health Inspection Service; Estados Unido
Pulmonary artery to aorta ratio for the detection of pulmonary hypertension: cardiovascular magnetic resonance and invasive hemodynamics in heart failure with preserved ejection fraction
Performance of coiled tube ultraviolet reactors to inactivate Escherichia coli W1485 and Bacillus cereus endospores in raw cow milk and commercially processed skimmed cow milk
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