Ultramafic geoecology of South and Southeast Asia

Globally, ultramafic outcrops are renowned for hosting floras with high levels of endemism, including plants with specialised adaptations such as nickel or manganese hyperaccumulation. Soils derived from ultramafic regoliths are generally nutrient-deficient, have major cation imbalances, and have concomitant high concentrations of potentially phytotoxic trace elements, especially nickel. The South and Southeast Asian region has the largest surface occurrences of ultramafic regoliths in the world, but the geoecology of these outcrops is still poorly studied despite severe conservation threats. Due to the paucity of systematic plant collections in many areas and the lack of georeferenced herbarium records and databased information, it is not possible to determine the distribution of species, levels of endemism, and the species most threatened. However, site-specific studies provide insights to the ultramafic geoecology of several locations in South and Southeast Asia. The geoecology of tropical ultramafic regions differs substantially from those in temperate regions in that the vegetation at lower elevations is generally tall forest with relatively low levels of endemism. On ultramafic mountaintops, where the combined forces of edaphic and climatic factors intersect, obligate ultramafic species and hyperendemics often occur. Forest clearing, agricultural development, mining, and climate change-related stressors have contributed to rapid and unprecedented loss of ultramafic-associated habitats in the region. The geoecology of the large ultramafic outcrops of Indonesia’s Sulawesi, Obi and Halmahera, and many other smaller outcrops in South and Southeast Asia, remains largely unexplored, and should be prioritised for study and conservation

Root foraging and avoidance in hyperaccumulator and excluder plants: a rhizotron experiment

Aims: Metal hyperaccumulation is a rare phenomenon described for an increasing number of plant taxa. In this study we investigated the root growth responses of the well-known nickel, zinc, cadmium hyperaccumulator Noccaea caerulescens and of the metal tolerant (non-accumulator) Stellaria media, in order to observe root foraging vs avoidance responses to nickel. Methods: To allow for observations of root growth and foraging preferences, two accessions of Noccaea caerulescens and two accessions of Stellaria media orginating from high nickel and low nickel habitats were grown in rhizotrons with localized nickel enrichment. Results: The root density in the control and nickel-enriched soil areas in the rhizotrons with different N. caerulescens accessions had distinct responses: moderate nickel avoidance was recorded for the non-nickel accession, while a clear foraging response was observed in N. caerulescens from the nickel accession. In contrast, nickel rooting avoidance was observed for both S. media accessions and was more pronounced in the non-nickel accession. Conclusions: This study shows that N. caerulescens originating from different accessions responded differently to soil nickel enrichment, with the nickel accession of N. caerulescens actively foraging for nickel, suggesting a physiological adaptation and demand for this metal. In contrast, a clear nickel avoidance response by a metal tolerant species, S. media, was observed in this study, a phenomenon which has not been previously described; this suggests that root avoidance responses might play a role in the adaptation of metal tolerant species to Ni-rich soils

Asymptomatic LV Dysfunction and Heart Failure: Neurohumeral and metabolic aspects of Pharmacological intervention

Heart failure is a clinical syndrome, which develops as a result of impaired function of the heart. The response of the body to impaired cardiac function includes cardiac and extra cardiac factors, like cardiac remodeling, structural and functional changes in peripheral skeletal muscle and neurohumoral activation. The latter involves increased levels of catecholamines, activation of the renin-angiotensin system, release of ANP, aldosterone and vasopressin and plays a central role in regulating constriction of the peripheral circulation and causes structural and functional changes in the vascular waH, modulation of water and salt retention and sympathetic tone, thus influencing hemodynamic changes. The activated neurohonnones have both vasodilating and vasoconstrictive action and growth modulating and promoting actions

Highly frequent infections with human rhinovirus in healthy young children: A longitudinal cohort study

AbstractBackgroundHuman rhinoviruses (HRVs) are an important cause of respiratory tract infections.ObjectivesWe questioned whether the high prevalence rates of HRVs found in epidemiological studies is due to long-term individual continuity or a result of frequent infections with different HRV subtypes.Study designIn a 6-month winter period 18 healthy controls, aged 0–7 years, were at least sampled every two weeks for HRV-PCR, irrespective of respiratory symptoms. All HRV positive samples were genotyped to determine HRV diversity.ResultsIn total 272 samples were collected. HRV was found in 101/272 (37%) samples. Genotyping revealed 27 different HRV subtypes. A median of 3.0 different HRV subtypes was found per child. Re-infections and continuity with identical HRV sequences were observed. The number of HRVs were higher in the youngest age group (p=0.01) and they had more different HRV subtypes (p=0.05) compared to oldest age group.ConclusionsWe found a high HRV exposition with a considerable diverse population of HRV subtypes in young children. These results have major implications for future research into the pathogenic role of HRV in respiratory diseases. Characterisation of subtypes will be necessary to discriminate between prolonged continuity and re-infections in patients with respiratory diseases

Priming of plant innate immunity by rhizobacteria and beta-aminobutyric acid: differences and similarities in regulation

P>Pseudomonas fluorescens WCS417r bacteria and beta-aminobutyric acid can induce disease resistance in Arabidopsis, which is based on priming of defence. In this study, we examined the differences and similarities of WCS417r- and beta-aminobutyric acid-induced priming. Both WCS417r and beta-aminobutyric acid prime for enhanced deposition of callose-rich papillae after infection by the oomycete Hyaloperonospora arabidopsis. This priming is regulated by convergent pathways, which depend on phosphoinositide- and ABA-dependent signalling components. Conversely, induced resistance by WCS417r and beta-aminobutyric acid against the bacterial pathogen Pseudomonas syringae are controlled by distinct NPR1-dependent signalling pathways. As WCS417r and beta-aminobutyric acid prime jasmonate- and salicylate-inducible genes, respectively, we subsequently investigated the role of transcription factors. A quantitative PCR-based genome-wide screen for putative WCS417r- and beta-aminobutyric acid-responsive transcription factor genes revealed distinct sets of priming-responsive genes. Transcriptional analysis of a selection of these genes showed that they can serve as specific markers for priming. Promoter analysis of WRKY genes identified a putative cis-element that is strongly over-represented in promoters of 21 NPR1-dependent, beta-aminobutyric acid-inducible WRKY genes. Our study shows that priming of defence is regulated by different pathways, depending on the inducing agent and the challenging pathogen. Furthermore, we demon-strated that priming is associated with the enhanced expression of transcription factors. New Phytologist (2009) 183: 419-431doi: 10.1111/j.1469-8137.2009.02851.x

The 3^3He(e, e′'d)p Reaction in qω\omega-constant Kinematics

The cross section for the $^3$He(e, e$'$d)p reaction has been measured as a function of the missing momentum $p_m$ in q$\omega$ -constant kinematics at beam energies of 370 and 576 MeV for values of the three-momentum transfer $q$ of 412, 504 and 604 \mevc. The L(+TT), T and LT structure functions have been separated for $q$ = 412 and 504 \mevc. The data are compared to three-body Faddeev calculations, including meson-exchange currents (MEC), and to calculations based on a covariant diagrammatic expansion. The influence of final-state interactions and meson-exchange currents is discussed. The $p_m$-dependence of the data is reasonably well described by all calculations. However, the most advanced Faddeev calculations, which employ the AV18 nucleon-nucleon interaction and include MEC, overestimate the measured cross sections, especially the longitudinal part, and at the larger values of $q$. The diagrammatic approach gives a fair description of the cross section, but under(over)estimates the longitudinal (transverse) structure function.Comment: 17 pages, 7 figure