1,032 research outputs found
Phosphorus supply affects seedling growth of mycorrhizal but not cluster-root forming jarrah-forest species
Aims
Fertiliser is often used to kick-start ecological restoration despite growing evidence of the potentially negative impacts on plant diversity. Jarrah (Eucalyptus marginata) forest species growing on nutrient (especially phosphorus) impoverished soils in southwestern Australia have a suite of adaptations for phosphorus (P) acquisition, including the formation of cluster roots, and associations with mycorrhizal fungi. Here we investigated how escalating P supply, along with a stoichiometric adjustment of nitrogen (N) supply, impacted the growth and nutrition of a wide range of jarrah forest seedlings.
Methods
In a pot experiment, we measured seedling biomass and nutritional responses of 12 jarrah forest species to a gradient of P supply in relation to N supply, and for the mycorrhizal species, inoculation with arbuscular mycorrhizal fungi.
Results
Three cluster-root forming species did not respond to increasing P, probably because they were reliant on seed P. Generally, mycorrhizal species showed a positive biomass response to increasing P when N was available. Mycorrhizas benefited seedling growth at low P (9 mg P added per kg of jarrah forest soil) when N was also available, and were parasitic to seedling growth at high P (243 mg P/ kg soil) without additional N.
Conclusions
These results highlight importance of P and N supply in determining the nature of the symbiosis between plants and mycorrhizal fungi. Since P supply has the potential to reduce plant growth, for a range of species, our results suggest careful consideration of fertiliser amounts for ecological restoration of ecosystems adapted to nutrient poor soils
Metrizability of Clifford topological semigroups
We prove that a topological Clifford semigroup is metrizable if and only
if is an -space and the set of idempotents of is
a metrizable -set in . The same metrization criterion holds also
for any countably compact Clifford topological semigroup .Comment: 4 page
Role of Tyk-2 in Th9 and Th17 cells in allergic asthma.
In a murine model of allergic asthma, we found that Tyk-2((-/-)) asthmatic mice have induced peribronchial collagen deposition, mucosal type mast cells in the lung, IRF4 and hyperproliferative lung Th2 CD4(+) effector T cells over-expressing IL-3, IL-4, IL-5, IL-10 and IL-13. We also observed increased Th9 cells expressing IL-9 and IL-10 as well as T helper cells expressing IL-6, IL-10 and IL-21 with a defect in IL-17A and IL-17F production. This T helper phenotype was accompanied by increased SOCS3 in the lung of Tyk-2 deficient asthmatic mice. Finally, in vivo treatment with rIL-17A inhibited local CD4(+)CD25(+)Foxp3(+) T regulatory cells as well as Th2 cytokines without affecting IL-9 in the lung. These results suggest a role of Tyk-2 in different subsets of T helper cells mediated by SOCS3 regulation that is relevant for the treatment of asthma, cancer and autoimmune diseases
Chiral Dynamics of Low-Energy Kaon-Baryon Interactions with Explicit Resonance
The processes involving low energy and interactions (where
or ) are studied in the framework of heavy baryon chiral
perturbation theory with the (1405) resonance appearing as an
independent field.
The leading and next-to-leading terms in the chiral expansion are taken into
account. We show that an approach which explicitly includes the (1405)
resonance as an elementary quantum field gives reasonable descriptions of both
the threshold branching ratios and the energy dependence of total cross
sections.Comment: 16 pages, 6 figure
Appraising the Effectiveness of a Simple Evaluational Approach to Problems of Retardation and Behavior in Childhood
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67035/2/10.1177_000992287201100921.pd
Density Functional Theory for a Confined Fermi System with Short-Range Interaction
Effective field theory (EFT) methods are applied to density functional theory
(DFT) as part of a program to systematically go beyond mean-field approaches to
medium and heavy nuclei. A system of fermions with short-range, natural
interactions and an external confining potential (e.g., fermionic atoms in an
optical trap) serves as a laboratory for studying DFT/EFT. An effective action
formalism leads to a Kohn-Sham DFT by applying an inversion method
order-by-order in the EFT expansion parameter. Representative results showing
the convergence of Kohn-Sham calculations at zero temperature in the local
density approximation (LDA) are compared to Thomas-Fermi calculations and to
power-counting estimates.Comment: 36 pages, 20 figures, RevTeX
- …