Porphyra: a marine crop shaped by stress Blouin, Nicolas A.; Brodie, Juliet A.; Grossman, Arthur C. ...
Trends in plant science,
2011, 2011-Jan, 2011-01-00, 20110101, Letnik:
16, Številka:
1
Journal Article
Recenzirano
The marine red alga
Porphyra is an important marine crop, worth ∼US$1.3 billion per year. Cultivation research now includes farm ecology, breeding, strain conservation and new net-seeding ...technologies. The success of cultivation is due, in part, to the high stress tolerance of
Porphyra. Many species of
Porphyra lose 85–95% of their cellular water during the daytime low tide, when they are also exposed to high light and temperature stress. Antioxidant and mycosporine-like amino acid activities have been partially characterized in
Porphyra, but, as we discuss here, the
Porphyra umbilicalis genome project will further elucidate proteins associated with stress tolerance. Furthermore, phylogenomic and transcriptomic investigations of
Porphyra sensu lato could elucidate tradeoffs made during physiological acclimation and factors associated with life-history evolution in this ancient lineage.
Allergic bronchopulmonary aspergillosis is a hypersensitivity disorder that can progress from an acute phase to chronic disease. The main treatment is systemic corticosteroids, but data from ...uncontrolled studies suggest that itraconazole, an orally administered antifungal agent, may be an effective adjunctive therapy.
We conducted a randomized, double-blind trial of treatment with either 200 mg of itraconazole twice daily or placebo for 16 weeks in patients who met immunologic and pulmonary-function criteria for corticosteroid-dependent allergic bronchopulmonary aspergillosis. A response was defined as a reduction of at least 50 percent in the corticosteroid dose, a decrease of at least 25 percent in the serum IgE concentration, and one of the following: an improvement of at least 25 percent in exercise tolerance or pulmonary-function tests or resolution or absence of pulmonary infiltrates. In a second, open-label part of the trial, all the patients received 200 mg of itraconazole per day for 16 weeks.
There were responses in 13 of 28 patients in the itraconazole group (46 percent), as compared with 5 of 27 patients in the placebo group (19 percent, P=0.04). The rate of adverse events was similar in the two groups. In the subsequent open-label phase, 12 of the 33 patients who had not had a response during the double-blind phase (36 percent) had responses, and none of the patients who had a response in the double-blind phase of the trial had a relapse.
For patients with corticosteroid-dependent allergic bronchopulmonary aspergillosis, the addition of itraconazole can lead to improvement in the condition without added toxicity.
Background: Inhaled corticosteroid therapy in severe persistent asthma has been shown to reduce or eliminate oral corticosteroid (OCS) use while retaining effective asthma control. Objective: We ...sought to evaluate the ability of mometasone furoate (MF) delivered by means of dry powder inhaler to reduce daily oral prednisone requirements in OCS-dependent patients with severe persistent asthma. Methods: We performed a 12-week, double-blind, placebocontrolled trial (21 centers, 132 patients) comparing 2 doses of MF (400 and 800 μg administered twice daily) with placebo, followed by a 9-month open-label phase in which 128 patients received treatment with MF. Results: At the endpoint of the double-blind trial, MF 400 and 800 mg twice daily reduced daily OCS requirements by 46.0% and 23.9%, respectively, whereas placebo increased OCS requirements by 164.4% (P < .01). Oral steroids were eliminated in 40%, 37%, and 0% of patients in the MF 400 and 800 mg twice daily and placebo groups, respectively. Pulmonary function and quality of life significantly increased for MF-treated patients. Further reductions in OCS requirements were achieved with long-term MF treatment in the open-label phase. Conclusion: MF inhaled orally as a dry powder is an effective alternative to systemic corticosteroids in patients with severe persistent asthma. (J Allergy Clin Immunol 2000;106:852-60.)
We present a new approximation to ionic conductivity well suited to dynamical atomic-scale simulations, based on the Nernst-Einstein equation. In our approximation, ionic aggregates constitute the ...elementary charge carriers, and are considered as noninteracting species. This approach conveniently captures the dominant effect of ion-ion correlations on conductivity, short range interactions in the form of clustering. In addition to providing better estimates to the conductivity at a lower computational cost than exact approaches, this new method allows us to understand the physical mechanisms driving ion conduction in concentrated electrolytes. As an example, we consider Li^{+} conduction in poly(ethylene oxide), a standard solid-state polymer electrolyte. Using our newly developed approach, we are able to reproduce recent experimental results reporting negative cation transference numbers at high salt concentrations, and to confirm that this effect can be caused by a large population of negatively charged clusters involving cations.
The global decline of reef-building corals is due in part to the loss of algal symbionts, or “bleaching,” during the increasingly frequent periods of high seawater temperatures 1, 2. During ...bleaching, endosymbiotic dinoflagellate algae (Symbiodinium spp.) either are lost from the animal tissue or lose their photosynthetic pigments, resulting in host mortality if the Symbiodinium populations fail to recover 3. The >1,000 studies of the causes of heat-induced bleaching have focused overwhelmingly on the consequences of damage to algal photosynthetic processes 4–6, and the prevailing model for bleaching invokes a light-dependent generation of toxic reactive oxygen species (ROS) by heat-damaged chloroplasts as the primary trigger 6–8. However, the precise mechanisms of bleaching remain unknown, and there is evidence for involvement of multiple cellular processes 9, 10. In this study, we asked the simple question of whether bleaching can be triggered by heat in the dark, in the absence of photosynthetically derived ROS. We used both the sea anemone model system Aiptasia 11, 12 and several species of reef-building corals to demonstrate that symbiont loss can occur rapidly during heat stress in complete darkness. Furthermore, we observed damage to the photosynthetic apparatus under these conditions in both Aiptasia endosymbionts and cultured Symbiodinium. These results do not directly contradict the view that light-stimulated ROS production is important in bleaching, but they do show that there must be another pathway leading to bleaching. Elucidation of this pathway should help to clarify bleaching mechanisms under the more usual conditions of heat stress in the light.
•Light is not required for bleaching of corals and other cnidarians•Bleaching under heat stress is due to a loss of algae and not a loss of pigments•Heat alone, without light, can damage the photosynthetic apparatus
Understanding the dynamical processes that govern the performance of functional materials is essential for the design of next generation materials to tackle global energy and environmental ...challenges. Many of these processes involve the dynamics of individual atoms or small molecules in condensed phases, e.g. lithium ions in electrolytes, water molecules in membranes, molten atoms at interfaces, etc., which are difficult to understand due to the complexity of local environments. In this work, we develop graph dynamical networks, an unsupervised learning approach for understanding atomic scale dynamics in arbitrary phases and environments from molecular dynamics simulations. We show that important dynamical information, which would be difficult to obtain otherwise, can be learned for various multi-component amorphous material systems. With the large amounts of molecular dynamics data generated every day in nearly every aspect of materials design, this approach provides a broadly applicable, automated tool to understand atomic scale dynamics in material systems.
Solid polymer electrolytes (SPEs) are considered promising building blocks of next-generation lithium-ion batteries due to their advantages in safety, cost, and flexibility. However, current SPEs ...suffer from a low ionic conductivity, motivating the development of novel highly conductive SPE materials. Here we propose a new SPE design approach that integrates coarse-grained molecular dynamics (CGMD) with machine learning. A continuous high-dimensional design space, composed of physically interpretable universal descriptors, was constructed by the coarse graining of chemical species. A Bayesian optimization (BO) algorithm was then employed to efficiently explore this space via autonomous CGMD simulations. Adopting this CGMD-BO approach, we obtained comprehensive descriptions of the relationships between the lithium conductivity and intrinsic material properties at the molecular level, such as the molecule size and nonbonding interaction strength, to provide guidance on directions to improve upon the components of the best-known electrolytes, including anion, secondary site, and backbone chain.
In cnidarian-Symbiodiniaceae symbioses, algal endosymbiont population control within the host is needed to sustain a symbiotic relationship. However, the molecular mechanisms that underlie such ...population control are unclear. Here we show that a cnidarian host uses nitrogen limitation as a primary mechanism to control endosymbiont populations. Nitrogen acquisition and assimilation transcripts become elevated in symbiotic Breviolum minutum algae as they reach high-densities within the sea anemone host Exaiptasia pallida. These same transcripts increase in free-living algae deprived of nitrogen. Symbiotic algae also have an elevated carbon-to-nitrogen ratio and shift metabolism towards scavenging nitrogen from purines relative to free-living algae. Exaiptasia glutamine synthetase and glutamate synthase transcripts concomitantly increase with the algal endosymbiont population, suggesting an increased ability of the host to assimilate ammonium. These results suggest algal growth and replication in hospite is controlled by access to nitrogen, which becomes limiting for the algae as their population within the host increases.
Photosynthetic organisms provide food and energy for nearly all life on Earth, yet half of their protein-coding genes remain uncharacterized
. Characterization of these genes could be greatly ...accelerated by new genetic resources for unicellular organisms. Here we generated a genome-wide, indexed library of mapped insertion mutants for the unicellular alga Chlamydomonas reinhardtii. The 62,389 mutants in the library, covering 83% of nuclear protein-coding genes, are available to the community. Each mutant contains unique DNA barcodes, allowing the collection to be screened as a pool. We performed a genome-wide survey of genes required for photosynthesis, which identified 303 candidate genes. Characterization of one of these genes, the conserved predicted phosphatase-encoding gene CPL3, showed that it is important for accumulation of multiple photosynthetic protein complexes. Notably, 21 of the 43 higher-confidence genes are novel, opening new opportunities for advances in understanding of this biogeochemically fundamental process. This library will accelerate the characterization of thousands of genes in algae, plants, and animals.
A major challenge in the development of anion exchange membranes for fuel cells is the design and synthesis of highly stable (chemically and mechanically) conducting membranes. Membranes that can ...endure highly alkaline environments while rapidly transporting hydroxides are desired. Herein, we present a design using cross-linked polymer membranes containing ionic highways along charge-delocalized pyrazolium cations and homoconjugated triptycenes. These ionic highway membranes show improved performance. Specifically, a conductivity of 111.6 mS cm–1 at 80 °C was obtained with a low 7.9% water uptake and 0.91 mmol g–1 ion exchange capacity. In contrast to existing materials, ionic highways produce higher conductivities at reduced hydration and ionic exchange capacities. The membranes retain more than 75% of their initial conductivity after 30 days of an alkaline stability test. The formation of ionic highways for ion transport is confirmed by density functional theory and Monte Carlo studies. A single cell with platinum metal catalysts at 80 °C showed a high peak density of 0.73 W cm–2 (0.45 W cm–2 from a silver-based cathode) and stable performance throughout 400 h tests.
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