Superconducting spintronic tunnel diode.

Diodes are key elements for electronics, optics, and detection. Their evolution towards low dissipation electronics has seen the hybridization with superconductors and the realization of supercurrent diodes with zero resistance in only one direction. Here, we present the quasi-particle counterpart, a superconducting tunnel diode with zero conductance in only one direction.

Transcriptional response of Emiliania huxleyi under changing nutrient environments in the North Pacific Subtropical Gyre.

The widespread coccolithophore Emiliania huxleyi is an abundant oceanic phytoplankton, impacting the global cycling of carbon through both photosynthesis and calcification. Here, we examined the transcriptional responses of populations of E. huxleyi in the North Pacific Subtropical Gyre to shifts in the nutrient environment.

Transcriptional patterns identify resource controls on the diazotroph Trichodesmium in the Atlantic and Pacific oceans.

The N-fixing cyanobacterium Trichodesmium is intensely studied because of the control this organism exerts over the cycling of carbon and nitrogen in the low nutrient ocean gyres. Although iron (Fe) and phosphorus (P) bioavailability are thought to be major drivers of Trichodesmium distributions and activities, identifying resource controls on Trichodesmium is challenging, as Fe and P are often organically complexed and their bioavailability to a single species in a mixed community is difficult to constrain. Further, Fe and P geochemistries are linked through the activities of metalloenzymes, such as the alkaline phosphatases (APs) PhoX and PhoA, which are used by microbes to access dissolved organic P (DOP).

Magnetization reversal in circular vortex dots of small radius.

We present a detailed study of the magnetic behavior of Permalloy (NiFe alloy) circular nanodots with small radii (30 nm and 70 nm) and different thicknesses (30 nm or 50 nm). Despite the small size of the dots, the measured hysteresis loops manifestly display the features of classical vortex behavior with zero remanence and lobes at high magnetic fields. This is remarkable because the size of the magnetic vortex core is comparable to the dot diameter, as revealed by magnetic force microscopy and micromagnetic simulations.

Epibionts dominate metabolic functional potential of Trichodesmium colonies from the oligotrophic ocean.

Trichodesmium is a genus of marine diazotrophic colonial cyanobacteria that exerts a profound influence on global biogeochemistry, by injecting 'new' nitrogen into the low nutrient systems where it occurs. Colonies of Trichodesmium ubiquitously contain a diverse assemblage of epibiotic microorganisms, constituting a microbiome on the Trichodesmium host. Metagenome sequences from Trichodesmium colonies were analyzed along a resource gradient in the western North Atlantic to examine microbiome community structure, functional diversity and metabolic contributions to the holobiont.

Variable depth distribution of Trichodesmium clades in the North Pacific Ocean.

Populations of nitrogen-fixing cyanobacteria in the genus Trichodesmium are critical to ocean ecosystems, yet predicting patterns of Trichodesmium distribution and their role in ocean biogeochemistry is an ongoing challenge. This may, in part, be due to differences in the physiological ecology of Trichodesmium species, which are not typically considered independently in field studies. In this study, the abundance of the two dominant Trichodesmium clades (Clade I and Clade III) was investigated during a survey at Station ALOHA in the North Pacific Subtropical Gyre (NPSG) using a clade-specific qPCR approach.

Microbial diversity within the Trichodesmium holobiont.

Nitrogen-fixing cyanobacteria in the genus Trichodesmium play a critical role in the productivity of the tropical and subtropical oligotrophic oceans. The ecological success of these populations is likely associated with the diverse microbial interactions occurring within the Trichodesmium holobiont, especially between Trichodesmium and heterotrophic bacterial epibionts. Yet, the composition of the Trichodesmium holobiont and the processes governing microbial assemblage are not well documented.

High-yield fabrication of 60 nm Permalloy nanodiscs in well-defined magnetic vortex state for biomedical applications.

Permalloy disc structures in magnetic vortex state constitute a promising new type of magnetic nanoparticles for biomedical applications. They present high saturation magnetisation and lack of remanence, which ease the remote manipulation of the particles by magnetic fields and avoid the problem of agglomeration, respectively. Importantly, they are also endowed with the capability of low-frequency magneto-mechanical actuation.

Functional group-specific traits drive phytoplankton dynamics in the oligotrophic ocean.

A diverse microbial assemblage in the ocean is responsible for nearly half of global primary production. It has been hypothesized and experimentally demonstrated that nutrient loading can stimulate blooms of large eukaryotic phytoplankton in oligotrophic systems. Although central to balancing biogeochemical models, knowledge of the metabolic traits that govern the dynamics of these bloom-forming phytoplankton is limited.

Phosphorus cycling. Major role of planktonic phosphate reduction in the marine phosphorus redox cycle.

Phosphorus in the +5 oxidation state (i.e., phosphate) is the most abundant form of phosphorus in the global ocean.

The limit of the genetic adaptation to copper in freshwater phytoplankton.

Copper is one of the most frequently used algaecides to control blooms of toxic cyanobacteria in water supply reservoirs. Among the negative impacts derived from the use of this substance is the increasing resistance of cyanobacteria to copper toxicity, as well as changes in the community structure of native phytoplankton. Here, we used the ratchet protocol to investigate the differential evolution and maximum adaptation capacity of selected freshwater phytoplankton species to the exposure of increasing doses of copper.

The effect of nitrate and phosphate availability on Emiliania huxleyi (NZEH) physiology under different CO2 scenarios.

Growth and calcification of the marine coccolithophorid Emiliania huxleyi is affected by ocean acidification and macronutrients limitation and its response varies between strains. Here we investigated the physiological performance of a highly calcified E. huxleyi strain, NZEH, in a multiparametric experiment.

Effects of adaptation, chance, and history on the evolution of the toxic dinoflagellate Alexandrium minutum under selection of increased temperature and acidification.

The roles of adaptation, chance, and history on evolution of the toxic dinoflagellate Alexandrium minutum Halim, under selective conditions simulating global change, have been addressed. Two toxic strains (AL1V and AL2V), previously acclimated for two years at pH 8.0 and 20°C, were transferred to selective conditions: pH 7.

Adaptation of microalgae to lindane: a new approach for bioremediation.

Lindane is especially worrisome because its persistence in aquatic ecosystems, tendency to bioaccumulation and toxicity. We studied the adaptation of freshwater cyanobacteria and microalgae to resist lindane using an experimental model to distinguish if lindane-resistant cells had their origin in random spontaneous pre-selective mutations (which occur prior to the lindane exposure), or if lindane-resistant cells arose by a mechanism of physiological acclimation during the exposure to the selective agent. Although further research is needed to determine the different mechanisms contributing to the bio-elimination of lindane, this study, however, provides an approach to the bioremediation abilities of the lindane-resistant cells.

GENETIC ADAPTATION AND ACCLIMATION OF PHYTOPLANKTON ALONG A STRESS GRADIENT IN THE EXTREME WATERS OF THE AGRIO RIVER-CAVIAHUE LAKE (ARGENTINA)(1).

We tested if different adaptation strategies were linked to a stress gradient in phytoplankton cells. For this purpose, we studied the adaptation and acclimation of Dictyosphaerium chlorelloides (Naumann) Komárek et Perman (Chlorophyta) and Microcystis aeruginosa (Kütz.) Kütz.

Warming will affect phytoplankton differently: evidence through a mechanistic approach.

Although the consequences of global warming in aquatic ecosystems are only beginning to be revealed, a key to forecasting the impact on aquatic communities is an understanding of individual species' vulnerability to increased temperature. Despite their microscopic size, phytoplankton support about half of the global primary production, drive essential biogeochemical cycles and represent the basis of the aquatic food web. At present, it is known that phytoplankton are important targets and, consequently, harbingers of climate change in aquatic systems.

Evolutionary changes in growth rate and toxin production in the cyanobacterium Microcystis aeruginosa under a scenario of eutrophication and temperature increase.

Toxic blooms of the cyanobacterium Microcystis aeruginosa affect humans and animals in inland water systems worldwide, and it has been hypothesized that the development of these blooms will increase under the future scenario of global change, considering eutrophication and temperature increase as two important consequences. The importance of genetic adaptation, chance and history on evolution of growth rate, and toxin production of M. aeruginosa was studied under these new conditions.

Estimating the capability of different phytoplankton groups to adapt to contamination: herbicides will affect phytoplankton species differently.

• Investigating the differential capacity of the response of phytoplankton to human-induced environmental forcing has become a key issue to understanding further the future repercussions on the functioning of aquatic ecosystems. • The initial tolerance to the widely dispersed herbicide simazine was measured in diverse phytoplankton species. An experimental ratchet system maintaining large populations of dividing cells (which ensures the occurrence of rare spontaneous mutations that confer adaptation) and a strong selection pressure (which ensures the preservation of such mutations within the population) was later applied to estimate the capability of different groups of phytoplankton to adapt to simazine.

Adaptation of green microalgae to the herbicides simazine and diquat as result of pre-selective mutations.

Aquatic ecosystems located close to agricultural areas are increasingly polluted by herbicides. We evaluated the capacity for adaptation of green microalgae to lethal concentrations of the herbicide simazine in one strain of Dictyosphaerium chlorelloides and two strains of Scenedesmus intermedius, as well as adaptation to the herbicide diquat in one of the strains of S. intermedius.

Toxicity and adaptation of Dictyosphaerium chlorelloides to extreme chromium contamination.

Metals are often spilled by industries into inland water environments, with adverse consequences. Numerous papers have reported that heavy metals produce massive destruction of algae. Nevertheless, algal populations seem to become tolerant when they have had previous exposures to heavy metals.

Toxic effect and adaptation in Scenedesmus intermedius to anthropogenic chloramphenicol contamination: genetic versus physiological mechanisms to rapid acquisition of xenobiotic resistance.

Anthropogenic water pollution is producing a challenge to the survival of phytoplankton populations. From an ecological point of view, the tolerance of these microorganisms to water pollution is of paramount importance since they are the principal primary producers of aquatic ecosystems. The adaptation of a common chlorophyta species (Scenedesmus intermedius) exposed to selected dose-response chloramphenicol (CAP) concentrations has been analyzed.

Adaptation of the chlorophycean Dictyosphaerium chlorelloides to stressful acidic, mine metal-rich waters as result of pre-selective mutations.

Several species of microalgae, closely related to mesophilic lineages, inhabit the extreme environment (pH 2.5, high levels of metals) of the Spain's Aguas Agrias Stream water (AASW). Consequently, AASW constitutes an interesting natural laboratory for analysis of adaptation by microalgae to extremely stressful conditions.

Adaptation of phytoplankton to novel residual materials of water pollution: an experimental model analysing the evolution of an experimental microalgal population under formaldehyde contamination.

The adaptation mechanisms of microalgae to grow in contaminated waters were analysed using a chlorophyta species under formaldehyde exposure as experimental model. Cultures initially collapsed after exposure to 16 ppm formaldehyde, but occasionally resistant cells were able to grow after further incubation. Resistant cells arose by rare spontaneous mutations that appeared before the exposure to formaldehyde (mutation rate=3.