Sediment microbial taxonomic and functional diversity in a natural salinity gradient challenge Remane’s “species minimum” concept

Several models have been developed for the description of diversity in estuaries and other brackish habitats, with the most recognized being Remane's Artenminimum (``species minimum'') concept. It was developed for the Baltic Sea, one of the world's largest semi-enclosed brackish water body with a unique permanent salinity gradient, and it argues that taxonomic diversity of macrobenthic organisms is lowest within the horohalinicum (5 to 8 psu). The aim of the present study was to investigate the relationship between salinity and sediment microbial diversity at a freshwater-marine transect in Amvrakikos Gulf (Ionian Sea, Western Greece) and assess whether species composition and community function follow a generalized concept such as Remane's. DNA was extracted from sediment samples from six stations along the aforementioned transect and sequenced for the 16S rRNA gene using high-throughput sequencing. The metabolic functions of the OTUs were predicted and the most abundant metabolic pathways were extracted. Key abiotic variables, i.e., salinity, temperature, chlorophyll-a and oxygen concentration etc., were measured and their relation with diversity and functional patterns was explored. Microbial communities were found to differ in the three habitats examined (river, lagoon and sea) with certain taxonomic groups being more abundant in the freshwater and less in the marine environment, and vice versa. Salinity was the environmental factor with the highest correlation to the microbial community pattern, while oxygen concentration was highly correlated to the metabolic functional pattern. The total number of OTUs showed a negative relationship with increasing salinity, thus the sediment microbial OTUs in this study area do not follow Remane's concept

Aristotle’s scientific contributions to the classification, nomenclature and distribution of marine organisms

The biological works of the Greek philosopher Aristotle include a significant amount of information on marine animals. This study is an overview of Aristotle’s scientific contribution to the knowledge of marine biodiversity and specifically to taxonomic classification, nomenclature and distribution of marine species. Our results show that Aristotle’s approach looks remarkably familiar to present day marine biologists since: (i) although not directly aiming at it, he gave a taxonomic classification of marine animals, which includes physical groups ranked on three levels at least; (ii) most of Aristotle’s marine “major groups” correspond to taxa of the order rank in Linnaeus’s classification and to taxa of the class rank in the current classification; (iii) a positive correlation was found between the number of taxa per group identified in Aristotle’s writings and those described by Linnaeus; (iv) Aristotle’s classification system exhibits similarities with the current one regarding the way taxa are distributed to higher categories; (v) a considerable number of Aristotle’s marine animal names have been used for the creation of the scientific names currently in use; (vi) he was the first to give an account of Mediterranean marine fauna, focusing on the Aegean Sea and adjacent areas. In view of the above, we suggest that the foundations of marine taxonomy as laid down by Aristotle are still echoing today

11^{11}B NMR study of pure and lightly carbon doped MgB2_2 superconductors

We report a $^{11}$B NMR line shape and spin-lattice relaxation rate ($1/(T_1T)$) study of pure and lightly carbon doped MgB$_{2-x}$C$_{x}$ for $x=0$, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB$_2$ exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase of $H_{c2}^c$ with carbon doping with respect to pure MgB$_2$. The spin-lattice relaxation rate $1/(T_1T)$ demonstrates clearly the presence of a coherence peak right below $T_c$ in pure MgB$_2$, followed by a typical BCS decrease on cooling. However, at temperatures lower than $\approx 10$K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon doped systems both the coherence peak and the BCS temperature dependence of $1/(T_1T)$ weaken, an effect attributed to the gradual shrinking of the $\sigma$ hole cylinders of the Fermi surface with electron doping.Comment: 8 pages, 6 figures, submitted to Phys. Rev.

Synthesis of monoclinic Celsian from coal fly ash by using a one-step solid-state reaction

Monoclinic (Celsian) and hexagonal (Hexacelsian) Ba1−xSrxAl2Si2O8 solid solutions, where x = 0, 0.25, 0.375, 0.5, 0.75 or 1, were synthesized by using Coal Fly Ash (CFA) as main raw material, employing a simple one-step solid-state reaction process involving thermal treatment for 5 h at 850–1300 °C. Fully monoclinic Celsian was obtained at 1200 °C/5 h, for SrO contents of 0.25 ≤ x ≤ 0.75. However, an optimum SrO level of 0.25 ≤ x ≤ 0.375 was recommended for the stabilization of Celsian. These synthesis conditions represent a significant improvement over the higher temperatures, longer times and/or multi-step processes needed to obtain fully monoclinic Celsian, when other raw materials are used for this purpose, according to previous literature. These results were attributed to the role of the chemical and phase constitution of CFA as well as to a likely mineralizing effect of CaO and TiO2 present in it, which enhanced the Hexacelsian to Celsian conversion

MarBEF, databases, and the legacy of John Gray

Within the European Network of Excellence (NoE) on Marine Biodiversity and Ecosystem Functioning (MarBEF), marine biodiversity scientists from across Europe have been brought together to focus on 3 broad themes. Theme 1 describes large-scale (and long-term) distribution patterns of marine biodiversity, Theme 2 examines the consequences of changes in marine biodiversity for the functioning of marine ecosystems, and Theme 3 explores and disseminates the socio-economic consequences of changes in marine biodiversity and biodiversity-mediated processes. Within MarBEF Theme 1, a large collaborative effort has produced an integrated database of species occurrence information (MacroBen), which contains data of quantitative samples of soft-sediment benthic infauna collected in European continental waters, from the Arctic to the Black Sea. Papers in this Theme Section describe initial studies based on the database. The late Prof. John S. Gray led activities within MarBEF Theme 1 for the first 2.5 yr, during which time the majority of the work described in this Theme Section was set in motion, and he continued to be involved in the work until his untimely death. We dedicate this body of work to his memory.

Genetic vs community diversity patterns of macrobenthic species: preliminary results from the lagoonal ecosystem

1 - The use of molecular data derived from multispecies assemblages in order to test ecological theory has only recently been introduced in the scientific literature.2 - As a first step, we compared patterns of abiotic environment, polychaeta distribution and their genetic diversity in five lagoon ecosystems in Greece. Our results confirm the hypothesis that higher genetic diversity is expected in the populations of the species occurring in the transitional waters rather than of those occurring in the marine environment.3 - Patterns derived from the polychaete community level and from the mitochondrial DNA (16S rRNA) obtained from Nephtys hombergii and Hediste diversicolor showed convergence, indicating the potential use of molecular matrices as surrogates in community analysis.4 - Finally, the high correlation between the genetic diversity pattern of H. diversicolor and the phosphorus concentration in the sediments may imply the broadening of the hierarchic-response-tostress hypothesis towards lower than species level

Elucidation of One Step Synthesis of PEGylated CuFe Bimetallic Nanoparticles. Antimicrobial Activity of CuFe@PEG vs Cu@PEG

There is a growing field of research on the physicochemical properties of bimetallic nanoparticles (BMNPs) and their potential use in different applications. Meanwhile, their antimicrobial activity is scarcely reported, although BMNPs can potentially achieve unique chemical transformations and synergetic effects can be presented. Towards this direction a reproducible simple hybrid polyol process under moderate temperature solvothermal conditions has been applied for the isolation of non-oxide contaminated bimetallic CuFe nanoparticles (NPs). 1,2-propylene glycol (PG), tetraethylene glycol (TEG) and polyethylene glycol (PEG 8000), that exhibit different physicochemical properties, have been utilized to regulate the size, structure, composition and the surface chemistry of NPs. The BMNPs were found to be of small crystalline size, 30–45 nm, and high hydrophilicity, different wt% percentage of organic coating and variable hydrodynamic size and surface charge. The antimicrobial activity of the BMNPs was evaluated against the bacterial strains B. subtilis, E. coli and fungus S. cerevisiae. The IC50 values for CuFe NPs were found significantly lower compared with Cu NPs of the same size, revealing an enhancement in the antimicrobial activity when iron and copper coexist in the crystal structure. The reactive oxygen species (ROS) production was measured intracellularly and extracellularly by the nitroblue tetrazolium assay in the fungal cultures. No extracellular ROS were measured suggesting that both CuFe and Cu NPs enter the fungal cells during the incubation, also verified by optical imaging of the fungal cells in the presence of NPs. Higher ROS concentrations were generated intracellularly for CuFe NPs supporting different red/ox reaction mechanisms

Data sharing tools adopted by the European Biodiversity Observation Network Project

A fundamental constituent of a biodiversity observation network is the technological infrastructure that underpins it. The European Biodiversity Network project (EU BON) has been working with and improving upon pre-existing tools for data mobilization, sharing and description. This paper provides conceptual and practical advice for the use of these tools. We review tools for managing metadata, occurrence data, and ecological data and give detailed description of these tools, their capabilities and limitations. This is followed by recommendations on their deployment and possible future enhancements. This is done from the perspective of the needs of the biodiversity observation community with a view to the development of a unified user interface to these data the European Biodiversity Portal (EBP). We described the steps taken to develop, adapt, deploy and test these tools. This document also gives an overview of the objectives that still need to be achieved and challenges to be addressed for the remainder of the project

Superconductivity: Exotic Commonalities in Phase and Mode

Recent muon and neutron experiments on the new FeAs-based superconductors revealed phase diagrams characterized by first-order evolution from antiferromagnetic to superconducting states, and an inelastic magnetic resonance mode whose energy scales as $\sim 4 k_{B}T_{c}$. These features exhibit striking commonalities with cuprate, backyball, organic, and heavy-fermion superconductors as well as superfluid $^{4}$He.Comment: 4 pages, 2 figures, original version of News and Views for Nature Materials submitted on Feb. 8, 2009; revised version will appear as Nature Materials 8 (April, 2009) 253-25