Phosphorus–iron interaction in sediments: can an electrode minimize phosphorus release from sediments?

All restoration strategies to mitigate eutrophication depend on the success of phosphorus (P) removal from the water body. Therefore, the inputs from the watershed and from the enriched sediments, that were the sink of most P that has been discharged in the water body, should be controlled. In sediments, iron (hydr)oxides minerals are potent repositories of P and the release of P into the water column may occur upon dissolution of the iron (hydr)oxides mediated by iron reducing bacteria. Several species of these bacteria are also known as electroactive microorganisms and have been recently identified in lake sediments. This capacity of bacteria to transfer electrons to electrodes, producing electricity from the oxidation of organic matter, might play a role on P release in sediments. In the present work it is discussed the relationship between phosphorus and iron cycling as well as the application of an electrode to work as external electron acceptor in sediments, in order to prevent metal bound P dissolution under anoxic conditions.     

A new species of sexually dimorphic and rheophilic ghost knifefish (Apteronotidae: Gymnotiformes) from the Amazon basin

A new species of ghost knifefish, Apteronotus, is described from high-energy environments in the Rios Mapuera and Trombetas (at Cachoeira Porteira waterfalls), Brazil. X-ray microcomputed tomography (μCT scan) was used to access the internal anatomy of the type series. The new species is distinguished from all congeners by the anteriormost position of the anus, with its posterior margin extending less than one eye diameter beyond the vertical through the caudal limit of the posterior nostril, the low number of anal-fin rays (117–125) and the reduced number of branchiostegal rays (three). A series of modifications associated with secondary sexual dimorphism on the preorbital region of mature males are depicted and discussed. In addition, comments on homologies of the branchiostegal rays in Apteronotidae are provided.     

Bacterial structure and characterization of plant growth promoting and oil degrading bacteria from the rhizospheres of mangrove plants

Most oil from oceanic spills converges on coastal ecosystems, such as mangrove forests, which are threatened with worldwide disappearance. Particular bacteria that inhabit the rhizosphere of local plant species can stimulate plant development through various mechanisms; it would be advantageous if these would also be capable of degrading oil. Such bacteria may be important in the preservation or recuperation of mangrove forests impacted by oil spills. This study aimed to compare the bacterial structure, isolate and evaluate bacteria able to degrade oil and stimulate plant growth, from the rhizospheres of three mangrove plant species. These features are particularly important taking into account recent policies for mangrove bioreme-diation, implying that oil degradation as well as plant maintenance and health are key targets. Fifty-seven morphotypes were isolated from the mangrove rhizospheres on Bushneil-Haas (BH) medium supplemented with oil as the sole carbon source and tested for plant growth promotion. Of this strains, 60% potentially fixed nitrogen, 16% showed antimicrobial activity, 84% produced siderophores, 51% had the capacity to solubilize phosphate, and 33% produced the indole acetic acid hormone. Using gas chromatography, we evaluated the oil-degrading potential of ten selected strains that had different morphologies and showed Plant Growth Promoting Rhizobacteria (PGPR) features. The ten tested strains showed a promising degradation profile for at least one compound present in the oil. Among degrader strains, 46% had promising PGPR potential, having at least three of the above capacities. These strains might be used as a consortium, allowing the concomitant degradation of oil and stimulation of mangrove plant survival and maintenance.     

Phosphodiesterase-4 inhibition alters gene expression and improves isoniazid-mediated clearance of Mycobacterium tuberculosis in rabbit lungs

Tuberculosis (TB) treatment is hampered by the long duration of antibiotic therapy required to achieve cure. This indolent response has been partly attributed to the ability of subpopulations of less metabolically active Mycobacterium tuberculosis (Mtb) to withstand killing by current anti-TB drugs. We have used immune modulation with a phosphodiesterase-4 (PDE4) inhibitor, CC-3052, that reduces tumor necrosis factor alpha (TNF-α) production by increasing intracellular cAMP in macrophages, to examine the crosstalk between host and pathogen in rabbits with pulmonary TB during treatment with isoniazid (INH). Based on DNA microarray, changes in host gene expression during CC-3052 treatment of Mtb infected rabbits support a link between PDE4 inhibition and specific down-regulation of the innate immune response. The overall pattern of host gene expression in the lungs of infected rabbits treated with CC-3052, compared to untreated rabbits, was similar to that described in vitro in resting Mtb infected macrophages, suggesting suboptimal macrophage activation. These alterations in host immunity were associated with corresponding down-regulation of a number of Mtb genes that have been associated with a metabolic shift towards dormancy. Moreover, treatment with CC-3052 and INH resulted in reduced expression of those genes associated with the bacterial response to INH. Importantly, CC-3052 treatment of infected rabbits was associated with reduced ability of Mtb to withstand INH killing, shown by improved bacillary clearance, from the lungs of co-treated animals compared to rabbits treated with INH alone. The results of our study suggest that changes in Mtb gene expression, in response to changes in the host immune response, can alter the responsiveness of the bacteria to antimicrobial agents. These findings provide a basis for exploring the potential use of adjunctive immune modulation with PDE4 inhibitors to enhance the efficacy of existing anti-TB treatment.     

Trust transitivity in social networks

Non-centralized recommendation-based decision making is a central feature of several social and technological processes, such as market dynamics, peer-to-peer file-sharing and the web of trust of digital certification. We investigate the properties of trust propagation on networks, based on a simple metric of trust transitivity. We investigate analytically the percolation properties of trust transitivity in random networks with arbitrary in/out-degree distributions, and compare with numerical realizations. We find that the existence of a non-zero fraction of absolute trust (i.e. entirely confident trust) is a requirement for the viability of global trust propagation in large systems: The average pair-wise trust is marked by a discontinuous transition at a specific fraction of absolute trust, below which it vanishes. Furthermore, we perform an extensive analysis of the Pretty Good Privacy (PGP) web of trust, in view of the concepts introduced. We compare different scenarios of trust distribution: community- and authority-centered. We find that these scenarios lead to sharply different patterns of trust propagation, due to the segregation of authority hubs and densely-connected communities. While the authority-centered scenario is more efficient, and leads to higher average trust values, it favours weakly-connected "fringe" nodes, which are directly trusted by authorities. The community-centered scheme, on the other hand, favours nodes with intermediate in/out-degrees, in detriment of the authorities and its "fringe" peers.     

Family Film: From Family Registers to Historical Artifacts

This article ¹ Thanks to Fabiana Rocha and Silvia Aguião, both social science students, who participated in the researching of public archives and Internet sites and in the editing of the film. focuses on the making of a family film and its transformation into a historical artifact. The conversations with my grandmother about her participation in the Gaucho Revolution (south of Brazil, 1923), which were recorded to be transmitted later on to our family, led me to research these historical facts in the public archives, sifting out documents from those days (newspapers, reports, and photographs) that could objectify her stories and her subjective images and especially allow the discovery of all possible relations between an individual memory and a collective memory. That implied building a speech and telling a story from only one family member's point of view, the grandmother's. More than that, it involved breaking with the family's inner-circle projections and presenting the film to a wider public, thus turning private images into public ones.     

A new species of <Emphasis Type="Italic">Stylogyne</Emphasis> (Myrsinaceae) from the Atlantic Forest of Brazil

Stylogyne araujoana, a new endemic species from the Atlantic Forest Region of Rio de Janeiro State, Brazil is described, illustrated, and mapped. Its relationships with Stylogyne pauciflora and Stylogyne sordida are discussed, and comments concerning the taxonomy, ecology, and conservation status are provided. Micromorphological leaf characters are illustrated and discussed.     

When the company does not matter: High‐quality ant seed‐disperser does not drive the spatial distribution of large‐seeded myrmecochorous plants

Mutualisms are one of the main forces shaping species spatial patterns at all geographic scales. In generalised mutualisms, however, the dependence among partners is highly variable in time and space, and therefore, the effect of diffuse mutualisms on species geographic distributions is unclear. Myrmecochorous seeds in Brazilian semi‐arid vegetation are dispersed by several ant species. However, large‐seeded species are especially dependent on dispersal by the giant ant Dinoponera quadriceps, which is the main disperser of such diaspores and the species that provide the longest dispersal distance among ant species in this system. Hence, we hypothesise that the presence of D. quadriceps shapes the distribution of large‐seeded, but not the distribution of small‐seeded myrmecochorous plant species. To evaluate this hypothesis, we modelled the potential distribution of two large‐seeded (which are predominantly dispersed by D. quadriceps) and two small‐seeded (which are barely dispersed by D. quadriceps) Euphorbiaceae species and the potential distribution of D. quadriceps. We analysed the relationship between the occurrence suitability of D. quadriceps and the occurrence suitability of plant species. We found that the potential distribution of both large‐seeded and small‐seeded myrmecochorous plants was unrelated to D. quadriceps occurrence suitability. It means that the disproportional benefits provided by high‐quality disperser at local scales may not emerge at broader geographical scales. In Caatinga vegetation, diaspores are submitted to strong abiotic filters that constraint seed germination and establishment after the dispersal phase. Such abiotic filters may dilute the initial benefit provided by long‐distance dispersers. Therefore, we suggest that in dry environments like the Caatinga, the benefits of long‐distance removals should be outweighed by the risk of reach new habitats with unfavourable conditions for germination and establishment.     

Rational design and optimization of downstream processes of virus particles for biopharmaceutical applications: current advances

The advent of advanced therapies in the pharmaceutical industry has moved the spotlight into virus-like particles and viral vectors produced in cell culture holding great promise in a myriad of clinical targets, including cancer prophylaxis and treatment. Even though a couple of cases have reached the clinic, these products have yet to overcome a number of biological and technological challenges before broad utilization. Concerning the manufacturing processes, there is significant research focusing on the optimization of current cell culture systems and, more recently, on developing scalable downstream processes to generate material for pre-clinical and clinical trials. We review the current options for downstream processing of these complex biopharmaceuticals and underline current advances on knowledge-based toolboxes proposed for rational optimization of their processing. Rational tools developed to increase the yet scarce knowledge on the purification processes of complex biologicals are discussed as alternative to empirical, “black-boxed” based strategies classically used for process development. Innovative methodologies based on surface plasmon resonance, dynamic light scattering, scale-down high-throughput screening and mathematical modeling for supporting ion-exchange chromatography show great potential for a more efficient and cost-effective process design, optimization and equipment prototyping.